Energy Conservation

Energy Conservation and Efficiency

Energy conservation is the efficient use of energy, without necessarily curtailing the services that energy provides. Conservation occurs when societies develop efficient technologies that reduce energy needs. Environmental concerns, such as acid rain and the potential for global warming, have increased public awareness about the importance of energy conservation.

Energy efficiency can be measured by two indicators. The first is energy consumption per person (per capita) per year. Annual per person energy consumption in the United States was 214 million British thermal units (Btu) in 1949. (See Figure 9.1.) It topped out at 359 million Btu in 1978 and 1979; dropped to 313 million Btu by 1983; and then slowly rose until it reached 352 million Btu in 2000. It leveled off through 2007, when the annual rate of consumption per capita was 337 million Btu.

The second indicator of efficiency is energy consumption per dollar of gross domestic product (GDP; the total value of goods and services produced by a nation). When a country grows in its energy efficiency, it uses less energy to produce the same amount of goods and services. In 1949 Americans paid about $19.00 per 1,000 Btu of energy. (See Figure 9.2.) In 1970 this rate decreased to $17.99 per 1,000 Btu of energy, and by 2007 Americans paid $8.78 per 1,000 Btu of energy.

Energy Conservation, Public Health, and the Environment

People living in cities with high levels of pollution have higher risks of mortality from certain diseases than those living in less polluted cities. Energy-related emissions generate a vast majority of these polluting chemicals. (Table 4.3 in Chapter 4 shows some air pollutants and their sources.) According to the American Lung Association, air pollution has been related to diseases such as asthma, bronchitis, emphysema, and lung cancer. The association estimates the annual health costs of exposure to the most serious air pollutants to be in the billions. Clean and efficient energy technologies, it states, represent a cost-effective investment in public health.

Global warming is long-term climate change—a worldwide temperature increase—caused by the green-house effect. This occurs when heat is trapped within the atmosphere by high levels of carbon dioxide, methane, nitrogen oxide, hydrofluorocarbons, sulfur dioxides, and perfluorocarbons. Just as the glass of a greenhouse or the windows of a car trap heat, the greenhouse gases keep the earth warmer than it would be if the atmosphere contained only oxygen and nitrogen.

The Intergovernmental Panel on Climate Change

In 1988 the United Nations established the Intergovernmental Panel on Climate Change (IPCC), a group of two thousand of the world’s leading scientists. The IPCC reported in Climate Change 1995 that climate change, which includes temperature rise (global warming), sea-level rise, precipitation change, and extreme climatic events, is real, serious, and accelerating. (This and other IPCC assessment reports can be accessed at http://www.ipcc.ch/ipccreports/assessments-reports.htm) The most likely cause, the IPCC said, is primarily the burning of coal, oil, and gasoline, which has increased the amount of carbon dioxide and other green-house gases in the atmosphere. Deforestation is another factor, because it reduces the amount of carbon dioxide that can be absorbed and stored in plants.

In its third assessment report, Climate Change 2001, the IPCC said it had a clearer understanding of the causes and consequences of climate change, largely because so much climate research and environmental monitoring had been undertaken. The IPCC described the effect that global warming would have on weather patterns, water resources, the seasons, ecosystems, and extreme climate events, and it urged governments to move quickly with policies to protect the planet.

In 2007 the IPCC won the Nobel Peace Prize, which was shared with the former vice president Albert Gore Jr. (1948–), for two decades of scientific reports on global warming and other climate change issues and their relationship to human activity. Also in 2007 the IPCC published its fourth assessment report, Climate Change 2007. The report noted that climate change, including global warming, was ‘‘unequivocal,’’ meaning that it is a certainty and undeniable. The report is extensive, but a few of its key points are that many natural systems are being affected by climate change and that some of the effects of climate change can be reduced, delayed, or avoided by taking action now, such as by reducing our emissions of greenhouse gases. The IPCC report forecasts that the earth will warm approximately 0.4° Fahrenheit (0.2°C) per decade.

The Kyoto Protocol

In December 1997 the United Nations convened a 160-nation conference on global warming in Kyoto, Japan, to develop a treaty on climate change that would place binding caps on industrial emissions. The initial draft of the treaty, called the Kyoto Protocol to the United Nations Framework Convention on Climate Change (or simply the Kyoto Protocol), bound industrialized nations to reducing their emissions of six greenhouse gases below 1990 levels. It marked the first time nations made such sweeping pledges to cut emissions.

