Replacing Gasoline: Alternative Fuels for Light-Duty Vehicles

Executive Summary OVERVIEW als requirements, feedstock requirements, and so forth. The variety of effects, coupled with the Recent interest in alternative fuels for light-duty existence of the three separate “policy drivers” for highway vehicles (automobiles and light trucks) is introducing alternative fuels, create a complex set of based on their potential to address three important trade-offs for policymakers to weigh. Further, there societal problems: unhealthy levels of ozone in are temporal trade-offs: decisions made now about major urban areas; growing U.S. dependence on promoting short-term fuel options will affect the imported petroleum; and rising emissions of carbon range of options open to future policymakers, e.g., dioxide and other greenhouse gases. This assess- by emplacing new infrastructure that is more or less ment examines the following alternative fuels: adaptable to future fuel options, or by easing methanol, ethanol, natural gas (in either compressed pressure on oil markets and reducing pressure for (CNG) or liquid (LNG) form), electricity (to drive development of nonfossil alternative fuels. Table 1 electric vehicles (EVs)), hydrogen, and reformulated presents some of the trade-offs among the alternative gasoline. fuels relative to gasoline. Substituting another fuel for gasoline affects the Much is known about these fuels from their use in entire fuel cycle, with impacts not only on vehicular commerce and some vehicular experience. Much performance but on fuel handling and safety, materi- remains to be learned, however, especially about Photo credtt General Motors Corp. GM’s Impact electric vehicle, though a prototype requiring much additional testing and development, represents a promising direction for alternative fuel vehicles: a “ground up,” innovative design focused on the unique requirements of the fuel sources, in this case electricity. –l– 2 ● Replacing Gasoline: Alternative Fuels for Light-Duty Vehicles Table l—Pros and Cons of Alternative Fuels Advantages Disadvantages Methanol . Familiar liquid fuel Range as much as 1/2 less, or larger fuel tanks Vehicle development relatively advanced Would likely be imported from overseas Organic emissions (ozone precursors) will have lower Formaldehyde emissions a potential problem, esp. at reactivity than gasoline emissions higher mileage, requires improved controls Lower emissions of toxic pollutants, except formaldehyde More toxic than gasoline Engine efficiency should be greater Ml 00 has non-visible flame, explosive in enclosed tanks Abundant natural gas feedstock Costs likely somewhat higher than gasoline, esp. during Less flammable than gasoline transition period Can be made from coal or wood (as can gasoline), though Cold starts a problem for Ml 00 at higher cost Greenhouse problem if made from coal Flexfuel “transition” vehicle available Ethanol . Familiar liquid fuel Much higher cost than gasoline Organic emissions will have lower reactivity than gaso- Food/fuel competition at high production levels line emissions (but higher than methanol) Supply is limited, esp. if made from corn Lower emissions of toxic pollutants Range as much as 1/3 less, or larger fuel tanks Engine efficiency should be greater Cold starts a problem for E1OO Produced from domestic sources Flexfuel “transition” vehicle available Lower CO with gasohol (1 O percent ethanol blend) Enzyme-based production from wood being developed Natural Gas . Though imported, likely North American source for Dedicated vehicles have remaining development needs moderate supply (1 mmbd or more gasoline dis- Retail fuel distribution system must be built placed) Range quite limited, need large fuel tanks w/added costs, Excellent emission characteristics except for potential of reduced space (LNG range not as limited, compara- somewhat higher NOX emissions ble to methanol) Gas is abundant worldwide Dual fuel “transition” vehicle has moderate performance, Modest greenhouse advantage space penalties Can be made from coal Slower refueling Greenhouse problem if made from coal Electric . Fuel is domestically produced and widely available Range, power very limited Minimal vehicular emissions Much battery development required Fuel capacity available (for nighttime recharging) Slow refueling Big greenhouse advantage if powered by nuclear or solar Batteries are heavy, bulky, have high replacement costs Wide variety of feedstocks in regular commercial use Vehicle space conditioning difficult Potential battery disposal problem Emissions for power generation can be significant Hydrogen . Excellent emission characteristics-minimal hydrocarbons Range very limited, need heavy, bulky fuel storage Would be domestically produced Vehicle and total costs high Big greenhouse advantage if derived from