Six Steps to Cut Global Warming Pollution in the …...Rising to the Challenge Six Steps to Cut...

U.S. PIRG Education Fund

Summer 2006

Rising to the ChallengeSix Steps to Cut

Global Warming Pollutionin the United States

Rising to the ChallengeSix Steps to Cut

Global Warming Pollutionin the United States

Tony Dutzik, Frontier GroupEmily Figdor, U.S. PIRG Education Fund

U.S. PIRG Education Fund

Summer 2006

Acknowledgments

The authors wish to thank K.C. Golden of Climate Solutions and Don MacKenzie of theUnion of Concerned Scientists for their incisive review of this report. Thanks also to RobSargent of the National Association of State PIRGs, Alison Cassady of U.S. PIRG Educa-tion Fund, and Susan Rakov and Elizabeth Ridlington of Frontier Group for their editorialassistance and to Travis Madsen of Frontier Group for his technical assistance.

This report is made possible with funding from The Pew Charitable Trusts, New YorkCommunity Trust, and Energy Foundation.

The opinions expressed are those of the authors and do not necessarily reflect the views ofour funders or those who provided editorial review. Any factual errors are strictly the re-sponsibility of the authors.

Copyright 2006 U.S. PIRG Education Fund

With public debate around important issues often dominated by special interests pursuingtheir own narrow agendas, U.S. PIRG Education Fund offers an independent voice thatworks on behalf of the public interest. U.S. PIRG Education Fund, a 501(c)(3) organiza-tion, works to preserve the environment, protect consumers and promote good govern-ment. We investigate problems, craft solutions, educate the public, and offer Americansmeaningful opportunities for civic participation.

Frontier Group is the research arm of the state Public Interest Research Groups (PIRGs)and affiliated environmental organizations. Frontier Group provides research and policyanalysis designed to support state-based advocacy for a cleaner, healthier and more demo-cratic society. www.frontiergroup.org

For additional copies of this report, please visit www.uspirg.org, or send $20 to:U.S. PIRG Education Fund218 D St. SEWashington, DC 20003

Harriet Eckstein Graphic Design

Table of Contents

Executive Summary 5

Introduction 9

Global Warming: The Need for Immediate Action 11Global Warming Is Happening 11Human Activities Are Causing Global Warming 13Global Warming Emissions Are Rising 15Global Warming Will Have a Severe Impact—Unless We Begin to Act Now 17

Six Steps to Reduce Global Warming Emissions 19Step 1: Stop growth in vehicle travel 19Step 2: Increase fuel economy standards to 40 MPG by 2020

and create fuel economy standards for heavy-duty trucks 22Step 3: Replace 10 percent of vehicle fuel with clean biofuels

or other clean options 25Step 4: Reduce energy consumption in homes, businesses and

industry by 10 percent 29Step 5: Obtain 20 percent of electricity from new renewables by 2020 32Step 6: Hold emissions from other parts of the economy to current levels 35

Conclusion and Recommendations 36

Methodology 39

Notes 43

4 Rising to the Challenge

Executive Summary 5

Executive Summary

E xtensive scientific evidence demon-strates that global warming is real, thatit is affecting us now, and that human

activities—particularly the burning of fos-sil fuels—are the primary cause.

Science is also clear about what we needto do to address the problem: immediatelyand significantly reduce emissions of thepollutants that cause global warming.Avoiding the worst consequences of globalwarming will require the United States andother industrialized countries to stabilizeemissions within the next decade andreduce them by about 80 percent by mid-century.

Achieving those reductions won’t beeasy, but it can be done. By improving theefficiency with which we use fossil fuels andincreasing our use of clean, renewable en-ergy, the United States can reduce its glo-bal warming emissions in the near future,while putting America on a path towarddramatically lower global warming emis-sions in the decades to come.

This report lists six challenging but fea-sible strategies that, if implemented, couldachieve these reductions, while improvingAmerica’s environment and our energysecurity.

Global warming is real, is happeningnow, and poses a serious threat toAmerica’s future.

• Global average temperatures increasedby 1˚ F in the 20th century and are nowincreasing at a rate of about 0.36˚ F perdecade. Sea levels are on the rise, iceand snow cover are decreasing, andhurricane intensity has increased.

• The consensus view of the scientificcommunity is that most of the globalwarming that has occurred is due tohuman activities—particularly theburning of fossil fuels. Fossil fuelconsumption releases carbon dioxide,which traps the sun’s radiation near theearth’s surface. Since 1750, the con-centration of carbon dioxide in theatmosphere has increased by 35percent—a rate of increase unprec-edented in the last 20,000 years.

• Should the world continue on itspresent course, global warmingemissions could triple in the next halfcentury, with global temperaturesincreasing by 8˚ F by 2100. Sea levelswould rise by one and a half feet (and


possibly more), threatening low-lyingcoastal areas. And the ecologicalbalance upon which life depends wouldbe irrevocably altered.

The United States has a responsibil-ity to take leadership in reducing globalwarming pollution.

• The United States is far and away theworld’s largest global warming pol-luter, accounting for 23 percent of theworld’s carbon dioxide emissions.

• Should current trends continue, by2030 the United States will emit 37percent more carbon dioxide than itdoes today, increasing the likelihood ofdramatic global climate change.

• To avoid the worst consequences ofglobal warming, scientists believe thatthe United States needs to stabilizeemissions within a decade, beginreducing them soon thereafter, and cutglobal warming pollution by 80percent by the middle of this century.

The United States can achieve signifi-cant reductions in global warming pol-lution by improving the energyefficiency of our economy and usingmore renewable energy.

The United States can reduce its globalwarming emissions by as much as 19 percentby 2020 by taking a set of aggressive butachievable steps toward improved energyefficiency and increased use of renewableenergy, within the context of mandatorylimits on global warming pollution.

1) Stabilize vehicle travel.Americans drive nearly twice as many milesper year as they did a quarter-century ago,leading to increased emissions of globalwarming pollutants. Americans are alreadycutting back on driving as a result of highergasoline prices, but many Americans havefew realistic alternatives to driving.

Through changes in public policy anddevelopment patterns, Americans can be

given more transportation choices, thusreducing the growth in vehicle travel. Suchchanges include:

o Encouraging the development ofcompact neighborhoods with a mix ofland uses, where more tasks can becompleted by foot, bike or transit.

o Expanding the reach and improvingthe quality of transit service.

o Supporting programs to encouragecarpooling, vanpooling,telecommuting and other alternativesto single-passenger car travel.

2) Increase vehicle fuel economy stan-dards to 40 miles per gallon and set fueleconomy standards for large trucks.The creation of federal fuel economy stan-dards for cars during the 1970s succeededin reducing gasoline consumption and oilimports, as well as global warming pollu-tion. But the fuel economy of new vehiclesis now lower than it was during most of theReagan administration.

Several recent studies show that we couldincrease the fuel economy of new vehiclesto 40 miles per gallon within the next de-cade using technologies that already existor will be available soon. All types of ve-hicles—from SUVs to compacts—can bedesigned to be far more energy efficient.And most of the improvements in fueleconomy can actually save money for con-sumers over the long term, especially withgasoline prices at nearly $3 per gallon. Simi-larly, major improvements in fuel economyare possible for heavy-duty trucks, whichare currently exempt from fuel economystandards.

3) Replace 10 percent of vehicle fuelwith biofuels or other clean alternatives.Ethanol and biodiesel that are producedcleanly and sustainably have the potentialto significantly reduce global warmingemissions from transportation—especiallyif these biofuels are produced from plantwastes and cellulose. Other vehicle tech-

Executive Summary 7

nologies—like “plug-in” hybrids, electricvehicles and fuel cell vehicles—have thepotential to dramatically reduce globalwarming emissions in the future.

4) Reduce energy consumption inhomes, business and industry by 10 per-cent from current levels.Dramatic improvements in energy effi-ciency are possible in virtually every aspectof American life. Studies show that we couldreduce our electricity consumption by asmuch as 20 percent at no net cost to theeconomy. For now, the U.S. can encour-age weatherization of buildings, deploy-ment of more efficient appliances andequipment, and efficiency improvements inindustry. Soon, using new technologiessuch as those in zero-energy homes, we cantransform the way we consume energy andachieve even larger improvements in effi-ciency.

5) Obtain 20 percent of our electricityfrom new renewable energy sources.America has virtually limitless potential forthe generation of power from naturalforces. By ramping up our use of windpower, solar power, geothermal and biom-ass energy and other renewable forms ofenergy—and using much of that energy to

replace power production at dirty, coal-fired power plants—the United Statescould dramatically reduce global warmingemissions from electric power production.

6) Hold emissions from other sourcesto current levels.The five strategies listed above would ad-dress the largest sources of energy use andglobal warming emissions in the UnitedStates But some other sources of globalwarming pollution—such as emissions fromair travel and emissions of some non-car-bon dioxide global warming gases—areprojected to increase significantly in theyears ahead. The United States must re-main vigilant about stabilizing, and even-tually reducing, global warming pollutionfrom all sectors of the economy. Manda-tory limits on global warming emissionswould help to achieve that goal.

These six steps would enable theUnited States to reduce its global warm-ing emissions by 19 percent below 2004levels by 2020.

• Taking these six steps would reduceU.S. carbon dioxide emissions byabout 23 percent and global warmingemissions by about 19 percent by2020. (See Table ES-1.)

Table ES-1. Global Warming Emission Impact of the Six Steps (million metrictons carbon dioxide equivalent)

Strategy Savings MMTCO2E

Stabilize Vehicle Travel 0*40 MPG Fuel Economy and Heavy-Duty Truck

Fuel Economy Standards 38310% of Transportation Fuel from Renewables 6110% Reduction in Energy Consumption 40020% of Electricity from New Renewables 511

Total Savings 1355

2004 U.S. Global Warming Emissions 7122Reduction Relative to 2004 19%

* Avoids increase in emissions resulting from projected increases in vehicle travel between now and 2020.


• In addition, taking these steps willreverse the trajectory of global warm-ing emissions, putting the UnitedStates on a path to achieving the evengreater reductions in global warmingpollution that will be required in thedecades to come.

The United States should adopt a se-ries of public policies designed toquickly and significantly reduce emis-sions of global warming pollutants:

Cap global warming emissions. TheUnited States should establish mandatory,science-based limits on carbon dioxide andother global warming pollutants that reduceemissions from today’s levels within 10years, by 15-20 percent by 2020, and by 80percent by 2050.

Adopt complementary policies to re-duce global warming emissions. TheUnited States should adopt policies thatwould achieve the targets laid out in thisreport, including, but not limited to:

• Transportation policies designed to reducegrowth in vehicle travel and promotealternatives to automobile travel.

• An increase in federal fuel economystandards for cars and light trucks.

• Creation of federal fuel economystandards for heavy trucks.

• A renewable fuel standard requiring asignificant share of transportation fuelto come from renewables by 2020.

• Policy support for the developmentand introduction of plug-in hybrid,electric and fuel-cell vehicles.

• Stronger appliance efficiency stan-dards, energy efficiency programs andother policies designed to improveenergy efficiency.

• A federal renewable energy standardrequiring a large and increasing shareof the nation’s electricity to come fromrenewable energy.

Encourage action at the state level.Federal action to reduce global warmingpollution should promote innovative ap-proaches at the state level and not impedeindividual states or groups of states frompursuing policies that go above and beyondthe commitments made by the federalgovernment.

Introduction 9

Introduction

G lobal warming is the most profoundenvironmental threat of our time.From thinning ice sheets to changes

in ocean currents and from rising globaltemperatures to more severe storms, glo-bal warming is already affecting our envi-ronment, our economy, and our lives.

Human activities are the dominant causeof global warming. Over the past three cen-turies—and especially in the last 100years—the concentrations of pollutantsknown to warm the climate have been in-creasing in the atmosphere. These increasesin pollution cannot be explained by natu-ral variables, but only by human activity.

Scientists tell us that if we continue on a“business-as-usual” path, releasing moreglobal warming pollution every year, theconsequences for human beings and theplanet will be dire. Scientists don’t yet havethe tools to tell us with certainty which ar-eas of the planet will be most dramaticallyaffected, but the overall picture is clear:unrestrained global warming will severelydisrupt the environment and the ecosys-tems on which all life depends.

But there is good news in the climatescience, too. The evidence suggests that ifwe begin to reduce emissions of globalwarming pollutants immediately and

significantly, we still have time to avoid themost catastrophic impacts of globalwarming.

The United States has an indispensablerole to play in reducing global warmingemissions. The United States is by far theworld’s largest consumer of fossil fuels andemitter of global warming pollution, andthus must make a firm commitment tocurbing emissions—and carry through onthat commitment—in order for the worldto achieve the emission reductions neededto safeguard the climate.

The road will not be easy. Climate sci-entists estimate that the world will need toreduce emissions of global warming pollu-tion by more than half below current lev-els by mid-century if we want to avoid theworst consequences of global warming. Butthe technology exists to begin making thattransition now.

About This ReportThis report documents one pathway bywhich the United States could significantlyreduce its emissions of global warming pol-lutants in the near future. We list six strat-egies that, combined, could reduce U.S.global warming emissions by approximately


19 percent by 2020—a significant downpayment on the larger reductions we andthe rest of the world will need to achieve inorder to safeguard the earth’s climate.

The six strategies presented here areambitious. Some are unprecedented in theirscope or the speed with which they mustbe implemented. Implementing these strat-egies will require new policy approaches,large capital investments, and determinedeffort by individuals, corporations and gov-ernment.

But the potential payback for those ef-forts is tremendous—both in avoided eco-nomic and environmental impacts fromglobal warming and in the establishmentof a more secure energy future for theUnited States. By investing now in dramaticimprovements in energy efficiency and the

development of clean, renewable energy,the United States can begin to meet itsobligation to address global warming whilereducing our dependence on scarce fossilfuels and, in many cases, creating jobs andsaving money. The result would be acleaner, more sustainable foundation onwhich to build America’s economy for the21st century.

To protect our children and future gen-erations, the United States must transitionto an energy economy that releases far lessglobal warming pollution. The six steps laidout in this document are not the only pos-sible path to that goal. But they show thatthe United States can address global warm-ing in ways that not only benefit the cli-mate, but benefit our economy and securityas well.

The Need for Immediate Action 11

Global WarmingIs Happening

The first signs of global warming are be-ginning to appear across the UnitedStates and throughout the world. Glo-

bal temperatures and sea levels are on therise. Other changes, such as the recent in-crease in the severity of hurricanes, are con-sistent with the kinds of changes scientistsexpect to occur on a warming planet andare harbingers of the dramatic climate shiftsthat await us if global warming pollutioncontinues unabated.

