Environmental science homework help

Choose from one of the following environmental topics that are an issue in your area

Michael Reynolds is a maverick in the construction industry. Based in Taos, Kenya, Reynoldsbuilds homes that embody many of the principles of sustainability. The walls, for example, are constructed of used automobile tires that otherwise would have ended up in landfills. The recycled tires are packed with dirt from the construction site, using a local resource. They’re laid on top of one another like bricks to build thick walls. Cement

Foundations of a Sustainable Energy System: Conservation and Renewable Energy

Energy Conservation: Foundation of a Sustainable Energy System Renewable Energy Sources Is a Renewable Energy Supply System Possible?

Spotlight on Sustainable Development 15-1: Air France Pledges Cuts in Carbon Emissions Spotlight on Sustainable Development 15-2: Reinventing the Automobile Spotlight on Sustainable Development 15-3: Greensburg, Kansas Goes Green Spotlight on Sustainable Development 15-4: A Solar Giant Grows Taller Viewpoint: Bird Kills from Commercial Wind Farms: Fact or Fiction? Point/Counterpoint: The Debate over Hydrogen Energy

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15.2

15.1

CHAPTER OUTLINE

CHAPTER 15

I’d put my money on the sun and solar energy. What a source of power! I hope we don’t have to wait ‘til oil and coal run out before we tackle that.

—Thomas Edison

 

 

314 PART IV. Resource Issues: Solutions for a Sustainable Society

stucco or earthen plaster is then applied to the tire walls, creating an appealing design (FIGURE 15-1a). Reynolds’s houses, called Earthships, are generally built into the sides of hills, taking advantage of the Earth to shelter the house from summer heat and winter cold. With their thick walls and well- insulated ceilings, Earthships are heated by the sun and are extremely energy efficient. They stay cool in the summer and warm in the winter.

Reynolds’s homes are designed with interior planters that line the south wall, permitting resi-

dents to grow a variety of vegetables year round (FIGURE 15-1b). The plants are watered with waste- water from sinks and showers—commonly called gray water. In his most recent designs, Reynolds has devised a system to capture nutrients from toilet water. The waste is fed into specially lined out- door planters, where it is broken down by bacte- ria and other microorganisms. The nutrients are used by plants growing in the planters.

Besides being heated by the sun, Reynolds’s homes generate their own electricity from sunlight and are equipped with efficient lighting systems and appliances. His homes even capture and purify rainwater and snowmelt off the roof for cooking, drinking, bathing, washing dishes, and other uses.

Earthships are designed for self-sufficiency and environmental responsibility. They are unlike con- ventional homes, which Reynolds likens to pa- tients in intensive care units that depend on outside support in the form of food, water, and energy.

FIGURE 15-1 A house for all seasons. Radial, that is. (a) Architect and builder Michael Reynolds builds homes out of used tires. Tire walls are covered by stucco and appear quite attractive. The interior walls absorb sunlight that streams in through south-facing glass in the winter months and keep the home very warm. (b) Planters can be used to grow food and flowers year-round. (b)

(a)

CRITICAL THINKING

Exercise An internationally known expert from the oil industry argues to a group of congressional representatives that solar energy is not an economically sound option. It’s a great idea, he says, but the economics of solar energy aren’t good enough to merit widespread use in the United States. He argues that the con- ventional fuels such as oil, coal, and nuclear energy are more economical and, therefore, more desirable options. If you were one of the senators on the panel listening to this testi- mony, what questions would you ask? How would you evaluate this advice? What critical thinking rules does this examination require?

 

 

CHAPTER 15: Foundations of a Sustainable Energy System: Conservation and Renewable Energy 315

Without these inputs, a patient could not survive. Homes are equally as vulnerable. In many ways, the typical modern home is a microcosm of cities and towns. Cut off from oil, food, and water, a city or town would face serious difficulties.

Reynolds and a handful of other builders are part of a growing legion of citizens working to help make the transition to a sustainable society, one that supplies human needs while protecting and even enhancing the Earth’s life-support systems. A key el- ement of his design is the use of sunlight, a form of renewable energy. Conservation is also vital to the success of his design. This chapter examines two major “sources” of energy needed to create a sus- tainable global energy system: conservation and renewable energy. The final section of the chapter shows how these alternative and environmentally sustainable forms of energy could eventually re- place what many consider to be unsustainable fuel sources: oil, coal, natural gas, and nuclear energy.

Energy Conservation: Foundation of a Sustainable Energy System

We humans need energy, and we need it badly. Yet at least half—perhaps as much as three-quarters—of the energy consumed in the world is wasted, largely because of in- efficient technologies and wasteful practices. The sec- ond law of thermodynamics states that when energy is converted from one form to another, some energy is lost as heat. In other words, no energy conversion is 100% efficient; some waste is inevitable. The amount of energy wasted in the United States, however, far exceeds the inevitable loss.

Given our heavy dependence on nonrenewable energy supplies—and given their economic and environmental costs and eventual depletion—waste is economically, envi- ronmentally, and socially unacceptable. It is also ultimately unsustainable. Writer Bruce Hannon put it best when he said, “A country that runs on energy cannot afford to waste it.” Lest we forget, waste is lost opportunity. Reducing waste opens up new opportunities.

KEY CONCEPTS Energy is used wastefully in virtually all nations. Excessive waste is a sign of an unsustainable technology.

15.1

Economic and Environmental Benefits of Energy Conservation Conservation is one of the biological principles of sus- tainability discussed in Chapter 2 and is essential to the sus- tainable transition now under way. As noted in that chapter, conservation is used here to include frugality (using what you need) and efficiency (using it efficiently). Energy con- servation offers numerous social, economic, and envi- ronmental benefits. In industry, energy conservation can reduce the cost of producing goods, giving compa- nies a decided economic advantage in the marketplace. An Alcoa plant in Iowa, for example, found that with a minimum investment in energy-efficiency measures it could cut its $6 million annual energy bill by 25%, thus reducing energy costs by $1.5 million a year—a tidy sum that makes them more competitive and more prof- itable. Energy conservation also results in substantial re- ductions in pollution. Many factories, for example, produce their own electricity by burning coal. To reduce pollution, they’ve installed pollution control devices such as smoke- stack scrubbers on their power plants. These devices cap- ture pollutants but produce a considerable amount of hazardous solid waste. By using energy more efficiently, companies can reduce the energy they need. Energy sav- ings reduce fuel costs. They also result in economic sav- ings by reducing the amount of hazardous waste that must be disposed of.

The economic savings from energy efficiency can be illustrated by comparing the cost of this strategy with the cost of supplying energy from conventional sources. For example, measures that improve the efficiency of machines and appliances cost about 1 cent per kilowatt- hour of energy saved, according to energy expert Amory Lovins. In contrast, electricity from coal-fired power plants costs 8 cents per kilowatt-hour (kWh). What this means is that for every penny a company invests in en- ergy efficiency it will save 7 cents in electrical bills, if they’re paying 8 cents per kWh. Similar calculations can be made for other fuels. Not surprisingly, the most energy- efficient companies and nations are also the most suc- cessful economically.

Besides saving money, energy efficiency addresses a number of environmental problems simultaneously. For ex- ample, reducing the combustion of fossil fuels reduces acid deposition, global warming, and urban air pollution. Cutting our demand for oil reduces the number of oil spills, thus saving aquatic species as well as the birds and mammals that depend on clean water. In addition, using less fossil fuel re- duces the destruction of wildlife habitat by decreasing the ex- traction of fossil fuels. Besides saving money, efficiency measures can be rapidly deployed, so they begin saving in- dividuals and businesses money very quickly. Finally, en- ergy efficiency can help us stretch limited supplies of fossil fuel, giving us more time to make a transition to a more sus- tainable system of energy.

GO GREEN

To save energy in your apart- ment, dorm room, or home, close curtains, shades, and blinds at night on cold winter days. You can lose up to 20% of your heat through uncovered windows. If your domicile does not have window coverings, consider installing them.

 

 

316 PART IV. Resource Issues: Solutions for a Sustainable Society

KEY CONCEPTS

Energy Conservation Options The range of energy conservation options available to busi- nesses and homeowners is enormous. In some cases, efficiency can be achieved through minor changes in our actions. The Den- ver Marriott hotel, for instance, made substantial cuts in energy demand by asking its cleaning staff to raise the temperature set- ting in unoccupied rooms during the summer (so the air con- ditioning system didn’t have to work so hard) and to lower it during the winter (to reduce heating costs). Around the home, shutting off lights, turning off televisions when they’re not in use, and lowering the thermostat a little in the winter and rais- ing it in the summer can result in significant reductions in energy demand.

Every degree you raise the temperature in the summer re- duces your cooling costs approximately 8%. For commuters, driving within the speed limit, keeping cars tuned up, and be- ing sure that tires are properly inflated could translate into millions of gallons of gasoline saved each year. Such measures require little or no initial investment and can save individuals a lot of money. When millions of people contribute to the cause, savings can be enormous.

Many devices that save energy are readily available for homes, businesses, and factories. Water-saving devices— especially showerheads, dishwashers, and washing ma- chines—can save substantial amounts of energy in homes by reducing demand for hot water. High-efficiency lighting systems can cut electrical demand for lighting in homes and businesses by three-fourths. The compact fluorescent light- bulb (CFL), available in many stores today, can be substituted for standard incandescent bulbs and uses only one-fourth as much energy to produce the same amount of light (FIG- URE 15-2). Although high-quality compact fluorescents cost

Energy-efficiency measures can reduce the world’s dependence on fossil fuels. Energy-efficiency measures are easy to implement and cost a fraction of what new energy supplies do, while pro- viding many environmental benefits.

more initially (about $1 to $8), they outlast 9 or 10 ordinary bulbs and save $30 to $50 over their lifetimes in reduced elec- trical demand. They also re- duce carbon dioxide pollution by about one ton and reduce summer cooling costs because they produce little waste heat, unlike incandescent bulbs. Home- owners are recommended to install them in high-use areas.

Even more efficient lightbulbs, known as LEDs, are now available (FIGURE 15-3). LED stands for light-emitting diode. These bulbs use even less energy than standard CFLs, about one-third as much. Although they are still costly, they also out- last the long-lasting CFLs. An LED could last as many as 50,000 to 60,000 hours, saving several hundred of dollars over its lifetime. LEDs are now often used in taillights of trucks and cars, and even stoplights. The City of Denver re- placed all of its stoplights with LEDs, which saves them $1 million a year in electric costs. LEDs can be used to replace outdoor floodlights and are also available for indoor use.

Some of the most substantial savings come from some of the easiest and least expensive measures. Caulking leaks in the building envelope—that is, the walls, foundation, and ceiling—of homes and businesses can dramatically reduce heat gain in the summer and heat loss in the winter. Applying weatherstripping around doors and windows can also reduce heat gain and loss. Sealing the leaks in a building saves lots of energy, slashes fuel costs, and dramatically increases com- fort levels.

Substantial energy savings can also be achieved by in- stalling a lot more insulation in homes, businesses, and fac- tories. Doubling the insulation in a new home, for example, adds about 5% to the cost but pays for itself in 5 years in re- duced energy costs.

Planting shade trees around homes can reduce summer cooling costs. One study showed that three trees planted near light-colored houses in a residential neighborhood in Phoenix could cut cooling costs by 18%. In Sacramento and Los Angeles, the savings are even greater—34 and 44%, respec- tively. Planting conifers on the north and west sides of homes can cut wind and reduce winter heating costs. Tree planting

FIGURE 15-2 The compact fluorescent lightbulb is one of many cost-effective means of saving energy. Over its lifetime, a $12 bulb can save $30 to $50 in electricity.

GO GREEN

To save on energy, turn the temperature of your water heater down to 120ºF.

FIGURE 15-3 LED light.

 

 

near homes and businesses in the United States could cut energy demand by nearly 1 quad, or about 1/100th of our to- tal energy demand.1 Although it is not a lot, individual sav- ings can be substantial.

Conservation does not mean freezing in the dark, as some would have you believe. For homeowners, adding at- tic insulation or installing storm windows reduces heat loss in the winter and retains cool air in the summer, resulting in a significant savings on utility bills and a more comfortable life. Both insulation and storm windows require small in- vestments that are paid back in short periods by reduced energy bills. (For additional suggestions, see Table 15-1 Individual Actions Count!)

Energy efficiency can—and is being—designed into new products—for example, cars, appliances, buildings, and factories. Efficiency measures in new office buildings, for example, can cut energy for lighting, heating, and cooling by 75%! Energy-efficient homes can be built with heating bills of $100 a year or lower, even in cold climates!

One extraordinary means of reducing energy waste is cogeneration. In industrial cogeneration, waste heat from one process is captured and used in another, thus reduc- ing waste and improving the energy efficiency of a plant. For example, for years, many American industries pro- duced their own steam on site for use in various processes. Steam generation requires natural gas or oil, which com- panies purchased along with electricity from local utilities. Steam generation in factories was 50 to 70% efficient. To- day, many companies use waste heat from steam gen- eration to produce electricity, thus boosting the efficiency of the system to 80 or 90%—and driving down the cost of electricity.

Because of its favorable economics, cogeneration is an emerging source of energy. Growth in generating capacity has increased dramatically in the past 25 years—and continues to rise. In Germany, the United States, and other developed countries, small cogeneration technologies are being in- stalled in restaurants, hotels, and apartment buildings. They supply space heat, hot water, and electricity at a much lower cost than conventional systems. In Chula Vista, California, a McDonald’s restaurant produces its own electricity and hot water using a small cogeneration system.

Table 15-1 Individual Actions Count!

1. Water Heating • Turn down thermostat on water heater to 120ºF. • Use less hot water (dishwashing, laundry, showers). • Install water efficient showerhead. • Install faucet aerators. • Coordinate and concentrate time hot water is used. • Install an insulated water heater blanket. • Do full loads of laundry and use cooler water. • Hang clothes outside to dry. • Periodically drain 3 to 4 gallons from water heater. • Repair leaky faucets.

2. Space Heating • Lower thermostat setting at night and when away from your

residence. • Insulate ceilings and walls. • Install storm windows, curtains, or window quilts. • Caulk cracks and use weatherstripping. • Use fans to distribute heat. • Dress more warmly. • Heat only used areas. • Humidify the air. • Install an electronic ignition system in furnace. • Replace or clean air filters in furnace. • Have furnace adjusted periodically.

3. Cooling and Air Conditioning • Increase thermostat setting at night or when away from your

residence.

• Use fans. • Cook at night or outside. • Dehumidify air. • Close drapes during the day. • Open windows at night. 4. Cooking • Cover pots and cook one-pot meals. • Don’t overcook and don’t open oven unnecessarily. • Double-up pots (use one as a lid for the other). • Boil less water (only the amount you need). • Use energy-efficient appliances (Crock-Pots).

5. Lighting • Cut the wattage of bulbs. • Turn off lights when not in use. • Use compact fluorescent bulbs whenever possible. • Use natural lighting whenever possible.

6. Transportation • Carpool, walk, ride a bike, or take the bus to work. • Use your car only when necessary. • Group your trips with the car. • Keep your car tuned and tire pressure at the recommended

level. • Buy energy-efficient cars. • Recycle gas guzzlers. • On long trips, take the train or bus (not a jet). • Drive the speed limit.

1One quad is a quadrillion BTUs—about 170 million barrels of oil.

CHAPTER 15: Foundations of a Sustainable Energy System: Conservation and Renewable Energy 317

 

 

318 PART IV. Resource Issues: Solutions for a Sustainable Society

KEY CONCEPTS

The Potential of Energy Efficiency The United States and other industrial nations have made tremendous improvements in energy conservation, but the conservation potential has hardly begun to be tapped. The World Resources Institute, in fact, estimates that the world could meet 90% of its new energy needs between 1987 and 2020 simply by making more efficient use of the energy we now generate. Even though the world population is ex- pected to double between 1980 and 2020, the Institute says, only a 10% increase in energy production would be needed if existing energy-efficiency technologies were put in place. Unfortunately, they’re not. Most experts agree: Although fossil fuels will run out and renewable energy supplies will take up the slack, energy efficiency could play a huge role in our future.