photovoltaic Extensive research and development effort required energy Needs new infrastructure Possible fuel cell use Reformulated Gasoline . No infrastructure chanqe except refineries Emission benefits remain highly uncertain Probable small to moderate emission reduction Costs uncertain, but will be significant Engine modifications not required No energy security or greenhouse advantage May be available for use by entire fleet, not just new vehicles SOURCE: Office of Technology Assessment, 1990. what a large-scale supply system would cost and ● sensitivity of costs and performance to numer- how it would perform relative to the gasoline ous (and difficult to predict) future decisions system. Key sources of uncertainty are: about regulating, manufacturing, financing, and marketing the fuel systems—for example, ● rapidly changing vehicle and fuel supply sys- design decisions trading off vehicle perform- tem technology; ance and fuel efficiency; and ● continuing evolution of the competing gasoline- ● for most of the fuels, limited experience with based system, for example, further improve- transportation use, often confined to laboratory ments in catalytic controls. or prototype systems that don’t reflect con- straints imposed by mass production require- In particular, most of the fuels have substantial ments or ‘‘real world” maintenance problems; potential for long-term technology advances that Executive Summary ● 3 could drastically alter costs and impacts: advanced quantities of CNG--enough to replace at least a few batteries for EVs, enzyme hydrolysis processes for hundred thousand barrels per day of gasoline, producing ethanol from lignocellulose materials, perhaps somewhat more-could come from domes- and so forth. tic and other North American sources; the rest would be imported by ship, as LNG, from distant sources. Given these uncertainties and potentialities, pro- Most likely, virtually all methanol will be imported jections of the costs and benefits of alternative fuels by ship. And reformulated gasoline, which merely rely on a series of assumptions about technology reshapes gasoline rather than replacing it, should successes, capital charges, feedstock costs, vehicle have little effect beyond that caused by the addition efficiencies, shipping methods, and so forth that are of oxygenates that may be made from natural gas or single points in a range of possible values. Changing biomass. Nevertheless, use of methanol and CNG these assumptions to other still-plausible values will still can enhance energy security by reducing change the cost and benefits results, sometimes pressure on oil markets and diversifying to an energy drastically. feedstock (natural gas) whose resource base is less Meeting Society’s Goals fully developed than oil’s, and thus has a greater potential for new sources of supply—and a less Air Quality Effects easily manipulated market. The degree of additional All of the fuels offer some potential to reduce security may be enhanced if the United States urban ozone and toxic emissions. Hydrogen, elec- supports the development of secure methanol or tricity, and natural gas offer large and quite certain LNG supply sources and if investors insist that per vehicle reductions (though emissions from supplier nations be large equity holders (and thus, power generation must be considered in evaluating risk-sharers) in the capital-intensive supply system. electricity’s net impact on air quality). Methanol and The longer term options, e.g., hydrogen and ethanol (as M85 and E85, mixtures of the alcohols electric vehicles, and ethanol or methanol from with 15 percent gasoline to improve cold starting), lignocellulosic materials, offer excellent energy offer smaller and, at this time, less quantifiable but security benefits if their costs are competitive with probably still significant reductions. For methanol, alternatives. improved control of formaldehyde is critical to its emissions benefits. The potential for reformulated Global Warming gasoline is speculative, because the makeup of this fuel is not yet known. For most of the fuels, insuring The potential of alternative fuels to affect green- that the potential benefits are actually obtained house gas emissions is primarily a long-term poten- requires vehicle emission standards that properly tial. Those fuels and technological systems most account for the differences in chemical composition likely to be used in the next few decades should not (and ozone-forming potential) between alternative have a large impact, either positive or negative, on fuel-related emissions and gasoline-related emis- net emissions. For example, combustion of methanol or natural gas produces less CO per unit of sions. 2 energy output than gasoline; however, producing The areawide

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