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Cars and Global Warming

Elizabeth RidlingtonTony DutzikMatt Auten

Rhode Island Public Interest Research GroupEducation Fund

Winter 2005

Policy Options For Rhode Islandto Reduce Global Warming Pollution

from Cars and Light Trucks

Acknowledgments

The authors wish to thank Dan Meszler of Meszler Associates for review of this report.Thanks also to Travis Madsen for his editorial assistance.

Sincere thanks to the Energy Foundation for providing financial support for this project.

The authors alone bear responsibility for any factual errors. The recommendations arethose of the RIPIRG Education Fund. The views expressed in this report are those of theauthors and do not necessarily reflect the views of those who provided editorial or technicalreview.

© 2005 Rhode Island Public Interest Research Group Education Fund

The Rhode Island Public Interest Research Group (RIPIRG) Education Fund is an advo-cate for the public interest. We uncover threats to public health and well-being and fight toend them, using the time tested tools of investigative research, advocacy, and grassrootsorganizing. RIPIRG’s mission is to deliver persistent, result-oriented activism that protectsthe environment, encourages a fair, sustainable economy, and fosters responsive, demo-cratic government.

For additional copies of this report, send $10 to:RIPIRG Education Fund11 South Angell Street, #337Providence, RI 02906

For more information on RIPIRG and the RIPIRG Education Fund, please contact ouroffice at 401-421-6578 or visit our web site at www.ripirg.org.

Table of Contents

Executive Summary 4

Introduction 7

Global Warming and Rhode Island 9Causes of Global Warming 9Range of Impacts of Global Warming 9Global Warming Emissions in Rhode Island 10The Regional Climate Change Action Plan and 12Rhode Island’s Climate Change Reduction EffortsThe Transportation Challenge 14Vehicle Carbon Dioxide Emissions in Rhode Island: Past and Future 18

Tools to Reduce Global Warming Emissionsfrom Cars and Light Trucks 18Clean Cars Standard 18Vehicle Global Warming Pollution Standards 23Low-Rolling Resistance Replacement Tires 25The Need for Additional Actions 26

Policy Findings 27

Assumptions and Methodology 28

Notes 34

4 Cars and Global Warming

Executive Summary

Rhode Island could significantly limitits contribution to global warmingover the next two decades by imple-

menting two policies to reduce carbon di-oxide pollution from cars and light trucks.

Global warming poses a serious threatto Rhode Island’s future. Scientists projectthat average temperatures in Rhode Islandcould increase by 1° to 10° F over the nextcentury if no action is taken to reduce emis-sions of global warming gases—potentiallyleading to coastal flooding, beach erosion,increased air pollution and heat relateddeaths, and a host of other impacts onRhode Island’s environment, public healthand economy.

Controlling global warming emissionsfrom the transportation sector—and par-ticularly cars and light trucks—is essentialto meeting the goals set by the Conferenceof New England Governors and EasternCanadian Premiers in 2001 of reducingglobal warming pollution to 1990 levels by2010 and to 10 percent below 1990 levelsby 2020.

The transportation sector is the largestsource of global warming pollution inRhode Island, responsible for over onethird of the state’s emissions. Cars and lighttrucks—such as pickups, minivans and

SUVs—are the most important sources ofglobal warming emissions in the transpor-tation sector, responsible for about two-thirds of all transportation sector emissionsand about one-quarter of Rhode Island’stotal emissions of global warming gases.

A number of public policies can reducethe contribution of cars and light trucks toglobal warming and help Rhode Islandmeet its commitments.

Carbon dioxide emissions from carsand light trucks in Rhode Island arelikely to increase by approximately 20percent over 1990 levels by 2020 unlessaction is taken to reduce emissions.

• The stagnation in federal corporateaverage fuel economy (CAFE)standards for cars and light trucks,the recent shift toward greater use ofless fuel-efficient SUVs, and increasingvehicle travel (to 23 million miles perday) have put Rhode Island on acourse toward dramatically increasedemissions of carbon dioxide fromtransportation over the next twodecades.

Rhode Island has already taken an im-portant first step to reducing greenhouse

Executive Summary 5

gas emissions from cars and trucks by adopt-ing the California Clean Cars Standard.

• The Clean Cars Standard (also knownas the “Zero Emission Vehicle” or“ZEV” program)—which has beenadopted, or is in the process of beingadopted, by California and sevennortheastern states – will pave the wayfor the widespread introduction ofclean, advanced technology vehicles(such as hybrid-electric and fuel-cellvehicles) that could result in dramatic,long-term reductions in carbonemissions. In the process, it will lead tolight-duty carbon dioxide emissionreductions of about 1.2 percent belowprojected levels by 2020.

Rhode Island can achieve more signifi-cant reductions in its carbon dioxideemissions by adopting global warmingpollution standards for vehicles.

• California’s forthcoming standards onglobal warming emissions fromautomobiles (also known as the“Pavley” standards for their originallegislative sponsor, AssemblywomanFran Pavley) could produce significant

reductions in vehicle carbon dioxideemissions. Adoption of a parallelprogram in Rhode Island taking effectin model year 2009 would reducecarbon dioxide emissions from carsand light trucks by about 12 percentbelow projected levels by 2020 at a neteconomic benefit to the state.

Further, the state could reduce emis-sions sooner and more dramatically byrequiring the sale of low-rolling resis-tance replacement tires.

• Automakers typically equip new carswith low-rolling resistance tires, butreplacement tires, which have higherresistance, cause the vehicle to be lessefficient, and therefore increase carbondioxide emissions. Enacting globalwarming pollution standards forvehicles and requiring that replace-ment tires have low rolling resistancewould reduce carbon dioxide emissionsby light-duty vehicles in Rhode Islandby 14 percent below projected levelsby 2020. Low-rolling resistance tirestandards would also save consumersmoney by reducing fuel costs.

Fig. ES-1. Estimated Rhode Island Carbon Dioxide Emissions from Cars and LightTrucks, 2000-2020, Under Policy Scenarios

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Clean Cars Standard

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Even with these three programs in place,carbon dioxide emissions from cars andlight trucks in 2020 would be just slightlylower than emissions in 2000 because of alarge projected increase in vehicle travel.Thus, Rhode Island will likely need toadopt additional policies to reduce emis-sions from the transportation sector if itwishes to achieve the regional goal of re-ducing overall global warming emissions to10 percent below 1990 levels by 2020.

Rhode Island should move quickly toadopt policies that will stabilize, and ul-timately reduce, emissions of carbondioxide from cars and light trucks.

• In 2005, Rhode Island should committo adopting vehicle global warmingemission standards identical to those

that are being adopted by the state ofCalifornia. To ensure the standardstake effect in model year 2009, RhodeIsland must draft the regulations bythe end of this year.

• Requiring the use of low-rollingresistance tires would reduce globalwarming pollution from all vehiclesonce replacement tires are installed.

• Rhode Island should adopt the pro-grams recommended by the stake-holder group—such as energy

efficiency standards for appliances, newincentives for the purchase of vehicleswith lower global warming emissions,“smart growth” policies that reducevehicle travel, mass transit improve-ments and other measures—to reduceglobal warming emissions.

Introduction 7

Introduction

In 2001, Rhode Island, in concert withother New England states and easternCanadian provinces, took a bold step to-

ward dealing with the problem of globalwarming by adopting a regional ClimateChange Action Plan. The plan committedthe region to significant reductions in emis-sions of global warming gases over the nexttwo decades and even greater reductions inthe future.

As the first step to meeting its commitment,Rhode Island initiated the Greenhouse GasStakeholder Process. Representatives of busi-ness, government, academia, and the non-profit sector gathered to develop a policyroadmap for Rhode Island to achieve itsglobal warming emission reduction goals.

In July 2002, the stakeholders issuedtheir recommendations, a package of 52policies that could be adopted at the state,regional and federal level that would stabi-lize and reduce Rhode Island’s global warm-ing emissions in the decades to come. Therecommendations cover every aspect ofenergy use in Rhode Island, includingtransportation.

Addressing emissions from the transpor-tation sector is Rhode Island’s biggest chal-lenge to meeting its emission reduction

goals, not only because transportation is thelargest source of the state’s global warmingemissions but also because emissions fromthe transportation sector are expected tobecome a larger share of total emissions incoming years.

The technology exists to reduce emis-sions from cars and light trucks, the largestsource of transportation emissions. Thetools to make less-polluting cars and truckscan be implemented at little cost—or evena net economic benefit—to most consum-ers. Meanwhile, a host of newer technolo-gies—ranging from hybrid-electric cars tofuel-cell vehicles that operate on hydrogen—could play an important role in meetingthe region’s long-term emission reductiongoals.

Three transportation policies couldbring these new technologies to RhodeIsland’s roads and help reduce global warm-ing pollution from cars and light trucks.California’s Clean Cars Standard, endorsedby the stakeholders after their initial roundof recommendations, sets sales require-ments for hybrid-electric and other cleanvehicles. Two significant policies not in-cluded by the stakeholders are adoption ofCalifornia’s forthcoming tailpipe emission


standards for carbon dioxide and using low-rolling resistance replacement tires.

Rhode Island has adopted the CleanCars Standard, which originated in Cali-fornia but has been adopted by other statesincluding Massachusetts, Connecticut,New York and New Jersey. It requires thata percentage of vehicles sold in Rhode Is-land in coming years be advanced-technol-ogy vehicles such as hybrids, which, thoughthey are designed to have lower emissionsof smog-forming and toxic air pollutants,also have modest global warming benefits.