Each country had a different target to reach by 2012: the United States was to cut emissions by 7%, most European nations by 8%, and Japan by 6%. Reductions were to begin by 2008. Developing nations were not required to make such pledges. The United States had proposed a program of voluntary pledges by developing nations, but that section was deleted, as was a tough system of enforcement. Instead, each country was to decide for itself how to achieve its goal. The draft treaty provided market-driven tools for reducing emissions. For example, nations would be allowed to sell emissions credits to other nations. The draft treaty also set up a Clean Development Fund to help poorer nations with technology to reduce their emissions.

Getting the treaty ratified proved difficult, however. President Bill Clinton (1946–) signed the protocol, but the U.S. Senate did not ratify it. To save the treaty, diplomats from 178 nations met in Bonn, Germany, in July 2001 and drafted a compromise treaty. In October 2001 two thousand delegates from 160 countries worked for twelve days in Marrakech, Morocco, to complete a final draft of the Kyoto Protocol.

President George W. Bush (1946–) (June 11, 2001, http://www.climatevision.gov/statements.html) rejected that final draft of the Kyoto Protocol, characterizing it as ‘‘fatally flawed.’’ He said implementation of the treaty would harm the U.S. economy and unfairly require only the industrial nations to cut emissions. In particular, he noted that neither China, the world’s second largest emitter of greenhouse gases, nor India, another high emitter, were bound by the protocol. He said at the time:

Our country, the United States, is the world’s largest emitter of manmade greenhouse gases. We account for almost 20 percent of the world’s man-made greenhouse emissions. We also account for about one-quarter of the world’s economic output. We recognize the responsibility to reduce our emissions. We also recognize the other part of the story—that the rest of the world emits 80 percent of all greenhouse gases. And many of those emissions come from developing countries . . . .

We recognize our responsibility and will meet it—at home, in our hemisphere, and in the world. My Cabinet-level working group on climate change is recommending a number of initial steps, and will continue to work on additional ideas. The working group proposes the United States help lead the way by advancing the science on climate change, advancing the technology to monitor and reduce greenhouse gases, and creating partnerships within our hemisphere and beyond to monitor and measure and mitigate emissions.

When Russia ratified the treaty in November 2004, the Kyoto Protocol had support from countries whose emissions totaled 55% of the world’s greenhouse gases, which was the minimum needed for the treaty to go into effect. At the end of that year, 130 countries had signed on, including all the European Union members, Japan, and Norway. The Kyoto Protocol took effect on February 16, 2005, without the support of the United States and Australia.

U.S. attitudes about the Kyoto Protocol varied widely. Most business leaders said the treaty went too far and was too costly for the U.S. economy, whereas environmentalists said the treaty’s standards did not go far enough. Some experts doubted that any action emerging from Kyoto would be sufficient to prevent the doubling of greenhouse gases. In May 2005—in response to the Bush administration’s policies—mayors from 132 cities in the United States joined a bipartisan coalition to fight global warming on the local level. The coalition pledged to have their cities meet Kyoto Protocol requirements for the United States: a reduction of heat-trapping gas emissions to 7% below 1990 levels by 2012.

Is Kyoto working? In ‘‘Time to Ditch Kyoto’’ (Nature, vol. 449, October 25, 2007), Gwyn Prins and Steve Rayner suggest that the Kyoto Protocol has failed to achieve green-house gas emissions reductions and slow global warming thus far. They suggest that including so many countries in the treaty was a mistake, making the initiative unwieldy. Prins and Rayner note that ‘‘fewer than 20 countries are responsible for about 80% of the world’s emissions,’’ so they suggest that only those countries be targeted. The researchers urge that those high-emissions countries should spend as much money on climate change research as they spend on their military. In addition, Prins and Rayner support a bottom-up approach to the problem, in which ‘‘countries would choose policies that suit their particular circumstances.’’ Paul Vallely reports in ‘‘The Big Question: Is the Kyoto Treaty an Outdated Failure Based on the Wrong Premises?’’ (The Independent [London, England], October 26, 2007) that other scientists and researchers believe that huge investments are needed in climate change research but are wary of abandoning the Kyoto process, which might delay progress as new international agreements are constructed.