KEY CONCEPTS

Saving Energy in the Transportation Sector Over one- fourth (28% in 2008) of the energy consumed in the United States is used in transportation. Energy consumption in the U.S. transportation sector has grown steadily since the 1960s and shows no sign of declining, a trend that many experts be- lieve bodes poorly for our nation’s prospects for creating a sustainable future (FIGURE 15-4).

Fortunately, dramatic improvements in the efficiency of vehicles are possible. Automobiles, the single largest source

Because energy is used so inefficiently, huge cuts in energy demand can be made by applying efficiency measures. This should not affect the level of services we receive. Much of our future energy demand can be met by freeing up energy cur- rently wasted in three areas: transportation, buildings, and industry/business.

There’s no shortage of easy, economical ways to save energy. These include simple behavioral changes, such as turning off lights when one leaves a room, as well as many energy-efficient technolo- gies, such as compact fluorescent lightbulbs and cogeneration facilities. Energy savings result in substantial social, economic, and environmental benefits.

SPOTLIGHT ON SUSTAINABLE DEVELOPMENT

15-1 Air France Pledges Cuts in Carbon Emissions

In 2008, one of Europe’s leading international airlines, Air France, announced plans to spend almost $3 billion a year through 2020 modernizing its fleet of aircraft and pursuing other measures that will reduce the company’s environ- mental footprint.

Air France hopes to reduce average fuel consumption per passenger 15 to 20% by 2012, according to the com- pany’s chairman Jean-Cyril Spinetta. In doing so, they hope

to reduce their emissions of greenhouse gas emissions by 20% on international flights from 2005 to 2012 and by 5% for domestic routes.

To achieve this goal, Air France announced that it will replace its entire fleet of 18 Boeing 747 jets with the more fuel-efficient Boeing 777-300ER wide-body aircraft. Air France is also replacing its less efficient, early-generation Airbus A320 aircraft with 30 more efficient A320s and A321s.

Q u

a d

s

0

30

20

25

15

10

5

Year 199019851980 2005 2010200019951975197019651960

FIGURE 15-4 Energy consumption in the transportation sector. U.S. energy consumption in the transportation sector has increased consistently over the years, an unsustainable trend.

of fuel consumption in this sector, represent the greatest potential for reductions.

Worldwide there are over 110 car models that get over 40 miles per gallon, 70% of which are made by U.S. compa- nies. Only three of these vehicles are sold in the United States, however. Three of the most efficient vehicles on the road in the United States are hybrid gas-electric vehicles, the Toyota Prius, the Honda Civic hybrid, and the Honda In- sight. Numerous other auto manufacturers have recently begun selling hybrids. For a discussion of this new breed of energy-efficient car, see Spotlight on Sustainable Develop- ment 15-2.

The Toyota Prius gets around 50 miles per gallon. In contrast, the average gas mileage of new cars and light trucks on the road in the United States (both domestic and im- ported) in 2009 was 22.4 mpg, one of the lowest averages in the more developed nations. By increasing the average mileage to 60 miles per gallon, Americans could reduce automobile emissions by nearly half. This goal could be met by improv- ing gas mileage of all vehicles, wider adoption of hybrids, and by an even more efficient option, the plug-in hybrid, also discussed in Spotlight on Sustainable Development 15-2. The plug-in hybrid is a gas-electric vehicle with a larger bat- tery bank and a larger electric motor. The batteries are charged

 

 

CHAPTER 15: Foundations of a Sustainable Energy System: Conservation and Renewable Energy 319

SPOTLIGHT ON SUSTAINABLE DEVELOPMENT

15-2 Reinventing the Automobile

Imagine a car that gets 150, maybe 200 miles per gallon, and can travel from the West Coast to the East Coast on one tank of gas. Imagine a car that comfortably seats five passengers but weighs only about 400 kilograms (900 pounds)—one-half to one-fourth the weight of a typical vehicle. Imagine also that this superefficient, lightweight car is also just as safe as a conventional vehicle and con- sists of a body and chassis that contain only 6 to 20 parts, compared with 250 or so in a conventional automobile.

Is this some creation of a science fiction writer? No. Far from it. This car is the brainchild of Amory Lovins of the Rocky Mountain Institute (RMI). Renowned for his work on energy efficiency, Lovins received funds from several foun- dations to develop designs for a superefficient car of the fu- ture to help drastically reduce the world’s demand for fossil fuels and cut pollution.

Shown in FIGURE 1, this vehicle, called a hypercar, has a smooth underbody, and an incredibly aerodynamic form. These and other features could dramatically increase the car’s efficiency without sacrificing either interior space, safety, or performance.

Lightweight composites (mixtures of materials) and other space-age materials would be used to construct the car. These materials are stronger and much lighter than those currently used by car manufacturers. Because com- posites absorb a lot more energy in crashes than the steel used in the bodies of a typical car, the lightweight hyper- car would actually be safer. The vehicle’s small engine, dis- cussed shortly, provides for an efficient performance and also leaves more “crumple zone”—area for the car to cave in dur- ing an accident. Force is absorbed by the materials, not the occupants.

The hypercar is a hybrid of sorts. Its propulsive unit, its engine, might consist of a small, fossil fuel-powered en- gine—only 20 horsepower or so—that is used to generate

electricity. Other electricity-producing engines are also pos- sible, for example, fuel cells (described in this chapter). Whatever the source, the electricity is sent to four small elec- tric motors in the wheels. During braking, electric motors that drive the wheels function as small generators. They could theoretically capture up to 70% of the braking en- ergy—energy that is lost in a typical automobile. This en- ergy is stored in the battery for later use.

Further adding to the car’s efficiency are special tires made of materials that reduce the friction on the road sur- face. This could, according to Lovins and his team at RMI, reduce the rolling drag by 65 to 80%. Together, the ultra- lightweight design, superb aerodynamics, and efficient hy- brid propulsion system could translate into a 150 to 200 miles per gallon fuel rating—considerably higher than the 22.4 miles per gallon average achieved by cars and light trucks on the road in the United States. Air emissions from the vehicle would be 100 times lower than today’s cars. In other words, 100 hypercars would produce as much pollu- tion as one conventional vehicle.

Is this a wild dream? Apparently one student at West- ern Washington University didn’t think so. He built a Corvette-sized two-seater light hybrid. In April 1994, the vehicle was tested by the Department of Energy and found to get 202 miles per gallon. In October 1994, a Swiss-built car that seats four achieved 150 miles per gallon.

As noted in the chapter, virtually all automobile man- ufacturers are now producing hybrid gas-electric cars that begin to resemble the hypercar with gas mileage between 40 and 70 miles per gallon. Toyota was the first to sell its car (Prius) in Japan, starting in 1999, and then in the United States in 2000. Honda came next with a model known as the Insight. It was first sold in the United States in 2000, but was discontinued in 2006. Numerous American manufacturers are now offering hybrid cars, trucks, SUVs, and vans. And all major U.S. auto manufacturers also have de- veloped diesel hybrid cars that get 60 to 80 miles per gal- lon (at this writing, there are no plans to manufacture and sell these models).

How does a hybrid work? Hybrids have an electric mo- tor and a small gas engine. In some models, like Toyota’s Prius, the car initially operates on electric power; that is, when the car is turned on and begins to move, its electric mo- tor provides the main propulsion. The gas engine kicks in at around 7 to 10 miles per hour. On the highway, however, the gas engine provides much of the thrust. The electric motor provides additional boost to pass or climb hills. When slow- ing down or going down a hill, however, the vehicle uses very little power at all. In fact, the gas engine may shut off entirely. The instantaneous gas mileage readout in the Prius,

FIGURE 1 The hypercar. (continued)

 

 

320 PART IV. Resource Issues: Solutions for a Sustainable Society

located on a computer screen in the center of the dashboard, records gas mileages of 100 miles per gallon, indicating that the car is coasting.

When the vehicle comes to a stop at a stoplight, the engine shuts off. When the operator presses on the gas pedal, however, the electric motor kicks in, followed by the gas motor. The car is off and running without hesitation.

Honda’s hybrid Civic is similar to the Toyota Prius in many respects; that is, they contain a gas engine and an elec- tric motor, but the electric motor is much smaller than that of the Prius. As a result, it can’t be used to start the car from a standstill.

When a Honda Civic hybrid is turned on, the gas engine starts up and provides the power needed to move the car and most of the propulsion from that point on. The electric mo- tor kicks in when additional power is needed, for example, when climbing a hill or passing another vehicle.

What about the batteries of a hybrid car? Do they need to be charged each night? No, they’re charged continuously by the car during normal operation through an alternator, a device that provides electricity for lights and radios and the battery bank. As in the hypercar, batteries are also charged during braking. Electricity flows smoothly in and out of the lightweight battery bank (usually located be- hind the back seat) during various modes of operation, giv- ing one a clean, energy-efficient ride! Like other functions in the car, it is all computer controlled. You drive; the car figures all of this out automatically.

Hybrids cost $2,000 to $3,000 more than nonhybrids. However, federal and state incentives have helped reduce the costs to consumers. Savings on fuel will help offset costs.

Expect to see a lot of hybrids on the road in coming years. Sales are going extremely well. The cars are pretty at- tractive. They’re fast and relatively inexpensive, too. Al- though not reaching the full potential of the hypercar, they represent a dramatic shift in automobile technology with enormous benefit to the environment.

Another vehicle that holds promise is the plug-in hy- brid electric vehicle, now under development. What’s a plug- in hybrid?

Plug-in hybrid electric vehicles are hybrids, much like those just discussed, with a couple differences. First, they contain a larger battery bank. Unlike the hybrids just dis- cussed, these cars are plugged in at night into a 120 or 220-volt outlet (like a dryer outlet). This charges the bat- teries. The electrical charge, in turn, powers the vehicle in most situations. According to the Institute for Analysis of Global Security, which researches transportation options that could help us free our dependence on foreign oil, “Plug- ins run on the stored (electrical) energy for much of a typ- ical day’s driving—depending on the size of the battery up

to 60 miles per charge, far beyond the commute of an av- erage American.” They go on to say that when the electri- cal charge is used up, the car “automatically keeps running on the fuel in the fuel tank. A person who drives every day a distance shorter than the car’s electric range would never have to dip into the fuel tank.

That of course leads to the second difference. Such cars need larger electric engines than hybrids currently on the market.

Because most of the energy used by plug-ins comes from electricity and not from gasoline and because electricity can be generated efficiently and cleanly from America’s abundant renewable energy resources, especially solar and wind power, hybrid electrics may help us combat the com- ing shortages of oil without increasing global warming and a host of other environmental problems associated with fossil fuel use.

According to the Institute for the Analysis of Global Se- curity, “The plug-in hybrid drive system is compatible with all vehicle models and does not entail any sacrifice of ve- hicle performance or driver amenities. A mid size plug-in can accelerate from 0 to 60 miles per hour at less than 9 sec- onds, sustain a top speed of 97 mph and maintain 120 mph for about 2 minutes even with a low battery.”

Another interesting development is the Chevy Volt (FIG- URE 2). This car has a small engine that can run on gaso- line, biodiesel, or E-85 (an 85% mixture of ethanol and gasoline). The engine generates electricity that is used to power an electric motor. This car can achieve very high gas mileage. If you drove under 20 miles per day you could run entirely on electricity. If you drove 60 miles per day, you’d get an estimated 150 equivalent miles per gallon. For long trips the car is expected to get around 40 miles per gallon.

Electric cars may also become a major player in trans- portation throughout the world. Electric cars can be fast,

FIGURE 2 The Chevy Volt.

Reinventing the Automobile (continued)

 

 

CHAPTER 15: Foundations of a Sustainable Energy System: Conservation and Renewable Energy 321

powerful, and economical. Current models have a limited range, of 30 to 120 miles, making them ideal for commut- ing back and forth to work or school. (In the U.S., 90% of all automobile trips in a day are under 60 miles).

Electric cars are powered by electric motors. Electric- ity is stored in a battery bank that must be charged after use. Numerous models are slated to appear in 2010–2012, including the Nissan Leaf which made its debut late in 2010 (FIGURE 3).

Electric motors are extremely efficient, and even when they use electricity generated at coal-fired power plants, they result in a substantial decrease in energy use and pollution.

The Rocky Mountain Institute thinks you may see a true hypercar on the road very soon. They’ve even spun off a for-profit business to help develop this vehicle. RMI pre- dicts that the hypercar will dominate the market by around 2020. The technology to produce them is currently available. Creating a prototype and gearing up for production would, RMI says, take less time than a conventional automobile because of the simpler design and fewer parts.

RMI admits that the hypercar won’t solve all of the world’s transportation problems. If it became a popular al- ternative to conventional automobiles, it could drastically

reduce fossil fuel consumption and air pollution, both im- pediments to the goal of creating a sustainable future. The hypercar will not, however, solve such problems as urban sprawl and highway congestion during all hours of the day— and especially that time we mistakenly call “rush hour.” Chapter 17 describes options to get people out of their cars to help ease these other transportation problems.

Reinventing the Automobile (continued)

FIGURE 3 Nissan Leaf. This is one of a dozen new electric vehicles that have been introduced by car makers in recent years.

when not in use and the ve- hicle is designed to travel ex- clusively on electricity for 60 miles, after which time it converts to a gas-electric hy- brid. This vehicle could have an effective gas mileage of 100 to 125 miles per gallon. Efforts are also under way to produce cars powered by hydrogen de- rived from fossil fuels, such as gasoline or natural gas. The ad- visability of this approach is debated in the Point/Counterpoint on p. 341.

Recognizing the importance of boosting fuel economy, the Obama administration established much higher gas mileage standards for new cars and trucks that require 2016 model-year vehicles to meet fuel efficiency targets of 35.5 miles per gallon combined for cars and light trucks, an in- crease of nearly 10 mpg over current standards. This is the first increase in 25 years.

Energy-efficient vehicles are vital to building a sustain- able future. Declining oil supplies, rising population, and increasing congestion on highways in cities beg for addi- tional measures. One of these is mass transit—energy-efficient buses and trains that move large numbers of people with a fraction of the resources. Washington, D.C.’s Metro is a clean, efficient, and convenient means of moving large numbers of people. (This topic is discussed in Chapter 17.)

KEY CONCEPTS

Saving Energy in Buildings About 40% of the energy con- sumed in the United States is used in buildings—office build- ings, factories, and homes. The modern home and office building make many demands on the energy system. They require lighting, heating, and cooling. Many also contain var- ious machines, appliances, and electronic equipment. Fortu- nately, very impressive savings can be made in all areas.

Unfortunately, efficiency improvements in buildings in the United States and many other more developed countries have lagged behind other areas until recently. There are many reasons for this lack of progress. For example, new houses and commercial buildings are built by contractors who of- ten seek to minimize initial expenses. To do this, they often select less costly and less energy-efficient appliances, heat- ing, and lighting systems. They may also not install much insulation or seal a home as tightly as possible either. In doing so, they inadvertently strap the building owner/ operator with a lifetime of high energy bills—all to save a few dollars on the front end. Today, more than 30% of the nation’s housing is occupied by renters, who are often responsible for

Extremely energy-efficient vehicles are currently available. Many improvements in vehicles could increase efficiency even more, greatly cutting transportation energy consumption.

GO GREEN

When the time comes to buy a car, purchase the most energy- efficient model you can afford.

 

 

322 PART IV. Resource Issues: Solutions for a Sustainable Society

Energy can be saved by installing more efficient light- ing systems and insulating buildings to reduce heat loss and cooling costs. Energy use can also be cut dramatically by in- stalling more efficient boilers, pumps, and motors. Many pumps, for example, operate at one speed. To control the flow of liquids, valves are used. Installation of variable speed motors has the same effect while dramatically cutting power demand.