Rising Global TemperaturesGlobal average temperatures increased dur-ing the 20th century by about 1˚ F. Whilethis increase may not seem extreme, it isunprecedented in the context of the last1,000 years of world history.1 Figure 1 (nextpage) shows temperature trends in theNorthern Hemisphere for the past 1,000years with a relatively recent upward spike.Temperatures in the past 150 years havebeen measured; earlier temperatures are de-rived from proxy measures such as tree

rings, corals, and ice cores. A recent Na-tional Academy of Sciences report foundthat it is highly likely that the last few de-cades of the 20th century were the warmestin at least the last 400 years.2

Global warming appears to have inten-sified in recent years. In 2006, scientists atthe National Aeronautics and Space Admin-istration (NASA) reported that, since 1975,temperatures have been increasing at a rateof about 0.36˚ F per decade.4 And 2005 wasthe hottest year on record worldwide.5 Nine-teen of the 20 hottest years ever recordedhave occurred since 1983 and nine of the10 hottest years have occurred since 1995.6

This warming trend cannot be explainedby natural variables—such as solar cyclesor volcanic eruptions—but it does corre-spond to models of climate change basedon human influence.7

Melting IceThe rise in global temperatures has resultedin thinning ice and decreasing snow cover.Over the last three decades, the volume andextent of ice cover in the Arctic has beendeclining rapidly, leading to the possibilitythat the Arctic could be ice-free during the

Global Warming:The Need for Immediate Action


summer by the end of this century.8 Moun-tain glaciers around the world have beenretreating, and since the late 1960s, North-ern Hemisphere snow cover has decreasedby 10 percent.9 Mountain snowpack—which is a particularly important source ofwater in much of the parched westernUnited States—has declined, with snow-pack in the Colorado River basin belowaverage in 11 of the last 16 years.10

It appears that, in some parts of theworld, the decrease in ice and snow coveris accelerating. One recent study, for ex-ample, found that Greenland’s glaciers areshedding twice as much ice into the oceanas they did just five years ago.11

Rising Sea LevelsOceans have risen with the melting of gla-cial ice and the expansion of the ocean as itwarms. Average sea levels have risen 0.1 to0.2 meters in the past century.12 Sea levelrise has already helped cause the inunda-tion of some coastal land. In ChesapeakeBay, 13 islands have disappeared entirelysince the beginning of European settlementfour centuries ago. Sea level in the Bay hasincreased by about 12 inches in the last

century, with scientists estimating that glo-bal warming accounts for 2 to 6 inches ofthe increase.13 Louisiana loses approxi-mately 24 square miles of wetlands eachyear, increasing the destructive potential ofhurricanes like Hurricane Katrina.14 Whiledevelopment and land subsidence contrib-ute to the loss of coastal land in these ar-eas, rising sea levels also have an impact,and threaten even greater changes in coastalareas in the decades to come.

More Severe StormsStorms throughout the middle and highlatitudes of the Northern Hemisphere havebeen getting more intense. The increasein the frequency of heavy precipitationevents arises from a number of causes, in-cluding changes in atmospheric moisture,thunderstorm activity and large-scalestorm activity.15

In addition, hurricanes have becomemore powerful and more destructive overthe last three decades, a phenomenon thatsome researchers link to increasing globaltemperatures.16 The number of Category4 and Category 5 hurricanes globally hasnearly doubled worldwide over the last 35

Fig. 1. Northern Hemisphere Temperature Trends3


years.17 And the Atlantic hurricane seasonof 2005 was the worst ever recorded withthe most named storms (28), the mosthurricanes (15), the most Category 5 hur-ricanes (4), the most major hurricanes tohit the United States (4), the costliest hur-ricane (Katrina, which caused more than$80 billion in damage), and three of the sixstrongest hurricanes recorded (Wilma, thestrongest ever, plus Katrina and Rita).18

Recent research suggests that higher seasurface temperatures caused by globalwarming had a large role to play in trig-gering the destructive 2005 hurricaneseason.19

Human Activities AreCausing Global WarmingThe changes described above are consis-tent with the kinds of widespread climaticshifts scientists believe will occur as a re-sult of global warming. They are also signsthat human activities have already begunto affect the climate through the release ofpollutants (known as greenhouse gases orglobal warming pollutants) that exacerbate

the earth’s natural greenhouse effect.In 2001, the Intergovernmental Panel on

Climate Change, the global body chargedwith assessing the scientific record on glo-bal warming, concluded that “most of theobserved warming over the last 50 years islikely to have been due to the increase ingreenhouse gas concentrations.”20

The Greenhouse EffectGlobal warming is caused by human exac-erbation of the greenhouse effect. Thegreenhouse effect is a natural phenomenonin which gases in the earth’s atmosphere,including water vapor and carbon dioxide,trap radiation from the sun near the planet’ssurface. The greenhouse effect is necessaryfor the survival of life; without it, tempera-tures on earth would be too cold for hu-mans and other life forms to survive.

But human activities, particularly overthe last century, have altered the composi-tion of the atmosphere in ways that inten-sify the greenhouse effect.

Since 1750, for example, the concentra-tion of carbon dioxide (the leading globalwarming pollutant) in the atmosphere hasincreased by 35 percent as a result of human

Fig. 2. Atmospheric Concentration of Carbon Dioxide23


Fig. 3. U.S. Global Warming Emissions byPollutant (carbon dioxide equivalent)26

Carbon Dioxide83.9%

Other0.3%

Fluorocarbons1.8%

Nitrous Oxide5.0%

Methane9.0%

Global Warming Pollutants

Human activities result in the release of many pollutants that are capable of alter-ing the global climate. The main pollutants that contribute to global warming

are the following:

• Carbon dioxide – Carbon dioxide is released mainly through the combustionof fossil fuels. Carbon dioxide emissions are the leading contributor to globalwarming and the leading global warming pollutant released in the UnitedStates. In 2004, carbon dioxide emissions represented approximately 84percent of America’s annual contribution to global warming.24

• Methane – Methane gas escapes from garbage landfills, is released during theextraction of fossil fuels, and is emitted by livestock and some agriculturalpractices. Methane represents about 9 percent of U.S. global warming emissions.

• Nitrous Oxide – Nitrous oxide is released in automobile exhaust, through theuse of nitrogen fertilizers, and from human and animal waste, and is respon-sible for about 5 percent of America’s contribution to global warming.

• Fluorocarbons – Used in refrigeration and other products, many fluorocar-bons are capable of inducing strong heat-trapping effects when they arereleased into the atmosphere. However, because they are generally emitted insmall quantities, fluorocarbons are responsible for only about 2 percent ofAmerica’s contribution to global warming.

• Sulfur Hexafluoride – Sulfur hexafluoride is mainly used as an insulator forelectrical transmission and distribution equipment. It is an extremely powerfulglobal warming gas, with more than 20,000 times the heat-trapping potentialof carbon dioxide. However, it is released in very small quantities and isresponsible for only a very small portion of the nation’s global warmingemissions.

• Black Carbon – Black carbon isa product of the burning offossil fuels, particularly coal anddiesel fuel. Recent research hassuggested that, because blackcarbon absorbs sunlight, it maybe a major contributor to globalwarming, perhaps second inimportance only to carbondioxide. Research is continuingon the degree to which blackcarbon emissions contribute toglobal warming and it is difficultto judge exactly how large of arole black carbon emissionsmight play in causing globalwarming.25


activity.21 The current rate of increase incarbon dioxide concentration is unprec-edented in the last 20,000 years.22 Concen-trations of other global warming pollutantshave increased as well. (See Fig. 2.)

Global Warming EmissionsAre RisingThe United States produces more globalwarming pollution than any other nationin the world. U.S. emissions of carbon diox-ide—the leading global warming pollutant—have increased by more than one-thirdsince 1983 and are projected to increasedramatically in the years to come.27 Suchan increase in emissions, were it to occur,would make it impossible for the world toachieve the emission reductions needed toprevent the worst repercussions of globalwarming, since carbon dioxide and otherglobal warming pollutants can stay in theatmosphere for a century or longer.

The United States was responsible for

nearly one-quarter of the world’s carbon di-oxide emissions in 2003. (See Fig. 4.) On aper-capita basis, the United States emitstwice as much carbon dioxide as Great Brit-ain or Japan, nearly three times as much asFrance, seven times as much as China, and20 times as much as India.28

Since World War II, U.S. carbon diox-ide emissions from energy use have increasedat a rate of just under 2 percent per year.30

(See Fig. 5.) The U.S. Energy Information

Fig. 4. Carbon Dioxide Emissions by Country, 200329

Fig. 5. Historic and Projected Emissions of Carbon Dioxide, United States32

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Administration (EIA) projects that U.S.emissions will continue to rise by an aver-age of 1.2 percent per year between nowand 2030.31 Should this occur, in 2030 theUnited States will release 37 percent morecarbon dioxide than it does today.

Americans use fossil fuels to heat andlight our homes, to power computers andindustrial machinery, and to fuel our carsand trucks, among other things. Transpor-tation energy use is the biggest source ofcarbon dioxide in America, but this hasn’talways been the case. In 1950, for example,transportation accounted for only slightlymore than a quarter of U.S. carbon diox-ide emissions; today it accounts for nearlyone-third. (See Fig. 6.)

Figure 6 assigns carbon dioxide emis-sions from electricity production to thevarious economic sectors that consume thatelectricity. However, electricity generationis a major contributor to global warmingin its own right. Nearly 39 percent of theUnited States’ carbon dioxide emissionscome from electric power plants, with therest resulting from the direct consumptionof fossil fuels in homes, businesses, indus-try and vehicles.34 (See Fig. 7.)

The large volume of global warmingemissions from electricity generation ismainly the result of America’s reliance oncarbon-intensive coal for electricity. Coal-fired power plants produce about half of

Fig. 6. U.S. Carbon Dioxide Emissions by End-Use Sector33

Fig. 7. Sources of Energy-Related Carbon DioxideEmissions in the United States35

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America’s electricity, but they produceabout 82 percent of the global warmingpollution resulting from electricitygeneration.36

Global Warming Will Have aSevere Impact—Unless WeBegin to Act NowClimate scientists warn that the world facesdire environmental consequences unless wefind a way to quickly and rapidly reduce ouremissions of global warming pollutants.

Many scientists and policy-makers (suchas the European Union) recognize a 2˚ Cel-sius (3.6˚ Fahrenheit) increase in global av-erage temperatures over pre-industriallevels as a rough limit beyond which large-scale, dangerous impacts of global warm-ing would become unavoidable.37 Evenbelow 2˚ C, significant impacts from glo-bal warming are likely, such as damage tomany ecosystems, decreases in crop yields,sea level rise, and the widespread loss ofcoral reefs.38

Beyond 2˚ C, however, the impacts ofglobal warming become much more severe,including some or all of the followingimpacts:

• Eventual loss of the Greenland icesheet, triggering a sea-level rise of 7meters over the next millennium (andpossibly much faster)39 ;

• A further increase in the intensity ofhurricanes;

• Loss of 97 percent of the world’s coralreefs;

• Displacement of tens of millions ofpeople due to sea level rise;

• Total loss of Arctic summer sea ice;

• Expansion of insect-borne disease;

• Greater risk of positive feedback

effects—such as the release of methanestored in permafrost—that could leadto even greater warming in the future.40

At temperature increases of 3 to 4˚ C,far more dramatic shifts would take place,including all of the above changes, plus:

• Increased potential for shutdown of thethermohaline circulation, which carrieswarmth from the tropics to Europe;

• Increased potential for melting of theWest Antarctic ice sheet, triggering anadditional 5 to 6 meter rise in sea level;

• Major crop failures in many parts ofthe world;

• Extreme disruptions to ecosystems. 41

In addition, the more global tempera-tures rise, the greater the risks of abruptclimate change increase. The historical cli-mate record includes many instances inwhich the world’s climate shifted dramati-cally in the course of decades, even years—with local temperature changes of 10˚ C ormore within 10 years.42

Should the world continue on its cur-rent course, with fossil fuel consumptioncontinuing to rise, temperature increasesof well above 2˚ C are likely to occur. TheIntergovernmental Panel on ClimateChange, in its 2001 Third Assessment Re-port, laid out a scenario in which popula-tion, economic output and fossil fuelconsumption continue to grow dramati-cally. Under that scenario, the concentra-tion of carbon dioxide in the atmospherein 2100 would be nearly three-and-a-halftimes its preindustrial level, global averagetemperatures by the end of the centurywould be 4.5˚ C higher than in 1990, andtemperatures would continue to rise forgenerations to come.43

On the other hand, if the world actsquickly and aggressively to reduce globalwarming emissions, there is a much greaterchance of staving off the worst impacts ofglobal warming. To have a reasonable


chance of keeping global temperaturesfrom rising by more than 2˚ C, the atmo-spheric concentration of carbon dioxidemust be held below 450 parts per million(ppm)—about 60 percent higher than pre-industrial levels and about 18 percenthigher than today.44 Holding concentra-tions below 400 ppm would be even moreeffective.

To stabilize carbon dioxide levels at 450ppm, however, the world will need to haltthe growth of global warming pollution inthis decade, begin reducing emissions soon,and slash emissions by more than half by2050.45 Greater reductions would be re-quired to limit carbon dioxide levels to

400 ppm. Because the United States is theworld’s largest global warming polluter, thedegree of emission reductions required herewill be greater.

The good news is that there are manytechnologies and practices that could be putinto place today that would lead to signifi-cant reductions in global warming pollu-tion. The six steps detailed here are not easy,nor are they the only available paths to re-ducing global warming emissions. But theydemonstrate the feasibility of achieving sig-nificant reductions in global warmingpollution in the United States within theforeseeable future, while at the same time re-sulting in other far-reaching, positive changes.

Six Steps to Reduce Global Warming Emissions 19

A chieving major reductions in globalwarming pollution in the UnitedStates will be challenging, but it can

be done. Many of those reductions can beachieved by improving energy efficiencyand expanding the amount of energy wederive from clean, renewable sources—measures that aren’t just good for the cli-mate, but are good for our economy andnational security as well.

The six steps detailed in this section can,if implemented immediately, reduceAmerica’s global warming pollution byabout 19 percent by 2020. Such a reduc-tion would be a significant step toward thelong-term emission reductions the nationand the world must achieve to prevent theworst impacts of global warming.