Levels of greenhouse gas emissions for the United States for 1990, 1995, and from 2000 through 2006 are shown in Table 9.1 in teragrams (Tg) of carbon dioxide equivalents. A teragram is a trillion grams. Each gas in the table is reported by its global-warming potential in teragrams, which allows these numbers to be compared. Higher numbers indicate greater harm done to the environment by the gas. Conversely, numbers in parentheses are for sources, such as land-use change and forestry, which reduce greenhouse gas emissions by the carbon equivalents shown. In 2006 emissions of greenhouse gases in the United States reached 7,054.2 Tg, which was 905.9 Tg (15%) higher than emissions in 1990.

Energy Efficiency in Transportation

The U.S. transportation system plays a central role in the economy. Highway transportation is dependent on vehicles with internal combustion engines, which are fueled almost exclusively by petroleum. According to the Energy Information Administration (EIA), in Annual Energy Review 2007 (June 2008, http://www.eia.doe.gov/aer/pdf/aer.pdf), the transportation sector accounted for nearly 29% of all energy consumed in the United States in 2007. Americans used 29 quadrillion Btu of energy for transportation that year, of which petroleum made up 97%. Despite the improvements in transportation efficiency in recent decades, the EIA predicts in Annual Energy Outlook 2008 (June 2008, http://www.eia.doe.gov/oiaf/aeo/pdf/0383(2008).pdf) that the transportation sector will consume 33 quadrillion Btu in 2030.

Automotive Efficiency

Policy makers interested in the energy used for transportation have an array of conservation options. (See Table 9.2.) However, not all options are mutually supportive. For example, efforts to promote a freer flow of automobile traffic, such as high-occupancy vehicle lanes or free parking for car pools, may sabotage efforts to shift travelers to mass transit or to reduce trip lengths and frequency.

In the United States light-duty vehicles dominate the transportation sector; cars, light trucks, and motorcycles used 60.1% of all transportation energy in 2006, as reported by the U.S. Department of Energy’s Center for Transportation Analysis, in Transportation Energy Data Book: Edition 27 (2008 http://cta.ornl.gov/data/tedb27/Edition27_Full_Doc.pdf). Furthermore, the EIA notes in Annual Energy Review 2007 that motor gasoline, which is divided among passenger cars, motorcycles, light-and heavy-duty trucks, and miscellaneous other modes of transportation, made up 45% of the total petroleum products supplied in the United States in 2007.

The major growth in fuel use since the 1970s has been that consumed by trucks, whereas fuel consumption

by vans, pickup trucks, and sport utility vehicles increased slightly during the 1970s, but has since slowly dropped. (See Table 9.3.) Fuel consumption by passenger cars rose slightly in the early 1970s, then dropped slightly in the mid-1970s, leveling off for a few years, dropping slightly once again in 1980, and remaining fairly constant since then. The use of automobile fuel has remained fairly constant because increases in fuel efficiency have offset the growth in car miles traveled. Boosting efficiency of all vehicles, especially trucks, will become increasingly important in controlling the demand for oil.

The Corporate Average Fuel Economy Standards. The 1973 oil embargo by the Organization of the Petroleum Exporting Countries painfully reminded the United States how dependent it had become on foreign sources of fuel. It prompted Congress to pass the 1975 Energy Policy and Conservation Act, which set the initial Corporate Average Fuel Economy (CAFE) standards. The standards were modified in 1980 with the Automobile Fuel Efficiency Act.

The standards required domestic automakers to increase the average mileage of new cars sold to 27.5 miles per gallon (mpg; 8.6 L/100 km) by 1985. Manufacturers could still sell large, less efficient cars, but to meet the average fuel efficiency rates, they also had to sell smaller, more efficient cars. Automakers that failed to meet each year’s standards were fined; those that managed to surpass the rates earned credits that they could use in years when they fell below the requirements. Even though keeping their cars relatively large and roomy, companies managed to improve mileage with innovations such as electronic fuel injection, which supplied fuel to an automotive engine more efficiently than its predecessor, the carburetor.