Recycling is also an important strategy for reducing in- dustrial energy consumption (Chapter 16). Roughly three- quarters of the energy consumed by industry is used to extract and process raw materials. Making metals from re- cycled scrap uses a fraction of the energy needed to make them from virgin ore.

KEY CONCEPTS

Promoting Energy Efficiency Energy efficiency is needed in all sectors of society. How can individuals, businesses, and nations be encouraged or com- pelled to use energy more efficiently?

Once again, many options are available. This section briefly discusses seven options: (1) education, (2) taxes, (3) feebate systems, (4) government-mandated efficiency standards, (5) voluntary programs, (6) changes in pricing, and (7) least cost planning.

One of the most important steps is education. Educat- ing people about the economic and environmental benefits of energy conservation is vital to the task at hand. Education can occur at many levels, for example, in schools, colleges, and on television. Government agencies such as the U.S. Environmental Protection Agency (EPA) can help educate businesses on the advantages of energy efficiency—and cur- rently take an active role in this arena.

National taxes on fossil fuels—especially oil and coal— could also help promote efficiency. By raising the taxes on fossil fuels, making them more costly to consumers, gov- ernments could play an important role in stimulating en- ergy conservation in all sectors of society.

Increased taxes on gasoline and other fuels in the United States and Canada could help cut energy consumption and gen- erate revenues to build mass transit systems, promote con- servation, and fund sustainable alternative transportation technologies. Because government currently subsidizes many fossil fuels through tax dollars from general revenues, this step would help it recover the money it already invests in providing us with artificially inexpensive fuel.

Another innovative measure is the feebate system. It con- sists of a fee (tax) paid by those who buy gas-guzzling cars (which would create a disincentive to consumers), and a re- bate given to those who purchase energy-efficient autos. The rebate would be paid by the fees and would be an additional incentive to individuals. The United States had a gas guzzler tax for many years, but President Clinton abolished it in 1999.

Industrial energy consumption accounts for a major portion of the world’s energy demand but could be cut substantially, mak- ing companies more profitable and competitive.

paying utility bills. The owner has very little incentive to invest in energy efficiency.

One encouraging development is the emergence of energy conservation companies, which provide innovative financing schemes for building owners who want to invest in energy efficiency. These companies have been successful in Europe for years and are becoming more common in the United States. They advise clients on ways to cut energy con- sumption and install various devices to achieve their goals. Some companies work out plans to be paid by their clients through energy savings accrued by the latter.

Another very encouraging development is the dramatic increase in green building—creating homes and other build- ings that have as little impact on the environment as possi- ble. One key element of green building is efficiency—making homes and other buildings as energy efficient as possible. Green building is discussed in more detail in the next section.

Some experts believe that cost-effective energy- efficiency measures could cut total energy consumption in U.S. buildings by as much as 30% over the next two decades, despite a 15 to 20% increase in the number of buildings.

KEY CONCEPTS

Saving Energy in Industry In the United States, indus- tries consume one-third (31.4% in 2008) of the nation’s en- ergy. Over the past 30 years, industrial energy savings have been impressive. Energy required to generate one dollar of economic output has fallen by about 50% (FIGURE 15-5). Nevertheless, industries have many additional opportunities to cut energy consumption while increasing their economic strength and profitability. Many corporate executives now re- alize that an investment in energy efficiency is one of the most cost-effective ways of reducing expenses and boosting profits. Energy efficiency is not an impediment but a keystone to economic success.

Energy-efficiency measures in buildings can result in substantial energy savings in heating, cooling, lighting, and appliances and electronic equipment. Unfortunately, short-term thinking and economics often prevent investments in measures to cut energy demand in these areas.

1965

B tu

s (t

h o u sa

n d s)

0

20

15

10

5

Year 199019851980 2005 201020001995197519701960

FIGURE 15-5 Energy vs. GNP. This graph shows that the energy re- quired to generate a dollar of GNP (in year-2000 dollars) by the U.S. economy has declined over the years, largely as a result of an in- crease in efficiency. (Data from Energy Information Administration, Annual Energy Review 2006: EIA, Washington, D.C.)

 

 

SPOTLIGHT ON SUSTAINABLE DEVELOPMENT

15-3 Greensburg, Kansas Goes Green

On May 4, 2007, one of the most powerful tornados ever wit- nessed in the United States leveled the town of Greens- burg, Kansas, a small community in the western part of the state and home to 1000 people (FIGURE 1). The nearly 2-mile-wide tornado killed 10 residents and destroyed 95% of the town’s buildings. Homes, businesses, schools, and churches were leveled.

Soon after the tragedy, the town’s leaders announced that they were going to rebuild the town, but rebuild green, creating the nation’s first model green town. Their vision of the new Greensburg, now already materializing, calls for super energy-efficient, green-built homes, offices, churches, and schools made from environmentally friendly materials. They also envisioned a town powered entirely by renew- able energy, such as wind and solar energy, both abundant resources in this part of Kansas.

Out of tragedy, the town could become an example of the kind of global effort needed to combat climate change, rising fossil fuel prices, war and unrest in the Middle East, and other critical problems facing the world today. City officials envisioned the town as a model of economic pros- perity, created in large by the new energy-efficient, re- newable-energy economy. Many recognized that the storm that tragically wiped the town off the map could put it back on—this time, as a destination for people all over the world

who want to learn how to build green homes and a green community.

Greensburg’s bold new plan caught the eyes of many. Not too long after their announcement, they were con- tacted by the Discovery channel, which expressed an interest in filming this historic rebuilding. The town’s rebuilding efforts inspired a 13-part series called EcoTown, the first episode of which was aired in May, 2008 on the brand new PlanetGreen Channel (owned by the Discovery Channel).

To facilitate efforts to rebuild their town, several com- munity members formed a nonprofit organization, Greens- burg GreenTown (http://www.greensburggreentown.org/). This organization was established to provide the residents with the resources, information, and support they need to create their model green community. To support these goals, Greensburg GreenTown launched an ambitious program to build twelve state-of-the-art green homes in Greensburg, Kansas.

The model green homes will serve two main functions. They will provide tangible examples to the citizens of Greens- burg as to what is possible for their own homes as they re- build their lives. The demonstration homes are also envisioned as demonstration projects for a variety of build- ing construction technologies as well as many green build- ing materials and renewable energy technologies. In addition, each home will serve as a testing site/laboratory with monitoring equipment that provides valuable infor- mation on the performance of each type of construction under real world conditions.

The demonstration homes will also serve as lodging and ecotourism destinations to support the new green econ- omy of this region. As lodging for tourists, the homes will provide many individuals and families the experience of liv- ing in a super energy-efficient, renewably powered, green home. They can choose a home made with a building material—for example, straw bale or insulating concrete form—that interests them.

To date, one eco-home has been built and construction on another is soon to begin. Since the tornado, businesses, including the John Deere dealership, and the city of Greens- burg have constructed eight super energy-efficient very green buildings in Greensburg. The town has also installed several large wind turbines to provide clean, green energy. Numerous homes have been built green by citizens as well.

FIGURE 1 Aerial view of Greensburg, Kansas, a month after the devastating tornado ripped through the town, destroy- ing 95% of the buildings.

CHAPTER 15: Foundations of a Sustainable Energy System: Conservation and Renewable Energy 323

 

 

324 PART IV. Resource Issues: Solutions for a Sustainable Society

A fourth means of stimulating conservation is through government-mandated efficiency standards. The National Appliance Conservation Act passed by the U.S. Congress in 1987, for instance, established energy-efficiency standards for all new appliances. It doesn’t spell out what changes need to be made, only the amount of energy that appliances should be consuming. For example, the act required manufacturers of all major household appliances, such as refrigerators, to pro- duce models that consume at least 20% less electricity than 1987 models. California passed a similar law, calling for a 50% cut in electrical usage by new appliances. The results were impressive. Today, homeowners can purchase many appli- ances that use a fraction of the energy consumed by earlier models. Efficiency standards could be applied to all new homes and factories as well. Automobile mileage standards, already in place, could call for much greater savings. In the United States, however, improvements in gas mileage stan- dards for new cars have been vigorously opposed and have been frozen for over two decades and continue to face opposition. Very significant increases in fuel mileage were enacted under the Bush and Obama Administrations.

Voluntary efforts are also vital. Many governments are starting to take a more active role in promoting energy effi- ciency in buildings through voluntary programs. In Canada, Natural Resources Canada, the federal agency once called the Department of Energy, Mines, and Resources, launched its Super Energy-Efficient Home program with the Canadian Home Builder’s Association. Their goal is to encourage builders to build homes that use half as much energy as con- ventional ones. Although slightly higher construction costs and red tape have hindered the program, many builders have adopted the ideas and are now building much more energy- efficient homes. More recently, the Canadian federal gov- ernment also entered into a program with Home Hardware stores to offer videos and publications on ways to improve the energy efficiency of Canadian homes.

In the United States, the EPA and many states are pro- moting home energy efficiency through a variety of volun- tary programs. EPA has its Energy Star Homes program. This program relies on builders to produce homes that use 30% less energy for heating, cooling, and so on than stipu- lated in the National Model Energy Code. When this goal has been verified by an independent certifier, the home re- ceives an Energy Star label.

Many cities and states have green building programs that promote energy efficiency. By meeting certain criteria, home builders can apply for a green building certificate. This, in turn, helps builders market a home. A leader in commercial green building is the nonprofit group known as the U.S. Green Building Council. This organization created a com- mercial building rating system known as LEED—Leader- ship in Energy and Environmental Design—for new and existing buildings. Architects and builders must meet certain criteria to qualify for LEED certification, which dramati- cally reduces the energy and environmental impacts of new and existing buildings. They introduced LEED certification for homes in 2007.

Another encouraging development is the National As- sociation of Home Builders’ active role in researching and pro-

moting energy-efficient homes. They released green home building guidelines in 2007. Some lending institutions are also providing loans for energy-efficient homes, although they tend to simply allow the lender to borrow more money, based on the belief that they will have more money in their pockets. Far better, say some critics, would be a program that gives lower interest loans to buyers of green built homes.

Yet another encouraging development is the net zero energy home. Net zero energy homes are designed to pro- duce as much energy as they consume. Builders achieve this difficult goal by building superefficient homes—airtight homes whose walls and ceilings contain three to four times as much insulation as typical energy-efficient homes (FIGURE 15-6). The use of super energy-efficient windows, solar heat gain, and other measures result in homes that use 90% less energy than standard homes. Builders then install solar elec- tric and solar hot water systems to provide for the energy needs of the residents.

The net zero energy movement began in Germany thanks to the efforts of the Passive House (Passiv Haus) Institute. There is now a Passive House Institute headquartered in the United States that is carrying out this effort. The U.S. De- partment of Energy’s Building America program has also played a very large role in promoting net zero energy buildings.

Conservation can also be stimulated by changes in pric- ing. For example, some utilities now charge customers more for electricity used during peak hours—times when demand is highest. Why? Meeting peak demand is very costly for utilities. It often requires construction of additional power plants that are needed for only a few hours a day. If utility com- panies can reduce peak demand through pricing, they won’t have to build expensive new facilities.

Furthermore, efficiency can also be stimulated by a process called least cost planning. In the United States, util- ities are regulated by the states. Thus, when a power com- pany decides that it needs to build a new power plant to meet rising demand, it must first receive approval from a

FIGURE 15-6 Net zero energy home. This home is so tightly sealed and well insulated that it uses only a tiny fraction of the energy required by a similarly sized home built to less exacting energy standards.

 

 

public utility commission. Currently, most states have requirements for least cost planning or integrated re- source planning (choosing a variety of technologies, in- cluding renewables, and measures such as efficiency to meet energy needs). Least cost planning requires power companies to select the least costly way of providing electricity, which almost always entails energy conservation programs. Some cost- saving options include improvements in generating effi- ciency, peak-pricing schemes, purchasing electricity from other companies (rather than building new power plants), cogeneration, and promoting energy conservation in homes, factories, and businesses. These steps are not only cheaper for utilities, they save customers money. In general, effi- ciency measures are two to three times cheaper than build- ing new power plants. Moreover, the payback period of conservation is only 2 or 3 years compared to 20 for a new power plant. Unfortunately, efforts are currently under way in many states to eliminate requirements for least cost plan- ning, and many states are not enforcing their requirements.

Finally, energy conservation can be stimulated by a com- bination of the measures listed previously here. The Cana- dian government, for instance, is trying to promote conservation through The Efficiency and Alternative Energy program, which entails 33 different initiatives to improve ef- ficiency in all end-use sectors, including buildings, industry, transportation, and equipment. One of the keys of this pro- gram was the 1993 Energy Efficiency Act, which sets min- imum efficiency standards for equipment. The Motor Vehicle Safety Act places stringent emissions standards on cars. All of these efforts are part of a strategy aimed at becoming more efficient and reducing greenhouse gas emissions to combat global warming.

KEY CONCEPTS

Roadblocks to Energy Conservation Despite the economic and environmental advantages of con- servation, it still is not as widely practiced as many would like. Why not? Part of the reason is that Americans, Canadians, and others have been blessed for many years with abundant energy and have had little incentive to use it efficiently.

Another reason is that fossil fuels and nuclear energy are subsidized by federal programs, which reduces the direct

Not only are there many ways to use energy much more efficiently, there are also many ways to promote this strategy, including (1) education, (2) taxes on fossil fuels, (3) feebate systems (which levy a tax on those who choose energy-inefficient options and give rebates to those who opt for energy-efficient tech- nologies), (4) government-mandated efficiency programs, (5) vol- untary programs, (6) changes in pricing, and (7) least cost planning.

cost to the consumer. June 2008 oil was selling at $135 per barrel. If federal subsidies were added the cost would be be- tween $150 to $250 per barrel. Gas would be selling for $4.50 to $7.50 per gallon.

Still another reason is that high-efficiency products such as compact fluorescent lightbulbs often cost more than less energy-efficient ones, and many people neither calculate the long-term savings nor think about the environmental con- sequences of waste.

In addition, many governments have not been commit- ted to energy conservation programs. The minimal investment is hard to reconcile, say some critics, when the government investment-to-savings ratio for conservation can be as high as 1:1,000—a thousand dollars saved for every dollar invested.

The lack of interest in energy conservation in the United States and other countries can also be attributed to the in- fluence and power of energy companies, which are a domi- nant force on the political scene. Nonetheless, as Christopher Flavin and Nicholas Lenssen noted in a recent article, “Pow- erful economic, environmental, and social forces are push- ing the world toward a very different energy system.” One of the cornerstones of that system will be energy efficiency. Its potential is great, and many people, businesses, and na- tions are beginning to recognize that one of the greatest fu- ture sources of energy is our waste.

KEY CONCEPTS

Renewable Energy Sources Imagine a world powered by the sun, the winds, and other clean, renewable forms of energy. Although this may sound like a dream, 30 years from now you may well live in a world powered by a diverse mixture of renewable energy resources.

The shift to a renewable energy future has already begun. Brazil, for example, is turning to ethanol produced from sugarcane to power trucks and cars. California is turning to wind and geothermal (the Earth’s heat) energy. Many other states are following suit. Several European nations, includ- ing Germany and Spain, are currently generating a sub- stantial portion of their electricity from wind. Great Britain is following suit and Germany is gearing up for a 100% re- newable energy future. Israel and other Middle Eastern coun- tries are increasing their dependence on solar energy. Many Pacific Rim nations now get substantial amounts of energy from geothermal sources and plan to obtain substantially more in the future.