Now it is time for Rhode Island to adoptlimits on vehicle global warming pollution.California’s forthcoming standards for ve-hicle global warming emissions will lead to

even greater progress toward realizing thepromise of new technologies to reduce theimpact of our transportation system on theclimate.

This report documents the impact thatadoption of vehicle global warming stan-dards and a low-rolling resistance tire salesrequirement could have for reducing glo-bal warming pollution from motor vehiclesin Rhode Island. But it also documents thechallenge the state faces in reining in emis-sions from the transportation sector. Evenwith adoption of these programs, RhodeIsland will still need to take additional stepsto curtail global warming pollution fromtransportation and achieve its overall cli-mate protection goals.

Global Warming and Rhode Island 9

Global Warming and Rhode Island

Human activities over the last century—particularly the burning of fossilfuels—have changed the composi-

tion of the atmosphere in ways that threatendramatic alteration of the global climate inthe years to come. Those changes couldhave serious repercussions for Rhode Island.

Causes of Global WarmingGlobal warming is caused by human activ-ity that exacerbates the greenhouse effect.The greenhouse effect is a natural phenom-enon in which gases in the earth’s atmo-sphere, including water vapor and carbondioxide, trap heat from the sun near theplanet’s surface. The greenhouse effect isnecessary for the survival of life; withoutit, temperatures on earth would be too coldfor humans and other life forms to survive.

But human activities, particularly overthe last century, have changed the atmo-sphere and intensified the greenhouse ef-fect by releasing pollution that traps moreof the sun’s heat near the earth’s surface. Thispollution comes largely from cars, powerplants, factories and homes when we burnfossil fuels such as coal, oil and gas—as wellas from other human and natural processes.

Since 1750, the atmospheric concentra-tion of carbon dioxide has increased by 31percent. The current rate of increase incarbon dioxide concentrations is unprec-edented in the last 20,000 years.1 Concen-trations of other global warming gases—such as methane and nitrous oxide—haveincreased as well.

As a result, global average temperaturesincreased during the 20th century by about1° F. And, if current trends in global warm-ing emissions continue, temperatures couldrise by an additional 2.5° F to 10.4° F overthe period 1990 to 2100.2

Range of Impacts ofGlobal WarmingThe impact of this increase in global tem-peratures will vary from place to place.Because the earth’s climate system is extraor-dinarily complex, warming may be more orless extreme at various points on the globeand at different times during the year. Someregions will experience drier weather, oth-ers will receive more precipitation. Stormcycles will also likely be affected in unpre-dictable yet significant ways.


There is little doubt, however, that thefirst signs of global warming are beginningto appear, both in Rhode Island and aroundthe world. There is also little doubt thatglobal warming could lead to dramatic dis-ruptions in our economy, environment andway of life.

Over the last century, for example, theaverage temperature in Providence has in-creased by 3.3° F.3 The average tempera-ture of surface water in Narragansett Bayhas risen 3° F since 1950.4 Meanwhile, pre-cipitation has increased by 20 percent.5

Should current emission trends con-tinue, temperatures in Rhode Island couldincrease by 1° F to 10° F by 2100.6 Othersestimate that a 1.8° F increase in averagetemperature could occur New England-wideas soon as 2030, with a 6° F to 10° F increaseover current average temperatures by 2100.7

Precipitation levels also could change.Scientific models suggest that precipitationmay increase in every season, most signifi-cantly in winter by 25 percent.8

In any event, the impacts of such a shiftin average temperature and precipitationwould be severe. Among the potential impacts:

• Longer and more severe smog seasonsas higher summer temperaturesfacilitate the formation of ground-levelozone, resulting in additional threatsto respiratory health, such as aggravatedcases of asthma.9

• Increased coastal flooding and beacherosion due to higher sea levels, withsea levels projected to rise by as muchas 30 inches over the next century.Rhode Island has over 400 miles ofheavily populated shoreline that couldbe affected by rising sea levels.10

• Increases in toxic algae blooms and“red tides,” resulting in fish kills andcontamination of shellfish.11

• Shifts in populations of fish, shellfish,and other aquatic species due tochanging water temperatures andchanges in the composition of coastalestuaries and wetlands.12

• Increased spread of mosquito and tick-borne illnesses, such as Lyme disease,West Nile virus and Eastern equineencephalitis.13

• Increased risk of heat-related illnessesand deaths.14

• Declines in freshwater quality due tomore severe storms, increased precipi-tation and intermittent drought,potentially leading to increases inwaterborne disease.15

• Increased spread of exotic pests andshifts in forest species—including theloss of hardwood trees responsible forvibrant fall foliage displays.

The likelihood and severity of these po-tential impacts is difficult to predict. Butthis much is certain: climate changes suchas those predicted by the latest scientificresearch would have a dramatic, disruptiveeffect on Rhode Island’s environment,economy and public health—unless imme-diate action is taken to limit our emissionsof global warming gases such as carbondioxide.

Global Warming Emissionsin Rhode IslandEmissions of global warming gases inRhode Island increased by 14 percent be-tween 1990 and 2000, to roughly 3,600thousand metric tons carbon equivalent(thousand MTCE, see note on units page 13).16

The transportation sector is responsiblefor approximately 37 percent of RhodeIsland’s contribution to global warming.(See Fig. 1.) Cars and light trucks—such aspickups, minivans and SUVs—are the mostimportant sources of global warming pol-lution within the transportation sector, re-sponsible for about two-thirds of alltransportation-sector emissions and aboutone-quarter of Rhode Island’s total emis-sions of global warming gases.19


Transportation37%

Electric Generation

25%

Forestry & Land Use1%

Wastewater Treatment

0%

Industry4%

Industrial Steam4%

Commercial9%

Residential20%

Other Global Warming PollutantsThis report focuses on transportation-related emissions of carbon dioxide—the lead-ing gas responsible for global warming and the global warming gas released in thelargest quantities by cars and trucks. Cars and trucks produce other global warminggases, however, that must be considered in any emission reduction strategy.

• Methane – Methane gas is likely the second-most important contributor toglobal warming in Rhode Island. Cars and light trucks produce methane intheir exhaust, but it is thought that they are only minor emitters of methaneand that emissions will be reduced in the future through improved emissioncontrol systems.17

• Nitrous Oxide – Nitrous oxide is also produced in automobile exhaust, withmobile sources estimated to contribute about 13 percent of U.S. nitrous oxideemissions in 2002.18 As with methane emissions, improved emission controlmeasures may reduce nitrous oxide emissions in the future.

• Hydrofluorocarbons (HFCs) – HFCs are extremely potent global warminggases, yet tend to be released in only very small quantities. HFCs are typicallyused as coolants in vehicle air conditioning systems and can escape from thosesystems into the environment.

• Black carbon – Black carbon, otherwise known as “soot,” is a product of theburning of fossil fuels, including diesel fuel used in heavy-duty trucks and asmall percentage of light-duty vehicles. Recent research has suggested that,because black carbon absorbs sunlight in the atmosphere and on snow andicepack, it may be a major contributor to global warming, perhaps second inimportance only to carbon dioxide. Research is continuing on the degree towhich black carbon emissions contribute to global warming.

Fig. 1. Rhode Island Sources of Global Warming Emissions20


The Regional ClimateChange Action Plan andRhode Island’s ClimateChange Reduction EffortsRecognizing the threat global warmingposes to Rhode Island—as well as the op-portunity for the state to make a signifi-cant contribution to reducing globalwarming emissions—in 2001, RhodeIsland’s governor joined with other NewEngland governors and premiers of east-ern Canadian provinces in adopting a re-gional Climate Change Action Plan.

The plan set goals for the region to sta-bilize, and ultimately reduce, its emissionsof global warming gases to the atmosphere.In the short term, the plan calls for regionalglobal warming emissions to be reduced to1990 levels by 2010. In the medium term,the region is committed to reductions of10 percent below 1990 levels by 2020. Andin the long term, the agreement calls for areduction in global warming emissions suf-ficient “to eliminate any dangerous threatto the climate”—a level of reduction esti-mated by scientists at 75 to 85 percent be-low present-day levels.21

The plan also acknowledged the impor-tance of the transportation sector to anyeffort to reduce overall global warmingemissions, and committed the region toattempt to “slow the growth rate of trans-portation emissions in the near future.”22

Specifically, the plan recommended that theregion “(p)romote the shift to higher effi-ciency vehicles, lower carbon fuels, andadvanced technologies through the use ofincentives and education,” among otherefforts.23

Notable in the plan’s language, however,is the failure to commit to specific, numeri-cal goals for the reduction of global warm-ing pollution from the transportation sector– even though similar goals were set forreductions from the electricity sector andthe public sector, and for improvements inenergy conservation. The reticence of thegovernors and premiers to make a concrete

commitment on this issue represents a weaklink in the agreement—one that could jeop-ardize the region’s ability to meet its over-all global warming emission reductiongoals.