Step 1: Stop growth invehicle travelAmericans spend more and more time intheir cars each year. Since 1980, the num-ber of miles driven on America’s roads hasnearly doubled, to just shy of 3 trillion miles

in 2004.46 (See Fig. 8.) Combined with thestagnating fuel economy of vehicles, thedramatic rise in vehicle-miles traveled(VMT) is largely responsible for the rapidincrease in global warming emissions fromcars and light trucks in the United States.

Vehicle travel has accelerated at a farfaster pace than population growth. In

Six Steps to ReduceGlobal Warming Emissions

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2004


1980, the number of vehicle-miles traveledper capita was just over 6,700 per year.48 In2004, for the first time, per-capita VMTsurpassed the 10,000 mile per year mark.49

Why are Americans driving so muchmore today than they did 25 years ago? Thereasons are complex and interrelated, butinclude:

• Sprawling development patterns,which have resulted in housing andjobs being pushed away from centercities and into distant suburbs andexurbs that are accessible only by car.

• Demographic shifts, including anincrease in the number of dual-workerhouseholds and the movement of the“baby boomers” through the primedriving-age 25 to 54-year-old agebracket.50

• Massive public investment in highways,coupled with insufficient investment inpublic transit, rail travel, bicycling andpedestrian infrastructure and othertransportation alternatives. In 2004,capital expenditures for highwaystotaled $70 billion across all levels ofgovernment, compared with $9.3billion for transit infrastructure.51

• Relatively inexpensive gasoline in the1990s. In inflation-adjusted terms,gasoline prices in the late 1990s (1994to 1999) were the lowest of any five-year period since at least 1948.52

The United States will not succeed insignificantly reducing its emissions of glo-bal warming pollutants without curtailingthe growth of vehicle travel. Petroleum usein the transportation sector accounts forone-third of U.S. carbon dioxide emissions,with light-duty vehicles (such as cars, SUVs,minivans and pickups) consuming morethan 60 percent of the petroleum used inthe transportation sector.53 The U.S. En-ergy Information Administration (EIA)projects that gasoline consumption in light-duty vehicles will increase by 23 percent

between 2005 and 2020.54 Eliminatingfuture VMT growth will avoid this increasein energy consumption and the coincidentincrease in global warming pollution.

The first step in reducing growth in ve-hicle travel is to expand the availability ofalternatives—high-quality transit service,car- and vanpooling, telecommuting, andbicycle and pedestrian facilities. Encourag-ing new patterns of land use that rely lesson the automobile is also important. Whileeven these changes will leave many Ameri-cans dependent on cars, expanding theavailability of alternatives will give morepeople the option to leave their automo-biles at home more often, thus reducingdemand for petroleum and emissions ofglobal warming pollutants.

Can it Be Done?Given the rapid rise in vehicle travel overthe past few decades, stabilizing the num-ber of miles driven in cars and trucks wouldappear to be a challenging task. But recentevidence suggests that many Americans arealready cutting back on driving as a resultof higher gasoline prices. And a large bodyof research suggests that making reason-able changes in our transportation systemand the way we build our communities canlead to significant decreases in driving.

Higher gasoline prices have already ledmany Americans to cut down on drivingwhere they can and to use alternativeswhere they are available. In 2005, vehicle-miles traveled increased by approximately0.1 percent, the slowest rate of increasesince 1980.55 Only the fast-growing south-central and western regions of the countryexperienced increases in vehicle travel dur-ing 2005. Over the first four months of2006, vehicle-miles traveled increased byabout 0.9 percent versus a year ago—higherthan the annual rate for 2005, but still lowerthan the annual rate of increase for anyother year in the last two decades.56 In ad-dition, a May 2006 poll found that nearly


two-thirds of Americans claimed to be cut-ting back on driving as a result of high gaso-line prices.57

While the slow growth in vehicle travelin 2005 was driven in part by higher gaso-line prices, it is part of a longer-term trendtoward slower travel growth. Since 2000,vehicle miles traveled have increased at anannual rate of 1.6 percent, compared to 2.5percent during the 1990s.58

As the growth in vehicle travel has beenmoderating, transit ridership has been in-creasing. Ridership on public transit in-creased nationwide in 2005, with thenumber of light-rail trips up nearly 6 per-cent and commuter rail trips up nearly 3percent.59 Between 1995 and 2003, thenumber of transit trips increased by 22 per-cent—a faster rate of growth than vehicle-miles traveled.60

Anecdotal evidence suggests that the useof other transportation alternatives has in-creased as well. Bicycle sales in 2005 werestrong, and many transit agencies reportedstrong interest in carpool and vanpool pro-grams.61

Achieving zero growth in vehicle travel,however, remains difficult. Many Ameri-cans do not have convenient alternatives todriving. Trips for work, shopping, schoolor recreation may be too long to carry outon foot or by bike. Public transportationservice is often inconvenient, unreliable,expensive or altogether unavailable. Ex-panding access to these transportationchoices can give Americans more ways toboth save money at the pump and to re-duce the nation’s emissions of global warm-ing pollution.

Numerous studies have shown that ex-panding access to transit, encouraging com-pact, vibrant communities with a mix ofland uses, and promoting transportationalternatives—among other measures—cansignificantly reduce VMT growth.

• Residents of cities with robust railtransit networks drive 12 percent lesseach year on average than residents ofcities with smaller rail networks and

20 percent less than residents of citieswith bus transit only.62

• Residents of higher density urban areasmake approximately 25 percent fewerautomobile trips than the nationalaverage. Further, residents of higherdensity suburbs make about 25 percentfewer trips than residents of lowerdensity, auto-dependent suburbs. 63

• Residents of areas with a mix of landuses (for example, homes, shops andoffices) and good transit service tendto walk, bike and use transit more thanresidents of areas with good transitservice alone. Per-capita VMT inmixed use neighborhoods with goodtransit is about 26 percent less thanper-capita VMT in single-use neigh-borhoods with good transit.64

• Individuals who telecommute (workfrom home) travel 53 to 77 percentfewer miles on telecommuting daysthan on non-telecommuting days.65

• Efforts by employers to promote theuse of transportation alternatives bytheir employees can get results.Washington State’s landmark com-mute-trip reduction program removesabout 20,000 vehicles from roadwaysevery morning, reducing congestion,oil consumption and pollution.66

• Even such simple measures as improv-ing sidewalks, storefronts and otherpedestrian amenities can lead tosignificant reductions in vehicletravel.67

Expanding transit networks and creat-ing communities that allow for a variety oftransportation options is a long-termproject requiring substantial financial in-vestment and committed work on the partof individuals, communities and govern-ment at all levels. But there are signs ofprogress—from the thriving new light-railnetworks in cities such as Salt Lake Cityand Dallas to new compact, transit-centered


developments in cities across the country.And there is much that can be done quicklyto promote alternatives such as carpooling,vanpooling, telecommuting, walkingand biking, without major new capitalinvestments.

Many Americans are looking for conve-nient and affordable alternatives to highergas prices and frustrating commutes. Byinvesting in a range of transportation op-tions and designing our communities so asto reduce automobile dependence, we canhalt the growth of vehicle travel—therebycurbing global warming pollution, reduc-ing our growing dependence on oil, andcreating clean and efficient new ways ofgetting from place to place.

Step 2: Increase fueleconomy standards to40 MPG and createfuel economy standardsfor heavy-duty trucksEstablishing minimum fuel economy stan-dards for automobiles in 1975 was one ofthe most effective steps ever taken to re-duce oil consumption in the United States.Between 1975 and 1987, the average fueleconomy of new cars and light trucks in-creased by nearly 70 percent—from 13.1miles per gallon (MPG) to 22.1 MPG.68

By 1978, gasoline consumption began tofall. Oil imports fell, too. Not until 1993would the United States again use as muchgasoline as it did in the late 1970s.69

Over the last two decades, however, thefuel economy of America’s vehicle fleet hasnot only stalled, but has actually declined.In 2004, new cars and light trucks achievedonly 20.8 MPG on average, a lower fueleconomy average than the new vehicle fleetachieved in 1982.70

The amount of global warming pollu-tion released from cars and light trucks

depends on three factors: 1) the type of fuelused, 2) the number of miles driven, and 3)the efficiency of the vehicle in making useof fuel. The recent decline in fuel economy,therefore, has helped lead to a significantincrease in global warming pollution fromtransportation.

Setting a 40 MPG fuel economy stan-dard for both cars and light trucks wouldlead to a significant reduction in globalwarming pollution. By phasing in such astandard beginning in 2009 and ending in2018 (along with stabilizing vehicle travel),the United States could reduce fuel con-sumption for cars and light trucks by about20 percent by 2020, reducing carbon diox-ide emissions by about 307 million metrictons—representing about a 5 percent re-duction in total U.S. carbon dioxide emis-sions compared to 2004 levels.71 Evengreater reductions would occur after 2020as older, less-efficient vehicles are retiredfrom the vehicle fleet.

Significant reductions in global warm-ing emissions are also possible from heavy-duty trucks, which are currently exemptfrom vehicle fuel economy standards. Set-ting fuel economy standards that wouldincrease the fuel economy of heavy-dutytrucks by 50 percent would reduce carbondioxide emissions by approximately 76 mil-lion metric tons, or 1.3 percent of U.S. car-bon dioxide emissions in 2004.

Can it Be Done?A variety of analyses over the past severalyears have found that dramatic improve-ments in fuel economy and per-mile glo-bal warming emissions are bothtechnologically feasible and cost-effective.

Car and Light Truck StandardsThe Union of Concerned Scientists (UCS)has concluded that average vehicle fueleconomy of 40 MPG is attainable within a10-year timeframe, even without the


widespread use of hybrid technology. Inaddition, UCS concluded that suchstandards would provide a net savings topurchasers of more-efficient light trucks,even given a relatively conservative esti-mate of gasoline prices ($1.75 per gallon).72

Similarly, the Consumer Federation ofAmerica concluded that a 50 MPG stan-dard would be both feasible and cost-ef-fective by 2030, assuming gasoline pricesof $3 per gallon, using technologies thatare either currently available or projectedto be available soon.73

A 2004 study by the Northeast StatesCenter for a Clean Air Future found thatcarbon dioxide emission reductions of upto 45 percent would be cost effective formost vehicle classes at gasoline prices of $2per gallon, using a variety of technologiescurrently in use or projected to be avail-able soon.74 These reductions translate toa near-doubling of vehicle fuel economyfrom today’s levels.

A similar study by the Union of Con-cerned Scientists found that light-dutyvehicles could produce 20 percent less

global warming pollution using technolo-gies available today and 40 percent less pol-lution using technologies to be developedwithin the next decade.76 The analysis didnot include hybrid-electric vehicles, butanother UCS study found that using hy-brid technology would eventually allow thefleet to achieve an average fuel economy of50 to 60 MPG.77

Most of the technologies used to achievethe fuel economy improvements and glo-bal warming pollution reductions describedabove are neither new nor exotic. Technolo-gies such as six-speed automatic transmis-sions, continuously variable transmissions,turbocharging and cylinder deactivation arealready finding their way into growingnumbers of vehicles. Other more advancedtechnologies, such as improved electricalsystems and idle-off (in which the gasolineengine is shut off during idling), can alsosignificantly reduce emissions.

Unfortunately, American consumershave had very limited choice of fuel-effi-cient vehicles. According to the EPA, therewere only 42 model year 2006 vehicle

Fig. 9. Cost-Effective Reductions in Carbon Dioxide Emissions (grams/mile)75

Car

bo

n D

ioxi

de

Emis

sio

ns

(gra

ms/

mile

)

300

355

410

525

210190

220250

285

460

0

100

200

300

400

500

600

Small Cars Large Cars Minivans Small LightTrucks

Large LightTrucks

Current (2002) EmissionsCost-Effective Reduction Level


models that achieved 30 MPG combinedcity/highway mileage or greater (comparedwith more than 400 models that achievedless than 20 MPG combined). Of those 42vehicles, 27 were compacts, subcompactsor other small cars. Only three mid-sizedcars, no mid-sized station wagons, and sixSUV models achieved 30 MPG orgreater.78

The experience of the 1970s and 1980sdemonstrates that automakers can makemore fuel-efficient vehicles if they get apush from government. China, Japan andthe European Union have all adopted fueleconomy or global warming pollution stan-dards for automobiles that, while not di-rectly comparable with U.S. standards,surpass them on paper.79 (See Table 1.) Andautomakers currently have access to a widevariety of technologies that can significantlyimprove fuel economy and curb globalwarming emissions.

A 40 MPG fuel economy standard,achieved over the course of a decade, wouldchallenge automakers to use their techni-cal know-how to help solve two of ourgreatest problems: global warming and de-pendence on oil.

Heavy Truck StandardsHeavy-duty trucks are major consumers offuel. Large tractor-trailers consumed about14 percent of the fuel used by all highwayvehicles in 2004, and fuel consumption bylarge trucks has been increasing by morethan 4 percent per year since the early1990s.81 As is the case with the light-dutyvehicle fleet, fuel economy among the larg-est trucks has also been declining, dropping5 percent between 1997 and 2002.82

Heavy-duty trucks are exempt from fed-eral fuel economy standards. But significantincreases in fuel economy for these trucksare possible at a net lifetime savings to ve-hicle owners. A 2004 study conducted bythe American Council for an Energy-Effi-cient Economy (ACEEE) found that fueleconomy improvements for tractor-trailersof 58 percent are achievable and cost-ef-fective. The study also identified cost-ef-fective improvements in fuel economy forother types of large trucks.83 Calculationsof cost-effectiveness were based on dieselfuel prices of $1.41 to $1.60 per gallon, wellbelow the recent prices of $2.80 and highercharged recently at pumps across the

Table 1. Fuel Economy and Global Warming Emission Standards in theUnited States, Other Countries80

Standard (MPG or By Year NotesMPG equivalent)

Japan 48.0 2010European Union 44.2 2008 (a,b)China 36.7 2008U.S. Clean Cars Program 35.6 2016 (b,c)Australia 34.4 2010 (a)United States 24.9 2007

(a) Voluntary standard(b) Standard is a carbon dioxide standard, not a fuel economy standard. MPG equivalentis approximate.(c) Has been adopted by 11 U.S. states: CA, CT, MA, ME, NJ, NY, PA, OR, RI, VT, WA.


United States.84 As a result, the ACEEEestimates of cost-effective savings are likelyconservative.