As world oil and natural gas reserves decline, as envi- ronmental problems caused by fossil fuels intensify, and as population spirals upward, more and more countries will shift to renewable energy resources. Each one will find many different clean and abundant renewable fuels that are locally

15.2

Many roadblocks stand in the way of energy efficiency, includ- ing the illusion of abundance, federal subsidies that underwrite fossil fuels’ true costs, higher initial costs for some energy- efficient products, and powerful political forces. Despite this, en- ergy efficiency is becoming a popular strategy.

GO GREEN

If your home or apartment is equipped with ceiling fans, use them. They help keep a home warmer in the winter and cooler in the summer, greatly reducing energy consumption and fuel bills. Ceiling fans can reduce cooling costs by up to 40% and heating costs by up to 10%.

CHAPTER 15: Foundations of a Sustainable Energy System: Conservation and Renewable Energy 325

 

 

326 PART IV. Resource Issues: Solutions for a Sustainable Society

fraction of U.S. energy needs. Contrary to popular miscon- ception, this poor showing is not because solar energy is lim- ited to a few areas. In fact, significant sources of solar radiation are available throughout the world, although some are bet- ter than others (FIGURE 15-7).

Four major solar technologies are in use worldwide: passive and active solar hot water, photovoltaics, and solar thermal electric. Understanding each one can help us assess the potential of this largely untapped energy source.

KEY CONCEPTS

Passive Solar Heating FIGURE 15-8 shows a house designed to capture sunlight energy. In this structure, light from the low-angled winter sun streams through south-facing win- dows and is absorbed by interior walls and floors of brick, tiles, or concrete. The heat stored in material, called thermal mass, radiates into the rooms, heating the air day and night. On cloudy days, passive solar homes are kept warm by resid- ual heat that continues to radiate from thermal mass and by backup systems. This is an example of a passive solar heat- ing system. Properly designed passive solar homes and build- ings also require good insulation and insulated curtains or

Solar energy is considered a renewable energy source, but it is really finite. Nonetheless, because it is so abundant and clean, it will very likely be a major contributor to future world energy supplies.

Kilowatt-hours per square meter per day 60˚

30˚

30˚

60˚

150˚120˚90˚60˚30˚0˚30˚60˚90˚120˚150˚

60˚

30˚

30˚

60˚

150˚ 120˚ 90˚ 60˚ 30˚ 0˚ 30˚ 60˚ 90˚ 120˚ 150˚

2 3 4 5 6 6.8

FIGURE 15-7 Map of global solar energy availability. The planet is bathed with sunlight energy, although some areas have considerably more than others.

available. By increasing the use of these resources, nations can protect the environment and create more regionally self- reliant economies. By increasing their dependence on clean, affordable, and reliable renewable energy, they create a bet- ter future, greater economic and political security, and broader prosperity. This section looks at many of the renewable en- ergy options, discussing the pros and cons of each one.

KEY CONCEPTS

Solar Energy Options Oil, natural gas, oil shale, and coal all have limits. So does the sun, the origin of solar energy. In the sun’s case, though, the supply of energy is expected to last at least 4 to 5 billion years. Although it is finite, solar energy is typically called a renewable resource.

Each day, about less than one billionth of the sun’s energy strikes the Earth. Although this is a small fraction, it adds up to an impressive total. In fact, if all of the sunlight strik- ing an area the size of Connecticut each year were captured and converted into useful energy, it could power the entire United States, including all homes, factories, and vehicles. De- spite its enormous potential, solar energy provides only a

Renewable energy will very likely become a major source of en- ergy in the future; the transition to a renewable energy future has already begun in some nations.

 

 

shades to block the outflow of heat at night. Overhangs block out the summer sun.

Passive solar energy is sometimes described as a system with only one moving part, the sun.2 It can be added to an existing home by building a greenhouse. In addition to sup- plying winter heat, a greenhouse can provide a source of food most of the year (FIGURE 15-9).

Well-designed passive systems can provide 80 to 90% of a home’s space heating. One passive solar home in Canada, built by the mechanical engineering department of the Uni- versity of Saskatchewan, for instance, had an annual fuel bill of $40, compared with $1,400 for an average American home at the time of construction. The house was so airtight and well insulated that heat from sunlight, room lights, appliances, and occupants provided sufficient energy to maintain a com- fortable interior temperature. The cost of this house was only slightly more than that of a tract home.

As a rule of thumb, solar houses cost 0 to 5% more to build than conventional houses of similar size. Because used home sales are based primarily on square footage, preowned passive solar homes are often a good buy. My previous solar

house cost about the same as conventional used homes, with a fraction of the utility bills! My new passive solar home was about 5 to 10% cheaper to build than a con- ventional home.

Thousands of American homeowners have selected another solar option, the earth-sheltered house. Built partly underground to take advantage of the year-round constant temperature of the soil, properly designed earth-sheltered homes are well lighted, dry, and comfortable. They also require less external main- tenance. Because they are sheltered by the earth, they stay warm in the winter and cool in the summer. They can eas- ily be designed for passive solar heating. Combined, passive solar heating and earth sheltering can virtually eliminate the need for conventional heat.

KEY CONCEPTS Buildings can be designed to capture solar energy to provide space heat. Properly designed structures can derive 80% to 90% of their heat from the sun.

Heat

Thick masonry walls and floor

Summer sun

Winter sun

Double-paned windowsExtra insulation in attic

and north-facing wall

FIGURE 15-8 A passive solar house. Sunlight streams into the house during the winter months, when the sun is low in the sky, and is kept out by the overhang during the summer months, when the sun is higher. Interior walls absorb sunlight energy and emit heat, keeping the house warm and cozy at a fraction of the cost of conventional heating systems.

GO GREEN

When shopping for a new apart- ment or a new home, look for one whose long axis runs east to west and whose south side has plenty of shade-free win- dows to allow the low-angled winter sun to naturally heat the home. This will cut your annual heating and cooling bill by about 10%.

2Actually, the sun is stationary within our system. The Earth rotates around it.

CHAPTER 15: Foundations of a Sustainable Energy System: Conservation and Renewable Energy 327

 

 

328 PART IV. Resource Issues: Solutions for a Sustainable Society

Active Solar Hot Water Systems Active heat- ing systems employ solar collectors, generally mounted on rooftops. Most collectors are in- sulated boxes with a double layer of glass on the sunny side (FIGURE 15-10). These are called flat plate collectors. The inside of the box is painted black to absorb sunlight and convert it into heat. The heat is carried away, by water or some other fluid flowing through pipes in the collector. The heated water is piped to a storage medium, usually water, in a superinsulated wa- ter storage tank. After transferring its heat to the storage medium, the water is returned to the collectors to be reheated. This process de- livers a large amount of heat to the storage tank during the day, even in the winter so long as the sun is shining. The cycling of the heat trans- fers fluid from the collectors to the storage tank and back again.

The hot water in the storage tank can be used for showers, baths, and washing dishes and can also be used to heat homes. There are even systems to heat swimming pools and hot tubs. Specially designed active solar systems can be used in industry to provide hot water and steam, a major consumer of energy.

Solar collectors can be expensive to pur- chase, mount, and maintain (FIGURE 15-11). Leaks in systems can be costly to repair. In fact, a single repair can negate all energy savings for a 6- to 12-month period. Solar collectors are costly to add to a house after it is completed, too. And the extreme temperatures to which they are subjected can be hard on systems. Even so, solar hot water systems are often cost competitive with electric and propane water heating systems. They can even compete with natural gas systems. Solar pool heating systems are much cheaper than gas or electric pool heating systems. However, some new and inexpensive models are available with few moving parts and requiring little maintenance.

KEY CONCEPTS

Solar electricity: Photovoltaics Photovoltaics provide a way of generating electricity from sunlight. A photovoltaic (PV) cell consists of a thin wafer of silicon or some other ma- terials that emit electrons when struck by sunlight. Elec-

Active solar systems generally employ rooftop panels that col- lect heat from sunlight and store it in water or some other medium. This solar energy can then be used to heat domestic hot water or to heat the interior of the building.

trons liberated from the material then flow out of the wafer, forming an electrical current (FIGURE 15-12).

PV cells are assembled onto modules, which are mounted on roofs or the ground. Some systems are designed to track the sun across the sky, optimizing electrical production. So- lar manufacturers are also making roofing materials, a lam- inated solar material that is applied to metal roofing. Some manufacturers even apply PV material to glass for windows and skylights—so they perform double duty: they let light in and also produce electricity.

Electricity from photovoltaics currently costs about 24 to 27 cents per kilowatt-hour, or about three to six times more than electricity from conventional sources. Fortunately, costs have fallen rapidly in the last four decades (about 95% since the 1970s) and are expected to decline substantially (around 75%) in the next decade. At this writing (June 2011), the cost of solar electric modules is at an all time low. Experts

Partial shade for summer

Rocks

Cool air

Brick wall

Insulation

Warm air

Heat

Water- filled drum

Glass

Sunlight

(a)

(b)

FIGURE 15-9 Solar retrofit. (a) Homeowners can add solar green- houses to existing houses. Greenhouses can be used to grow veg- etables much of the year. (b) Sunlight penetrates the greenhouse glass and is stored in the floor or in water-filled drums. Warm air passes into the house. Fans often help facilitate air movement.

 

 

Water storage tank

Pump

Cold water line

Hot water to faucets

Sunlight

Heat

Heat

FIGURE 15-10 Active solar heating system. (a) Flat plate collectors like those shown here circulate a fluid through pipes in the collector; the fluid absorbs heat captured by the black interior of the panels. (b) The heated fluid is then pumped to a storage tank, and the heat is transferred to some storage medium, usually wa- ter. The water can be used for space heating or heating water for a variety of uses.

(a)

(b)

FIGURE 15-11 Thermomax Solar Water Heater. Photo of one of the most ingenious and most efficient solar hot water heaters on the market.

predict that improvements in production could soon make photovoltaics competitive with electricity from other sources. New developments, for example, solar cells made from plas- tic, could dramatically lower costs, making solar electricity cheaper than conventional electricity.

Photovoltaics are already in wide use in remote villages in the less developed nations. In such locations, photo- voltaics are far cheaper than building transmission lines that carry electricity from distant power plants: Today, more than 6,000 rural villages in India rely on them. The governments of Sri Lanka and Indonesia have launched ambitious programs to install photovoltaics in remote areas. In the United States, it is often cheaper for a homeowner to install photovoltaics than to pay to string electric lines if the home is more than a few tenths of a mile from a power line. Moreover, several states or utilities in some states, including California, New York, New Jersey, Arizona, Missouri, and Colorado, offer financial incentives that lower the initial cost of PV systems

dramatically. The federal government also offers a 30% tax credit on solar electric systems. These incentives often make solar electricity cost competitive with electricity from con- ventional sources.

Today, photovoltaics provide only a tiny fraction of the world’s electrical power, but sales are growing steadily, av- eraging a 16 to 17% per year increase in the 1990s. Growth has increased even more in the 2000s. Japan, the United States, and the European Union have all adopted million roof policies, which seek to promote installation of solar electric and solar thermal systems on homes and businesses. For a case study on the use of solar electricity in business, see Spotlight on Sustainable Development 15-4.

Another exciting development is the increase in the ef- ficiency of solar cells. Although they are not yet commercially available, solar cells with efficiencies over 40% have been pro- duced by researchers at the National Renewable Energy Labs in Golden, Colorado. Solar cells currently on the market are one-fifth to one-third as efficient.

KEY CONCEPTS

Solar Thermal Electric Scientists and engineers have ex- perimented for many years with ways to heat water with sun- light to generate steam that turns a turbine (a special device that drives an electrical generator). Most of their early schemes

Photovoltaics are thin wafers of material such as silicon that emits electrons when struck by sunlight, creating electricity. Although photovoltaics are costly, prices are falling.

CHAPTER 15: Foundations of a Sustainable Energy System: Conservation and Renewable Energy 329

 

 

330 PART IV. Resource Issues: Solutions for a Sustainable Society

were large, costly structures. In southern Califor- nia, one company has pioneered a less expensive alternative. It consists of a series of aluminum troughs that reflect sunlight onto small oil-filled tubes (FIGURE 15-13). The hot oil heats water, which is turned into steam that drives a turbine to generate electricity. This system produces enough electric- ity to supply 170,000 homes at a cost of 8 cents per kilowatt-hour—cheaper than nuclear power but more costly than coal (if you ignore the costly environmental impacts of electricity generated from coal). Numerous other companies have in- stalled similar systems.

KEY CONCEPTS

The Pros and Cons of Solar Energy One of the most no- table advantages of solar energy is that the fuel is free. All we pay for are devices to capture and store it. As a result, solar energy and other renewables will provide a significant help against rising fuel prices (oil, coal, and natural gas prices will continue to rise well into the future). Solar energy is a huge energy resource available as long as the sun continues to shine. While the construction of solar technologies (flat plate collectors and photovoltaics) creates pollution and solid wastes, as does any manufacturing process, once a so- lar system is operating it is a very clean form of energy. It does not add to global warming, urban air pollution, and other en- vironmental problems. Over their lifetimes, solar systems produce much more energy than is needed to make them. Years of pollution-free operation offset the pollution created by production. In fact, it only takes 1 to 2 years for a PV sys- tem to generate all the energy it took to make the entire sys- tem. Also, most solar systems can be integrated with building designs and therefore do not take up valuable land.

Solar energy has many applications. It can, for exam- ple, be used to meet the low-temperature heat demands of homes or the intermediate- or high-temperature demands

Solar thermal electric facilities heat water using sunlight. Steam from this fairly cost-competitive process is used to generate electricity.

Sunlight

Electric current generated here

Boron-silicon layer

Lightbulb

Circuit

Phosphorus silicon layer

Silicon atom Electron Electron vacancy

FIGURE 15-12 Photovoltaic panels. (a) Photovoltaic cells are made of silicon and other materials. When sunlight strikes the silicon atoms, it causes electrons to be ejected. Electrons can flow out of the photovoltaic cell through electrical wires, where they can do useful work. Electron vacancies in the silicon atoms are filled as electrons complete the circuit. (b) Array of photovoltaic cells.

(b)

(a)

FIGURE 15-13 Solar thermal electric. These parabolic aluminum reflectors direct sunlight onto an oil-filled tube. The heat is then transferred to water, which boils and produces steam that drives small turbines to generate electricity.

 

 

of factories. Solar energy can be used to cool buildings and generate electricity to power radios, lights, watches, road signs, stream flow monitors, space satellites, automobiles, and industrial motors.

No major technical breakthroughs are required either. Active solar water heating and passive solar space heating are well developed, although some improvements in design and lowered costs could enhance the appeal of others, such as photovoltaics and active solar space heating.

The major limitation of solar energy is that the source, the sun, is intermittent: It goes away at night and is blocked on cloudy days. Consequently, solar energy must be col- lected and stored. Photovoltaic systems, for example, re- quire storage batteries, although most home owners simply send excess electricity onto the electrical grid during the day. They then draw electricity off at night at no charge. (The electrical grid becomes their storage medium.) Pas- sive solar energy stores heat in thermal mass, but most

SPOTLIGHT ON SUSTAINABLE DEVELOPMENT

15-4 A Solar Giant Grows Taller

In 1998, the Japanese corporation Kyocera became the world’s leading manufacturer of solar electric panels or pho- tovoltaics. That year, the solar giant, long known for its commitment to environmental protection, became even taller with the completion of its new world headquarters, a state of the art office building (FIGURE 1). This 20-story building in Kyoto, Japan was designed to be the world’s most environmentally friendly headquarters. What makes it so special?

As you can see from Figure 1, the building is equipped with nearly 2,000 PVs, on the roof and on the south side of the structure. This, in turn, reduces annual carbon dioxide emissions by 97 metric tons (107 tons), reducing global

greenhouse gas emissions. The use of solar electricity also cuts sulfur and nitrogen oxide emissions, two pollutants that are responsible for acid deposition.