During the past three years, Rhode Is-land has reinforced its commitment toachieving the regional goals and has begunto develop a plan designed to achieve them.The Rhode Island Department of Environ-mental Management and the State EnergyOffice initiated a public process to developa list of recommended actions Rhode Is-land could take to reduce its global warm-ing emissions. The extensive stakeholderprocess has involved representatives frombusiness, government, academia and thenonprofit sector. They suggested a list of52 programs and policies to reduce thestate’s contribution to global warming fromall sectors of the economy, including trans-portation, land use, building and facilitiesuse, electricity generation, and waste man-agement.

A Note on UnitsBecause various gases contributeto global warming, and the po-tency of the warming effects ofthose gases varies, inventories ofglobal warming emissions typi-cally use units that communicateemissions in terms of their globalwarming potential.

In this report, we use units of“carbon equivalent” – the amountof carbon that would need to bereleased to create a similar globalwarming effect. Other documentscommunicate emissions in termsof “carbon dioxide equivalent.” Totranslate the carbon equivalent tocarbon dioxide equivalent, one cansimply multiply by 3.66.


Rhode Island has already implementedsome of the programs endorsed by thestakeholders. One of the policies supportedby the stakeholders is a renewable energystandard, enacted in June 2004, which willincrease the percentage of electricity usedin the state that is generated by clean, re-newable sources which have zero or lowglobal warming emissions.

By the group’s analysis, implementationof the in-state policy options endorsed byall the stakeholders will bring the state closebut not all the way to meeting its regional2020 emissions-reduction target. Addi-tional in-state policies, particularly in thetransportation sector, will be needed.

Further, implementation of programs haslagged, and thus adoption of additionalpolicies that are cost-effective is especiallyimportant.

One additional program Rhode Islandhas recently adopted is the California CleanCars Standard to reduce emissions of toxicand global warming gases from vehicles (thebenefits of this program will be discussedin the following section on “Tools to Re-duce Global Warming Emissions from Carsand Light Trucks”). Two additional pro-grams that Rhode Island should adopt areglobal warming pollution standards forvehicles and low-rolling resistance tirerequirements.

Transportation and Global Warming: A Primer

A gallon of gasoline contains a set amount of carbon, nearly all of which isreleased to the atmosphere when it is burned. Some of the carbon is releasedin the form of hydrocarbons, carbon monoxide, and particulate matter; mostof it is released in the form of carbon dioxide. For each gallon of gasolineburned in a vehicle, over 19 pounds of carbon dioxide (or approximately 5pounds of carbon) is released to the atmosphere. In addition, the consumptionof gasoline creates significant additional “upstream” emissions of carbon diox-ide resulting from the extraction, transportation, refining and distribution ofthe fuel. Other fuels have greater or smaller amounts of carbon in a gallon (orits equivalent).

Unlike other vehicular air pollutants that result from the incomplete com-bustion of fossil fuels or from fuel impurities, carbon dioxide is a natural resultof the combustion process. As a result, there are three main ways to limitcarbon dioxide emissions from motor vehicles:

1. Drive more efficient vehicles.

2. Reduce the number of miles traveled.

3. Switch to fuels with a lower carbon content.

Vehicles also emit smaller amounts of other global warming gases, such asmethane and nitrous oxide, as well as hydrofluorocarbons from the use of theair conditioning system. Control of some of these emissions is possible throughmeans other than reducing fuel use or substituting low-carbon fuels.


The TransportationChallengeThe challenge of reducing global warmingemissions from cars and trucks is formi-dable, and three recent trends in the trans-portation sector make the challenge ofreducing global warming emissions inRhode Island even greater.

Increasing Vehicle Miles TraveledRhode Islanders are traveling more milesin their cars and light trucks than ever be-fore. Between 1990 and 2003, the numberof vehicle-miles traveled (VMT) annuallyon Rhode Island highways increased from7.4 billion miles to 8.4 billion miles a year,or over 23 million miles a day—an increaseof 14 percent.24

Stagnating Fuel EconomyThe imposition of federal Corporate Av-erage Fuel Economy (CAFE) standardsbeginning in 1975 led to dramatic improve-ments in the fuel efficiency of American carsand light duty trucks. The CAFE standardsrequired a gradual increase in fuel economyduring the 1970s and 1980s, topping out atan average fuel economy for new cars of

27.5 miles per gallon (MPG) by 1990 and20.7 MPG for light trucks by 1996.26 (TheNational Highway Traffic Safety Adminis-tration recently increased the light truckstandard to 22.2 MPG, to be achieved bymodel year 2007.)

In the decade-and-a-half following en-actment of the CAFE standards, the “realworld” fuel economy of passenger carsnearly doubled—from 13.4 MPG in 1975to 24.0 MPG in 1988. Similarly, light trucksexperienced an increase in real-world fueleconomy from 11.8 MPG in 1975 to 18.3MPG in 1987.27

However, the momentum toward morefuel efficient cars has not only stalled sincethe late 1980s, but it has actually reversed.Indeed, in many cases, Americans get fewermiles per gallon from their new vehiclestoday than they did during the Reagan ad-ministration.

Until recently, the federal governmenthad refused to increase CAFE standards formore than a decade, and changes in driv-ing patterns—including higher speeds andincreased urban driving—have led to a real-world decrease in fuel economy. An EPAanalysis of fuel economy trends found thatthe average real-world fuel economy oflight-duty vehicles sold in 2003 was lowerthan the average fuel economy of vehicles

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sold in 1981. Indeed, the average real-worldfuel economy of new cars and light trucksactually declined by 7 percent between 1988and 2003.28

Amid growing public pressure to im-prove vehicle fuel economy, the U.S. De-partment of Transportation plans toincrease CAFE standards for light trucksby a modest 1.5 MPG between 2005 and2007. While this proposal fails to take ad-vantage of many technologies that couldcost-effectively improve fuel economy, evena modest increase in CAFE standards hassome effect in reducing the rate of growthof transportation carbon dioxide emissions.

Growing Numbers of SUVs andLight TrucksWhile the fuel economy of the average carand light truck has stagnated over the pasttwo decades, the average fuel economy ofthe entire new-car fleet has declined—thanks to the dramatic shift in purchasinghabits toward sport utility vehicles (SUVs),vans and light trucks.

In 1975, when the first federal CAFEstandards were enacted, SUVs made up 2percent of the national light-duty vehiclemarket, vans 5 percent, and pickup trucks

Figure 3. Average Fuel Economy for New Light-Duty Vehicle Fleet on the Decline29

13 percent. By model year 2004, however,SUVs accounted for 26 percent of light-duty vehicle sales, vans 7 percent, and pick-up trucks 15 percent. The light-dutymarket share of passenger cars and stationwagons dropped over the same period from80 percent to 52 percent.30 (See Fig. 4.)

This shift in purchasing habits hascaused the average fuel economy of thenation’s new light-duty vehicle fleet to dipas low as 20.4 MPG in 2001—lower thanat any time since 1980 and down by nearly8 percent from the historical peak in 1987and 1988.31

The trend toward SUVs and light trucksis expected to continue, with light trucksmaking up an increasing percentage of theentire light-duty fleet as time goes on. TheEnvironmental Protection Agency projectsthat by 2020, 64 percent of all light-dutyvehicles on the road nationally will be lighttrucks.32

The combination of these three factors—more miles traveled, increasingly intrucks and SUVs, with stagnant fueleconomy across the entire vehicle fleet—poses a great challenge to Rhode Islandpolicymakers as they attempt to reduce glo-bal warming emissions from the transpor-tation sector.

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Vehicle Carbon DioxideEmissions in Rhode Island:Past and FutureBased on Rhode Island-specific fuel con-sumption data compiled by the U.S. EnergyInformation Administration (EIA), cars andlight-duty trucks released approximately820 thousand metric tons carbon equiva-lent (thousand MTCE) of carbon dioxideinto the atmosphere in 1990. By 2000, thoseemissions had increased by about 6 percent,to 870 thousand MTCE—meaning thatcars and trucks were responsible for ap-proximately one-quarter of Rhode Island’s

Fig. 4 (a-c). National Purchasing of Light-Duty Vehicles Shifts from Cars to Trucks,Vans and SUVs

contribution to global warming in 2000.33

Any attempt to project Rhode Island’sfuture global warming emissions dependsgreatly on the assumptions used. The “As-sumptions and Methodology” section at theconclusion of this report describes theseassumptions in detail. Simply put, the fol-lowing projections (which are based largelyon data and projections by state and fed-eral government agencies and which we willterm the “base case”) assume continuedgrowth in vehicle travel, slight improve-ment in vehicle fuel economy, and a con-tinuation of the trend toward increasedpurchases of sport utility vehicles and otherlight trucks.34

71%

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%Pickups 15%

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Based on these assumptions, carbon di-oxide emissions from the Rhode Islandlight-duty vehicle fleet are projected to ex-perience a 3 percent increase over 2000 lev-els by 2010, followed by a further 10percent increase between 2010 and 2020.In other words, by 2020, carbon dioxideemissions from cars and light trucks willexceed 1990 levels by 21 percent in the ab-sence of action to reduce emissions. (SeeFig. 5.)

An increase of such magnitude wouldchallenge Rhode Island’s ability to meet itsglobal warming emission reduction goals.Should these increases in global warmingpollution from cars and light trucks occur,

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Fig. 5. Actual and Projected Carbon Dioxide Emissions from Light-Duty Vehicles inRhode Island, 1990-2020

Rhode Island would need to achieve dra-matic reductions in global warming pollu-tion from other sectors of the state’seconomy over the next two decades in or-der to meet the goals of the plan.