Imposing federal fuel-economy stan-dards designed to increase the fuel economyof tractor-trailers by 50 percent would sig-nificantly reduce global warming pollutionfrom the fast-growing freight transporta-tion sector. The increase would be suffi-cient to raise the average fuel economy ofheavy-duty trucks from approximately 5.7MPG to about 8.5 MPG. The UnitedStates should also devise strategies to re-duce fuel consumption and promote en-ergy-efficient technologies in all medium-and heavy-duty trucks.

Step 3: Replace 10 percentof vehicle fuel withclean biofuels or otherclean optionsShifting away from fossil fuels and towardrenewable energy can significantly reduceAmerica’s contribution to global warming.Across the country, states have pressed for-ward with ambitious initiatives to increasethe use of wind, solar, geothermal and otherforms of renewable energy for the genera-tion of electricity. (See Step 5.)

Using renewables to fuel our transpor-tation system is trickier, however. America’scars and trucks are built to run on liquidfuels, particularly gasoline and diesel. Forrenewables to play a part in the poweringof America’s cars and trucks will requireeither using renewable liquid fuels (likecleanly produced ethanol or biodiesel) oraugmenting or replacing liquid fuels withother sources of energy, such as renewablygenerated electricity.

Renewable fuels, such as ethanol andbiodiesel, are made from crops such as cornand soybeans, and could soon be manufac-tured from specialized “energy crops” like

switchgrass. While some fossil fuels areexpended in the production of ethanol andbiodiesel, the energy value of the crops ex-ceeds the energy used to grow them. Andboth ethanol and biodiesel generally pro-duce less global warming pollution thantheir fossil fuel equivalents, though the de-gree of emission reductions depends onhow the fuels are produced. (See “MakingBiofuels Sustainable,” page 27.)

Cars that are partially or fully poweredby electricity, meanwhile, produce less glo-bal warming pollution than conventionalvehicles and could eventually reduce a largeshare of the nation’s petroleum consump-tion. Electric motors are far more energyefficient than internal combustion engines.Improvements to hybrid-electric vehiclesthat allow them to run entirely on electric-ity for short distances using power from theelectric grid are technologically feasibletoday. And advances in battery and fuel-celltechnologies could allow vehicles to breaktheir dependence on petroleum entirely.

Were America to replace 10 percent ofvehicle gasoline use with ethanol and 10percent of transportation diesel use withbiodiesel, it would reduce vehicle carbondioxide emissions by approximately 61 mil-lion metric tons in 2020, or about 1 per-cent of America’s 2004 carbon dioxideemissions.85 Replacing large amounts of ve-hicle fuel with electricity—particularly ifthat electricity were to come from renew-able or low-carbon sources—would lead toeven steeper emission reductions.

Can it Be Done?Expanding the use of renewable fuels inAmerica’s transportation fleet would re-quire an expansion of the infrastructure forgrowing, processing, and distributing plant-based fuels. Achieving a goal of 10 percentethanol use for gasoline-powered vehicleswould require annual production of about17 billion gallons of ethanol.86 Fuel etha-nol production in the United States nearly


doubled between 2002 and 2005, to a totalof 4 billion gallons annually.87 An additional2 billion gallons of capacity is currentlyunder construction.88 Virtually all of thiscapacity is to produce corn-based ethanol.

Great potential exists for future produc-tion from ethanol from cellulose, whichrequires fewer fossil energy inputs andtherefore delivers greater reductions in glo-bal warming pollution. A 2004 study by agroup of academics and non-profit orga-nizations laid out a pathway for obtaining1 billion gallons of ethanol annually fromcellulose by 2015, with production increas-ing by 30 percent annually thereafter.89

Such a scenario would result in the pro-duction of about 3.7 billion gallons ofcellulosic ethanol annually by 2020. Com-bined with the 7.5 billion gallons of etha-nol required annually by 2012 under therenewable fuel standard in the 2005 En-ergy Policy Act, this would bring annualethanol production to at least 11 billiongallons by 2020. The remainder of the etha-nol needed to satisfy 10 percent of gaso-line use could be obtained from continuedincremental growth in corn ethanol pro-duction beyond 2012 or faster growth incellulosic ethanol production.

Achieving a 10 percent standard forbiodiesel use would require annual produc-tion of about 4 billion gallons of biodieselby 2020.90 In 2005, approximately 75 mil-lion gallons of biodiesel were produced inthe United States, triple the amount of theyear before.91 The U.S. Department ofEnergy has identified the potential for 10billion gallons of biodiesel production an-nually by 2030, while the 2004 study refer-enced above identified the ultimatepotential for 16 billion gallons of produc-tion of Fischer-Tropsch fuel (a substitutefor diesel) as a co-product of cellulosic etha-nol production.92

Achieving a 10 percent ethanol/biodieselgoal will also require investments in infra-structure, particularly related to ethanol.Policy initiatives will be needed to encouragethe deployment of infrastructure capable

of transporting and distributing E85 to abroader segment of the public.

It is important to note that greater per-centages of biofuels are possible in the de-cades ahead as the cellulosic biofuelsindustry grows. The 2004 study by academ-ics and non-profit environmental organi-zations, for example, laid out a pathway bywhich more than 41 billion gallons of cel-lulosic ethanol could be produced by2030.93

Production and use of ethanol andbiodiesel should be managed so as to pro-vide the greatest environmental benefit.(See “Making Biofuels Sustainable,” page27.) But biofuels are not the only alterna-tive to petroleum that can reduce globalwarming emissions. Vehicles that are pow-ered by electricity—either obtained fromthe electric grid or generated in a hydro-gen fuel cell—could be even more effec-tive options for reducing the globalwarming impact of transportation.

“Plug-in” hybrid vehicles are perhaps theclosest such vehicles to market readiness.Plug-in hybrids are similar in most ways toadvanced hybrid vehicles like the ToyotaPrius. But there are two main differences:plug-in hybrid vehicles are capable of run-ning for significant distances on electricityalone, and their larger on-board batteriesare recharged in part using power from theelectric grid. While current hybrid tech-nologies can reduce global warming emis-sions by 28 percent per mile compared withconventional vehicles, plug-in hybrids canachieve 40 percent reductions per mile,with even greater reductions in areas of thecountry that generate less of their electric-ity with carbon-intensive coal.99 Eventually,plug-in hybrids could be paired with en-gines running primarily on biofuels suchas ethanol to create vehicles with a smallfraction of the global warming impact ofvehicles on the road today.

Plug-in hybrids still face obstacles of costand automaker acceptance, but numerousplug-in hybrids are currently traveling theroads in demonstration projects, and Ford,


Making Biofuels Sustainable

Ethanol, biodiesel and other biomass-based fuels can make a significant contribu-tion to reducing global warming pollution—if they are produced sustainably.

However, environmental damage can result if the transition to biofuels is managedpoorly. Indeed, under some circumstances, production and use of biofuels couldlead to greater global warming emissions than the petroleum products they aredesigned to replace.

To maximize the environmental benefits of biofuels, policies must be in place toensure that they are developed sustainably.

• Protect air quality – Low concentrations of ethanol in gasoline (such as E10)can result in increased emissions of smog-forming pollutants.94 Motor vehicleair pollution standards should be revised to ensure that the use of ethanol doesnot result in overall increases in urban smog. In addition, public policy shouldencourage the use of ethanol fuels in higher blends (such as E85), which donot pose a threat to air quality.

• Ensure sustainable production – The way biofuels are produced has a largeimpact on their ultimate environmental benefits. Some agricultural methodsfor producing biomass can contribute to environmental problems such aseutrophication (nutrient enrichment) of waterways and soil erosion.95 Undersome production methods, biofuels can provide negligible global warmingbenefits or even result in higher global warming emissions. For example, thehigh price of natural gas has led some ethanol producers to use coal as a fuelfor their plants, a change that could reduce, or even eliminate, the globalwarming benefits of ethanol use.96 Some biomass production methods can alsolead to increases in global warming emissions from land use that reduce orcancel out the benefits from reducing consumption of fossil fuels.97 Finally,increasing production of feedstocks for biofuels could encourage negativeagricultural practices (such as broader use of genetically modified crops orapplications of toxic pesticides) or the conversion of ecologically importantareas to “energy crops.”

A sustainable biofuels strategy must recognize these challenges and ensure thatthe agricultural and industrial processes used to produce biofuels do not causeunintended harm to the environment or the climate.

• Don’t substitute biofuels for efficiency improvements – Biofuels canprovide an important supplement to fossil fuels, but they are no substitute forusing energy more efficiently. The “dual-fuel” loophole in U.S. automobilefuel economy standards, for example, gives automakers credit toward their fueleconomy goals for the production of vehicles that are capable of running onalternative fuels such as E85, even though the vast majority of dual-fuelvehicles are operated entirely on gasoline.98 Public policy should drive bothimprovements in fuel economy and sustainable expansion of biofuels in orderto reduce fossil fuel use and achieve reductions in global warming pollution.


among other automakers, is considering thetechnology.100

Vehicles fully powered from the electricgrid and those powered by hydrogen fuelcells may be somewhat further off. Bothtypes of vehicles have been produced fordemonstration projects (and several thou-sand pure electric vehicles were sold inCalifornia in the late 1990s and early2000s), but both face significant technologi-cal hurdles—limited driving range, long re-charging times and high cost for electric

vehicles, and range, fuel storage and costissues for hydrogen fuel-cell vehicles. Bothtechnologies, however, have the potentialto drive significant reductions in globalwarming emissions—particularly if theelectricity or hydrogen used to fuel the ve-hicles comes from clean, renewable sources.

Government should consider mea-sures—such as the zero-emission vehicleprogram pioneered by the state of Califor-nia—to ensure the eventual integration ofhigh-technology vehicles into the U.S. fleet.

The Importance of Mandatory Global WarmingPollution Limits

Improving the energy efficiency of America’s economy and expanding the use ofrenewable energy give the United States a golden opportunity to reduce its emis-

sions of global warming pollution. Instead of facing constant pressure to build newpower plants to serve ever-growing demand, the nation would have the ability tofinally replace its oldest and most polluting sources of electricity.

To take full advantage of that opportunity, however, the United States must pairsmart energy strategies that promote energy efficiency and renewables with man-datory limits on global warming pollution.

A strong, mandatory cap on global warming pollution would encourage theshut-down of the dirtiest forms of electricity generation (such as older, coal-firedpower plants) and their replacement with forms of generation that have less im-pact on the climate. Such a program can take the form of a “cap-and-trade” sys-tem—similar to a program recently agreed upon by eight northeastern states—inwhich companies that make emission reductions can sell their pollution permits(or “allowances”) to other firms, thus delivering emission reductions at the lowestaggregate cost to the economy.103

To illustrate the potential global warming impact of a cap on global warmingemissions, we compiled a second set of estimates for global warming emission re-ductions resulting from reducing electricity consumption by 10 percent by 2020.Instead of assuming that 75 percent of the energy saved is used to reduce demandfor coal-fired power, we assumed that the same amount of energy is used to dis-place high-efficiency natural gas combined cycle power plants. In that case, a 10percent reduction in electricity consumption would result in only 118 million met-ric tons of carbon dioxide emission reductions, as opposed to 284 million metrictons if efficiency improvements are used mainly to reduce coal-fired generation.

Mandatory limits on global warming pollution are central to any strategy toreduce the U.S. contribution to global warming, and should be adopted alongsidethe clean energy strategies discussed in this paper.


Step 4: Reduce energyconsumption in homes,businesses and industryby 10 percentEnergy consumption in homes, businessesand industry accounts for two-thirds of U.S.emissions of carbon dioxide (includingemissions resulting from the generation ofelectricity for residential, commercial andindustrial use).101 Reducing consumption ofoil, natural gas and electricity in these sec-tors can lead to significant reductions inglobal warming pollution in the UnitedStates.

The impact of energy conservation andefficiency on global warming emissions de-pends in part on the form of electricity gen-eration that is displaced. Electricity in theUnited States is generated from sourcesthat produce huge volumes of global warm-ing pollution (older coal-fired powerplants), sources that produce less globalwarming pollution (modern natural gas-fired power plants), and sources that pro-duce little or no pollution (renewablepower).

For the purposes of this scenario, we as-sume that 75 percent of the electricity savedthrough efficiency and conservation is usedto offset generation from existing coal-firedpower plants, with the remaining 25 per-cent used to offset generation from nuclearpower plants, many of which are nearingthe end of their operating licenses.102 Sucha reduction in coal-fired power generationwould likely only occur in the presence ofa strong federal policy designed to reducecarbon dioxide emissions. (See “The Im-portance of Mandatory Global WarmingPollution Limits,” page 28.)

Based on those assumptions, reducingoil, natural gas and electricity consumptionby 10 percent below today’s levels wouldreduce carbon dioxide emissions by about400 million metric tons from 2004 levels—or about 7 percent—by 2020.104

Can it Be Done?The electricity savings required to meet the10 percent goal amount to 380 millionMegawatt-hours (MWh) of electricity in2020 compared to 2004 generation levels.Compared to the U.S. Energy InformationAdministration’s 2020 projected generationlevels, savings of 1,400 million MWh, orabout 29 percent of projected generation,would be required. On the natural gas side,reductions of about 3.7 quadrillion BTUversus projected levels, or about 21 percent,would be needed by 2020.105

A 2004 review of 11 energy efficiencystudies by the American Council for anEnergy-Efficient Economy (ACEEE)found a mean economic potential for en-ergy efficiency improvements (i.e., effi-ciency savings that would be cost-effective)of 20 percent for electricity and 21.5 per-cent for natural gas.106 The dramatic in-crease in natural gas and electricity pricesin some parts of the country in the yearssince the studies were conducted could re-sult in the cost-effective energy efficiencypotential being even higher today.

Achieving a 10 percent reduction in en-ergy use by 2020 is, therefore, a very ambi-tious goal, requiring the United States toreap virtually all currently economic en-ergy-efficiency opportunities, continue todevelop new energy-saving technologies,and begin to deploy next-generation tech-nologies that can transform the way Ameri-cans use energy in their homes, offices andfactories.

Current Energy EfficiencyOpportunitiesVirtually every aspect of American life hasthe potential to be more energy efficient—often in ways that not only reduce globalwarming pollution, but that save money as well.