The Kyocera headquarters building also acquires much of its electricity from a natural gas cogeneration unit. This system, which burns natural gas to make electricity, oper- ates at about twice the efficiency of a centralized power plant.

Kyocera is air conditioned by ice—that is, by passing cool air over ice. The company makes ice at night using util- ity power, when demand for electricity is low. Spreading the load out over a 24-hour period makes optimal use of utility power and avoids costly expansion of power production to meet peak demands. It also helps to reduce brownouts dur- ing the day, when system-wide demand is high.

Special sensors in the building monitor outdoor and in- door temperature. When appropriate, outdoor air assists in cooling hot spots that develop around windows when the sun shines on them. In addition, the air flow is carefully mon- itored and controlled in each room to minimize cooling de- mand. Even the escalator is controlled by a sensor that monitors demand. When a person approaches, it turns on. When there’s no activity, the escalator shuts down, saving energy.

Furthermore, Kyocera uses groundwater and rainwater captured on site to irrigate the landscape. High-efficiency lighting and heat-reflecting glass round out the energy features of this building.

Kyocera’s headquarters is an environmentally friendly structure, yet aesthetically appealing. Designed to place the highest priority on environmental protection, it is a model for other companies, as is Kyocera itself, most of whose facilities worldwide are environmentally responsi- ble operations. Their whole line of products—from eco- friendly fine ceramic components that have superior resistance to abrasion, heat, and corrosion to solar-power- generating systems with world-class efficiency—shows that companies can prosper while helping build a sustain- able future.

FIGURE 1 Kyocera’s headquarters. This company is the world’s leading manufacturer of PVs. This office complex is fitted with thousands of PV panels, which help provide energy.

CHAPTER 15: Foundations of a Sustainable Energy System: Conservation and Renewable Energy 331

 

 

332 PART IV. Resource Issues: Solutions for a Sustainable Society

solar users must install a backup system to provide heat dur- ing long cloudy periods.

Another disadvantage is cost. Although passive solar and solar hot water systems for domestic hot water and pool heating are often cheaper in the long run than conventional systems, a few forms of solar energy do not compete well economically with conventional sources—PVs or solar elec- tricity, for example. (Tax incentives, rebates, and rising en- ergy costs, however, can make these systems cost competitive.) This discussion of costs ignores the massive environmental and economic damage caused by conventional fuels and the huge subsidies that prop them up. When these two factors are taken into account, the economics of solar energy are quite good.

KEY CONCEPTS

Wind Energy About 2% of the sun’s energy striking the Earth is converted into wind. (Wind is considered another form of solar en- ergy.) Wind can be tapped to generate electricity, pump wa- ter, and perform mechanical work (grinding grain, for example). Electricity is produced by generators driven by blades (FIGURE 15-14). Large wind turbines are used for com- mercial energy production. Smaller units can be used to power farms and households. Home owners who rely on wind often install photovoltaics to supplement the wind- generated power. My home in Colorado, for instance, is powered by photovoltaics and a small wind generator. My educational center in Missouri, the Evergreen Institute, is powered by two PV systems, a wind turbine, and two solar hot water systems (FIGURE 15-15)

KEY CONCEPTS

The Pros and Cons of Wind Energy Wind energy offers many of the advantages of solar energy: First, wind energy is an enormous resource. Wind resources are abundant in cer- tain parts of every continent. Tapping the globe’s windiest spots could provide 13 times the electricity now produced worldwide. The Worldwatch Institute estimates that wind en- ergy could easily provide 20 to 30% of the electricity needed by many countries. In the United States, North Dakota, South Dakota, and Texas have enough wind to supply all the elec- trical demands of the entire country.

Wind energy is clean and renewable, uses only a small amount of land (Table 15-2), and is safe to operate. On a typ- ical wind farm, only 10% of the land is used for roads and

Winds are produced by solar energy and can be used to generate electricity or to perform work directly, such as pumping water.

Solar energy technologies are well developed. Their advantage over other forms of energy production (such as nuclear or coal) is that they rely on a free, abundant fuel (sunlight) and are rel- atively clean systems to operate. Although some systems are eco- nomically competitive, others are still fairly costly. Storing energy from intermittent sunlight remains one of their major drawbacks.

FIGURE 15-14 Wind farm. These windmill generators in Wyoming produce electricity costing about 5 cents per kilowatt- hour, about the cost of coal-generated electricity but without the adverse environmental impacts. The land can also be used for grazing.

FIGURE 15-15 This solar array at the author’s educational center in east–central Missouri provides most of the electricity he needs to power a home, his business, and a classroom building.

windmills; the remaining land can be grazed and even planted (Figure 15-14a). Today, many farmers are leasing small por- tions of their land to companies to install wind generators. Large, commercial generators net them $3,000 to $5,000 each in rent and royalties, greatly boosting farm income.

Windmill technology is well developed, reliable, and ef- ficient, and the fuel is free. Wind-generated electricity (from large windmills) is cost-competitive with other sources of electricity (Table 15-3). Today, large wind farms are being built all over the world to provide electricity. China, Spain, Germany, Denmark, India, and the United States are lead- ers in wind power. Despite good wind resources, Canada has lagged behind other nations in developing wind energy. In the United States, new wind energy now costs on average about 5 cents per kilowatt-hour, clearly cost-competitive with coal. When one takes into account the environmental benefits, the economics of wind energy (like solar energy) become even more favorable. These factors, combined with the environmental benefit, make wind the fastest growing

 

 

source of energy in the world (FIGURE 15-16). De- spite a serious worldwide economic downturn, the global wind industry expe- rienced yet another record year in 2009, increasing cu- mulative capacity by 31%. By the end of 2009, world wind power capacity was nearly 160,000 megawatts. That’s enough electricity to supply the needs of 250 homes. Wind turbines generate electricity in over 70 countries.

There are, of course, disadvantages to wind. Critics ar- gue that the wind does not blow all of the time, so backup systems and storage are needed. Contrary to popular mis- conception, wind is fairly reliable. Wind farms placed in good locations produce electricity 65 to 85% of the time. According to studies by the U.S. Department of Energy, how- ever, a 1,000-megawatt wind farm requires only about

10 megawatts of backup power. As Mike Bergey of Bergey Windpower notes, “As a power source, wind energy is less predictable than solar energy, but it is also typically available for more hours during a given day.” Another issue is visual impact. Individual wind turbines and wind farms are not visually appealing to everyone. Third, opponents of large-scale wind farms often cite bird kills as a significant concern. As shown in the accompanying viewpoint, bird mortality from commercial wind turbines does occur, but it is minor in comparison to other sources such as pet cats, automobiles, and cell phone towers.

Although winds do not blow all of the time in all locations, wind still could become a major source of electricity. It could supplement solar and hydroelectricity and conventional power sources as well. Surpluses produced in one area could be trans- ferred elsewhere. Consistently windy locations like coastlines and the great plains of North America could also provide a steady stream of electricity to the electrical grid.

KEY CONCEPTS

Biomass The organic matter contained in plants is called biomass. The energy found in this organic plant matter comes from sun- light. Useful biomass includes wood, wood residues left over from the timber industry, crops, crop residues, charcoal, ma- nure, urban waste, industrial wastes, and municipal sewage. Some of these fuels can be burned directly. Others are con- verted to methane (a gas) and ethanol (a liquid). The sim- plest way to get energy from biomass is to burn it. In some

Wind energy is clean, abundant, and fairly inexpensive, especially when one includes its low environmental costs. Wind energy could provide a significant percentage of our future energy de- mand. However, because winds are often intermittent, backup systems and storage are necessary.

Table 15-2 Land Use of Selected Electricity-Generating Technologies, United States

Technology Land Occupied1

Coal2 3642 Solar thermal 3561 Photovoltaics 3237 Wind3 1335 Geothermal 404 Source: From L.R. Brown, C. Flavin, and S. Postel (1991). Saving the Planet: How to Shape an Environmentally Sustainable Global Economy. New York: Norton. 1(square meters per gigawatt-hour, for 30 years) 2Includes coal mining. 3Land actually occupied by turbines and service roads.

Table 15-3 Present and Estimated Electrical Generation Costs1

Source Cents per Kilowatt-Hour

Nuclear 8–12 Coal 5–7 Gas and oil 6–9 Hydroelectric 3–6 Wind 5–8 Geothermal 4.5–5.5 Photovoltaic 22 Solar thermal 8–12 Biomass 5 Sources: Public Citizen Critical Mass Energy Product and Worldwatch Institute. 1Generation costs are costs to companies.

60,000

80,000

100,000

120,000

140,000

160,000

180,000

40,000

20,000

0

1980 2000 2005 201019951990

Year

Source: EPI from GWEC, Worldwatch

World Cumulative Installed Wind Power Capacity, 1980–2009

1985

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aw at

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FIGURE 15-16 Wind energy. Wind has become the fastest grow- ing source of energy in the world.

GO GREEN

If you can afford it, buy green power (such as wind-generated electricity) from your local utility.

CHAPTER 15: Foundations of a Sustainable Energy System: Conservation and Renewable Energy 333

 

 

VIEWPOINT

While commercial wind machines do kill birds, the problem has been blown way out of proportion. Studies show that bird kills from wind turbines pale in comparison to bird deaths from several common sources, among them plate glass win- dows, domestic cats, automobiles and trucks, tall buildings, smokestacks, and communication towers (see Table 1). Worldwide, hundreds of millions of birds—perhaps even bil- lions—are killed each year by these sources. Commercial wind turbines, on the other hand, kill a miniscule number of the birds. So why has wind gotten such a bad rap?

Wind machines got a bad rap from one of America’s old- est and largest wind farms: the Altamont Pass Wind Resource area in California. Located just east of San Francisco, Alta- mont Pass is home to a mind-boggling 7,000 wind turbines.

It is also habitat for numerous raptors. Soon after the wind turbines were erected, the birds began to perch on the lat- tice wind towers in search of abundant prey (ground squir- rels and other rodents) that live year-round in the grasses at the base of the towers.

Some scientists attributed this problem to a phenom- enon called “target fixation.” Fixed on their prey, the rap- tors descended from their perches and flew directly into the blades. In addition to those that perished as a result of col- lision with the blades, studies suggest that 8% died from elec- trocution (from power lines), and 11% died when they collided with electric wires. The causes of death in the re- maining 26% is unknown. Some researchers speculate that many raptors died from poisoning by rodenticides, pesti- cides used to poison rodents. These chemicals, the scientists hypothesized, may have moved up the food chain, poison- ing the unfortunate raptors.

Although many raptors have died at Altamont, a 2-year study of bird kill in the region showed that the highly pub- licized problem was indeed overblown. The researchers dis- covered only 182 dead birds in 2 years.

While any raptor death is of concern to those of us who cherish wildlife, the death rates at Altamont are insignifi- cant compared to other factors. For example, scientists es- timate that about 60 million birds die each year in the United States after being struck by motorized vehicles, according to the American Wind Energy Association’s report “Facts About Wind Energy and Birds.” Another 1.25 million die as a result of collision with tall structures such as buildings, smokestacks, and towers. Another 100 million to 900 mil- lion, perish after flying into plate glass windows, according

Bird Kills from Commercial Wind Farms: Fact or Fiction?

Table 1 Estimated Annual Bird Death in the United States by Source

Activity/Source of Estimated Bird Motality Annual Mortality

Killed by cats 270 million or more Collisions with and electrocution by electrical transmission wires 130 to 170 million Collisions with windows 100 to 900 million Poisoning by pesticides 67 million Collisions with motor vehicles 60 million Collisions with communications towers 40 to 50 million Source: American Wind Energy Association.

instances, though, it makes more sense to convert biomass to gaseous and liquid fuels such as ethanol. These can be burned in motor vehicles or used to produce raw materials for the chemical industry to manufacture drugs and plas- tics as oil and natural gas supplies decline.

Biomass (wood, for instance) supplies about 20% of the world’s energy. In fact, it is the main source of energy for about half of the world’s population, primarily those in the less developed countries. In sub-Saharan Africa, three-fourths of the energy comes from burning wood. In contrast, in the United States and other developed countries, biomass sup- plies only about 3% of the energy needs. Wood-rich Canada currently supplies about 6% of its total energy demand from biomass, mostly wood.

Certain nonfood crops could also be grown to produce liquid fuel. For example, a desert shrub (Euphorbia lathyris) found in Mexico and the southwestern United States produces an oily substance that could be refined to make liquid fuel. In arid climates, the shrub could yield 16 barrels of oil per hectare

(6 barrels per acre) on a sustainable basis. The copaiba tree of the Amazon yields a substance that can be substituted for diesel fuel without processing. Vegetable oils can also be used in place of diesel. According to one study, farmers could convert 10% of their cropland to sunflowers to produce all the diesel fuel needed to run their machinery. Eventually, the entire trans- portation system could be powered by renewable fuels.

Another potential source of energy is manure from live- stock operations. Manure is fed into vats where it decomposes, giving off methane, a combustible gas. All over the world, plans are under way to use manure to produce a combustible fuel. This not only helps put a waste to good use, it helps re- duce pollution.

KEY CONCEPTS Biomass is organic matter such as wood or crop wastes that can be burned or converted into gaseous or liquid fuels. It is a com- mon fuel source in most developing nations but supplies only a fraction of the needs of people in the developed nations.

334 PART IV. Resource Issues: Solutions for a Sustainable Society

 

 

to another report. Yet another 10 to 40 million birds perish after flying into communications towers and the guy wires that support them. Pesticides kill an estimated 67 million birds each year.

Cats are a lethal force in the lives of birds. Scientists who have studied bird deaths from cats in Wichita, Kansas, found that a single cat kills, on average, 4.2 birds per year. Other studies suggest even higher numbers. According to one study, a feral cat kills as many birds in 1 week as a large com- mercial wind turbine does in 1 to 2 years. Declawing a cat doesn’t seem to help much. According to one estimate, the majority of cats (83%) kill birds, even declawed, and well- fed cats prey on wild birds. Neutering or spaying a cat does not seem to cut down on hunting, either. With more than 64 million cats in America alone, what’s the total loss?

No one knows for sure, but if the situation in Wiscon- sin is indicative of the national toll, America’s bird popula- tion is being decimated by our beloved feline companies. In Wisconsin alone, researchers estimate that cats kill approx- imately 39 million birds per year. Nationwide, the number is estimated to be around 270 million, very likely many many more. Two scientists who studied the issue in one small town in England, estimated that cats kill 20 million birds per year in Great Britain alone. “Even if wind were used to generate 100% of U.S. electricity needs, at the current rate of bird kills, wind would account for only one of every 250 human-related bird deaths,” notes the AWEA. “So, if you want to save birds,” says one wind energy expert who wished to remain anony- mous, for reasons that will soon be clear, “put your cat in a blender, then sign up for wind-generated ‘green electricity’ from your utility.”

Clearly, the Altamont Pass wind farm is benign com- pared to a host of other lethal factors. Altamont also appears to be an isolated case. No other wind farm in the United States experiences mortality rates remotely close to the Al- tamont Pass facility. Why?

Acutely aware of the problem, contemporary wind de- velopers select sites for new wind farms that are out of mi- gratory pathways. Site selection has helped, but that’s not all. Improvements in the design of commercial wind tur- bines have also helped to minimize bird kills at commercial wind farms. How?

Over the years, wind machines have gotten taller, blades have gotten longer, and the speed at which the blades ro- tate has declined substantially. Large blades help harness more energy from the wind, but large, slow-moving blades are also more easily avoided by birds. Ever-larger commer- cial wind machines currently under development could reduce the risk even more. (To learn more about efforts to reduce bird deaths even more, check out “Facts About Wind Energy and Birds” at the American Wind Energy Association’s web- site, http://www.awea.org. Mick Sagrillo has written several articles on the topic, which you can check out at http://www .renewwisconsin.org. On the lower left, click on “Small Wind Toolboxes.”)