The standards have had a significant effect. (See Table 9.3.) Fuel economy of all motor vehicles (which includes passenger cars, vans, pickup trucks, sport utility vehicles, and trucks) increased from 11.9 mpg (19.8 L/100 km) in 1973 to 17.2 mpg (13.7 L/100 km) in 2006. Greater gains have been made in the economy of passenger cars. In 1974, just after the oil embargo, cars averaged 13.6 mpg (17.3 L/100 km); in 2006 the average new-car fuel economy was 22.4 mpg (10.5 L/100 km).

The U.S. Environmental Protection Agency (EPA) computes the data in a different way by using a procedure called an adjusted real-world estimate, which takes into account factors that affect fuel economy, such as higher highway speeds, more aggressive driving, and greater use of air conditioning than in previous years. Using this estimate, the EPA indicates that the fuel economy of cars and trucks increased rapidly from 1975 to the early 1980s. (See Figure 9.3.) The increase slowed through 1987, declined gradually through 2004, and then increased slightly.

Cheap gasoline prices throughout the 1990s took away the sense of urgency surrounding fuel efficiency, which was demonstrated by the high growth of large-vehicle sales. (See Figure 9.4.) In addition, after repeal of the federal law that set the speed limit at 55 miles per hour (88.5 km/hr), many states allowed higher speed limits, which lowered fuel efficiency.

The total fuel economy of automobiles is expected to increase, however, as more fuel-efficient cars enter the market and older, less fuel-efficient autos drop out of operation. Nonetheless, new-car fuel economy has risen only slightly since 1986, and nearly all gains in automobile efficiency have been offset by increased weight and power in new vehicles since 1988. Recently, however, changes have been made to the CAFE standards.

During President Bush’s administration (2001 to 2009), changes were made twice to the CAFE standards by increasing mileage requirements for light trucks. The president also addressed fuel efficiency standards for passenger vehicles in his 2007 State of the Union address, with a ‘‘Twenty in Ten’’ policy (January 2007, http://www.whitehouse.gov/stateoftheunion/2007/initiatives/energy.html) of reducing by 20% the amount of gasoline Americans used within the next ten years by increasing the CAFE standards and using alternative fuels. Congress responded by developing the Energy Independence and Security Act (EISA) of 2007, which mandated that fuel producers make at least 36 billion gallons (136.3 billion L) of biofuel annually by 2022. EISA also required that the CAFE standard be raised for cars and light trucks to 35 miles per gallon (6.7 L/100 km) by model year 2020.

On April 22, 2008, the U.S. secretary of transportation Mary Peters (1948–; http://www.dot.gov/affairs/peters042208.htm) announced new proposed fuel standards that would achieve a 25% improvement in fuel economy between 2010 and 2015—a 4.5% average annual increase. (The mandate from Congress had been at least a 3.3% average annual increase in fuel economy.) For automobiles, a 25% increase in fuel economy would mean raising the mpg average from 27.5 to 35.7 (8.6 L to 6.7 L/100 km). For light trucks, that would mean raising the mpg average from 23.5 to 28.6 (10 L to 8.2 L/100 km). Peters projected that these fuel economy increases would save nearly 55 billion gallons (208.2 L) of fuel and $100 billion in fuel costs over the lifetime of the affected vehicles.

Alternative Fuel Vehicles

Numbers And Types. In 2003, 533,999 alternative fuel vehicles were on U.S. roads. (See Table 9.4.) By 2006 this total had increased to 634,562. These totals include vehicles originally manufactured to run on alternative fuels as well as gasoline or diesel vehicles that had been converted. The manufacture of new alternative fuel vehicles has increased steadily.

A number of different types of fuels are used in these vehicles (see Table 9.4):

• Compressed natural gas is natural gas that is stored in pressurized tanks. When burned, it releases one-tenth the carbon monoxide, hydrocarbon, and nitrogen of gasoline. It powered 18% of alternative fuel vehicles in 2006.
• Electricity, used by 8% of alternative fuel vehicles in 2006, can be used for battery-powered, fuel-cell, or hybrid vehicles.
• Ethanol is ethyl alcohol, a grain alcohol, mixed with gasoline and sold as gasohol. The 85% formulation of gasohol was the most common fuel for alternative fuel vehicles in 2006, powering 47% of them.