However, this path toward increasingcarbon dioxide emissions from cars andlight trucks is not inevitable. Public poli-cies that require or encourage the purchaseof more fuel-efficient or advanced technol-ogy cars can make a significant dent inRhode Island’s future emissions of globalwarming gases. One of the most powerfulsuch policy options is California’s forth-coming limits on global warming pollutionfrom vehicles.

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Rhode Island has many potential toolsavailable to reduce emissions of glo-bal warming gases from the transpor-

tation sector. Among the most powerful ofthose tools are the global warming pollu-tion standards for cars and trucks beingdeveloped by California.

The Clean Air Act gives most states twooptions for control of motor vehicle emis-sions: states may choose to comply withfederal emission standards or to adopt themore protective standards implemented bythe state of California, the only state em-powered by the Clean Air Act to devise itsown emission regulations.

Rhode Island—like six other states in theNortheast—has chosen to implementCalifornia’s Clean Cars Standard for smog-forming and other toxic pollutants (whichwere updated in the late 1990s and are nowknown as the Low Emission Vehicle II, orLEV II, standards).

In addition, Rhode Island and otherstates will soon have the opportunity toadopt forthcoming standards to limit glo-bal warming pollution from cars and lighttrucks. The standards will likely bring aboutsignificant reductions in carbon dioxideemissions from cars and light trucks overthe next decade.

Tools to Reduce Global WarmingEmissions from Cars and Light Trucks

As discussed below, Rhode Island’s adop-tion of California’s Clean Cars Standardprovides a first step in reducing greenhousegas emissions from vehicles. Adding globalwarming pollution standards would likelyresult in even more significant reductionsin emissions of global warming gases fromcars and trucks.

Rhode Island’s options are not limitedto these California-based policies. Otherpolicies, such as requiring the use of low-rolling resistance tires on vehicles, can pro-vide important assistance in Rhode Island’sefforts to meet the state’s climate changegoals.

Clean Cars StandardThe California Clean Cars Standard seeksto reduce emissions of smog-forming andother hazardous pollutants. It achieves itsgoals by establishing fleet-wide limits ontailpipe emissions and by requiring the saleof advanced-technology vehicles such ashybrids that have even lower emissions.Eventually, the program calls for the saleof zero-emission vehicles (ZEVs). It islikely, however, that some of the techno-logical changes encouraged by the Clean

Tools to Reduce Global Warming 19

Cars Standard will also reduce emissionsof global warming gases as well.

By adopting the program, Rhode Islandhas laid the groundwork to have increas-ing percentages of advanced-technologyvehicles on the road over the next decadeand more. The program currently has threemain components:

Pure Zero-Emission Vehicles“Pure” zero-emission vehicles (pure ZEVs)are those—like battery-electric and fuel-cellvehicles—that release no toxic or smog-forming pollutants from their tailpipes orfuel systems. They also have the potentialto release far fewer global warming gasesthan today’s vehicles.

The most recent revision to the CleanCars Standard shifted the emphasis of theprogram from near-term deployment ofbattery-electric vehicles to the long-termdevelopment of hydrogen fuel-cell vehicles.As a result, automakers will not have to sellfuel-cell or other pure zero-emission ve-hicles in Rhode Island until at least modelyear 2012. Even then, the number of pureZEVs required for sale in Rhode Islandwould be small, representing less than onepercent of new car and light truck sales untilmodel year 2016.35

In addition, the California Air ResourcesBoard (CARB), which administers the pro-gram, is scheduled to review the status offuel-cell technology prior to enforcing anypure ZEV requirements for the 2009 modelyear and beyond.36

Currently, the Clean Cars Standard re-quires the sale of very few pure zero-emis-sion vehicles over the next decade. But itdoes provide an incentive for automakersto continue research and development workon technologies such as hydrogen fuel-cellvehicles that could provide zero-emissiontransportation in the future.

Partial Zero-Emission Vehicle(PZEV) CreditsThe majority of vehicles that automakersproduce to comply with the Clean Cars

Standard will be vehicles that receive“partial ZEV credit”—otherwise known as“PZEVs.” PZEVs are like conventionalgasoline vehicles in every way but one: theyare engineered to produce dramaticallylower emissions of smog-forming and otherhazardous pollutants. Indeed, PZEVs are90 percent cleaner than the average newvehicle sold today.37

While PZEVs would play an importantrole in helping Rhode Island to achieve itsair quality goals, the technologies used inPZEVs do not necessarily make a substan-tial contribution to reducing global warm-ing emissions from cars. Thus, we do notassume any global warming benefits fromthe PZEV portion of the program.

Advanced Technology PZEVs(AT-PZEVs)The greatest near-term global warmingimpact of the Clean Cars Standard willlikely come from provisions to encouragethe sale of advanced technology PZEVs, orAT-PZEVs, that can run on a cleaner al-ternative fuel, such as compressed naturalgas, or that use advanced technologies, suchas hybrid-electric drive. To encourageautomakers to release additional new hy-brid vehicles as early as possible, auto-mak-ers are allowed to comply with up to 40percent of their Clean Cars sales obliga-tions in the early years of the programthrough the sale of AT-PZEVs.

Hybrid-electric vehicles are the mostlikely technology to be used to comply withAT-PZEV standards. Hybrids have provento be very popular with consumers, espe-cially in an era of higher and rapidly fluc-tuating gasoline prices. Sales of hybridvehicles have increased steadily since theirintroduction to the domestic market inDecember 1999. About 85,000 hybridswere sold in the U.S. in 2004, an increaseof 63 percent from the previous year.38

Thus far, there are four models of ve-hicles that have been certified to AT-PZEVemission standards: the hybrid ToyotaPrius, Honda Civic, and Ford Escape, and


the natural gas-powered Honda CivicGX.39 (Note that not all hybrid vehicleshave low enough emissions to quality forAT-PZEV certification.) Unfortunately,although a healthy market for hybrids ap-pears to exist, automakers have not yet sup-plied hybrids in large enough quantities tomeet consumer demand. By the end of2005, the demand crunch could ease asautomakers plan to introduce at least sixadditional hybrid models—including hy-brid versions of the Toyota HighlanderSUV and Chevy Silverado pickup—that mayqualify as AT-PZEVs if their emissions meet“super low-emission” (SULEV) standards.40

Should automakers choose to maximizetheir use of AT-PZEVs to comply with theClean Cars Standard—and do so using ve-hicles similar to the Toyota Prius— hybridscould make up about 3.5 percent of car andlight truck sales in 2007, increasing to 7percent by 2012. (See Fig. 6.) This trans-lates to sales of about 1,900 hybrids inRhode Island in 2007, increasing to ap-proximately 5,000 annually by 2014. Be-cause the Clean Cars Standard offers a greatdeal of flexibility, however, automakerscould choose to comply by manufacturinggreater numbers of less-advanced hybrids

or smaller numbers of pure ZEVs, amongother options.

Also unclear is the degree of globalwarming pollution reductions that can beexpected from vehicles complying with AT-PZEV standards. Hybrid-electric vehiclesand alternative-fuel vehicles vary greatly intheir emissions of global warming pollu-tion. Some, like the Toyota Prius, offergreat reductions in global warming pollu-tion, while others, such as hybrid pickuptrucks to be sold by General Motors andDaimlerChrysler, offer little reduction inglobal warming pollution versus conven-tional models. The Clean Cars Standarddoes provide additional credit to hybrid-electric vehicles that attain a greater shareof their power from an electric motor (gen-erally allowing them to achieve lower car-bon dioxide emissions), but these credits arenot directly tied to global warming pollu-tion. (Note also that not all hybrids qualifyfor AT-PZEV credit because their emis-sions of other air pollutants are too high.)For the purposes of this analysis, we assumethat hybrids manufactured to comply withAT-PZEV standards will release about 30percent fewer global warming gases permile than conventional vehicles.42

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Clean Cars Standard Impacts:Long TermOn the front end, no assessment of short-term global warming pollution reductionscan precisely capture the potential long-term and indirect benefits of the Clean CarsStandard in reducing carbon dioxide emis-sions. At its heart, the program is a “tech-nology forcing” program—one that

attempts to jump-start advanced technol-ogy vehicle development and the adoptionof these technologies in the mainstreamauto market. That being said, however,adoption of the program will likely bringabout significant long-term emission reduc-tions as technological changes broughtabout by the program spread to other ve-hicles in the Rhode Island car and truckfleet.

Additional Uncertainty: Alternative Compliance Paths

In addition to the compliance flexibility that California designed into the CleanCars Standard, Rhode Island offers manufacturers two early compliance optionsthat introduce greater uncertainty about how automakers will choose to complywith the program’s requirements, especially in the early years of implementation.

Both alternative compliance paths allow manufacturers to build credit for CleanCars Standard-compliant vehicles placed in Rhode Island or California before theprogram begins in Rhode Island.41 In one alternative compliance option, automakerscan draw upon credits earned in California by selling advanced-technology ve-hicles. In model year 2008, credits that a manufacturer has not used up in Califor-nia can be counted in Rhode Island, adjusted proportionally to Rhode Island’s smallervehicle market. The manufacturer can then use those credits to offset require-ments of the Clean Cars Standard in Rhode Island.