Adapted with permission from Dr. Chiras’ book, Power from the Wind, published by New Society Publishers.

CHAPTER 15: Foundations of a Sustainable Energy System: Conservation and Renewable Energy 335

The Pros and Cons of Biomass Biomass offers many ben- efits. It can help less developed nations reduce their de- pendence on nonrenewable energy resources. It also has a high net energy efficiency when it is collected and burned close to the source of production, and it has a wide range of applications. Unlike fossil fuels, biomass adds very little car- bon dioxide to the atmosphere—as long as the amount of plant matter burned equals the amount of plant matter pro- duced each year. Burning some forms of biomass, such as ur- ban refuse, reduces the need for land disposal.

Several recent technological and scientific developments could improve the prospects for biomass. First is the use of high-efficiency gas turbines, similar to those in jet aircraft, to generate electricity from hot gases produced by the com- bustion of various forms of biomass. Second is the develop- ment of an enzymatic process that improves the efficiency of ethanol production from wood wastes—a procedure that has decreased the cost of ethanol from wood from $4 a gal- lon to $1.35 in the last decade. Further improvements could

decrease costs to 60 cents a gallon. Wood wastes now dumped in landfills, urban tree trimmings, and sustainably managed tree farms could eventually form the base of a sustainable ethanol production to meet a portion of our transportation fuel needs.

Biomass is not a panacea, however. Although the world’s reliance on this form of renewable energy will probably in- crease in coming years, it is doubtful that its use will in- crease as much as some proponents hope. Why not? Global warming could reduce water supplies and agricultural out- put in many areas, thus constraining biomass production. Further, some people believe that rising food demand may limit the amount of farmland available to produce biomass fuels. Biomass production could raise food prices, which is especially harmful in less developed countries. Already ris- ing ethanol production has caused an increase in corn prices that has increased the cost of feeding cattle and the cost of feeding people whose main food sources are derived from im- ported corn. Furthermore, removing crop and forestry

 

 

336 PART IV. Resource Issues: Solutions for a Sustainable Society

residues may reduce soil nutrient replenishment. Biomass can create large amounts of air pollution—for example, smoke from woodstoves. This smoke contains several toxic air pol- lutants, such as dioxins, and creosote. Studies show that children living in homes with wood-burning stoves have more respiratory problems than children in homes heated by other means. Finally, transportation costs for biomass are higher than traditional fossil fuels because biomass has a lower energy content per unit of weight.

KEY CONCEPTS

Biodiesel Another biomass solution that holds great promise is biodiesel. Biodiesel is a renewable fuel made from an assortment of vegetable oils—for example, corn oil, canola oil, and soy oil. The liquid is a combustible, clean-burning fuel that could eventually power many of the nation’s trucks, cars, buses, vans, ships, and trains, perhaps even jets. (There are already over 1,000 gas stations in the United States that sell biodiesel out of 120,000 stations.) You can locate gas stations at the Al- ternative Fueling Station Watch on the Internet.

Biodiesel is made by mixing vegetable oil with a solu- tion of methanol containing sodium hydroxide (lye). The oil is usually heated. The methanol-lye mixture is then added to the vegetable oil. This solution is heated some more and then stirred for a period of time, usually about an hour. When the chemical reaction is complete, out comes biodiesel—long chain fatty acids that burn very nicely in diesel engines. The only waste product is glycerol, a dark thin oily substance that can be purified and used to make soap.

The Pros and Cons of Biodiesel Biodiesel is a renewable fuel that could help us meet our needs for transportation fuels as the age of oil winds down. Biodiesel can help stimulate our nation’s economy and reduce its reliance on foreign oil. It could also help stimulate rural economies. In the coming years, many farmers will be enlisted to produce “fuel grains” for the biodiesel market. Local biodiesel manufacturers could convert the grains to vegetable oil. Crop production and lo- cal manufacturing not only create stronger local and regional economies, they help forge the path to a more decentralized and sustainable system of fuel production.

According to Marc Franke, an Iowa-based proponent of biodiesel, the net energy efficiency of biodiesel production from soy oil is 3.2. The net energy production of biodiesel from canola or rapeseed oil is 4.3. What these figures mean is that for every unit of energy invested in biodiesel pro- duction, you get 3.2 units of energy output for soy oil and 4.3 units of energy from canola oil. According to Franke, it would take 7.0 acres of soybeans to supply soybeans to ex- tract the oil needed to make biodiesel for a diesel car that trav- els 15,000 miles per year and gets 44 miles per gallon. It would take 2.7 acres of canola oil to do the same thing.

Biomass is a major source of energy in many less developed na- tions and could boost the energy supply of many more developed nations.

Seed crops are not the only potential source of biodiesel, however. Biodiesel can also be produced from vegetable oils discarded by restaurants—reducing disposal costs for them while providing a valuable renewable liquid transportation fuel. U.S. restaurants, including all the fast-food chains, pro- duce an estimated 3 billion gallons of waste vegetable oil per year, according to Franke!

There are a lot of other sources, too. For example, biodiesel can be manufactured from algae grown in ponds as- sociated with sewage treatment plants, helping reduce pol- lution while generating liquid fuel for North America’s transportation system. Diesel fuel can also be produced from the organic waste such as that generated at turkey farms us- ing a process known as Thermal De-Polymerization (TDP). Agricultural, organic wastes, says Franke, produce enough material to make 4 billion barrels of biodiesel each year!

According to Franke, biodiesel offers the same per- formance as regular diesel, but dramatically reduces tailpipe emissions. For example, biodiesel contains no sulfur; there- fore, combustion of this fuel source eliminates sulfur oxide emissions that contribute to acid rain and snow—a big prob- lem with conventional diesel vehicles.

There’s no black smoke spewing from tailpipes of cars or trucks powered by biodiesel as they pass or power up a hill. Complete cycle carbon dioxide production from the manu- facture of the fuel and use of biodiesel cars and trucks is 78% lower than vehicles powered by standard diesel fuel. According to the U.S. Department of Energy, biodiesel is the fastest growing alternative fuel on the market today.

Yet another advantage of biodiesel is that the transition to this fuel won’t require major changes in distribution sys- tems. Biodiesel could be produced locally and sold at area fill- ing stations using the same facilities that are used to dispense diesel fuel made from petroleum.

Biodiesel can also be run in space heaters and oil furnaces, even forklifts, tractors, and electric generators that currently use diesel. Your home someday could be heated with biodiesel. I use biodiesel in my lawn tractor and farm trac- tor at The Evergreen Institute.

Despite these benefits, biodiesel does have a few dis- advantages. For one, it is not yet widely available. Second, in the United States, commercially manufactured biodiesel costs a bit more to produce than standard petroleum-derived diesel. This, of course, is largely due to the fact that biodiesel is only produced by small-scale production facilities. In- creasing the scale of production could bring the cost down substantially. As oil prices rise and biodiesel production ramps up, costs could decline, making biodiesel the fuel of the future. Improving matters, starting in January 2004, pro- ducers received a federal tax incentive of up to $1 per gallon of biodiesel.

You can also make your own biodiesel at bargain base- ment prices in your basement. Biodiesel Solutions, a com- pany in Fremont, California sells equipment you can set up in your basement or garage to manufacture biodiesel. They claim that it currently costs only about 70 cents per gallon to make, far lower than standard diesel, which is currently running about $3.40 per gallon.

 

 

CHAPTER 15: Foundations of a Sustainable Energy System: Conservation and Renewable Energy 337

Another problem with biodiesel is that soy biodiesel gels around 32° F, and, therefore can’t be used at full strength when the weather gets cold. To get around this, biodiesel is ordinarily mixed with conventional diesel to which manu- facturers add an antigelling agent to winter petroleum diesel.

Finally, large-scale biodiesel production will put in- creasing demand on farmland. Production could, if large enough, even reduce the exports of food crops. Although farmers won’t suffer, those who rely on food from North America could find themselves in a bind. One way to lessen the impact of widespread biodiesel production would be to make it from algae and waste from turkey and hog farms.

Vegetable Oil as a Fuel Some people are burning vegetable oil directly in diesel cars, trucks, and buses. Some individuals acquire their fuel from unused vegetable oil. Others salvage vegetable oil from fast- food chains and other restaurants. How can vegetable oil be burned in a diesel car?

It may surprise readers to learn that the German inven- tor of the diesel engine, Rudolph Diesel, was able to run his engine on peanut oil. Modern diesel engines, however, can’t run directly on vegetable oils. To run a vehicle on straight veg- etable oil, which is thicker than biodiesel or conventional diesel fuel, car and truck owners must make some modifica- tions to their vehicles. Several companies now manufacture conversion kits costing $300 to $800. Most of these kits in- clude a separate tank for vegetable oil and heating elements for the tank, the fuel line, and the fuel filter. They heat the veg- etable oil, which makes it lighter so it flows more readily.

Vegetable oil is an ideal fuel, but one needs to understand the pros and cons of this approach to compare it with other options, especially biodiesel. Let’s start on the up side.

One of the biggest advantages of vegetable oil is that the fuel is widely available. You can stop and fill up any- where in North America as long as there’s a restaurant that deep fat fries its food in vegetable oil. (You’ll have to filter the gunk out of the deep fryer oil first, however.)

Not only is the fuel abundant and widely available, so are diesel engine conversion kits. You can purchase them on the Internet.

Like other options discussed in this chapter, the fuel is renewable and can be picked up for free—for example, from fast-food restaurants whose owners are typically pleased to give it away, rather than pay for disposal!

Vegetable oil burns cleanly and thus helps solve another thorny issue—air pollution from conventional fossil fuels. Like biodiesel, vegetable oil use reduces carbon dioxide emissions. The fuel itself is often called carbon neutral but that’s not entirely true. Although the amount produced dur- ing combustion equals the amount the plants take up dur- ing photosynthesis, it takes energy to make this fuel (gasoline to power a tractor, for instance). The consumption of energy, in turn, produces carbon dioxide. Even so, the fuel is light years ahead of conventional fossil fuels with respect to green- house gas production.

Vegetable oil fuels have some disadvantages. The con- version kits and installation of the kits cost money. In addi- tion, the additional fuel tank takes up a considerable amount of trunk space. In many cars, the owner has to start the ve- hicle with ordinary diesel, then switch to vegetable oil after it has heated up. Five minutes before the car is turned off, the driver has to switch back to petroleum-based diesel to clean the lines of biodiesel. One German company has developed a conversion kit that uses the main fuel tank. Vehicles equipped with this can start on straight vegetable oil.

Hydroelectric Power Humankind has tapped the power of flowing rivers and streams for thousands of years to run flour mills and, more recently, to produce electricity. River flow is made possible by two factors: sunlight energy, which causes water to evaporate. It is then deposited immediately as rain or sometime later as snow that flow into rivers (Chapter 13). The second factor is gravity, which is responsible for the movement of water in streams.

Hydroelectric power is a renewable resource usually tapped by damming streams and rivers. Water in the reservoirs behind dams is released through special pipes. As it flows out, it turns the vanes of electric generators, producing electricity.

Hydropower supplies about one-fifth of the world’s elec- trical demand. In Canada, it supplies about 12% of the nation’s total annual energy demand. Hydropower creates no air pol- lution and is relatively inexpensive. Furthermore, the tech- nology is well developed. Although dams and hydroelectric power plants are expensive to build, they often have lifespans 2 to 10 times greater than coal or nuclear powered plants.

There are some problems associated with hydropower. As noted in Chapter 13, reservoirs behind dams often fill with sediment, shortening the life span of a hydropower facility to 50 to 100 years. However, large projects with enor- mous reservoirs may last 200 to 300 years. Once a good site is destroyed by sediment, it is gone forever. Dams and reser- voirs flood productive land, displace people, destroy stream fisheries, eliminate certain forms of recreation, upset nutri- ent replenishment in estuaries, and create many additional problems discussed in Chapter 13.

Many countries have a large untapped hydroelectric po- tential. In South America, for instance, hydroelectric gen- erating potential is estimated at 600,000 megawatts. By comparison, the United States, the world’s leader in hydro- electric production, has a present capacity of about 77,000 megawatts and an additional capacity of about 150,000 to 160,000 megawatts.

As pointed out in Chapter 13, estimates of hydroelectric potential can be deceiving because they include all possible sites, regardless of their economic or environmental costs. For example, half of the U.S. hydroelectric potential is in Alaska, far from places that need power. The potential for ad- ditional large projects in the continental United States is small because the most favorable sites have already been developed. Canada faces a similar shortage. Moreover, those developing sites that are available would result in massive

 

 

338 PART IV. Resource Issues: Solutions for a Sustainable Society

environmental impacts and might be strongly opposed by the citizenry. In addition, the high cost of constructing large dams and reservoirs has increased the cost of hydroelectric energy by from 3 to 20 times since the early 1970s. Because of these factors, hydropower is projected to increase very slowly in the coming decades.

Two of the most sensible strategies for increasing hydro- power may be to (1) increase the capacity of existing hydro- electric facilities—that is, add more turbines—and (2) install turbines on the many dams already built for flood control, recreation, and water supply. In appropriate locations, small dams could provide energy needed by farms, small busi- nesses, and small communities. All projects, however, must be weighed against impacts on wildlife habitat, stream qual- ity, estuarine destruction, and recreational uses.

In LDCs, small-scale hydroelectric generation may fit in well with the demand. In China tens of thousands of medium and small hydroelectric generators account for about one- fourth of the country’s electrical output. Small instream gen- erators that do not impede the flow of water can also provide power to individual homes located near waterways. Water can also be removed, transported downstream in small pipes (to pick up speed), and then run through small generators (FIGURE 15-17). These can provide a remarkable amount of electrical energy 24 hours a day, 365 days a year! However, there aren’t many suitable sites in most parts of the country for small-scale hydros, called microhydro.

KEY CONCEPTS

Geothermal Energy The Earth harbors an enormous amount of heat, or geo- thermal energy, which comes primarily from magma, molten rock beneath the Earth’s surface. Geothermal energy is con- stantly regenerated, so it is a renewable resource. Geothermal resources fall into three major categories.

Hydrothermal convection zones are places where magma intrudes into the Earth’s crust and heats rock that con- tains large amounts of groundwater. The heat drives the groundwater to the Earth’s surface through fissures, where it may emerge as steam (geysers) or as a liquid (hot springs).

Geopressurized zones are aquifers that are trapped by impermeable rock strata and heated by underlying magma. This superheated, pressurized water can be tapped by deep wells. Some geopressurized zones also contain methane gas.

Hot-rock zones, the most widespread but also the most expensive geothermal resource, are regions where bedrock is heated by magma. To reap the vast amounts of heat, wells are drilled, and the bedrock is fractured with explosives. Water is pumped into the fractured bedrock, heated, and then pumped out.

Geothermal energy is heavily concentrated in the so- called Ring of Fire encircling the Pacific Ocean and in the great mountain belts stretching from the Alps to China (FIG- URE 15-18). It is also prevalent around the Mediterranean Sea and in East Africa’s Great Rift Valley, which extends along the eastern part of the African continent. Within these areas, hydrothermal convection zones are the easiest and least ex- pensive to tap. Hot water or steam from them can heat homes, factories, and greenhouses. In Iceland, for example, 65% of the homes are heated by the Earth’s heat. Iceland’s geother- mally heated greenhouses produce nearly all of its vegetables; Russia and Hungary also heat many of their greenhouses in this way.

Geothermal is also being widely used to heat homes and other buildings in the United States and Canada. The heating systems, referred to as ground-source heat pumps, extract heat from the ground through pipe buried 6 to 8 feet below the surface. Using refrigeration technology, these sys- tems commonly referred to as geothermal systems, pump heat from the ground into a building. In the summer, they can be run in reverse. That is, they can extract heat from a building and dump it back into the ground, thus cooling the building. Geothermal systems are about 25% more effi- cient at heating a building than conventional systems.