• Hydrogen is a gas, but its pure, gaseous form is not found in nature. It must be made from other energy sources, such as fossil fuels. In hydrogen fuel cells, oxygen and hydrogen react to produce water and electricity. Alternatively, hydrogen can be burned in an engine, much like gasoline. Less than 0.1% of alternative fuel vehicles were powered by hydrogen in 2006.
• Liquefied natural gas is primarily methane that has been liquefied by reducing its temperature to -260° Fahrenheit (-162.2°C). It was used by only 0.4% of all alternative fuel vehicles in 2006.
• Liquefied petroleum gas is a mixture of propane and butane. Twenty-six percent of all alternative fuel vehicles ran on liquefied petroleum gas in 2006.
• Biodiesels (not listed in Table 9.4) are liquid biofuels made from soybean, rapeseed, or sunflower oil. They can also be made from animal tallow and from agricultural by-products such as rice hulls.

In 2006 the largest numbers of alternative fuel vehicles (not including hybrid vehicles) were being used in California (105,594), Texas (92,968), Florida (29,280), New York (28,064), and Arizona (26,862). (See Table 9.5.) In 2006 manufacturers made available 1,723 alternative fuel buses (not including those already in operation). Most were transit buses (See Table 9.6.)

Alternative Fuel Vehicles and the Marketplace. A fuel supply must be readily available if alternative fuel vehicles are to become a viable transportation option. Ideally, an infrastructure for supplying alternative

fuels would be developed simultaneously with the vehicles. Table 9.7 shows the types and numbers of alternative fuel stations available in each state. In July 2008, 5,689 alternative fueling sites were in operation in the United States.

In the early days of the automobile, electric cars outnumbered vehicles with internal combustion engines. However, with the introduction of technology for producing low-cost gasoline, electric vehicles fell out of favor. As cities became choked with air pollution, the idea of an efficient electric car reemerged. To make it acceptable to the public, several considerations have had to be addressed: How many miles could an electric car be driven before it needed to be recharged? How lightweight would the vehicle need to be? And could the electric car keep up with the speed and driving conditions of busy freeways and highways?

Electric vehicles can be battery powered, run on fuel cells, or be hybrids, which are powered by both an electric motor and a small conventional engine. EV1, a two-seater by General Motors (GM), was the first commercially available electric car. In 1999 the company introduced its second-generation electric car, the Gen II, which used a lead-acid battery pack and had a driving range of approximately

95 miles (153 km). The Gen II was also offered with an optional nickel-metal hydride battery pack, which increased its range to 130 miles (209 km). However, after the California Air Resources Board relaxed automobile-emissions requirements by phasing them in through 2017 rather than by 2003, GM found that it could no longer market the electric cars effectively. When leases on the cars ran out in 2003, GM began reclaiming them.

Fuel-cell electric vehicles use an electrochemical process that converts a fuel’s energy into usable electricity. Fuel cells produce very little sulfur and nitrogen dioxide and generate less than half the carbon dioxide of internal combustion engines. Rather than needing to be recharged, they are simply refueled. Hydrogen, natural gas, methanol, and gasoline can all be used with a fuel cell.

DaimlerChrysler’s Mercedes-Benz division unveiled the first driveable fuel-cell car in 1999. Called the New Electric Car, it produced zero emissions, ran on liquid hydrogen, and traveled 280 miles on a full 11-gallon (42-L) tank. Since then, several models have been road tested. Ecostar, an alliance between Ford, DaimlerChrysler, and Ballard Power Systems, is also working on developing new fuel cells to power vehicles. In his 2003 State of the Union address, President

Bush announced the Hydrogen Fuel Initiative (http://www1.eere.energy.gov/hydrogenandfuelcells/presidents_initiative.html), which appropriated funds and set a research agenda to bring hydrogen and hydrogen fuel cell vehicles to consumers by 2020. In 2006 about three hundred fuel cell cars were being tested worldwide. Harry Stoffer reports in ‘‘Study: Hydrogen Research Worth the Cost’’ (Automotive News, March 24, 2008) that in March 2008 the National Research Council released a comprehensive study on research progress on hydrogen and hydrogen fuel cell vehicles. The council concluded that considerable progress had been made and that the research had the potential to provide enormous benefits to Americans.