Rhode Island’s other alternative compliance option encourages manufacturersto sell cleaner cars in Rhode Island as soon as possible. Manufacturers may propor-tionally transfer their California credits to Rhode Island in model year 2005 andadd to that credit bank by selling cars in Rhode Island. Each low- or zero-emissioncar sold in Rhode Island before the Clean Cars Standard officially begins in modelyear 2008 will be credited. In addition, for introducing cleaner vehicles in RhodeIsland before being required to do so, an automaker earns a 25% bonus. For ex-ample, an AT-PZEV sold in model year 2005 is credited as if it were 1.25 AT-PZEVs sold in model year 2009. To ensure manufacturers are not over-credited forearly implementation, any credits expended in California during 2005-2007 will bescaled to the Rhode Island market and subtracted from the credit bank.

The alternative compliance paths will reduce the number of advanced technol-ogy vehicles that manufacturers must sell in Rhode Island versus the conventionalcompliance paths available through the California version of the program. How-ever, because of the many variables involved (including manufacturers’ sales plansin both Rhode Island and California) it is difficult to make a reliable estimate ofhow great those reductions will be. As a result, we do not factor the availability ofRhode Island’s alternative compliance paths into our analysis, meaning that thereal carbon dioxide emission reductions achieved by the program could be lowerthan estimated here.


An example of the potential power of theprogram to hasten technological change isthe development of hybrid vehicles.California’s adoption of the original ZEVrequirement sparked public and private-sector research efforts into the developmentof advanced batteries and electric-drivetechnologies. While the generation of full-function electric vehicles that resulted fromthat research—such as Honda’s EV-Plusand General Motors’ EV1—were not soldin large quantities, the research effort droveadvances in electric vehicle technology thatfacilitated the birth of the popular hybrid-electric systems that now power hundredsof thousands of vehicles worldwide andhave laid the groundwork for recent ad-vances in fuel-cell vehicle technology.43

Similarly, the current form of the CleanCars Standard is designed to encouragecontinued investment in hybrid-electricand hydrogen fuel-cell vehicle developmentand may lead to the development of newtypes of vehicles (such as “plug-in hybrids”that combine the benefits of battery-elec-tric and hybrid-electric vehicles) with sig-nificant benefits for the climate. Oncedeveloped and offered to consumers, it ispossible that these vehicles could come torepresent a far greater share of the new carmarket than is estimated below.

Clean Cars Standard Impacts:Short TermThe short-term impact of the Clean CarsStandard on carbon dioxide emissions inRhode Island will largely be determined byhow automakers choose to comply with theprogram’s flexible provisions. There arealmost infinite options available toautomakers for compliance—however, it islikely that one or several technologies willdominate the mix of vehicles certified un-der the program.

We assume that automakers will takemaximum advantage of the ability to meetClean Cars Standard requirements withPZEVs and AT-PZEVs. We also assumethat vehicles sold to meet AT-PZEV re-quirements are hybrid-electric vehicles withsimilar technological characteristics to theToyota Prius. We assume that any vehiclessold to meet pure ZEV requirements arehydrogen fuel-cell vehicles whose fuel isgenerated from natural gas. We use con-servative assumptions about the carbon di-oxide emission reductions that could resultfrom hybrid or fuel-cell vehicles. And, asnoted above, we do not factor the availabil-ity of Rhode Island’s alternative compliancepaths into our analysis.

Using these assumptions, implementation

Fig. 7. Reductions in Carbon Dioxide Emissions Under Clean CarsStandard (Light-Duty Vehicles)

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of the program in Rhode Island as sched-uled beginning in the 2008 model yearwould reduce light-duty vehicle carbon di-oxide emissions by about 1.2 percent ver-sus base case projections by 2020—for atotal reduction in emissions of about 12thousand MTCE. (See Fig. 7.)

Rhode Island’s adoption of the CleanCars Standard will result in reduced globalwarming and toxic emissions from vehicles.Adopting California’s global warming pol-lution standards for vehicles will provideeven greater emission reductions.

Vehicle Global WarmingPollution StandardsIn July 2002, California adopted the firstlaw to control carbon dioxide emissionsfrom automobiles. Beginning in model year2009, automakers will have to adhere tofleet average emission limits for carbon di-oxide similar to current limits on smog-forming and other pollutants.

The California legislation requiresCARB to propose limits that “achieve themaximum feasible and cost effective reduc-tion of greenhouse gas emissions frommotor vehicles.” Limits on vehicle travel,new gasoline or vehicle taxes, or limitationson ownership of SUVs or other light truckscannot be imposed to attain the new stan-dards.44

In September 2004, CARB adopted rulesfor implementation of the global warmingpollution standards. As required by the ini-tial legislation, CARB has submitted theregulations to the California Legislature forreview during 2005. Those proposed rulesprovided the basis of our analysis here.

In developing the global warming pol-lution standards, the CARB staff reviewedseveral analyses of the types of technolo-gies that could be used to achieve “maxi-mum feasible and cost effective” reductionsin global warming emissions from vehicles.Among the technological advances that canreduce global warming emissions are:

• Smaller, more efficient engines,made possible through the use ofturbocharging, in which a turbinerecaptures the 25 to 50 percent of anengine’s energy that is lost throughexhaust and redirects it into theengine; or through variable compres-sion ratios that allow an engine totailor compression rates to loadconditions.45

• Direct-injection engines that allowgreater control of the engine’s use offuel.46

• Advanced transmissions – such asfive- and six-speed automatics andcontinuously variable transmissions—that allow a broader range of gearratios.47

• Integrated starter-generators thatallow greater power and enable thevehicle to take advantage of somefeatures of hybridization (such asidle-off).48

• Improved air conditioning systems,which may include a more efficientcompressor, leak less, and be filledwith a refrigerant that contributes lessto global warming.49

• Weight reduction, achieved throughthe use of lightweight materials such ashigh-strength low-alloy steel, alumi-num, or magnesium alloys, or redesignto use less material in a car.50

• More aerodynamic designs, whichcan include a modified body shape orcovers below the vehicle to reduce airdrag.51

• Cylinder deactivation technology,which turns off half of the cylinders inthe engine during some operatingmodes, such as steady-speed freewaydriving.52

• Improved lubricating oil that reducesfriction and cuts global warmingemissions.53


CARB’s proposal estimates that near-term technologies could reduce averageglobal warming emissions from cars by 25percent and from light trucks by 18 per-cent. Over the medium term (2013 to2016), cost-effective reductions of 34 per-cent for cars and 25 percent for light-trucksare feasible.54

The technological changes needed toachieve these reductions will likely resultin modest increases in vehicle costs thatwould be more than recouped over time byconsumers in the form of reduced fuel ex-penses. CARB projects that cars attainingthe 34 percent reduction in global warm-ing emissions required by 2016 would costan average of $1,064 more for consumers,while light trucks achieving the required 25percent reduction would cost about $1,029more.55

However, the agency also estimates thatthe rules will significantly reduce operat-ing costs for new vehicles—particularly forfuel. By subtracting operating cost savingsfrom the projected additional monthly pay-ment associated with purchasing vehiclesthat comply with the standard, CARB

projects that, upon full phase-in, consum-ers will save $3 to $7 every month as a re-sult of the standards. CARB also projectsthat the net impact of the standards to thestate’s economy will be positive, suggest-ing that Rhode Island could save moneywhile at the same time reducing the state’soverall emissions of global warming gases.56

Assuming that the September 2004 ver-sion of the global warming pollution stan-dards are adopted as proposed—and thatRhode Island would implement those stan-dards beginning with the 2009 model year—the reductions in global warming pollu-tion that would result would be significant.Compared to the base case projection, thepollution standards would reduce light-duty carbon dioxide emissions by 12 per-cent by 2020 – for a total reduction of 121thousand MTCE. (See Fig. 8.) In addition,upstream carbon emissions likely would bereduced through lower demand for produc-ing, refining and transporting fuel, but be-cause many of these reductions would takeplace elsewhere, and not in Rhode Island,we do not count them in the benefits RhodeIsland would achieve with this policy.

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Fig. 8. Reductions in Carbon Dioxide Emissions Under Global Warming PollutionStandards (Light-Duty Vehicles)

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Low-RollingResistance Tires

Global WarmingPollution Standards& Low-RollingResistance Tires

Low-Rolling ResistanceReplacement TiresRhode Island can both enhance the savingsachieved through global warming pollutionstandards for vehicles and begin reducingemissions sooner by requiring that replace-ment tires sold to consumers have low roll-ing resistance. Vehicles that comply withthe ZEV standards or meet vehicle globalwarming emission limits, and vehicles thatwere sold before those programs wereimplemented can benefit from low-rollingresistance tires.

Automobile manufacturers typically in-clude low-rolling resistance (LRR) tires ontheir new vehicles in order to meet federalcorporate average fuel economy (CAFE)standards, and including LRR tires on newvehicles is one tool manufacturers may useto meet global warming pollution limits.However, LRR tires are generally not avail-able to consumers as replacements whenoriginal tires have worn out. As a result,vehicles with replacement tires do notachieve the same fuel economy as vehicleswith original tires.