The potential for quick, dramatic reduc-tions in energy use was demonstrated inCalifornia during that state’s 2000-2001


energy crisis. Faced with the possibility ofrolling blackouts during the summer of2001, the state of California launched anunprecedented energy conservation effortthat coupled stronger energy efficiencystandards, public education efforts and fi-nancial incentives. The drive resulted inCalifornia slashing its electricity consump-tion by 6.7 percent within a single year,while curbing summer peak electricity de-mand by 14 percent.107

Such bold, comprehensive energy effi-ciency and conservation efforts have rarelybeen attempted elsewhere in the UnitedStates. The American Council for an En-ergy-Efficient Economy (ACEEE) reportsthat spending on state and utility-run en-ergy efficiency programs is less than it wasa decade ago, totaling only $1.35 billion in2003.108 Federal energy efficiency pro-grams continue to face severe budget pres-sure; President Bush’s proposed fiscal year2007 federal budget slashed core energy ef-ficiency funding by about $100 million, rep-resenting a 32 percent cut from fiscal year2002 levels.109

There are plenty of options for devel-oping America’s “strategic reserves” of en-ergy efficiency. The options below may ormay not be sufficient to achieve the 10 per-cent reduction goal—indeed, the UnitedStates will almost certainly need to developnew policies, programs and technologies toachieve that target. But these options areillustrative of the types of energy efficiencyopportunities that are available today.

Space heating – Space heating is the larg-est source of energy consumption in homesand businesses.110 Despite dramatic im-provements to the energy efficiency of theaverage American home since the energycrises of the 1970s, opportunities to reduceenergy consumption for space heating stillexist.

Comprehensive weatherization can cutenergy consumption in single-family homesby 12 to 23 percent or more.111 Air sealing,insulation and window replacements can

reduce energy consumption by 20 percent.112

High-efficiency residential furnaces, suchas those meeting the federal government’sEnergy Star standards, can reduce fuel useby about 20 percent compared to furnacesmeeting the government’s minimum fur-nace efficiency standard, and by 40 percentor more compared to older furnaces.113

Considering that about one-quarter of allhomes have furnaces that are 20 years oldor older, the opportunity for energy sav-ings is large.114

On the commercial side, comprehensiveretrofits that include heating, lighting andother uses of energy have been shown toachieve energy savings on the order of 11to 26 percent.115

Air conditioning – Air conditioning ac-counts for 16 percent of residential elec-tricity consumption and 26 percent ofcommercial electricity consumption.116

New federal standards for residential andcommercial air conditioners will improveefficiency for new units by 30 percent and26 percent, respectively.117 However, airconditioners currently exist that exceed thenew federal standard by 15 percent or more.

Appliances – Many household and com-mercial appliances can be made vastly moreenergy efficient than they are today. Re-frigerators, for example, consume 14 per-cent of residential electricity.118

Refrigerators meeting Energy Star effi-ciency standards are 10 to 15 percent moreefficient than average models.119 Manyother household and commercial appli-ances are available in more energy-efficientmodels or could be made to be more en-ergy efficient using technologies availabletoday.

In addition, many household appli-ances—from televisions and VCRs to com-puters and telephones—consume energyeven when they are turned off. One studyof 10 homes in California found thatconsumption of “standby” poweramounted to 5 to 26 percent of these


homes’ annual electricity use. Replacingexisting appliances with those that mini-mize standby power use could reduce theselosses by 68 percent.120

Energy efficiency in industry – Industryhas been among the most aggressive adopt-ers of energy-efficiency technologies, giventhe large amount of energy often used inmanufacturing and its impact on the bot-tom line. Nonetheless, significant room forimprovement exists in the efficiency withwhich industrial facilities make use of energy.121

Transformative TechnologiesMaking the appliances and heating, cool-ing and lighting systems we currently usemore efficient is a significant step towardusing less energy. To achieve maximum en-ergy savings, however, American homes,businesses and factories will need to adoptnew or improved technologies that trans-form the way we use energy.

Zero-energy and low-energy buildings– Zero-energy buildings are those that pro-duce as much energy as they consume.Zero-energy buildings typically combine anarray of energy-saving technologies withsmall-scale renewable energy production.For example, the U.S. Department of En-ergy worked with Habitat for Humanity todesign and build several near-zero-energyhomes in Tennessee. The buildings com-bined an airtight building envelope withenergy-efficient windows, a geothermalheat pump, solar panels and energy-effi-cient appliances. Costs for building thehomes were around $100,000 and daily ex-penditures for purchased energy were about$1 per day.122 Near-zero-energy homes arebecoming increasingly common in Califor-nia and have the potential to dramaticallyreduce all forms of residential energyconsumption.

Not all new buildings have the potentialto use “zero” energy, but most residential

and commercial buildings can be built inways that use much less energy. The Ameri-can Institute of Architects has set a targetof reducing fossil fuel consumption in theconstruction and operation of new buildingsby 50 percent by 2010 and to make all newbuildings carbon-neutral by 2035.123

Solar water heating and passive solar –While most discussions of solar power fo-cus on solar photovoltaics—which convertsunlight into electricity—solar thermaltechnologies may have as great a role to playin saving energy and reducing global warm-ing pollution. Solar water heaters can re-duce energy consumption for water heatingby about two-thirds and pay for themselveswithin four to eight years.124 New homesand businesses can be designed to makemaximum use of the sun for lighting andheating.

Combined heat and power – Electricpower plants that burn fossil fuels producelarge amounts of waste heat. Many largeapartment buildings, commercial develop-ments and industrial facilities could makegreater use of combined heat and power(CHP) in which electricity is generated on-site, with the remaining heat then used toprovide space heating or other energyneeds. CHP systems can reach 70 to 90percent thermal efficiency, compared to the33 percent efficiency of today’s powerplants.125 Many industrial facilities alreadyuse CHP, but the potential for growth isenormous. Studies conducted for the U.S.Department of Energy found a market po-tential of 33 gigawatts for industrial CHPsystems (compared to current deploymentof 11 GW), and as much as 77 gigawatts inthe commercial and institutional sector(compared to deployment of 5 gigawatts asof 1999).126 Building out this existing CHPpotential would equal about 1 percent ofAmerica’s current generation capacity, andtechnological improvements could allowCHP technologies to spread even furtherin the years to come.127


ConclusionEncouraging the installation of energy ef-ficient technologies in homes, businessesand industry, while simultaneously openingthe door for transformative technologiessuch as zero-energy buildings, solar waterheating and combined heat and power, canreduce the amount of fossil fuels and cen-trally generated electricity consumed in theUnited States. Policies such as tax breaks forenergy efficient equipment, stronger energyefficiency standards for appliances and homes,energy efficiency portfolio standards forutilities, the elimination of market barriersto technologies such as CHP, and others canmove the United States toward a goal of reduc-ing energy use in the residential, commer-cial and industrial sectors by 10 percent by 2020.

Step 5: Obtain 20 percentof electricity from newrenewables by 2020America has virtually unlimited technicalpotential for the generation of power fromthe wind, sun and other natural forces.Using new, zero-carbon renewable sourcesof energy such as solar and wind to pro-duce 20 percent of America’s power by2020, while implementing a strong,mandatory cap on global warming emis-sions that reduces demand for power frominefficient existing coal-fired powerplants, would reduce carbon dioxide emis-sions by approximately 511 million metrictons, or more than 8 percent of 2004emission levels.128

Renewable Energy Growth Around the World

Countries around the world are demonstrating that renewable power sourcescan be ramped up quickly and play a significant role in their nations’ electric-

ity supplies.The United States has historically been a leader in the deployment of renew-

able energy technologies. As recently as 1996, the United States had more solarphotovoltaic (PV) capacity than any other nation in the world. And as recently as1997, the United States was number two in wind power capacity, trailing onlyGermany.139

In the years since, however, other nations—primarily European countries andJapan—have dramatically ramped up their production of renewable energy. By2004, Japan had triple the solar PV capacity of the United States, while Germanyhad more than double the capacity. (See Fig. 10.) The United States now standsthird in installed wind power capacity behind Germany (which now has twice thewind generation of the United States) and Spain, which has increased its windpower generation nearly 20-fold in just the last eight years. (See Fig. 11.)140

In several countries, renewable power now represents a sizeable share of over-all electricity generation. Denmark now generates more than 16 percent of itselectricity from wind power, with Spain generating 8 percent and Germany nearly5 percent.143

The growth of renewable energy in these nations is no accident—rather it is adirect result of aggressive public policies designed to prioritize renewable energydevelopment.


0

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Fig. 11. Cumulative Installed Wind Power Generating Capacity142

Fig. 10. Cumulative Installed Solar Photovoltaic Generating Capacity141

* “Other” includes other members of the International Energy Agency’s Photovoltaic Power System Program.

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Can it Be Done?A 1993 U.S. Department of Energy studyfound that wind turbines on 0.6 percent ofthe nation’s land area could produce 20 per-cent of the nation’s electricity.129 Prelimi-nary data from the U.S. Department ofEnergy estimate that the potential windgeneration capacity of America’s offshoreareas exceeds 1,000 gigawatts (GW), aboutas much as America’s current generationcapacity from all sources.130 America’s so-lar photovoltaic resource is similarly vast—the solar energy available in a 100square-mile section of Nevada could pro-vide electricity equivalent to America’s an-nual consumption.131

Tapping this potential will require swiftdeployment of renewable energy technolo-gies. To achieve the 20 percent goal,America will need to generate approxi-mately 700 million MWh of electricityfrom new renewable sources by 2020.

Wind power installations have increaseddramatically in the United States, withnearly 2.5 GW of wind power installed inthe United States in 2005, representing anincrease of 35 percent in the nation’s windpower capacity over the year before. An ad-ditional 3 GW of wind capacity is expectedto be installed in 2006.132

The U.S. wind industry has set a goal ofhaving 100 GW of wind power installed inthe United States by 2020, enough to gen-erate about 289 million MWh of power.133

But a more rapid ramp-up of wind poweris certainly possible with vigorous publicpolicy support. Spain, for example, now hasmore than 10 GW of installed wind capac-ity—more than the United States—and hasseen its installed wind capacity triple withina four-year period. Applying Spain’s 32 per-cent annual growth rate to the UnitedStates would result in America generatingtwice the amount of power required to meetthe 20 percent new renewables goal.134

Solar photovoltaics can also play an im-portant role in meeting the 20 percent tar-get. The state of California, for example,recently launched an incentive program

designed to bring 3 GW of distributed so-lar power on line within the next 11years.135 The U.S. solar industry has set atarget of having 36 GW of solar PV capac-ity installed by 2020, increasing to 200 GWby 2030.136 This would result in the gen-eration of about 79 million MWh of powerfrom solar photovoltaics by 2020.137

Another form of solar electricity—con-centrating solar thermal energy—is alsopoised to make major strides. Unlike morefamiliar solar photovoltaic panels, whichconvert sunlight directly to electricity, con-centrating solar power plants use mirrorsto reflect and concentrate sunlight, whichis then used to heat a liquid or gas that isthen used to generate electricity. Withinjust the past year, California utilities havecommitted to concentrating solar thermalprojects that could eventually add 1.7 GWof solar power generating capacity.138

Geothermal energy also has the poten-tial to make an important contribution,particularly in the western United States.The U.S. Department of Energy is target-ing the installation of another 15 GW of geo-thermal electricity generation capacity bythe end of this decade, enough to generateapproximately 118 million MWh of power.144

Achieving the goals mentioned above forwind, solar photovoltaics and geothermalenergy would allow the United States toget more than two-thirds of the way to thegoal of obtaining 20 percent of electricityfrom new renewable sources. Other renew-able energy sources—including central-sta-tion solar power, small-scale wind, tidalpower, biomass energy, landfill gas and oth-ers—have the potential to make significantcontributions.

Significant hurdles remain in the way ofa dramatic expansion of renewable energy.Concerns about the siting of wind turbinesand long-distance transmission of windpower, utility interconnection problemsand lack of equitable net metering forsolar power in some parts of the country,as well as other roadblocks, must be ad-dressed if renewable energy is to experience


significant growth over the next two de-cades. But, given the enormity of America’srenewable resource base—and the success-ful track record of other nations in bring-ing renewable energy on line quickly—thereis little reason that a goal of generating 20percent of America’s power from newrenewables cannot be achieved.

Step 6: Hold emissions fromother parts of the economyto current levelsThe five steps above address the vast ma-jority of U.S. energy use and global warm-ing emissions. However, achieving a goalof reducing U.S. global warming pollutionby 15 to 20 percent by 2020 will requirevigorous action in all sectors of theeconomy to ensure that energy use and glo-bal warming pollution at least remain stable.Mandatory limits on global warming pollu-tion would help to achieve that goal.

Several areas in which global warmingpollution could increase significantly in theyears ahead are the following:

Air travel – The Energy Information Ad-ministration projects that jet fuel consump-tion will increase by 35 percent between2004 and 2020, due to a projected increasein air travel.145 This increase in jet fuel usewould amount to an increase in carbon di-oxide emissions of approximately 83 mil-lion metric tons. Air travel is among theleast energy efficient modes of travel, con-suming more than 50 percent more energyper passenger mile than rail travel.146 Whilesome improvements in aircraft fuel effi-ciency are possible, greater gains are pos-sible by shifting some air trips tolower-emission modes.

More than half of all flights in the UnitedStates are less than 500 miles in length—adistance at which rail travel, particularlyhigh-speed rail, can be competitive in terms

of time and convenience.147 Shifting evena portion of short- to medium-distance airtravel to rail can reduce global warmingemissions. Bolstering the nation’s rail net-work to accommodate such a shift couldalso allow some trips to be shifted fromautomobile and other high-emitting modesas well.

Freight transportation – The energy ef-ficiency of freight transport in the UnitedStates has been declining for more than adecade, due in part to a decline in the en-ergy efficiency of moving freight by air,water and pipeline.148 While improving fueleconomy and increasing the use of renew-able fuels in heavy-duty trucks will reducethe global warming impacts of increasedfreight transport, the United States shouldalso seek out ways to increase the amountof freight that travels by low-emissionmodes such as rail.

Other global warming pollutants – Inaddition to carbon dioxide, the UnitedStates emits a variety of other pollutantsthat contribute to global warming. In 2000,these emissions represented about 16 per-cent of the United States contribution toglobal warming.149 Emissions of globalwarming pollutants like methane and ni-trous oxide are projected to increase mod-estly or decrease over the next two decades,but emissions of several “high global warm-ing potential” pollutants could skyrocket—more than tripling between 2000 and2020.150 Currently, the federal governmentis involved in voluntary partnerships withindustry to reduce emissions of high glo-bal warming potential pollutants. To stemincreases in these pollutants, all globalwarming pollutants should be included ina comprehensive program to limit globalwarming emissions.