In 2008 hybrid cars were the type of alternative fuel vehicle primarily available to consumers. Hybrid cars have both an electric motor and a small internal combustion engine. A sophisticated computer system automatically shifts from the electric motor to the gas engine, as needed, for optimum driving. The electric motor is recharged while the car is driving and braking. Because the gasoline engine does only part of the work, fuel economy is high. The engines are also designed to produce low emissions.

The commercialization of hybrid cars began in 2002 in the United States with the Toyota Prius, a sedan with front and back seating, and the two-passenger Honda Insight. Both cars were sold in Japan for several years before being introduced to the U.S. market. In model year 2005 Ford offered the first hybrid sport utility vehicle, the Escape, which won the 2004 North American Truck of the Year Award. The vehicle was reported to get 35 mpg (6.7 L/100 km) with city driving and traveling about 400 miles (644 km) on a 15-gallon (57-L) tank. By model year 2006, many auto manufacturers— including Honda, Ford, Toyota, Lexus, and Mercury—offered gas-electric hybrids. Table 9.6 shows the number of alternative fuel and hybrid vehicles, by vehicle type, made available in the United States in 2006. By model year 2008, Chevrolet, GMC, Mazda, Nissan, and Saturn offered hybrid car models to consumers as well.

Mandating Alternative Fuels. Several laws have been passed to encourage or mandate the use of vehicles powered by fuels other than gasoline. The Clean Air Act Amendments of 1990 required certain businesses and local governments with fleets of ten or more vehicles in twenty-one metropolitan areas to phase in alternative fuel vehicles over time—20% of those fleets had to be alternative fuel vehicles by 1998. Even though great strides have been made, compliance with the mandates cannot be determined because reporting and enforcement methods are inadequate.

The Energy Policy Act of 1992 was passed in the wake of the 1991 Persian Gulf War to conserve energy and increase the proportion of energy supplied domestically. It required that 75% of all vehicles purchased by the federal government in 1999 and thereafter be alternative fuel vehicles. Agency budget cuts and inadequate enforcement have slowed compliance with these regulations. Still, many municipal governments and the U.S. Postal Service have put into operation fleets of natural gas vehicles, such as garbage trucks, transit buses, and postal vans. The number of alternative fuel and hybrid trucks and buses made available by manufacturers in 2006 is shown in Table 9.6.

Air Travel Efficiency

Flying carries an environmental price, as it is an energy-intensive form of transportation. In much of the industrialized world, air travel is replacing more energy-efficient rail or bus travel. According to the Bureau of Transportation Statistics (2008, http://www.bts.gov/publications/national_transportation_statistics/html/table_04_05.html), jet fuel consumption rose from 12.7 billion gallons (47.9 billion L) in 1995 to 13.5 billion gallons (50.9 billion L) in 2006.

Jet fuel consumption affects global warming. Airplanes spew nitrogen oxide and carbon dioxide into the air, much of it while cruising in the tropospheric zone, which is about 5 miles (8 km) above the planet, where ozone is formed. (See Figure 9.5.) The IPCC notes that emissions deposited directly into the atmosphere do greater harm than those released at ground level. In Aviation and the Environment: Aviation’s Effects on the Global Atmosphere Are Potentially Significant and Expected to Grow (February 2000, http:// www.gao.gov/new.items/rc00057.pdf), the U.S. General Accounting Office (now the U.S. Government Accountability Office) estimates that in 2000 air traffic accounted for about 3% of all global greenhouse warming. Jane Kay reports in ‘‘There’s Something in the Air’’ (San Francisco Chronicle, December 5, 2007) that by 2007 the EPA reported it accounted for up to 12% of the greenhouse gases produced by all forms of transportation in the United States. For this reason, and because air traffic is expected to rise, the EPA reduced the limits on emissions of nitrogen oxides for new commercial aircraft engines beginning in 2005.

Even though each generation of airplane engines gets cleaner and more fuel efficient, there are also other engines in the airline industry—those in the trucks, cars, and carts that service airplane fleets. Electric utility companies, including the Edison Electric Institute and the Electric Power Research Institute, launched a program in 1993 to electrify airports. By converting terminal transport buses, food trucks, and baggage-handling carts to electricity, airports could reduce air pollution considerably. As of December 2005, only a few U.S. airports and airlines were operating significant numbers of electric ground support equipment.