The potential savings in fuel—and car-bon dioxide pollution—are significant. A2003 report conducted for the CaliforniaEnergy Commission found that LRR tireswould improve the fuel economy of vehicles

operating on replacement tires by about 3percent, with the average driver replacinga vehicle’s tires when the vehicle reachesfour, seven and 11 years of age. The result-ing fuel savings would pay off the additional$5 to $12 cost per set of tires in about oneyear, the report found, without compromis-ing safety or tire longevity.57

Several potential approaches exist toencourage the sale and use of LRR tires—ranging from labeling campaigns (similarto the Energy Star program) to mandatoryfuel efficiency standards for all light-dutytires sold in the state. California recentlychose the latter approach, adopting legis-lation requiring that replacement tires soldto consumers beginning in July 2008 havethe same average energy efficiency as theoriginal tires provided by automakers.58

The state will rate the energy efficiency ofdifferent tires based on testing informationprovided by manufacturers. The law doesnot require that each tire be labeled withits efficiency rating, but the information willbe readily available to Rhode Island to de-velop similar requirements.

A standards program that required thesale of LRR tires beginning in 2007 inRhode Island—assuming the same tire re-placement schedule and per-vehicle emis-sion reductions found in the Californiastudy—would ultimately reduce carbon

Fig. 9. Reductions in Carbon Dioxide Pollution Under Low-Rolling ResistanceReplacement Tires (Light-Duty Vehicles)

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dioxide emissions from the light-duty fleetby about 1.5 percent by 2010 and 2.2 per-cent by 2020, while also providing a net fi-nancial benefit to consumers throughreduced gasoline costs.

Adopting both global warming pollutionstandards for vehicles and a LRR tires salesrequirement would reduce vehicle globalwarming pollution in Rhode Island by 2.2percent by 2010 and 14 percent by 2020. (SeeFig. 9.)

Further, Rhode Island should encourageneighboring states to adopt similar require-ments for the sale of replacement tires, cre-ating a regional bloc of states with uniformrequests for tire manufacturers and reduc-ing the degree to which the impact of theprogram could be muted by consumersbuying replacement tires in other states.

The Need for AdditionalActionsAdopting global warming pollution stan-dards in addition to the Clean Cars Stan-dard can contribute significantly to RhodeIsland’s efforts to reduce global warmingpollution from the transportation sector.Adopting the global warming pollutionstandards and a low-rolling resistance tireprogram would reduce global warmingpollution from light-duty cars and trucksto slightly below 2000 levels in 2020. If noaction is taken, pollution levels are expectedto rise by 14 percent compared to 2000.

Thus, adoption of global warming pol-lution standards for vehicles and low-rolling

resistance tire standards would not beenough to return transportation sectoremissions to 10 percent below 1990 levelsby 2020, the target Rhode Island agreed tounder the Conference of New EnglandGovernors and Eastern Canadian PremiersClimate Change Action Plan. ShouldRhode Island seek to achieve reductionssimilar to those called for in the plan forcars and light trucks, the state would needto achieve an additional 58 thousandMTCE of reductions by 2010 and 116thousand MTCE of reductions by 2020.

A number of policy options, many ofwhich were endorsed by the stakeholders,exist for closing this gap, including:

• Measures to reduce per-mile globalwarming pollution from vehicles,such as:

o State or federal incentives for thepurchase of vehicles with lowercarbon emissions.

• Measures to reduce the rate of growthin vehicle travel, such as:

o Improvements in the public transitsystem and other alternatives toautomobile use.

o Adoption of “pay-as-you-drive”insurance, in which insurance ischarged by the mile, discouragingexcessive driving.

o Implementation of “smart growth”measures to reduce sprawlingdevelopment and the accompanyingneed for vehicle travel.

Policy Findings 27

A ttaining the reductions in globalwarming pollution required ofRhode Island under the regional

Climate Change Action Plan will requiresignificant actions to reduce emissions fromlight-duty vehicles.

To achieve this goal:

• The state should announce itscommitment to adopt California’sglobal warming pollution standardsfor cars and light trucks in 2005.

Policy Findings

• Rhode Island should require the saleof low-rolling resistance tires to reduceemissions from all vehicles equippedwith replacement tires.

• The state should take aggressive actionto reduce transportation-sector globalwarming pollution, including actionsthat speed the deployment of environ-mentally preferable advanced-technol-ogy vehicles (such as hybrids), reducethe rate of growth in vehicle travel,and encourage improvements in thefuel economy of conventional vehicles.


P rojections of future global warmingemissions from automobiles dependa great deal on the assumptions used.

This section details the assumptions wemade about future trends, explains themethodology we used to estimate the impactof various programs, and compares theresults with data recently published byothers.

Baseline Light-Duty VehicleCarbon Dioxide EmissionsCarbon dioxide emissions from light-dutyvehicles (cars and light trucks) in RhodeIsland in 1990 and 2000 were based on state-specific motor gasoline usage data fromU.S. Department of Energy, Energy Infor-mation Administration (EIA), State EnergyData 2000 Consumption, downloaded fromw w w. e i a . d o e . g o v / e m e u / s t a t e s /_use_multistate.html, 7 December 2004.Fuel consumption data for the transporta-tion sector in BTU was converted to carbondioxide emissions based on conversion fac-tors from EIA, Annual Energy Outlook 2003,Appendix H and EIA, Emiss ions ofGreenhouse Gases in the United States 2001,

Appendix B. The proportion of transpor-tation-sector gasoline emissions attribut-able to light-duty vehicles was estimated bydividing energy use by light-duty vehiclesby total transportation-sector motor gaso-line use as reported in EIA, Annual EnergyOutlook 2003. Emissions from vehiclesmore than three years old were adjustedupward by 3 percent to account for the de-crease in fuel efficiency that results whenconsumers replace the original low-rollingresistance tires provided by the manufacturer.

Vehicle-Miles TraveledHistoric vehicle-miles traveled data forRhode Island were obtained from the Fed-eral Highway Administration, Office ofHighway Policy Information. Projectedvehicle-miles traveled were estimated us-ing an average annual growth rate of 1.17percent. Twenty-year VMT growth datawere provided by Gary Bowen, Transpor-tation Management Center, Rhode IslandDepartment of Transportation, personalcommunication, 9 December 2004. Thisgrowth rate is slightly higher than RhodeIsland’s average annual VMT growth ratefrom 1990 to 2003.

Assumptions and Methodology


VMT Percentages by Vehicle TypeTo estimate the percentage of vehicle-milestraveled accounted for by cars and light-duty trucks, we relied on two sources ofdata: actual VMT splits by vehicle type for2000 through 2002 from the Federal High-way Administration, Highway Statistics se-ries of reports and projections of futureVMT splits output from the EPA’s MO-BILE6 mobile source emission estimatingmodel. (Rhode Island-specific data onVMT splits are unavailable, but the statehas a higher ratio of registered cars to trucksthan is the case nationally according to Fed-eral Highway Administration, Highway Sta-tistics 2002, October 2003, Table MV-1.This should make our analysis of the pro-grams’ benefits slightly lower than what isactually likely to occur because per-mileemissions reductions for cars are greaterthan for trucks and total emissions reduc-tions in Rhode Island are undercounted byusing national figures for car and light truckregistrations.)

EPA’s projections of the VMT splitamong cars and light-duty trucks assign sig-nificantly more VMT to light-duty trucksthan has been the case over the past severalyears, according to FHWA data. However,EPA’s long-term projection that light truckswill eventually represent 60 percent oflight-duty vehicle sales by 2008 appears to

be reasonable in light of the continuedtrend toward sales of light trucks.

In order to estimate a trend that reflectsboth the more car-heavy current makeupof VMT and the long-term trend towardincreasing travel in light trucks, we createdtwo curves, one extrapolating the contin-ued linear decline in the car portion oflight-duty VMT based on trends in FHWAdata from 1990 to 2002 and another usingthe EPA MOBILE6 estimates. We thenassumed that the split in VMT would trendtoward the EPA estimate over time, so thatby 2020, cars are responsible for approxi-mately 40 percent of light-duty VMT. (SeeFig. 10.)

VMT in the light-truck category werefurther disaggregated into VMT by “light”light trucks (in the California LDT1 cat-egory) and heavier light trucks (CaliforniaLDT2s), per EPA, Fleet CharacterizationData for MOBILE6: Development and Use ofAge Distributions, Average Annual MileageAccumulation Rates, and Projected VehicleCounts for Use in MOBILE6, September 2001.

VMT Percentages by Vehicle AgeVehicle-miles traveled by age of vehiclewere determined based on VMT accumu-lation data presented in EPA, Fleet Charac-terization Data for MOBILE6: Development

Fig. 10. Percentage of Light-Duty Vehicle-Miles Traveled in Cars

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and Use of Age Distributions, Average AnnualMileage Accumulation Rates, and ProjectedVehicle Counts for Use in MOBILE6, Septem-ber 2001.

Vehicle Carbon Dioxide EmissionsPer-mile carbon dioxide emissions fromvehicles were based on assumed levels ofcarbon dioxide emissions per gallon ofgasoline (or equivalent amount of otherfuel), coupled with assumptions as to miles-per-gallon fuel efficiency.