A mandatory, economy-wide cap on glo-bal warming pollution would ensure thatincreases in emissions from other sectorsof the economy do not offset or overwhelmthe emission reductions achieved throughclean energy strategies.


Conclusion & Recommendations

Table 2. Global Warming Emission Impact of the Six Steps (Relative to 2004Emissions)

Strategy Savings MMTCO2E

Stabilize Vehicle Travel 0*40 MPG Fuel Economy and Heavy-Duty Truck

Fuel Economy Standards 38310% of Transportation Fuel from Renewables 6110% Reduction in Energy Consumption 40020% of Electricity from New Renewables 511

Total Savings 1355

2004 U.S. Global Warming Emissions 7122Reduction Relative to 2004 19%

* Avoids increase in emissions resulting from projected increases in vehicle travel between now and 2020.

Benefits of the Six Steps

The six strategies listed above, if imple-mented and augmented by strong,mandatory limits on global warming

pollution, would reduce U.S. global warm-ing emissions by about 19 percent below2004 levels by 2020. Carbon dioxide emis-sions would be reduced by about 23 per-cent below 2004 levels.

Achieving significant reductions in glo-bal warming pollution over the next decadeand a half will help reduce the impact ofglobal warming in the next century andposition the United States as a leader in theworldwide effort to forestall dangerous cli-mate change.

But pursuing the six strategies listedabove will also have other benefits forAmerica’s economy and environment.

Conclusions and Recommendations 37

• Reduced fossil fuel dependence –Holding vehicle travel stable whileimproving fuel economy and increas-ing our use of biofuels will dramati-cally reduce America’s addiction tooil—slashing light-duty vehiclegasoline use by more than one-quarter.At the same time, the United Statescan reduce its dependence on otherscarce fossil fuels, such as natural gas,ensuring America’s long-term energysecurity.

• Create jobs – A variety of studies haveshown that investing in energy effi-ciency and renewable energy createsmore jobs than investing in fossil fuels.One 2005 study estimated that a cleanenergy strategy, coupled with a shiftingof federal energy subsidies torenewables and efficiency, could createas many as 154,000 new jobs in theUnited States and increase net wagesby $6.8 billion.151 The Union ofConcerned Scientists estimates that a20 percent national renewable energystandard for electricity would createtwice as many new jobs as meetingdemand with fossil fuels, while adding$10.2 billion to the nation’s grossdomestic product.152

• Save money – Many of the stepsmentioned above—including majorimprovements in vehicle fuel economy,improvements in energy efficiency, andsome investments in renewablepower—are cost-effective today. Thatis, they save money for Americanconsumers over the lifetime of theinvestment. At a time when manyAmericans face rising energy costs atthe pump and in their homes, investingin efficient, clean energy sources todayis likely to reap a substantial long-termsavings, helping to ensure America’seconomic stability long into the future.

• Reduce other environmental andpublic health threats – America’sdependence on fossil fuels causes a

litany of environmental and publichealth problems from urban smogcaused by motor vehicle exhaust tomercury pollution from coal-firedpower plants. Reducing our consump-tion of fossil fuels can alleviate many ofthese threats.

RecommendationsThe United States should pursue the fol-lowing strategy for achieving the necessaryreductions in global warming emissions:

Cap Global Warming Emissions – Es-tablish mandatory, science-based limits oncarbon dioxide and other global warminggases that reduce emissions from today’slevels within 10 years, by 15-20 percent by2020, and by 80 percent by 2050.

Adopt Complementary Policies to Re-duce Global Warming Emissions –Adopt public policies that would achievethe specific targets laid out in this report,including:

• Transportation policies designed toreduce growth in vehicle travel andpromote alternatives to automobiletravel.

• An increase in federal fuel economystandards for cars and light trucks.

• Creation of federal fuel economystandards for heavy trucks.

• A renewable fuel standard requiring asignificant share of transportation fuelto come from renewables by 2020.

• Policy support for the developmentand introduction of plug-in hybrid,electric and fuel-cell vehicles.

• Stronger appliance efficiency stan-dards, energy efficiency programs andother policies designed to improveenergy efficiency.


• A federal renewable energy standardrequiring a large and increasing shareof the nation’s electricity to come fromrenewable energy.

Encourage Action at the State Level –Many states have taken action to reduceglobal warming pollution, either by adopt-ing specific goals or targets for emission

reductions or by adopting clean energypolicies designed to improve energy effi-ciency or promote renewable energy. Fed-eral action to reduce global warmingpollution should in no way impede indi-vidual states or groups of states from pur-suing policies that go above and beyondthe commitment made by the federalgovernment.

Methodology 39

The estimated global warming emissionreductions presented in this report arebased on a comparison with 2004 U.S.

global warming emissions as presented inU.S. Department of Energy, Energy Infor-mation Administration (EIA), Emissions ofGreenhouse Gases in the United States 2004,December 2005.

To estimate the reductions that wouldresult from each of the strategies, we beganwith estimates of energy use in vehicles,homes, businesses, industry and electricpower plants in 2004 from the EIA’sAnnual Energy Outlook 2006 (AEO 2006).Except where otherwise noted, the amountof carbon dioxide released from the con-sumption of various fossil fuels is based oncarbon coefficients from the EIA’s Documen-tation for Emissions of Greenhouse Gases in theUnited States 2003, May 2005.

Specific assumptions and quantificationmethods for the various strategies follow:

1. Stabilization of Vehicle TravelEmissions from light-duty vehicles wereassumed to be held constant at 2004 levelsin 2020.

2. Increase Fuel EconomyStandards to 40 MPG andSet Fuel Economy Standardsfor Heavy-Duty TrucksTo estimate the benefits of increased fueleconomy standards for light-duty vehicles,we first assumed that vehicle fuel economywould remain constant at 2005 levels in theabsence of policy action to the contrary.Estimated 2005 laboratory fuel economyfor cars of 28.9 MPG and for light trucksof 21.3 MPG were obtained from U.S.Environmental Protection Agency, Light-Duty Automotive Technology and Fuel EconomyTrends: 1975 Through 2005, July 2005.These laboratory fuel economy values werereduced by approximately 20 percent toapproximate “real world” conditions, basedon on-road fuel economy degradation factorsfor 2020 from EIA, Assumptions to AEO 2006.

The on-road fuel economy for new ve-hicles under a 40 MPG fuel economy sce-nario was assumed to be 32 MPG for bothcars and light trucks, taking into accountthe 20 percent difference between labora-tory and on-road values described above.The 40 MPG standard was assumed to bephased in linearly, with gradual increases

Methodology


in new vehicle fuel economy beginning in2009 and ending with the 40 MPG stan-dard in 2018.

To estimate how increasing fuel economystandards would affect vehicle emissions in2020 among all vehicles (not just new ve-hicles), we made assumptions about theproportion of miles that will be driven byvehicles of various ages in 2020 and aboutthe split in vehicle-miles traveled betweenpassenger cars and light trucks, such asSUVs. To make the former estimate, werelied on data on VMT accumulation byvehicle age from the U.S. Department ofTransportation’s 2001 National HouseholdTransportation Survey (NHTS, down-loaded from nhts.ornl.gov/2001/index.shtml,21 June 2006). We used the estimates ofthe number of miles driven per vehicle byvehicles of various ages from NHTS to es-timate the percentage of total VMT in 2020that could be allocated to vehicles of vari-ous model years. (To eliminate year-to-yearanomalies in the NHTS data, we smoothedthe VMT accumulation curves for cars andlight trucks using several sixth-degree poly-nomial curve fits.) These percentages werethen applied to the on-road fuel economystandard for new vehicles of each modelyear to create a weighted average fleetwidefuel economy estimate for both cars andlight trucks in 2020, which we then com-pared with the baseline estimate of whatfleetwide fuel economy would be withoutstronger fuel economy standards. Finally,we assumed that 40 percent of VMT in 2020would take place in cars and 60 percent inlight trucks, per a methodology describedin Environment Maine Research and PolicyCenter, Natural Resources Council ofMaine, Cars and Global Warming, Fall 2004.The weighted average fleetwide fueleconomy for cars and light trucks was thenmultiplied by their share of total VMT toarrive at a percentage reduction in fuel con-sumption that would result from the higherfuel economy standards in 2020.

The percentage reduction in per-milefuel consumption was then applied to theestimated gasoline consumption of light-duty

vehicles in 2004 (from AEO 2006) to esti-mate the amount of gasoline that would besaved. Global warming emission reductionsfrom those fuel savings were calculated us-ing carbon dioxide coefficients for tailpipeemissions (approximately 19.3 pounds ofcarbon dioxide per gallon, based on EIA,Documentation for Emissions of GreenhouseGases in the United States 2003) and for “up-stream” emissions resulting from the pro-duction and distribution of gasoline(approximately 5.7 pounds of carbon diox-ide per gallon, based on well-to-tank re-sults from General Motors Corporation,Argonne National Laboratory, et al., Well-to-Wheel Energy Use and Greenhouse GasEmissions of Advanced Fuel/Vehicle Systems –North American Analysis, Volume I, June2001).

For heavy-duty truck fuel economy stan-dards, we used 2004 fuel economy estimatesfor heavy-duty diesel and gasoline-poweredtrucks from AEO 2006 to establish abaseline. We then assumed that fueleconomy standards equivalent to a 50 per-cent increase in miles-per-gallon fueleconomy would be phased in linearly be-ginning in 2009 and ending in 2020. Fueleconomy improvements were assumed topenetrate the vehicle fleet according toVMT accumulation by vehicle age esti-mates from U.S. Census Bureau, 2002 Eco-nomic Census: Vehicle Inventory and UseSurvey, December 2004. Fuel consumptionper mile for vehicles of each model year wasthen multiplied by the percentage of VMTtraveled in vehicles of each model year, andthen summed across model years to arriveat an estimate of fleetwide fuel economyafter imposition of fuel economy standards.The fleet fuel economy estimate for heavy-duty trucks was then divided by currentaverage fleet fuel economy to arrive at apercentage reduction in fuel consumptionper mile driven. This percentage reductionwas then applied to estimates of diesel andgasoline use by heavy-duty trucks in AEO2006 to arrive at an estimate of total fuelsavings. The fuel savings estimate was thenconverted to carbon dioxide emission savings

Methodology 41

using tailpipe and upstream emission fac-tors from the same sources used for light-duty vehicle gasoline use, described above.

Increases in fuel economy may haveother impacts on consumers’ driving andvehicle purchasing habits. Many studieshave identified a “rebound effect” in whichpurchasers of more efficient vehicles in-crease their vehicle travel. In addition,changes in fuel economy standards cancause consumers to shift from one class ofvehicles to another (for example, from carsto SUVs). We do not include the reboundeffect in these calculations, on the assump-tion that strategies to eliminate growth invehicle travel (See Step 1) will achieve theirgoal. We also do not include “mix shifting”among vehicle types.

3. Replace 10 Percent ofVehicle Fuel with BiofuelsThe energy value of gasoline and diesel fuelthat would be replaced with biofuels wasdetermined by multiplying the amount oflight-duty vehicle gasoline use (or, in thecase of biodiesel, transportation sector die-sel use) remaining after the imposition ofstronger fuel economy standards, in BTU,by 10 percent.

Avoided global warming pollutant emis-sions from biofuels were estimated by mul-tiplying the life-cycle (tailpipe plusupstream) emissions from the avoided gaso-line and diesel use by the percentage life-cycle reductions in global warmingemissions from the various biofuels com-pared to their petroleum equivalents. Forethanol, separate emission reduction fac-tors were estimated for corn-based and cel-lulosic ethanol. Per-mile global warmingemission reductions from corn-based etha-nol were assumed to be 13 percent com-pared with conventional gasoline based onAlexander E. Farrell, et al., “Ethanol CanContribute to Energy and EnvironmentalGoals,” Science, 311: 506-508, 27 January2006. Per-mile global warming emissionreductions from cellulosic ethanol were

assumed to be 85 percent, based on MichaelWang, Argonne National Laboratory, Up-dated Energy and Greenhouse Gas EmissionsResults of Fuel Ethanol, PowerPoint presen-tation to the 15th International Symposiumon Alcohol Fuels, 26-28 September 2005.

We assumed that 80 percent of ethanolused in 2020 would come from corn, with20 percent (approximately 3.4 billion gal-lons per year) coming from cellulosicsources. The amount of cellulosic ethanolis consistent with a pathway for the devel-opment of cellulosic ethanol described inNathanael Greene, et al., Growing Energy:How Biofuels Can Help End America’s OilDependence, December 2004. That pathwaycalls for production of 1 billion gallons ofcellulosic ethanol in 2015, with a 30 per-cent annual growth rate thereafter.

Per-mile global warming emission re-ductions from biodiesel were assumed tobe 65 percent per two life-cycle studies:(S&T)2 Consultants Inc., Biodiesel GHGEmissions Using GHGenius: An Update, pre-pared for Natural Resources Canada, 31January 2005 and Tom Beer, et al., Com-parison of Transport Fuels: Final Report to theAustralian Greenhouse Office on the Stage 2Study of Life-Cycle Emissions Analysis of Al-ternative Fuels for Heavy Vehicles.

4. Reduce Energy Consumptionin Homes, Business and Industryby 10 PercentReductions in energy consumption wereassumed to be 10 percent versus 2004 en-ergy consumption as estimated in AEO2006. The 10 percent reduction was appliedto all electricity, natural gas and petroleumconsumed in the residential and commer-cial sectors. For the industrial sector, the10 percent reduction was applied to all elec-tricity and natural gas consumption, and toall petroleum consumption except con-sumption of “other petroleum” and “petro-leum feedstocks” as defined by the EIA,which were excluded completely, andindustrial consumption of liquefied


petroleum gas, 75 percent of which wereexcluded. These petroleum products arefrequently consumed for non-energy pur-poses, and therefore were not assumed tobe affected by energy efficiency programs.

For natural gas and petroleum, globalwarming emission reductions were calcu-lated by multiplying the amount of energysaved by the carbon coefficients in EIA,Documentation for Emissions of GreenhouseGases in the United States 2003. For elec-tricity, the 10 percent reduction in residen-tial, commercial and industrial electricityconsumption was assumed to result in a 10percent reduction in net electricity genera-tion from 2004 levels. We assumed that 25percent of the reduction in generationwould offset generation from existingnuclear power plants. For the main scenarioin this report, we assumed that the remain-ing 75 percent of reduced electricity con-sumption would be used to offsetgeneration at existing coal-fired powerplants. To determine the amount of coalconsumption that would be eliminated, wemultiplied the amount of electricity savedthrough efficiency improvements by 0.75and then by the average heat rate of U.S.coal-fired power plants in 2004 (10,476BTU/kWh) per AEO 2006. We then mul-tiplied this reduction in coal consumptionby the carbon coefficient for coal from EIA,Documentation for Emissions of GreenhouseGases in the United States 2003, to arrive atthe estimated reduction in global warmingemissions.