In Cost Benefit Analysis Modeling Tool for Electric vs. ICE Airport Ground Support Equipment—Development and Results (February 2007, http://avt.inl.gov/pdf/airport/GSECostBenefitSmall.pdf), Kevin Morrow, Dimitri Hochard, and James Francfort evaluate the costs associated with airports operating their current baggage tractors, belt loaders, and pushback tractors versus the costs associated with changing to and operating electric versions of this equipment. Morrow, Hochard, and Francfort provided airports with the tools necessary to conduct their own cost-benefit analyses for their own particular situations, and they conclude that replacing current baggage tractors and belt loaders with electric equipment would be cost-effective and that replacement of pushback tractors could be cost effective if implemented properly.

Residential and Commercial Conservation

Total energy use in buildings in the United States has increased because the numbers of people, households, and offices has increased. However, energy use per unit area (commercial) or per person (residential) has roughly stabilized due to a variety of efficiency measures. The sources of energy in buildings have changed dramatically. The use of fuel oil has dropped, with natural gas making up most of the difference. At the same time, other energy demands have risen. Electronic office equipment, such as computers, fax machines, printers, and copiers, has sharply increased electricity loads in commercial buildings. According to the EIA, in Annual Energy Review 2007, energy use in the residential and commercial sectors accounted for an increasing share of total U.S. energy consumption: 29% in 1950, 33% in 1970, and 39% in 2007.

Building Efficiency

Energy conservation in buildings in both the residential and commercial sectors has improved considerably since the early 1980s. Among the techniques for reducing energy use are advanced window designs, ‘‘daylighting’’ (letting light in from the outside by adding a skylight or building a large building around an atrium), solar water heating, landscaping, and planting trees.

Residential energy consumption has been reduced by building more efficient new housing and appliances, improving energy efficiency in existing housing, and building more multiple-family units. Also, many people have migrated to the South and West, where their combined use of heating and cooling has generally been lower than usage in other parts of the country.

In the residential sector the largest share of energy savings has been the result of better construction, higher quality insulation, and more energy-efficient windows and doors. According to the Department of Energy, in ‘‘Energy Savers: Tips on Saving Energy and Money at Home’’ (May 31, 2006, http://www1.eere.energy.gov/consumer/tips/windows.html), from 10% to 25% of the energy used to heat and cool buildings can be lost through its windows. Before the 1973 energy crisis, most new windows sold were single glazed (only a single pane of glass). By 1990, because of changes in building codes and public interest, most windows sold were double glazed, which dramatically cut energy loss. Double-glazed windows have two panes of glass sandwiched together with a small space in between. The glass may be specially treated or the space between the panes may be filled with a gas, either of which increases the insulating effectiveness of the window.

Overall, however, energy consumption per household has remained fairly steady since 1982. Technology gains have been offset by an increase in the size of new homes and more demand for energy services. (See Figure 9.6.)

As in the residential sector, improved technology, materials, and construction methods have helped slow the growth of energy use in commercial buildings. Glass-walled buildings, especially, have undergone transformation: certain types of glass are now chosen for their ability to divert the heat of the sun and reduce the amount of energy needed for cooling. Like homes, many commercial structures are now designed to take advantage of breezes in the summer and to deflect cold winds in the winter.

Home Appliance Efficiency

The number of households in the United States is increasing, which is increasing the demand for energy-intensive products and services such as air conditioning. According to the EIA, in Annual Energy Review 2007, residential energy use accounted for 21% of total national energy consumption in 2007. In 2001 (the most recent year for which the EIA has compiled data) space heating used 47% of the total residential energy consumed, down from 51% in 1997; appliances 30%, up from 27%; water heating 17%, down from 19%; and air conditioners 6%, up from 4%.

The number of electrical appliances in U.S. households has increased steadily over the past few of decades. (See Figure 9.7.) By 2005 about 99% of American homes had color televisions, 88% had microwave ovens, 83% had clothes washers, and 68% had personal computers.