For conventional vehicles, a gallon ofgasoline was assumed to produce 8,869grams (19.6 pounds) of carbon dioxide.This figure is based on carbon coefficientsand heat content data from U.S. Depart-ment of Energy, Energy Information Ad-ministration, Emissions of Greenhouse Gasesin the United States 2001, Appendix B. Fueleconomy estimates were based on EPAlaboratory fuel economy values from EPA,Light-Duty Automotive Technology and FuelEconomy Trends: 1975 Through 2004, April2004, multiplied by a degradation factor of0.84 for years 2000 through 2020, basedon the ratio of revised mpg to lab testedmpg as reported by EPA, Light-Duty Auto-motive Technology and Fuel Economy Trends:1975-2004, April 2004. (The degradationfactor represents the degree to which real-world fuel economy falls below that re-ported as a result of EPA testing.)

For hybrid-electric vehicles used to com-ply with AT-PZEV requirements, fueleconomy was estimated to exceed that ofconventional vehicles by 45 percent, perNational Research Council, National Acad-emy of Engineering, The Hydrogen Economy:Opportunities, Costs, Barriers and R&D Needs,the National Academies Press, 2004. Thissame document provided the assumptionthat hydrogen fuel-cell vehicles wouldachieve 140 percent greater fuel economythan conventional vehicles. This figure wasthen input into the Argonne NationalLaboratory’s Greenhouse Gases RegulatedEmissions and Energy Use in Transpor-tation (GREET) model version 1.5a to

produce an estimated grams CO2/gasolinegallon equivalent for fuel-cell vehicles of3,816 grams, which was then used to esti-mate emissions from hydrogen fuel-cellvehicles manufactured to comply with theClean Cars Standard. (Fuel-cycle emissionsfrom hydrogen fuel-cell vehicles were usedin lieu of direct tailpipe emissions since fuel-cell vehicles emit no pollution from thetailpipe and it was assumed that the hydro-gen fuel—and its associated emissions—would be created within Rhode Island.)

For the global warming gas emissionstandards, we assumed percentage reduc-tions in per-mile vehicle emissions as de-scribed in California EnvironmentalProtection Agency, Air Resources Board,Staff Report: Initial Statement of Reasons forProposed Rulemaking, Public Hearing to Con-sider Adoption of Regulations to Control Green-house Gas Emissions from Motor Vehicles, 6August 2004.

Clean Cars StandardImplementationIn calculating emission reductions result-ing from the Clean Cars Standard, we as-sumed implementation of the programbeginning in model year 2009 with thesame requirements as the California pro-gram. Vehicles meeting the AT-PZEV stan-dards were assumed to be “Type D”Hybrids (similar to the Toyota Prius), whilevehicles meeting pure ZEV standards wereassumed to be hydrogen fuel-cell vehicleswhose fuel was produced from natural gas.

Percentages of vehicles meeting PZEV,AT-PZEV and ZEV criteria were estimatedin the following manner:

• Light-duty vehicle sales in RhodeIsland for each category (cars and lighttrucks) were estimated based on year2003 new vehicle registration figuresfrom Alliance of Automobile Manufac-turers, Light Truck Country, down-loaded from autoalliance.org/archives/000141.html, 27 August 2004, with thelight truck category divided into heavy


and light light-duty trucks using EPAfleet composition estimates as de-scribed above. These figures were thenmultiplied by the percentage of salessubject to the Clean Cars Standard foreach year.

• This number was multiplied by 0.9 toaccount for the six-year time lag incalculating the sales base subject to theClean Cars Standard. (For example, amanufacturer’s requirements in the2009 through 2011 model years arebased on percentages of sales duringmodel years 2003 through 2005.)

• Where necessary, these values weremultiplied by the percentage ofvehicles supplied by major manufactur-ers versus all manufacturers as calcu-lated from Ward’s Communications,2003 Ward’s Automotive Yearbook, 233.(Non-major manufacturers maycomply with the entire Clean CarsStandard requirement by supplyingPZEVs.)

• This value was then multiplied by thepercentage sales requirement to arriveat the number of Clean Cars Standardcredits that would need to be accumu-lated in each model year.

• The credit requirement was divided bythe number of credits received by eachvehicle supplied as described inCalifornia Environmental ProtectionAgency, Air Resources Board, FinalRegulation Order: The 2003 Amend-ments to the California Zero EmissionVehicle Regulation, 9 January 2004.

• The resulting number of vehicles wasthen divided by total light-duty vehiclesales to arrive at the percentage of salesrequired of each vehicle type.

• No pure ZEVs were assumed to berequired for sale in Rhode Island untilthe 2012 model year. For the 2012through 2017 model years, in whichthe pure ZEV requirement is based ona specific number of California sales,

we divided the annual pure ZEVrequirement in the California regula-tions by the number of new vehiclesregistered in California in 2001 perWard’s Communications, 2002 Ward’sAutomotive Yearbook, 272. We assumedthat the same percentage would applyto vehicle sales in Rhode Island.

It was assumed that manufacturers wouldcomply with ZEV and AT-PZEV require-ments through the sale of fuel-cell and hy-brid passenger cars. While heavier lighttrucks are also covered by the Clean CarsStandard, manufacturers have the flexibil-ity to use credits accumulated from the saleof cars to achieve the light-truck require-ment. Percentages of various vehicle typesassumed to be required under the CleanCars Standard are depicted in Fig. 6, page20 (assuming a roughly 60/40 percentagesplit between light-truck sales and car salesthroughout the entire period).

Low-Rolling Resistance TiresSavings from the use of low-rolling resis-tance replacement tires were estimated byreducing carbon dioxide emission factorsby 3 percent from baseline assumptions andfrom the vehicle global warming emissionstandards scenario for vehicles reachingfour, seven and 11 years of age beginningin 2005, per California Energy Commis-sion, California Fuel-Efficient Tire Report,Volume II, January 2003. This estimate as-sumes that the tire stock will completelyturn over; that is, that LRR tires will sup-plant non-LRR replacement tires in themarketplace through a state requirement.Other policies to encourage, but not man-date, LRR tires will likely produce reducedsavings.

Fleet Emissions ProjectionsBased on the above data, five scenarios werecreated: a “Base Case” scenario based onprojected trends in vehicle fuel economy,VMT and vehicle mix; a “Clean Cars


Standard” scenario based on the implemen-tation scenario described above; a “GlobalWarming Pollution Standards” scenariobased on the percentage emission reduc-tions proposed by the CARB staff in Au-gust 2004; a “Low-Rolling Resistance Tire”scenario based on the percentage emissionreductions found by the California EnergyCommission; and a combined “GlobalWarming Pollution Standards and Low-Rolling Resistance Tire” scenario.

Projected emissions were based on the year-to-year increase (or decrease) in emissionsderived from the estimation techniquesdescribed above. These year-to-year changeswere then applied to the 2000 baseline emis-sion level to create projections through 2020.

Other AssumptionsIn addition to the above, we made the fol-lowing assumptions:

• Rebound effects – Research hasshown that improved vehicle fueleconomy often results in an increase invehicle-miles traveled. By reducing themarginal cost of driving, fuel economystandards and other efforts to improveefficiency provide an economicincentive for additional vehicle travel.Studies have found that this “reboundeffect” may reduce the carbon dioxideemission savings of fuel economy-improving policies by as much as 20 to30 percent.59 To account for thiseffect, carbon dioxide reductions ineach of the scenarios were discountedby 20 percent. This estimate is likelyquite conservative: in its own analysisusing California-specific income andtransportation data, CARB estimated arebound effect ranging from 7 percentto less than 1 percent.60

• Mix shifting – We assumed that noneof the policies under study wouldresult in changes in the class ofvehicles purchased by Rhode Islandresidents or the relative amount that

they are driven (rebound effectexcluded). In addition, we assumedthat the vehicle age distributionsassumed by EPA remain constantunder each of the policies. In otherwords, we assumed that any increase invehicle prices brought about by theClean Cars Standard or globalwarming emission standards would notdissuade consumers from purchasingnew vehicles or encourage them topurchase light trucks when they wouldotherwise purchase cars (or vice versa).Mix shifting impacts such as these arequite complex and modeling them wasbeyond the scope of this report, butthey do have the potential to make asignificant impact on future carbondioxide emissions.

Comparison With OtherPublished EstimatesOver the past year, several estimates of thebenefits of the Clean Cars Standard andglobal warming gas emission standards havebeen made.

• Clean Cars Standard – The emissionreductions from the Clean CarsStandard estimated here (12 thousandMTCE by 2020) are about 60 percentless than the reductions estimated inRhode Island Responds to Global Warm-ing. This is likely due to more conser-vative assumptions about the relativecarbon dioxide emission reductionsassumed to result from hybrid-electricand fuel-cell vehicles and a delay in theassumed date of implementation tomodel year 2008.

• Global warming emission standards– The emission reductions from theglobal warming emission standardsestimated here (124 thousand MTCEby 2020) are approximately 30 percentgreater than those estimated in RhodeIsland Responds to Global Warming. Theearlier report was produced prior to


California’s proposal for implementa-tion of the standards and included very

conservative assumptions about theoutcome of the program.


Notes

1. Intergovernmental Panel on Climate Change,IPCC Third Assessment Report – Climate Change2001: Summary for Policy Makers, 2001.2. Ibid.3. U.S. Environmental Protection Agency,Global Warming-State Impacts: Rhode Island,Office of Policy, Planning, and Evaluation,September 1998.4. Forestry, Land Use, and Climate Change:Strategies for Rhode Island, presentation atworkshop of Rhode Island Greenhouse GasProcess, 1 June 2004.5. See note 3.6. Ibid.7. New England Regional Assessment Group,U.S. Global Change Research Program,Preparing for a Changing Climate: The PotentialConsequences of Climate Variability and Change,Foundation Report, September 2001.8. See note 3.9. U.S. Environmental Protection Agency,Global Warming-State Impacts: Rhode Island,Office of Policy, Planning, and Evaluation,September 1998; New England RegionalAssessment Group, U.S. Global ChangeResearch Program, Preparing for a ChangingClimate: The Potential Consequences of ClimateVariability and Change, Foundation Report,September 2001.10. Ibid.11. Ibid.