To illustrate the centrality of strong,mandatory limits on global warming pol-lution to successful efforts to curb globalwarming emissions, we also constructed analternative case, in which energy efficiencysavings were used to reduce generationfrom new, efficient natural gas combinedcycle power plants instead of existing coal-fired power plants. We multiplied theamount of electricity saved through effi-ciency improvements by 0.75 and then bythe estimated heat rate of a natural gas com-bined cycle power plant (7,844 BTU/kWh,based on Pamela L. Spath and Margaret K.

Mann, National Renewable Energy Labo-ratory, Life Cycle Assessment of a Natural GasCombined-Cycle Power Generation System,September 2000). We then multiplied thisreduction in natural gas consumption by thecarbon coefficient for natural gas from EIA,Documentation for Emissions of GreenhouseGases in the United States 2003, to arrive atthe estimated reduction in global warmingemissions for the alternative case.

“Upstream” global warming emissionreductions resulting from reduced produc-tion of coal, oil and natural gas were notincluded in the estimated emission reduc-tions from this scenario. Including up-stream emissions would lead to greaterglobal warming emission reductions fromthis strategy than are estimated here.

5. Obtain 20 Percent of Electricityfrom New Renewables by 2020The amount of fossil fuel power genera-tion that would be displaced by 20 percentnew renewables was calculated by taking theamount of electricity generation needed tosupply demand after the 10 percent reduc-tion in consumption in Step 4, and multi-plying it by 20 percent. Global warmingemission reductions were calculated as de-scribed in the scenario above. Newrenewables were assumed to have zero car-bon dioxide emissions. In reality, some re-newable energy sources (such as geothermalenergy) do result in some global warmingemissions, while all renewable technologiescreate some “upstream” emissions. As aresult, the emission reductions estimatedhere may slightly overestimate the reduc-tions that would result from receiving 20percent of U.S. electricity from new renew-able sources.

6. Hold Other Emissions to 2004LevelsNo increase was assumed in energy use orglobal warming emissions from other sec-tors of the economy.

Notes 43

1 Intergovernmental Panel on Climate Change,IPCC Third Assessment Report – Climate Change2001: Summary for Policy Makers, The ScientificBasis, 2001.2 National Research Council, Division on Earthand Life Studies, Surface Temperature Reconstruc-tions for the Last 2,000 Years, National AcademiesPress, Washington, D.C., 2006.3 See note 1.4 J. Hansen, et al., NASA Goddard Institute forSpace Studies, GISS Surface Temperature Analysis:Global Temperature Trends: 2005 Summation,downloaded from data.giss.nasa.gov/gistemp/2005/, 23 May 2006.5 Ibid.6 Union of Concerned Scientists, GlobalWarming 101: 2005 Vies for Hottest Year onRecord, downloaded from www.ucsusa.org/global_warming/science/recordtemp2005.html,23 May 2006.7 See note 1.8 J.T. Overpeck, et al., “Arctic System onTrajectory to New, Seasonally Ice-Free State,”Eos, 86(34):309-316, August 2005.9 See note 1.10 Stephen Saunders and Maureen Maxwell,The Rocky Mountain Climate Organization,Less Snow, Less Water: Climate Disruption in theWest, September 2005.11 American Academy for the Advancement ofScience, New Study in Science Warns of

Greenland’s Accelerating Glaciers (press release),16 February 2006.12 See note 1.13 U.S. Environmental Protection Agency,Global Warming – Impacts: Chesapeake Bay,downloaded from yosemite.epa.gov/oar%5Cglobalwarming.nsf/content/ImpactsCoastalZonesChesapeakeBay.html, 23May 2006.14 National Oceanic and Atmospheric Adminis-tration, Subsidence and Sea Level Rise in Louisiana:A Study in Disappearing Land, 21 July 2003.15 See note 1.16 Kerry Emanuel, “Increasing Destructivenessof Tropical Cyclones Over the Last 30 Years,”Nature, 436:686-688, 4 August 2005.17 P.J. Webster, et al., “Changes in TropicalCyclone Number, Duration, and Intensity in aWarming Environment,” Science,309(5742):1844-1846, 16 September 2005.18 National Oceanic and Atmospheric Adminis-tration, Noteworthy Records of the 2005 AtlanticHurricane Season, originally published 29November 2005, updated 13 April 2006.19 Kevin E. Trenberth and Dennis J. Shea,“Atlantic Hurricanes and Natural Variability in2005,” Geophysical Research Letters, 33(12)L12704, 27 June 2006.20 Intergovernmental Panel on ClimateChange, IPCC Third Assessment Report – ClimateChange 2001: Synthesis Report, 2001.

Notes


21 World Meteorological Organization, FirstWMO Greenhouse Gas Bulletin: Greenhouse GasConcentrations Reach New Highs in 2004 (pressrelease), 14 March 2006.22 See note 1.23 Ibid.24 Percentage contribution to global warmingin this section based on U.S. Department ofEnergy, Energy Information Administration,Emissions of Greenhouse Gases in the United States,Executive Summary, March 2006.25 See, for example, James Hansen and LarissaNazarenko, “Soot Climate Forcing via Snow andIce Albedos,” Proceedings of the National Academyof Sciences, 101: 423-428, 13 January 2004 for adiscussion of the potential impact of blackcarbon on global warming and the uncertainty inestimating the magnitude of that impact.26 U.S. Department of Energy, EnergyInformation Administration, Emissions ofGreenhouse Gases in the United States 2004,Executive Summary, March 2006.27 More than one-third based on comparison of2004 data from U.S. Department of Energy,Energy Information Administration, Emissions ofGreenhouse Gases in the United States 2004, March2006, with 1983 data from U.S. Department ofEnergy, Energy Information Administration,International Energy Annual 2003, 11 July 2005.28 U.S. Department of Energy, EnergyInformation Administration, International EnergyAnnual 2003, 11 July 200529 Ibid.30 U.S. Department of Energy, EnergyInformation Administration, Emissions ofGreenhouse Gases in the United States 2004, TableB3, December 2005.31 Historic emissions from U.S. Department ofEnergy, Energy Information Administration,Emissions of Greenhouse Gases in the United States2004, Table B3, December 2005. Projectedemissions from U.S. Department of Energy,Energy Information Administration, AnnualEnergy Outlook 2006, February 2006.32 Ibid.33 See note 30.34 Ibid.35 Ibid.36 Percentage of generation from U.S. Depart-ment of Energy, Energy Information Adminis-tration, Electric Power Annual with Data for 2004,November 2005; percentage of global warmingemissions from electricity generation from U.S.

Department of Energy, Energy InformationAdministration, Emissions of Greenhouse Gases inthe United States, Table B3, December 2005.37 Malte Meinshausen, “What Does a 2˚ CTarget Mean for Greenhouse Gas Concentra-tions? A Brief Analysis Based on Multi-GasEmission Pathways and Several ClimateSensitivity Uncertainty Estimates,” in HansJoachim Schnellnhuber, ed., Avoiding DangerousClimate Change, Cambridge University Press,2006.38 Rachel Warren, “Impacts of Global ClimateChange at Different Annual Mean GlobalTemperature Increases,” in Hans JoachimSchnellnhuber, ed., Avoiding Dangerous ClimateChange, Cambridge University Press, 2006.39 James Hansen, “A Slippery Slope: HowMuch Global Warming Constitutes ‘DangerousAnthropogenic Interference?’” Climatic Change,68:269-279, 2005.40 Rachel Warren, “Impacts of Global ClimateChange at Different Annual Mean GlobalTemperature Increases,” in Hans JoachimSchnellnhuber, ed., Avoiding Dangerous ClimateChange, Cambridge University Press, 2006, andMalte Meinshausen, “What Does a 2˚ C TargetMean for Greenhouse Gas Concentrations? ABrief Analysis Based on Multi-Gas EmissionPathways and Several Climate SensitivityUncertainty Estimates,” in Hans JoachimSchnellnhuber, ed., Avoiding Dangerous ClimateChange, Cambridge University Press, 2006.41 Ibid.42 National Research Council, Abrupt ClimateChange: Inevitable Surprises, National AcademiesPress, Washington, D.C., 2002.43 Corresponds to scenario A1F1 in Intergov-ernmental Panel on Climate Change, IPCCThird Assessment Report – Climate Change 2001:Synthesis Report, 2001.44 See note 37. Meinshausen estimated thatcarbon dioxide stabilization at 450 ppm wouldresult in a mean probability of 54 percent thatglobal average temperatures would increase bymore than 2˚ C versus pre-industrial levels. Bycontrast, stabilizing carbon dioxide concentra-tions at 400 ppm would reduce the meanprobability of exceeding a 2˚ C increase to 28percent.45 See note 37.46 U.S. Department of Transportation, FederalHighway Administration, Highway Statisticsseries of reports, Summary to 1995 and 1996through 2004.

Notes 45

47 Ibid.48 Stacy C. Davis, Susan W. Diegel, Oak RidgeNational Laboratory, Transportation Energy DataBook, Edition 25, 2006.49 Based on vehicle-miles traveled data fromU.S. Department of Transportation, FederalHighway Administration, Highway Statistics2004, March 2006, divided by U.S. populationestimate from July 2004 from U.S. CensusBureau, National Population Estimates: AnnualEstimates of the Population by Sex and Five-YearAge Groups for the United States: April 1, 2000 toJuly 1, 2005, downloaded from www.census.gov/popest/national/asrh/NC-EST2005-sa.html, 23May 2006.50 Todd Litman, Victoria Transport PolicyInstitute, The Future Isn’t What it Used to Be:Changing Trends and Their Implications forTransport Planning, 26 April 2006.51 Based on U.S. Department of Transporta-tion, Federal Highway Administration, HighwayStatistics 2004, March 2006, Table HF-10; U.S.Department of Transportation, Federal TransitAdministration, 2004 National Transit Summariesand Trends, downloaded from www.ntdprogram.com/NTD/NTST/2004/PDFFiles 2004%20Na-tional %20Transit%20Summaries %20and%20Trends%20(NTST).pdf, 23 May 2006. Note:capital expenditures for transit infrastructure donot include capital expenditures for rollingstock. Since highway capital expenditures do notinclude capital expenditures for private vehicles,including expenditures for transit rolling stockwould create an “apples-to-oranges” comparison.52 U.S. Department of Energy, EnergyInformation Administration, Annual EnergyReview 2004, 15 August 2005, Table 5.24. Pricecomparison based on five-year average of pricesof leaded regular gasoline until 1979 andunleaded regular thereafter.53 U.S. Department of Energy, EnergyInformation Administration, Emissions ofGreenhouse Gases in the United States 2004,December 2005. U.S. Department of Energy,Annual Energy Outlook 2006, February 2006.Percentage calculated on BTU equivalent basis.54 U.S. Department of Energy, EnergyInformation Administration, Annual EnergyOutlook 2006, February 2006.55 U.S. Department of Transportation, FederalHighway Administration, Traffic Volume Trends,December 2005. Slowest rate of increase since1980 from: U.S. Department of Transportation,Federal Highway Administration, Annual

Vehicle-Miles of Travel, downloaded fromwww.fhwa.dot.gov/ohim/onh00/graph1.htm, 20March 2006.56 U.S. Department of Transportation, FederalHighway Administration, Traffic Volume Trends,April 2006.57 Based on results of CBS/New York Times pollconducted May 4-8, 2006, obtained atwww.pollingreport.com/energy.htm.58 U.S. Department of Transportation, FederalHighway Administration, Highway Statisticsseries of reports, Summary to 1995 and 1996through 2004; U.S. Department of Transporta-tion, Federal Highway Administration, TrafficVolume Trends, December 2005.59 American Public Transportation Association,Transit Ridership Report – Fourth Quarter 2005, 4April 2006.60 U.S. Department of Transportation, Bureauof Transportation Statistics, National Transporta-tion Statistics, downloaded from www.bts.gov/publications/national_transportation_statistics/,30 June 2006.61 Bicycle sales from National Bicycle DealersAssociation, Industry Overview 2006, downloadedfrom nbda.com/page.cfm?PageID=34, 23 May2006. Carpool and vanpool interest fromAmerican Public Transportation Association,High Gas Prices, Emerging Technologies SpurTransit Ridership Increases (press release), 26September 2005.62 Todd Litman, Victoria Transport PolicyInstitute, Rail Transit in America: A Comprehen-sive Evaluation of Benefits, 4 November 2004.63 Todd Litman, Victoria Transport PolicyInstitute, Land Use Impacts on Transport: HowLand Use Factors Affect Travel Behavior, 16November 2005.64 Metro, Travel Behavior Survey for Portland,Multnomah County, Oregon, 1994, as cited inCalifornia Department of Transportation,Statewide Transit-Oriented Development Study:Factors for Success in California, September 2002.65 Margaret Walls and Elena Safirova, Re-sources for the Future, A Review of the Literatureon Telecommuting and Its Implications for VehicleTravel and Emissions, December 2004.66 Washington State Department of Transpor-tation, Commute Trip Reduction Program,downloaded from www.wsdot.wa.gov/tdm/program_summaries/ctr_summ.cfm.67 Transit Cooperative Research Program,National Research Council, National Academy


of Sciences, “An Evaluation of the RelationshipsBetween Transit and Urban Form,” TCRPResearch Results Digest No. 7, June 1995.68 U.S. Environmental Protection Agency,Light-Duty Automotive Technology and FuelEconomy Trends: 1975 Through 2005, July 2005.Based on EPA adjusted laboratory estimates.69 See U.S. Department of Energy, EnergyInformation Administration, Annual EnergyReview 2004, 15 August 2005, Chapter 5.70 See note 68.71 See Methodology for details on howemission reductions were estimated.72 Don MacKenzie and David Friedman,Union of Concerned Scientists, UCS Analysis ofFuel Economy Potential, memorandum to JulieAbraham and Peter Feather, NHTSA, 29 April2005.73 Mark Cooper, Consumer Federation ofAmerica, 50 by 2030: Why $3.00 Gasoline Makesthe 50 Mile per Gallon Car Feasible, Affordable andEconomic, May 2006.74 Northeast States Center for a Clean AirFuture, Reducing Greenhouse Gas Emissions fromLight-Duty Motor Vehicles, September 2004.75 Ibid.76 Louise Wells Bedsworth, Union of Con-cerned Scientists, Climate Control: GlobalWarming Solutions for California Cars, April 2004.77 David Friedman, Union of ConcernedScientists, A New Road: The Technology andPotential of Hybrid Vehicles, January 2003.78 Based on U.S. Environmental ProtectionAgency, EPA Fuel Economy Datafile, downloadedfrom www.fueleconomy.gov/feg/download.shtml, 24 May 2006.79 Standards in Japan and China are weight-based standards, meaning that the ultimate fleet-average fuel economy depends in part on themix of vehicles sold.80 Feng An and Amanda Sauer, Pew Center onGlobal Climate Change, Comparison of PassengerVehicle Fuel Economy and Greenhouse Gas EmissionStandards Around the World, December 2004.Comparison based on values normalized for theU.S. corporate average fuel economy test cycle.81 14 percent from U.S. Department ofTransportation, Federal Highway Administra-tion, Highway Statistics 2004, October 2005;increasing by more than 4 percent per year fromStacy C. Davis, Susan W. Diegel, Oak RidgeNational Laboratory, Transportation Energy DataBook: Edition 25, 2006.