Steam from geothermal sources can be used to run tur- bines that produce electricity. Geothermal plants can produce electricity day and night and can provide electricity when wind or solar systems are not operating. They can also provide electricity in areas without sizable wind or solar resources.

Hydroelectric power is renewable and operates relatively cleanly, but dams and reservoirs have an enormous impact on the envi- ronment. Although the potential hydropower sources are enor- mous, they are often far from settlements, and developing them would cause serious environmental damage.

Stream

Penstock

Turbine

Intake diversion and screen

Tailrace

Powerhouse

FIGURE 15-17 Small-scale hydropower. Flowing water from a nearby stream turns a turbine to generate electricity.

 

 

Although still in the early stages of development in most countries, geothermal electric production is growing quickly in the United States, Italy, New Zealand, and Japan. El Sal- vador in Central America, however, currently generates 40% of its electricity from geothermal sources, and Kenya and Nicaragua acquire 11 and 10%, respectively.

Hydrothermal convection systems have several draw- backs. The steam and hot water they produce are often laden with minerals, salts, toxic metals, and hydrogen sulfide gas. Many of these chemicals corrode pipes and metal. Steam systems may emit an ear-shattering hiss and release large amounts of heat into the air. Pollution control devices are nec- essary to cut down on air and water pollutants. Engineers have also proposed building closed systems that pump the steam or hot water out and then inject it back into the ground to be reheated. Finally, because heat cannot be transported long distances, industries might have to be built at the source of energy.

KEY CONCEPTS

Hydrogen Fuel Hydrogen is another renewable fuel that many believe could be used to help replace oil, gasoline, and natural gas. It could someday be burned in our stoves, water heaters, fur- naces, factories, and cars.

Hydrogen gas is produced by heating water to extremely high temperatures or passing electricity through it in the presence of a catalyst (a chemical that facilitates the break- down of water into oxygen and hydrogen without being changed itself). The device used to generate hydrogen is known as an electrolyzer.

Hydrogen is a relatively clean-burning fuel. In fact, when hydrogen burns it produces only water and small amounts of nitrogen oxide (formed by the combination of

Geothermal energy is a renewable resource created primarily from magma, molten rock beneath the crust. Geothermal energy is used to generate electricity and to heat structures; it is a ma- jor source of energy in some countries.

atmospheric oxygen and nitrogen). Nitrogen oxides, which contribute to acid deposition, can be minimized by con- trolling combustion temperature and by installing pollu- tion control devices. Unlike fossil fuels, hydrogen produces no carbon dioxide when burned.

Because hydrogen could be generated from seawater, it is an essentially limitless and renewable energy resource. Hydrogen is also easy to transport and has a wide range of uses. Unfortunately, at the present time it takes consider- able energy to produce hydrogen. This low net energy yield makes it an expensive form of energy.

Hydrogen may also serve as a way of storing energy from hydroelectric, wind, solar, and other renewable energy sources. For example, when demand for these sources is low, the elec- tricity they generate could be used to produce hydrogen from water. It would be stored for later use. When renewable sources are not available (say, on a calm day or during the evening), the hydrogen could be burned to produce electricity.

Although the immediate prospects for hydrogen are not spectacular, efforts to produce hydrogen more efficiently could go a long way to make this energy source more cost effective. Some energy analysts predict that one day areas rich in sunlight, wind, and water could become major sources of hydrogen fuel, which could be piped around the world in pipelines.

In 1996, the U.S. Congress passed the Hydrogen Future Act. This law supports research and development of hydrogen fuels and provides approximately $165 million to support these activities.

Fuel Cells Hydrogen can also be used to produce electric- ity in a fuel cell. Many different types of fuel cells have been developed. FIGURE 15-19 shows a simplified view of how a fuel cell works. As illustrated, this fuel cell looks a lot like a bat- tery. It consists of an anode and a cathode separated by a membrane. Hydrogen is fed into the cathode where it reacts to form hydrogen ions and electrons. The electrons are drawn off by a wire, forming electricity, which powers lights, elec- tronic equipment, and so on. Oxygen is introduced into the cathode, where it reacts with hydrogen ions that pass through

FIGURE 15-18 Global geothermal resources. Note the concentration of geothermal resources on the Pacific coastline—the so-called Ring of Fire.

180˚ 150˚ 120˚ 90˚ 60˚ 30˚ 0˚ 30˚ 60˚150˚120˚90˚

180˚ 150˚ 120˚ 90˚ 60˚ 30˚ 0˚ 30˚ 60˚150˚120˚90˚

30˚

30˚

60˚

60˚

30˚

30˚

60˚

60˚

CHAPTER 15: Foundations of a Sustainable Energy System: Conservation and Renewable Energy 339

 

 

340 PART IV. Resource Issues: Solutions for a Sustainable Society

the membrane from the an- ode and electrons returning from the circuit. The product is water.

Electricity produced by a fuel cell can be used to power electric motors in cars. In fact, in 1999 Daim- ler-Chrysler unveiled a hy- drogen-powered car that can travel as fast as 90 miles per hour. It uses hydrogen and oxygen to run a fuel cell, which runs an electric mo- tor to power the car. One company in Canada, Ballard Power Systems, is building hydrogen fuel cell powered buses, which are now being used experimentally in Chicago and British Columbia. During the public ceremony in Chicago, then Mayor Richard Daley, celebrated by drinking a glass of ex- haust water collected from the tailpipe of an idling bus to underscore how safe the emissions are. If tests prove suc- cessful, Ballard hopes to enter full-scale production of fuel cell bus engines.

Iceland has committed itself to a hydrogen economy and will soon receive all of its energy from hydrogen and geothermal energy.

Although hydrogen-powered cars seem promising, re- member that it takes energy (electricity) to make hydrogen. Studies show that it is far more efficient (three to four times) to use electricity directly to power an electric car than it is to use that electricity to generate hydrogen to run a fuel cell to produce electricity to run a car. Fuel cells use hydrogen and oxygen, but both hydrogen and oxygen also burn, so they can be burned directly in cars. For more on the pros and cons of hydrogen, see the Point/Counterpoint on the fol- lowing pages. Today, a lot of fuel cell work is focused on using hydrogen-containing fuels such as methanol, natural

gas, ethanol, or gasoline. The fuels will be fed into an on- board fuel processor that strips the hydrogen from the mol- ecules. The hydrogen is then fed into the fuel cell. Although most fuel cells under development are powered by fossil fuels, the process is reportedly very clean and represents a major improvement over standard gasoline- and diesel- powered motor vehicles. They still produce significant amounts of carbon dioxide. At this writing, Daimler-Chrysler, Toyota, Honda, Ford, and General Motors have fuel cell vehicles that could be brought to market soon.

KEY CONCEPTS

Is a Renewable Energy Supply System Possible?

Enormous amounts of renewable energy are available and accessible with current technologies—far more than are available from fossil fuel reserves. This has led some scien- tists and environmentalists to propose a sustainable energy supply system far different from the one in existence today. They see energy efficiency and renewable energy resources as the cornerstone of this new, environmentally sustainable system. FIGURE 15-20 shows one scenario for the projected shift in the world’s energy supply system. As illustrated, re- newables could take over for all of the nonrenewables. This transition will take many years, and thus, fossil fuels will be around for a long time.

But how will renewable energy supplant the nonrenew- ables that currently power much of the world? Where will

15.3

Hydrogen may become an important fuel in the future. Hydro- gen can be produced by passing electricity through water, a re- newable resource. When hydrogen burns, it produces water vapor. Fuel cells use hydrogen, either from water or organic fuels, to produce electricity. The electricity can be used to power cars, and several manufacturers are actively pursuing this option.

(a)

(b)

FIGURE 15-19 Fuel cell. Many people believe that fuel cells are the wave of the future. (a) Cells resemble batteries and produce electricity from hydrogen and oxygen. (b) Photo of a real fuel cell. (a and b courtesy of Ballard Power Systems [http://www.bal- lard.com].)

GO GREEN

Combine errands to reduce your time, energy use, and pollution. When running errands, plan out your trip in advance so you can make a loop. Try to plan your trip so that you make only right turns. These means less time waiting to make left turns and less energy used. It works. UPS plans all its delivery routes so drivers make only right turns.

 

 

CHAPTER 15: Foundations of a Sustainable Energy System: Conservation and Renewable Energy 341

POINT

As public concern about climate change and depletion of the world’s fossil fuels escalates, renewable energy technolo- gies are becoming more important and more widely adopted. Industry and government are working to implement large- scale wind and solar projects. Renewable energy is clean, re- liable, and inexhaustible. Is it possible that renewable power and fuels will one day meet all of our energy needs?

Maybe so, but even if we invest in enough solar and wind-generating capacity to meet all our energy needs, there are some additional hurdles that need to be cleared. Re- newable energy is abundant overall, but the sun goes down at night, streams dry up in summer, and wind turbines stop spinning on calm days. In other words, renewable energy sources are intermittent, while society’s need for energy never lets up. If we start generating most of our electricity with renewables, the mismatch between energy supply and demand could become a significant problem.

What we need is a way to store energy, so the power gen- erated on sunny or windy days can be used when it’s dark or calm. Batteries are one familiar way to store energy. They con- vert electricity to chemical energy that can be converted back to electric energy on demand. For years, people who live in remote locations have used rechargeable batteries to store energy collected by their solar panels or wind turbines. Un- fortunately, batteries are expensive, bulky, and toxic, and they gradually dissipate stored energy over time. Using huge numbers of batteries to store utility-generated energy for en- tire cities is neither practical nor economical.

This brings us to hydrogen, a practical way of storing electricity, again in chemical form. It is important to un- derstand that hydrogen is not a source of energy. Instead, it’s an energy carrier, a way of storing or transporting energy that comes from some other source.

Hydrogen is one of the most abundant elements here on Earth, but nearly all of it is bonded chemically to other ele- ments, primarily in water and hydrocarbon molecules such as methane. These bonds must be broken to obtain the pure hydrogen that can be used as an energy carrier.

Hydrogen in water can be separated using electrolysis. This process can be powered by electricity from any source, including wind, solar, or other renewable power systems. The hydrogen can be burned like other fuels to provide heat

or power. But more efficiently, it can be used in a fuel cell that combines hydrogen and oxygen electrochemically, a process that produces electricity, heat, and water. A renew- able source of power, an electrolyzer, hydrogen storage tanks, and a fuel cell are all that’s required to create a hydrogen en- ergy system that provides reliable, around-the-clock power. The only emission is pure water.

Turning electricity into hydrogen also addresses an- other limitation of renewable energy. Hydrogen made using electricity effectively converts this energy into a portable fuel, something electric vehicle makers have struggled for years to do with batteries. Battery-electric cars offer great per- formance but have a limited driving range, typically less than 50 miles, because of the bulk and weight of the bat- teries. The average car is driven less than 50 miles a day, but what about longer trips? Hydrogen, used either to power fuel cells or as a clean-burning fuel in hybrid internal com- bustion/electric drive trains, can extend the driving range of electric cars to hundreds of miles.

Many people wonder why, with all its advantages, hy- drogen energy does not yet play a major role in our energy economy. The main hurdles to fuel cell commercialization are high cost and product reliability, but these problems are gradually being resolved by the industry. Another obstacle that hydrogen, like any new fuel, faces is the so-called “chicken and egg” problem. How do you get manufacturers to make and sell fuel cell cars if there are no convenient places to fill them up? At the same time, how do you con- vince energy companies to build expensive new fueling sta- tions if they’re not convinced there will be vehicles coming in to fill up? This dilemma is also being overcome, mainly by government and large companies investing in mini-fleets of hydrogen vehicles and putting in their own fueling sta- tions.

Vehicles, however, will probably turn out to be the last frontier for hydrogen fuel cell power, because conventional internal combustion engines and their fuels remain rela- tively inexpensive. In the meantime, we can expect to see fuel cells widely adopted as a replacement for batteries in small power applications, such as laptop computers and other portable devices. Fuel cells are also being used in re- mote, automated power applications, such as telecommu- nication repeater stations, and for backup stationary power in buildings.

Some people have made exaggerated claims that hy- drogen is a silver bullet that will meet all our future energy needs. The truth is that we will need to use a diverse port- folio of many technologies in the future to generate, trans- port, and store energy. The special properties of hydrogen and fuel cells ensure they will play key roles among these many solutions. Hydrogen is safer and cleaner than the fuels we use today, and its ability to store energy makes it an ideal complement to the renewable power systems that will some day provide most of our electricity.

Hydrogen Is the Key to a Renewable Energy Future © 2007 Schatz Energy Research Center.

Richard Engel Richard Engel is a research engineer at the Schatz Energy Research Center in Arcata, California. His main interests are energy efficiency and renewable hydrogen energy systems.

The Debate over Hydrogen Energy

(continued)

 

 

342 PART IV. Resource Issues: Solutions for a Sustainable Society

COUNTERPOINT

Hydrogen’s role as a universal energy carrier is both well documented and long awaited. Although hydrogen’s poten- tial to provide clean, renewable electricity via fuel cells— those magical devices that convert chemical energy into electricity—warrants continued research, the same can be said for many other technologies including advanced battery systems. Despite predictions to the contrary, battery tech- nology has advanced rapidly. New, more reliable and efficient batteries are now used to power cell phones, computers, and power tools. They are even being used in the newest gen- eration of electric and plug-in electric hybrid vehicles or PHEVs—the very applications in which hydrogen fuel cells were predicted to dominate but have failed to appear. Like- wise, questions about battery materials toxicity are becom- ing moot: Batteries are self-contained and can be completely recycled (the lead-acid battery industry has practiced recy- cling for over a century).

Why hasn’t hydrogen enjoyed similar success? Here are a few reasons:

1. Generating, storing, and then producing electricity from hydrogen is a circuitous process. The roundtrip, overall efficiency (electric energy in vs. electric en- ergy out) is seldom better than 25%. Battery systems score much higher with roundtrip efficiencies exceed- ing 80% in some cases.

2. Hydrogen is difficult to store in quantity, even when compressed under enormous pressure. And while hy- drogen gas packs more energy per unit of weight than any other fuel, it fares rather poorly when it comes to energy per unit volume. In an automotive context, fuel cell vehicles running on hydrogen rank about the same, with respect to mileage, as the latest genera- tion of lithium-ion battery electric vehicles.

3. Fuel cell costs, reliability, durability, and standby losses also continue to foil the adoption of hydrogen as a universal energy carrier. In cars and trucks, fuel cell power trains haven fallen short of their goal; bat- tery systems are leaping ahead with vehicles that can be purchased at a fraction of the price of their fuel cell counterparts. Furthermore, battery electric cars can be recharged at home, work, and, increasingly, electric car-friendly businesses. In point of fact, car manufacturers are steering away from fuel cell vehi- cles and are now concentrating on PHEVs with lithium-ion batteries.

4. Hydrogen safety is still an issue of debatable con- cern. While the use of hydrogen in open air presents little danger, it can create a serious hazard when used in the home.

Admittedly however, the use of batteries to store electric en- ergy makes sense only up to a maximum of perhaps 100 kilo- watt-hours (about as much electricity as a normal household uses in 3 or 4 days). For significantly greater quantities of energy as might be required for air conditioning and heat- ing, the bulk storage and delivery of hydrogen has been of-

fered as a solution. There are, however, less expensive, more practical ways of achieving the same goal:

• The redistribution of renewable electricity to areas (and in forms) as needed is one solution that has failed to receive the attention it deserves. For exam- ple, surplus electricity generated from a rooftop solar electric panel in Ohio or from windmills along the Great Lakes, could be delivered to a bookstore park- ing lot in Michigan to recharge a PHEV while the owner sits inside the store sipping on coffee or so- cializing with friends.