12 Ibid.13. Ibid.14. Ibid.15. Ibid.16. Alison Bailie, et al, Tellus Institute, AppendixD: Rhode Island Greenhouse Gas Baseline Scenario:Summary Figures and Tables, prepared for theRhode Island Greenhouse Gas Policy Stake-holder Group, 15 July 2002.17. California Environmental ProtectionAgency, Air Resources Board, Draft StaffProposal Regarding the Maximum Feasible andCost-Effective Reduction of Greenhouse GasEmissions from Motor Vehicles, 14 June 2004.18. U.S. Environmental Protection Agency,Inventory of U.S. Greenhouse Gas Emissions andSinks, 1990-2002, 15 April 2004.19. Based on data compiled for Rhode IslandPublic Interest Research Group EducationFund, Clean Water Fund, Rhode Island Respondsto Global Warming: Priority Policies for ReducingRhode Island’s Contribution to Global Warming,Summer 2004.20. See note 16.21. Conference of New England Governors andEastern Canadian Premiers, Climate ChangeAction Plan 2001, August 2001.22. Ibid.23. Ibid.24. VMT figures from Federal HighwayAdministration, Highway Statistics.

Notes 35

25. Ibid.26. Stacy Davis and Susan Deigel, Center forTransportation Analysis, Oak Ridge NationalLaboratory, Transportation Energy Data Book:Edition 22, September 2002, Chapter 7. Thefederal government has approved an slightincrease in light truck CAFE standards thattakes effect for the 2005 model year.27. U.S. Environmental Protection Agency,Light-Duty Automotive Technology and FuelEconomy Trends: 1975 Through 2004, AppendixC, April 2004. The federal law that establishedCAFE standards also established the means fortesting of vehicles to determine compliance withthe standards. It has long been recognized thatthese testing methods overstate the “real world”fuel economy of vehicles. EPA has begun toinclude adjusted figures in its reporting of fueleconomy trends and, in its 2004 report, includedan estimate of real-world vehicle mileage basedon increases in the percentage of urban driving.In this report, all discussions of vehicle fueleconomy refer to “real world” efficiency levelsrather than “EPA rated” levels.28. Ibid.29. Real world fuel economy: U.S. Environmen-tal Protection Agency, Light-Duty AutomotiveTechnology and Fuel Economy Trends: 1975Through 2004, Appendix C, April 2004. CAFEstandards: U.S. Department of Transportation,Summary of Fuel Economy Performance, March 2003.30. U.S. Environmental Protection Agency,Light-Duty Automotive Technology and FuelEconomy Trends: 1975 Through 2004, AppendixC, April 2004.31. Ibid.32. U.S. Environmental Protection Agency, FleetCharacterization Data for MOBILE6: Developmentand Use of Age Distributions, Average AnnualMileage Accumulation Rates, and Projected VehicleCounts for Use in MOBILE6, September 2001.MOBILE6 run conducted by MASSPIRGEducation Fund based on national defaults,January 2003.33. Based on comparison of light-duty vehicleemissions with overall Rhode Island globalwarming emissions from Tellus Institute,Appendix D: Rhode Island Greenhouse Gas BaselineScenario: Summary Figures and Tables, preparedfor the Rhode Island Greenhouse Gas PolicyStakeholder Group, 15 July 2002.34. The projected emissions presented here aresomewhat lower than the projections presentedin Rhode Island Public Interest Research Group

Education Fund, Clean Water Fund, RhodeIsland Responds to Global Warming: Priority Policiesfor Reducing Rhode Island’s Contributions to GlobalWarming, Summer 2004. See “Assumptions andMethodology” for a more detailed descriptionthe assumptions and estimation techniques usedin this report.35. See “Assumptions and Methodology” formethod of calculation.36. State of California, Air Resources Board,Resolution 03-4, 24 April 2003.37. California Air Resources Board, Cleaner GasCars, downloaded from www.driveclean.ca.gov/en/gv/driveclean/vtype_cleaner.asp, 1 July 2004.38. 2004 sales information based on announce-ments from Honda, Toyota, and Ford, whichwere the only manufacturers to sell significantnumbers of hybrids in 2004. Toyota, ToyotaReaches Two Million in Sales For The First Time in47-Year History (press release), 4 January 2005;Honda, American Honda Sets New All-Time SalesRecord (press release), 4 January 2005; and SteveGeimann, Bloomberg, “Ford Expands Lineup ofGas-Electric Hybrid Vehicles (Update3),” 9January 2005.39. California Air Resources Board, Clean VehicleSearch results for hybrid-electric vehicles,downloaded from www.driveclean.ca.gov/en/gv/vsearch/cleansearch_result.asp?vehicletypeid=7,1 July 2004; Ford Motor Company, 2005 FordEscape Hybrid Launches, 6 August 2004.40. California Air Resources Board, UpcomingClean Cars: Hybrids, downloaded fromwww.driveclean.ca.gov/en/gv/vsearch/upcoming.asp, 30 June 2004.41. State of Connecticut, Department ofEnvironmental Protection, Hearing Report:Regarding Regulations for the Abatement of AirPollution: Proposed Adoption of Section 22a-174-35band Proposed Amendment of Section 22-1-174-36(i)of the Regulations of Connecticut State Agencies, 7May 2004.42. Based on estimated 45 percent improvementin fuel economy from hybrid-electric vehiclesversus conventional vehicles in NationalResearch Council, National Academy ofEngineering, The Hydrogen Economy: Opportuni-ties, Costs, Barriers and R&D Needs, The NationalAcademies Press, 2004.43. The reasons behind the lack of marketsuccess of the EV-Plus, EV1 and similar electricvehicles are complex, and may have much to dowith automakers’ failure to properly markettheir vehicles to the public.


44. California Assembly Bill 1493, adopted 29July 2002.45. Reducing Greenhouse Gas Emissions from Light-Duty Motor Vehicles, Northeast States Center fora Clean Air Future, September 2004.46. John DeCicco, Feng An, and Marc Ross,Technical Options for Improving the Fuel Economy ofU.S. Cars and Light Trucks by 2010-2015,American Council for an Energy-EfficientEconomy, July 2001.47. Ibid.48. Ibid.49. California Environmental ProtectionAgency, Air Resources Board, Staff Report: InitialStatement of Reasons for Proposed Rulemaking,Public Hearing to Consider Adoption of Regulationsto Control Greenhouse Gas Emissions from MotorVehicles, 6 August 2004.50. See note 46.51. See note 45.52. Ibid.53. Ibid.54. California Environmental ProtectionAgency, Air Resources Board, Staff Report: InitialStatement of Reasons for Proposed Rulemaking,Public Hearing to Consider Adoption of Regulationsto Control Greenhouse Gas Emissions from MotorVehicles, 6 August 2004. Earlier analysis byCARB suggested that even deeper cuts in vehicleemissions could be made more quickly. CARB’sinitial draft proposal for implementation of thestandards called for cost-effective emissionreductions of 22 percent from cars and 24percent from light trucks in the near term. Overthe medium term (2012 to 2014), cost-effectivereductions of 32 percent for cars and 30 percentfor light-trucks were deemed feasible. Inaddition, the standards were assumed to bephased in much more quickly than under

CARB’s final initial proposal. See CaliforniaEnvironmental Protection Agency, Air Re-sources Board, Draft Staff Proposal Regarding theMaximum Feasible and Cost-Effective Reduction ofGreenhouse Gas Emissions from Motor Vehicles, 14June 2004.55. California Environmental ProtectionAgency, Air Resources Board, AddendumPresenting and Describing Revisions to: InitialStatement of Reasons for Proposed Rulemaking,Public Hearing to Consider Adoption of Regulationsto Control Greenhouse Gas Emissions from MotorVehicles, 10 September 2004.56. California Environmental ProtectionAgency, Air Resources Board, Staff Report: InitialStatement of Reasons for Proposed Rulemaking,Public Hearing to Consider Adoption of Regulationsto Control Greenhouse Gas Emissions from MotorVehicles, 6 August 2004; California Environmen-tal Protection Agency, Air Resources Board,Addendum Presenting and Describing Revisions to:Initial Statement of Reasons for ProposedRulemaking, Public Hearing to Consider Adoption ofRegulations to Control Greenhouse Gas Emissionsfrom Motor Vehicles, 10 September 2004.57. California Energy Commission, CaliforniaState Fuel-Efficient Tire Report: Volume 2, January2003.58. Assembly Bill No. 844, signed into law 1October 2003.59. Paul Schimek, “Gasoline and TravelDemand Models Using Time Series and Cross-Section Data from the United States,” Transpor-tation Research Record, no. 1558 (1996), 83; U.S.General Accounting Office, Energy Policy Act of1992: Limited Progress in Acquiring AlternativeFuel Vehicles and Reaching Fuel Goals, February2000.60. Ibid.

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