82 Stacy C. Davis, Susan W. Diegel, Oak RidgeNational Laboratory, Transportation Energy DataBook: Edition 25, 2006.83 Therese Langer, American Council for anEnergy-Efficient Economy, Energy SavingsThrough Increased Fuel Economy for Heavy-DutyTrucks, prepared for the National Commissionon Energy Policy, 11 February 2004.84 $2.80 per gallon based on U.S. Departmentof Energy, Energy Information Administration,Gasoline and Diesel Fuel Update, 5 June 2006.85 See Methodology for method of calculation.86 Estimate based on replacing 10 percent ofgasoline use remaining after improvement offuel economy standards to 40 MPG. BTU valueof gasoline converted to gallons of ethanolrequired to replace it based on estimate of BTUcontent of ethanol from Oak Ridge NationalLaboratory, Bioenergy Conversion Factors,downloaded from bioenergy.ornl.gov/papers/misc/energy_conv.html, 25 May 2006.87 Renewable Fuels Association, From Niche toNation: Ethanol Industry Outlook 2006, February2006.88 Renewable Fuels Association, Plant Locations:U.S. Fuel Ethanol Industry Plants and ProductionCapacity, downloaded from www.ethanolrfa.org/industry/locations/, 20 March 2006.89 Nathanael Greene, et al., Growing Energy:How Biofuels Can Help End America’s Oil Depen-dence, December 2004.90 BTU value of diesel converted to gallons ofbiodiesel required to replace it based on estimateof BTU content of biodiesel from NationalBiodiesel Board, Energy Content, downloadedfrom www.biodiesel.org/pdf_files/fuelfactsheets/BTU_Content_Final_Oct2005.pdf, 25 May 2006.91 National Biodiesel Board, Fifth AnnualNational Biodiesel Day Underscores Industry Growth(press release), 17 March 2006.92 K. Shaine Tyson, et al., National RenewableEnergy Laboratory, Biomass Oil Analysis: ResearchNeeds and Recommendations, June 2004;Nathanael Greene, et al., Growing Energy: HowBiofuels Can Help End America’s Oil Dependence,December 2004.93 See note 89.94 See Nathanael Greene and Yerina Mugica,Natural Resources Defense Council, BringingBiofuels to the Pump: An Aggressive Plan for EndingAmerica’s Oil Dependence, July 2005.95 See Seungdo Kim, Bruce E. Dale, “LifeCycle Assessment of Various Cropping Systems

Notes 47

Utilized for Producing Biofuels: Bioethanol andBiodiesel,” Biomass & Energy, 29: 426-439, 2005.96 Mark Clayton, “Carbon Cloud Over a GreenFuel,” Christian Science Monitor, 23 March 2006.97 See, for example, Mark A. Deluchi, LifecycleAnalyses of Biofuels (draft manuscript), May 2006.This analysis finds that biodiesel derived fromsoy causes a net increase in global warmingemissions vis-à-vis conventional diesel, due tolarge nitrous oxide and carbon dioxide emissionsfrom agricultural practices. Deluchi’s resultsdiffer significantly from those of several otherstudies of the global warming impact ofbiodiesel (see Methodology), in part because ofthe use of different methods for the calculationof global warming impacts of various green-house gases than the approach used by theIntergovernmental Panel on Climate Change(IPCC) and in part due to the assumption thatland used for biomass cultivation will replacenative vegetation. The variation in estimates ofthe global warming impacts of biofuels demon-strates the uncertainty surrounding the impactof agricultural practices on global warming.Additional research is needed to resolve theseuncertainties and provide policy-makers withguidance for how to ensure that biofuelsproduction delivers the maximum benefit for theenvironment and the global climate.98 See, for example, American Council for anEnergy-Efficient Economy, Reforming DualFueled Vehicle CAFE Credits, 4 March 2004.99 Based on M.Q. Wang, Argonne NationalLaboratory, Development and Use of GREET 1.6Fuel-Cycle Model for Transportation Fuels andVehicle Technologies, June 2001.100 California Cars Initiative, Plug-In HybridAdvocates Welcome Ford’s Interest in the Technology,accessed at www.evworld.com, 12 May 2006.101 U.S. Department of Energy, EnergyInformation Administration, Emissions ofGreenhouse Gases in the United States 2004,December 2005.102 The bulk of America’s nuclear fleet isbetween 20 and 37 years old and the initiallicenses granted to those power plants are for 40years. The Nuclear Regulatory Commission hasbegun to issue routine 20-year license extensionsfor nuclear plants that are nearing the end oftheir planned lifetimes, increasing the potentialfor age-related equipment failures. For more onthe dangers and economic risks posed by nuclearpower, see National Association of State PIRGs,Challenging Nuclear Power in the States: Policy andOrganizing Tools for Slowing the “Nuclear

Renaissance,” Spring 2006.103 For more information on the Northeastcap-and-trade system, visit the RegionalGreenhouse Gas Initiative at www.rggi.org.104 See Methodology for more details on howemission reductions were calculated.105 U.S. Department of Energy, EnergyInformation Administration, Annual EnergyOutlook 2006, February 2006.106 Steven Nadel, Anna Shipley and R. NealElliott, American Council for an Energy-Efficient Economy, The Technical, Economic andAchievable Potential for Energy-Efficiency in theU.S. – A Meta-Analysis of Recent Studies, 2004.This analysis finds the achievable potential fornatural gas savings to be much lower, but thatconclusion is based on a smaller number ofanalyses of natural gas efficiency programs.107 Devra Bachrach, Natural ResourcesDefense Council and Matt Ardema and AlexLeupp, Silicon Valley Manufacturing Group,Energy Efficiency Leadership in California:Preventing the Next Crisis, April 2003.108 Dan York and Martin Kushler, AmericanCouncil for an Energy-Efficient Economy,ACEEE’s 3rd National Scorecard on Utility andPublic Benefits Energy Efficiency Programs: ANational Review and Update of State-Level Activity,October 2005.109 American Council for an Energy-EfficientEconomy, President’s Budget Slashes Efficiency –The First Step in Oil Addiction Recovery (pressrelease), 7 February 2006.110 Space heating accounts for more than two-thirds of household natural gas use, 80 percentof home oil use, and 10 percent of homeelectricity use. Space heating also accounts forthree-quarters of commercial sector natural gasuse and 5 percent of commercial electricity use.Sources: U.S. Department of Energy, EnergyInformation Administration, 2001 ResidentialEnergy Consumption Survey Consumption andExpenditures Fuel Tables, downloaded fromwww.eia.doe.gov/emeu/recs/byfuels/2001/byfuels_2001.html; U.S. Department of Energy,Energy Information Administration, 1999Commercial Buildings Energy Consumption Survey:Preliminary End-Use Consumption Estimates,downloaded from www.eia.doe.gov/emeu/cbecs/enduse_consumption/intro.htm, 22 May 2006.111 U.S. Department of Energy, FederalEnergy Management Program, Technology Focus:Single-Family Residential Building Weatherization,September 1998.


112 Jennifer Thorne, American Council for anEnergy-Efficient Economy, Residential Retrofits:Directions in Market Transformation, December2003.113 Based on American Council for an Energy-Efficient Economy, Consumer Guide to HomeEnergy Savings: Condensed Online Version,downloaded from www.aceee.org/consumerguide/mostenef.htm, 22 May 2006114 Based on U.S. Department of Energy,Energy Information Administration, 2001Residential Energy Consumption Survey, TableHC3-1a.115 Jennifer Thorne Amman and EricMendelsohn, American Council for an Energy-Efficient Economy, Comprehensive CommercialRetrofit Programs: A Review of Activity andOpportunities, April 2005.116 U.S. Energy Information Administration,2001 Residential Energy Consumption Survey: End-Use Consumption of Electricity 2001, updated 25April 2005; U.S. Energy Information Adminis-tration, 1999 Commercial Buildings EnergyConsumption Survey: Preliminary End-UseConsumption Estimates, updated 27 October2003.117 Residential savings: American Council foran Energy-Efficient Economy, Consumer Guideto Home Energy Savings: Condensed Online Version,downloaded from www.aceee.org/consumerguide/mostenef.htm, 22 May 2006;Commercial savings: Greenbiz.com, “U.S.Manufacturers Reach Landmark Agreement onAir Conditioner Efficiency Standards,” 15November 2004.118 U.S. Energy Information Administration,2001 Residential Energy Consumption Survey: End-Use Consumption of Electricity 2001, updated 25April 2005.119 See note 113.120 J.P. Ross and Alan Meier, Whole-HouseMeasurements of Standby Power Consumption,downloaded from www.osti.gov/energycitations/servlets/purl/793739-FoRVRe/native/793739.pdf, 22 May 2006.121 Anna Monis Shipley and R. Neal Elliott,American Council for an Energy-EfficientEconomy, Ripe for the Picking: Have We Exhaustedthe Low-Hanging Fruit in the Industrial Sector?,April 2006.122 Oak Ridge National Laboratory, Near-Zero-Energy Buildings Blessing to Owners, Environment(press release), 11 August 2004.

123 American Institute of Architects, Architectsand Climate Change, downloaded fromwww.aia.org/SiteObjects/files/architectsandclimatechange.pdf, 25 May 2006.124 Environmental and Energy Study Institute,Renewable Energy Fact Sheet: Solar Water Heating:Using the Sun’s Energy to Heat Water, May 2006.125 70 to 90 percent from U.S. Combined Heatand Power Association, CHP Basics, downloadedfrom uschpa.admgt.com/CHPbasics.htm, 25May 2006; 33 percent from U.S. Department ofEnergy and U.S. Environmental ProtectionAgency, Carbon Dioxide Emissions from theGeneration of Electric Power in the United States,July 2000.126 Industrial: Resource Dynamics Corpora-tion, Cooling, Heating, and Power for Industry: AMarket Assessment, prepared for the U.S.Department of Energy and Oak Ridge NationalLaboratory, August 2003; Commercial andinstitutional: ONSITE SYCOM EnergyCorporation, The Market and Technical Potentialfor Combined Heat and Power in the Commercial/Institutional Sector, prepared for the U.S.Department of Energy, January 2000.127 1 percent based on comparison of potentiallevels above with U.S. Department of Energy,Energy Information Administration, ElectricPower Annual with Data for 2004, November2005.128 An alternative case that assumes thatrenewables are used to offset new, highlyefficient natural gas combined cycle plantsrather than existing coal-fired power plantsyields emission reductions of 212 million metrictons of carbon dioxide, as opposed to the 511million metric tons listed here. See “TheImportance of Mandatory Limits on GlobalWarming Pollution,” page 28.129 D.L. Elliot and M.N. Schwartz, PacificNorthwest Laboratory, Wind Energy Potential inthe United States, September 1993.130 Walt Musial, National Renewable EnergyLaboratory, Offshore Wind Energy Potential for theUnited States, PowerPoint presentation to theWind Powering America Annual State Summit,19 May 2005.131 U.S. Department of Energy, Office ofEnergy Efficiency and Renewable Energy,Learning About PV: The Myths of Solar Electricity,downloaded from www1.eere.energy.gov/solar/myths.html#1, 20 March 2005.132 American Wind Energy Association, U.S.Wind Industry Ends Most Productive Year,

Notes 49

Sustained Growth Expected for at Least Next TwoYears (press release), 24 January 2006.133 U.S. Department of Energy, Office ofEnergy Efficiency and Renewable Energy, WindPower Today & Tomorrow, March 2004. 289million MWh based on assumed 33% capacityfactor.134 Spain wind power consumption fromGlobal Wind Energy Council, Global Wind 2005Report, downloaded from www.gwec.net/uploads/media/Global_WindPower_05_Report.pdf, 25 May2006.135 California Public Utilities Commission,PUC Creates Groundbreaking Solar EnergyProgram (press release), 12 January 2006.136 Solar Energy Industry Association, OurSolar Power Future: The U.S. PhotovoltaicsIndustry Roadmap Through 2030 and Beyond,September 2004.137 Based on 25% estimated capacity factor forsolar.138 Stirling Energy Systems, Stirling EnergySystems Signs Second Large Solar Deal in California(press release), 7 September 2005.139 BP, BP Statistical Review of World Energy2006, June 2006.140 Ibid.141 Ibid.

142 Ibid.143 Ibid.144 15 GW based on U.S. Department ofEnergy, Office of Energy Efficiency andRenewable Energy, Geothermal TechnologiesProgram: Geothermal Power Plants, downloadedfrom www1.eere.energy.gov/geothermal/powerplants.html, 25 May 2006.145 See note 105.146 U.S. Department of Transportation, Bureauof Transportation Statistics, National Transporta-tion Statistics 2005, Summer 2005.147 Half of all flights from Reconnecting America,Why Now?: Our Proposal, downloaded fromwww.reconnectingamerica.org/html/RATN/why_now.htm, 26 May 2006.148 U.S. Department of Transportation, Bureauof Transportation Statistics, TransportationStatistics Annual Report, November 2005.149 U.S. Department of State, U.S. ClimateAction Report 2002, May 2002.150 Ibid.151 U.S. PIRG Education Fund, RedirectingAmerica’s Energy: The Economic and ConsumerBenefits of Clean Energy Policies, February 2005.152 Union of Concerned Scientists, RenewingAmerica’s Economy, September 2004.

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