In 1987 Congress passed the National Appliance Energy Conservation Act, which gave the Department of Energy the authority to formulate minimum efficiency requirements for thirteen classes of consumer products. It could also revise and update those standards as technologies and economic conditions changed. Table 9.8 shows the products affected and the years in which appliance efficiency standards were established or revised for each.

Energy efficiency has increased for all major household appliances but most dramatically for refrigerators and freezers. In Good Stuff? A Behind-the-Scenes Guide to the Things We Buy (2006, http://www.worldwatch.org/system/files/GS0000.pdf), the World Watch Institute explains that since 1972 the energy efficiency of new refrigerators and freezers has more than tripled because of better insulation, motors, compressors, and accessories such as automatic defrost. These improvements have been accomplished at relatively low cost to manufacturers. In addition, efficiency labels are now required on appliances, which makes purchasing efficient models easier.

Besides concerns about efficiency, appliance makers— especially those who make refrigerators and air conditioning systems—are developing alternative cooling techniques to replace chlorofluorocarbons (CFCs), which are ozone-damaging chemicals that can no longer be legally sold in the United States. CFCs were initially substituted with somewhat less dangerous hydrochlorofluorocarbons (HCFCs), but they are now being replaced with hydroflourocarbons (HFCs), which lack chlorine. In Europe other substances, such as propane and butane, are being used as refrigerants. Known as greenfreeze technology, these materials are rapidly replacing HCFCs.

International Comparisons of Conservation Efforts

One test of a country’s efficiency is the amount of energy it consumes for every dollar of goods and services it produces. According to the EIA, in International Energy Annual 2005 (October 2007, http://www.eia.doe.gov/emeu/iea/contents.html), the United States lags behind some industrialized countries in energy efficiency and conservation efforts but is also considerably ahead of others. In 2005 the United States consumed 9,113 Btu per dollar (in 2000 U.S. dollars) of GDP, compared to 7,994 Btu per dollar for France, 7,396 Btu per dollar for Germany, and 4,519 Btu per dollar for Japan. That same year, however, Canada consumed 17,404 Btu per dollar of GDP; Belgium, 10,352 Btu per dollar; and Spain, 9,681 Btu per dollar.

The EIA also determines the carbon intensity of countries by comparing the metric tons of carbon dioxide they produce per thousand dollars of GDP. The figures for 2005 show that the carbon intensity of the United States was substantially higher than that of many other industrialized nations. For example, the carbon intensity of the United States was 0.15, which was equal to that of Belgium. Other industrialized nations’ carbon intensity was lower: Germany’s was 0.12, France’s was 0.08, and Japan’s was 0.07. Spain’s carbon intensity was 0.16, slightly higher than that of the United States, whereas Canada’s was much higher at 0.21.

Future Trends in Conservation

In Annual Energy Outlook 2008, the EIA notes that U.S. total energy consumption is expected to increase at a fairly steady rate from nearly 100 quadrillion Btu in 2006 to about 118 quadrillion Btu in 2030, even with efficiency standards for new equipment taken into consideration. This represents a 19% increase and an average rate of 0.7% per year. Per capita energy use is expected to remain relatively stable from 2006 through 2030. (See Figure 9.8.)

According to the projections, homes will be larger in 2030, but electricity will be used more efficiently. Higher energy prices will encourage conservation. Even though annual personal highway and air travel will increase, efficiency improvements will offset much of that increase. The EIA also suggests that growth will continue in lower energy intensive industries. Thus, energy use per dollar of GDP is expected to decrease at an average annual rate of 1.7% from 2006 to 2030 as energy gains more than offset a higher demand for energy. (See Figure 9.8.)

Transportation fuel efficiency for light-duty vehicles is also projected to improve dramatically from 2006 through 2020 due to EISA, which sets a new CAFE standard of 35 miles per gallon (6.7 L/100 km) for cars and light trucks by model year 2020. After 2020, fuel efficiency in these light-duty vehicles is projected to increase minimally, but fuel efficiency will increase more in higher-priced, high-technology vehicles than in lower-priced vehicles. (See Figure 9.9.)

The EIA predicts that the market for alternative fuel vehicles will grow as a result of EISA. By 2030 about 7.7 million alternative fuel vehicles of all types are expected to be sold in that year—about 42% of total light-duty vehicle sales.