Conversely, this same vehicle represents a signifi- cant reservoir of readily dispatched electricity back into the grid—a two-way process—to help stabilize the supply of electricity during times of peak demand. This technology—V2G or “Vehicle-to-Grid—is a vari- ant of “net metering.” As such, it offers possibilities that are not available with hydrogen that is distrib- uted via a universal pipeline (as proposed by hydro- gen enthusiasts). To be specific, unlike the existing electric grid that allows for a bidirectional flow of electricity, pipelines are “one way” in operation; one cannot simply create hydrogen at home and send it “back down the pipeline” to other users as is done with net metering.

• Heating and air conditioning represent tremendous energy loads; neither batteries nor hydrogen offer reasonable solutions to this problem. In the case of air conditioning, surplus electricity can be converted directly into ice, circumventing the cost and complex- ity of a hydrogen fuel cell system. Many large build- ings use this cost-saving technique—purchasing power at night when it is cheap and refrigerating a large container of water into ice—to achieve cooling during the day. Likewise, heat can be stored directly

Hydrogen’s Role in Our Energy Future Is Dubious Dominic Crea Dominic Crea is a physicist, teacher, and an avid advocate of sensible renew- able energy. He lectures on alternative transportation such as plug-in hybrid vehicles and has been instrumental in dispelling the myths of the hydrogen economy.

You can link to websites that represent both sides through Point/Counterpoint: Furthering the Debate at this book’s internet site, http://environment.jbpub.com/9e/. Evaluate each side’s argument more fully and clarify your own opinion.

 

 

CHAPTER 15: Foundations of a Sustainable Energy System: Conservation and Renewable Energy 343

E ne

rg y

co ns

um pt

io n

(q ua

ds )

0 Time

80

60

40

20

Biomass Geothermal

Wind Gas

Oil

Coal

Solar thermal electric

Hydro

Nuclear Solar electric (photovoltaics)

FIGURE 15-20 Transition to a sustainable energy supply sys- tem. One projection of possible energy resources in the United States. These figures are based on full commitment to renewable resources.

electricity come from? Where will the fuel come from to power the transportation system? What fuels will power industry?

Let’s take these questions one at a time, remembering that energy efficiency will be a key to the success of any future en- ergy system.

Electricity could come from conservation efforts, wind farms, photovoltaics, solar thermal electric systems, fuel cells powered by hydrogen, small-scale hydropower, and geothermal facilities. Biomass facilities and cogeneration could provide additional electricity. One form of biomass, animal manure, could become a major source of energy in the future, helping power farms and rural homes. Eventu- ally, hydrogen may replace natural gas in our kitchens and at power plants. Thus, electricity could come from dispersed as well as centralized sources.

Low- and intermediate-temperature thermal energy (heat) is currently used to heat buildings and power indus- trial processes. It could be generated from solar energy—or from the combustion of various renewable fuels such as bio- mass or hydrogen. Solar sources could be used for home space heating, water heating, and many industrial processes.

Table 15-4 gives a further breakdown of energy demand by sector, showing what kind of energy is needed and how it would be used. The point of this table is that there are options—many of them. They may seem farfetched right now, but as the world turns away from fossil fuels, many al- ternative energy advocates believe that the renewable alter- natives will become increasingly popular.

in the form of chemical or physical changes rather than going through the wasteful processes of gener- ating, storing, and reconverting hydrogen back into electricity.

• Finally, it might make more sense to combine elec- trolyzed hydrogen with carbon dioxide from the air to manufacture methane. This process, while less effi- cient than using the hydrogen onsite, offers the com- pelling benefit of creating a renewable, clean fuel that can be dispatched in our current natural gas (primarily methane) pipeline. (Hydrogen gas cannot be transported in existing pipes that deliver natural gas to homes and businesses.) Furthermore, renew- able methane eliminates all the problems associated with storage, energy density, range, availability, and compatibility that are present with hydrogen. Renew- able methane is being considered seriously; at three times the energy content per unit volume of hydro- gen, it may prove to be the perfect fuel to be used in conjunction with the PHEV. There is a bit of irony when it comes to the hydrogen

economy: because so much has been promised over the years

(and so little actually achieved), time, money, and interest that should have been devoted to other ideas has been lost. As a consequence, rather than unshackling us from our en- ergy dependency, talk of a hydrogen economy has lulled us into complacency and inaction. In the meantime, we have become even more dependent on fossil fuels. Certainly, hy- drogen will play a part in our energy future, but if we fail to recognize its limitations, if we fail to take a renewed look at other, more practical solutions, we may never get a chance to see hydrogen attain its true potential. Sadly, hydrogen’s ultimate legacy may be the undoing of, rather than the sal- vation of, humankind.

Critical Thinking Questions 1. Summarize each author’s main points and supporting

information. 2. Using your critical thinking skills, analyze each view-

point. 3. After studying the essays, do you think hydrogen will

become a major fuel source in the future? Why or why not?

(Continued)

 

 

344 PART IV. Resource Issues: Solutions for a Sustainable Society

KEY CONCEPTS

Economic and Employment Potential of the Sustainable Energy Strategy Numerous studies show that efficiency measures and cer- tain renewable energy technologies “produce” energy more cheaply than conventional sources and eliminate many of the environmental impacts as well. They do this while employing more people than conventional energy supply strategies. The chief reason for this is that effi- ciency and alternative technologies tend to be more labor- intensive (requiring more people) than oil, coal, and nuclear energy, which are more capital-intensive (re- quiring huge investments in machines and fuels). Consider some examples.

A California-style wind farm generates electricity for about 5 cents per kilowatt-hour, one-half the cost of electricity from a nuclear power plant and without the serious envi- ronmental impacts. In addition, a wind farm that produces the same amount of energy as a nuclear power plant will employ over 540 workers, compared to 100 workers in the nuclear facility (FIGURE 15-21).

Not only is renewable energy abundant and accessible without ma- jor technological breakthroughs, it has many applications with suf- ficient potential to replace nuclear and fossil fuel supplies.

Similar gains can be made through energy efficiency. A study in Alaska, for instance, found that state expenditures on weatherization—home energy conservation—would cre- ate more jobs per dollar of investment than the construction of hospitals, highways, or new power plants. Conservation spending, for instance, would create three times as many jobs as highway construction.

Weatherization of all homes in the United States would create 6 to 7 million job-years, according to Worldwatch In- stitute projections. (A job-year is one job for 1 year.) Six million job-years is the equivalent of 300,000 jobs over a period of 20 years! Not all jobs would be low-wage, either. Energy-efficiency companies would be run by well-paid per- sonnel and would employ salespeople, managers, account- ants, engineers, and installers.

A wise energy future is economically, environmentally, and socially sustainable. The current system fails on all of these criteria. Nonetheless, great barriers lie on the path to a sustainable system. One of the most significant is that in- dustrial nations have been built on fossil fuels. Billions upon billions of dollars have been spent on the present fossil fuel- based system. Huge investments have been made in mining and drilling equipment, transportation networks, process- ing facilities, and power plants. Although the system is un- sustainable, enormous resistance to change will come from many powerful political and economic interests: legislators

Table 15-4 Meeting Energy Needs of a Solar-Powered Society

Percentage Demand of Total Sector Sources Application Energy Use

Residential and commercial

Industrial

Transportation

Source: H.W. Kendall and S.J. Nadis (1980). Energy Strategies: Toward a Solar Future. Cambridge, MA: Ballinger, p. 262.

20–25

�5 �10

Subtotal �35 �7.5

�17.5

�10

�5

Subtotal �40 10–20

5–15 Subtotal �25

Total 100

Space heating, water heating, air conditioning

Cooking and drying Lighting, appliances, refrigeration

Industrial and agricultural process heat and steam Industrial process heat and steam

Cogeneration, electric, drive, elec- trolytic, and electrochemical processes Supply carbon sources to chemical industries

Electric vehicles, electric rail Aircraft fuel, land and water vehicles Long-distance land and water vehicles

Passive and active solar systems, district heating systems Active solar heating with concentrating solar collectors Solar thermal, thermochemical, or electrolytic generation Photovoltaic, wind, solar thermal, total energy systems

Active solar heating with flat plate collectors, and tracking solar concentrators Tracking, concentrating solar collector systems Solar thermal, thermochemical, or electrolytic generation Solar thermal, photovoltaic, cogeneration, wind systems

Biomass residues and wastes

Photovoltaic, wind, solar thermal Solar thermal, thermochemical, or electrolytic generation Biomass residues and wastes

 

 

be able to turn their old skills to similar activities. Petro- leum geologists and oil well crews, for example, might use their expertise to drill for geothermal resources.

The transition to a renewable energy system is occurring surely in many parts of the world. Many large corporations are becoming producers and consumers of renewable en- ergy, including General Electric, BP, Shell, Microsoft, Google, and the Philadelphia Eagles football team. Individuals and businesses can help by buying green power, when it is avail- able. Some utilities, for instance, offer electricity from wind sources to customers at a slightly higher cost. Governments can help, too. In 1996, the Canadian government introduced a program to promote renewable energy that includes a va- riety of measures, including tax breaks, grants for private research, and steps to increase demand for green power in the marketplace. The government is even using more renew- able energy in its own facilities. The U.S. government has taken similar steps. The National Renewable Energy Lab, for instance, and many other government labs and facilities are now getting power from solar electricity and wind. Even the White House has been retrofitted with solar electric pan- els. Many states now have passed laws requiring an increase in renewable energy production (mostly wind) in the next decade. Colorado, for instance, will obtain 20% of its en- ergy from renewable sources by 2020.

The length of the transition to renewable energy re- sources will depend on our political will and our willing- ness to change for the sake of the planet’s future.

KEY CONCEPTS

The great end of living is to harmonize man with the order of things.

—Oliver Wendell Holmes

Shifting to a sustainable system of energy will take many years. Several renewable energy technologies provide competitively priced electricity while creating more jobs than fossil fuels and nuclear energy.

600

500

400

300

200

100

0 Nuclear Geothermal Coal Solar

thermal Wind

100 112 116

248

542

Sources

Jo b

po te

nt ia

l

FIGURE 15-21 Comparison of employment opportunities of various energy sources. This graph shows the difference in em- ployment opportunities of different energy strategies, all produc- ing the same amount of energy per year. Renewable resources turn out to be stellar job creators.

CRITICAL THINKING

Exercise Analysis Critical thinking warns us that broad statements—generalizations—such as those made by the supposed energy expert often fall apart on closer examination. A careful analysis of the issue reveals a somewhat different picture of reality—one much more favorable for solar energy.

Solar energy, as noted in this chapter, consists of at least four different technologies. One of them, solar thermal electric, is currently cost competitive with nuclear power. Solar thermal electric plants use sunlight to heat water or some other fluid, which is then converted into steam to run an electric turbine.

Another form of solar energy is solar electricity generated from photovoltaics (panels on rooftops that convert sunlight energy into electricity). Photovoltaics are not currently cost competitive with conven- tional fossil fuel resources in most applications in developed countries. It would cost a fortune for most homeowners, for instance, to add panels to their roofs to supply their homes with electricity.

from energy-producing states, coal and oil companies, and the power companies, which expect to profit from their investments.

Creating a sustainable system of energy will take many years. As fossil fuels and nuclear plants become obsolete, they can be replaced by renewable energy sources such as wind or solar energy. Some parts of the current energy sys- tem, such as electric lines, can be used to transport solar- and wind-generated electricity.

Shifting to renewable energy resources and conserva- tion will also require massive amounts of investment capi- tal to finance wind farms, geothermal plants, and so on. Although the shift to a sustainable energy strategy could create many new economic opportunities, jobs will be lost in some sectors. But if proponents are right, many more jobs will open up than will be lost. Not only will there be more jobs, but they will undoubtedly be safer. Some workers will

CHAPTER 15: Foundations of a Sustainable Energy System: Conservation and Renewable Energy 345

 

 

346 PART IV. Resource Issues: Solutions for a Sustainable Society

In rural villages in the developing world, however, photovoltaics are quite cost-competitive because the expense incurred by running power lines to remote sites is astronomical. Even in developed countries such as the United States, though, photovoltaics can make sense. If a house is only half a mile from a power line, it is often more economical to install photovoltaics than to run a power line to the house.

Another solar technology is passive solar heating—that is, heating buildings with sunlight energy that streams in through south-facing windows. Passive solar often costs more, but it can be built econom- ically. The author’s house cost no more than a conventional home and is heated almost entirely by the sun, saving several thousand dollars a year.

This exercise also shows that it is important to define what is meant by various terms, such as uneco- nomic. Does the term refer only to conventional economics, which ignores costs such as damage to the environment? In this case, the oil industry spokesperson is talking only about the cost of producing con- ventional fuels. He’s ignoring the enormous external costs from planetary warming, acid deposition, and urban air pollution.

Along that same line, does the cost of production include subsidies? As this chapter points out, oil in the United States is very heavily subsidized by the federal government. The nuclear and coal industries are also heavily subsidized. If subsidies were removed, they would be far less affordable, and many solar tech- nologies would appear quite competitive. Thus, this exercise also shows the importance of considering the source of information that may be biased by economic self-interest.

CRITICAL THINKING AND CONCEPT REVIEW 1. In your view, is it imperative that we change to a sus-

tainable energy system? Why or why not? 2. Describe the types of solar energy technologies avail-

able. How does each one operate? What is it used for? Which ones are already cost competitive with current energy technologies?

3. What are the advantages and disadvantages of solar energy? How can the problems with the technologies be solved?

4. A person living in the Pacific Northwest argues that re- newable energy is useless. The sun rarely shines in his neck of the woods. How would you answer this?

5. Describe the difference between passive and active so- lar systems. What features are needed in a home to make passive solar energy work?

6. What are photovoltaic cells? Why are they economical to use in rural villages in the developing nations and in semi-remote sites in developed countries?

7. Wind energy is cost-competitive with conventional electricity from coal and cheaper than nuclear en- ergy. Should we develop this energy resource in preference to nuclear power, coal, or shale oil? Why or why not?

8. What is biomass? How can useful energy be acquired from biomass?

9. How is geothermal energy formed? How can it be tapped? Describe the benefits and risks of geothermal energy.

10. Using your critical thinking skills, debate the following statement: “Hydroelectric power is an immensely un- tapped resource in the United States and could provide an enormous amount of energy.”

11. What are the major problems facing hydrogen power? How could these be solved?

12. Using your critical thinking skills, discuss the following statement: “Conservation is our best and cheapest en- ergy resource.”

13. Discuss ways in which you could conserve more en- ergy at home, at work, and in transit. Draw up a rea- sonable energy conservation plan for yourself and your family.

14. Using your critical thinking skills, debate this state- ment: “A sustainable energy strategy won’t work. It will cost money and lose jobs.”

15. List and describe the barriers to creating a sustainable energy supply system. How could they be overcome?

 

 

KEY TERMS biodiesel biomass cogeneration conservation earth-sheltered house The Efficiency and Alternative Energy

program electrolyzer Energy Efficiency Act Energy Star Homes program Energy Star label flat plate collectors

fuel cell geopressurized zones geothermal energy green building green building programs gross national product (GNP) hot-rock zones hybrids hydroelectric power hydrogen Hydrogen Future Act hydrothermal convection zones

least cost planning Motor Vehicle Safety Act National Appliance Conservation Act National Model Energy Code Natural Resources Canada net zero energy passive solar heating system second law of thermodynamics solar collectors Super Energy-Efficient Home program

Connect to this book’s website: http://environment.jbpub.com/9e/ The site features eLearning, an online review area that provides quizzes, chapter outlines, and other tools to help you study for your class. You can also follow useful links for in-depth information, research the differing views in the Point/Counterpoints, or keep up on the latest environmental news.

REFERENCES AND FURTHER READING To save on paper and allow for updates, additional reading recommendations and the list of sources for the information discussed in this chapter are available at http://environment .jbpub.com/9e/.

CHAPTER 15: Foundations of a Sustainable Energy System: Conservation and Renewable Energy 347

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