Alternative fuel consumption is growing in the U.S., but the volume is minimal compared to traditional petroleum-based fuels.
According a 1997 Energy Information Administration survey,1 the total volume of alternative fuels consumed in vehicles, however, still accounts for only about 0.2% of total fuel consumption.
Energy Information Agency (EIA) forecasts show a steady growth in both alternative fuels and petroleum-based fuels. Population growth and increased travel account for the steady increase.2
The largest barriers to market entry for alternative fuels are cost competitiveness and existing infrastructure. Other outstanding issues for alternative fuels include power, fuel range, reliability, and storage. Legislative mandates and government subsidies, however, encourage investments in alternative fuels.
Reason for change
Petroleum-based fuels enjoy an economic advantage over alternative fuels. Existing infrastructure, ease of production, and low prices encourage its use. Costs for fuel cell systems, for example, according to DaimlerChrysler AG, are 10 times too expensive for today`s consumers.
Concerns about air pollutants caused by petroleum-based fuels have prompted government involvement in alternative fuels. Pollutants of concern include nitrous oxides (NOx), carbon monoxide (CO), carbon dioxide (CO2), sulfur oxides, hydrocarbons (HC), and particulate matter (PM).
Today`s new cars produce about 95% less air pollutants (volatile organic compounds, CO, (NOx) than new cars in the 1960s.3 Three-way catalytic converters, direct-injection engines, and other advanced automotive technologies have greatly improved the efficiency of light-duty vehicles. This efficiency, however, is offset by increased travel each year.3
In search of a way to reduce the U.S.`s dependence on petroleum-based fuels, the government has used legislation and tax incentives to promote alternative fuels.
The Clean Air Act Amendments of 1990 (CAAA90) set Tier 1 exhaust emission standards for CO, HC, NOx, and PM for light-duty vehicles and trucks beginning with model year 1994. CAAA90 also required the U.S. EPA to study Tier 2 emission standards that would be effective for vehicles with model years 2004 and 2007.
Tier 2 standards focus on legislation to reduce gasoline-sulfur content. Sulfur reduces the effectiveness of the catalyst used in the emission control systems of advanced technology vehicles, which increases their emissions of HC, CO, and NOx (OGJ, Apr. 26, 1999, p. 19).
Alternative fuels
Alternative fuels use surveyed by the EIA in its annual Alternatives to Transportation Fuels report1 includes LNG, compressed natural gas (CNG), LPG, methanol, ethanol, electricity, and neat biodiesel. Although not included in this EIA evaluation, dimethyl ether (DME) and hydrogen are also popular alternative transportation fuels.
In 1998, based on 1997 data, the EIA estimated that a total of 418,128 vehicles would be running on alternative fuels in the U.S. in 1999. Thus, the number of alternative-fueled vehicles is expected to grow by 6.3%/year between 1997 and 1999. The average annual growth rate between 1992 and 1997 for vehicles with alternative fuels was 8.0%.
In 1999, about 274,000 of these 418,128 vehicles are expected to use LPG; that is, LPG should account for more than half of the number of alternative vehicles used in the U.S.
Although LPG, LNG, and CNG engines are efficient and emit less ozone-forming emissions than gasoline, their main disadvantages are the weight and space needed to store the gas.
Table 1 summarizes these vehicle data. Of the alternative-fueled vehicles surveyed, E85 ethanol-based vehicles are expected to have had the highest future growth in the past 7 years. In this same period, the number of vehicles using neat methanol (M100) and 95% ethanol (E95) will have declined.
On the basis of fuel consumption rather than vehicle number, the EIA expects the rate of consumption of traditional fuels to slow only slightly. From 1997 to 1999, it expects an average annual growth of 1.6% in volume consumption of gasoline and diesel. From 1992 to 1997, the growth in consumption was 2.5%/year.
For alternative fuels, on the other hand, the EIA expects a continued annual growth of about 6.2%, which is close to the 6.3% average annual growth between 1992 and 1997.
Despite slow growth rates, the absolute volume of traditional fuels is still formidable. In 1999, American vehicles are expected to consume about 157 billion gal of gasoline and diesel, or 99.8% of total fuel consumption. Gasoline consumption includes ethanol in gasohol and methyl tertiary butyl ether (MTBE).
Comparatively, in 1999, the EIA expects alternative fuels to account for about 352 million gasoline-equivalent gal of the vehicle fuel pool, or about 0.2% of total fuel consumption.
Methanol, ethanol
In the transportation sector, methanol can be used as a liquid fuel (M100, M85) in itself or as a feed for fuel-cell applications.
Methanol is considered a clean-burning alternative to gasoline and diesel because it emits very few pollutants. It can be fueled like conventional fuels, and it is less expensive than gasoline. Currently, methanol is a leading candidate for fuel-cell applications.
One disadvantage of methanol is its energy density, which for the same volume, is half that of gasoline. This property reduces the fuel range on existing vehicles. Its low vapor pressure may also make vehicle starts difficult in cold temperatures.4
Ethanol is most often touted as an additive for enhancing octane (E10) although it can also be used as a gasoline substitute (E85). In concentrations of less than 85 vol %, ethanol adversely increases the Rvp of gasoline,4 which increases evaporative emissions.
Controversy surrounds the production costs of ethanol. Opponents counter that without the federal tax, ethanol is not competitive with other fuels. Also, the effectiveness of oxygenates in general have been questioned by the National Research Council (OGJ, May 24, 1999, p. 39).
Proponents of ethanol stand behind the ability of ethanol to reduce HC and CO tailpipe emissions, and justify the tax credit on this basis.
The ethanol tax credit, which is currently 54¢/gal, effectively reduces the cost of ethanol and ETBE, making them more attractive for blending with gasoline.2 The Federal Highway Bill of 1998 specifies 1¢/gal reductions in 2001, 2003, and 2005.
Gas-to-liquids fuels
The abundance of global natural gas resources can be used to make cleaner gasoline and diesel fuels. Natural gas-derived fuels such as dimethyl ether (DME) are also potential future fuels.
These fuels will have no or very low sulfur, nitrogen, aromatics, and particulate levels.
Unlike some alternative fuels, the burden of the production of these clean fuels is not to prove performance or technology. Rather, South Africa and Germany have both used the Fischer-Tropsch process to make synthetic fuels from synthetic gas.
Gas-to-liquids fuels, however, share the burden of competing with low cost traditional fuels. According to Michael Corke, Purvin & Gertz, London, based on several assumptions, a Brent crude oil fob price of $16/bbl is required for gas-to-liquids fuel to even begin to be economically feasible (OGJ, Sept. 28, 1998, p. 96). Higher oil prices (>$20/bbl), however, are often quoted for GTL production to be profitable.
Low wellhead gas prices (<$1/million BTU), lower syngas production costs, and a niche market for high-added-value products would improve the competitive position of gas-to-liquid fuels.5
Biodiesel - Biodiesel is the ester produced from reacting vegetable oils, such as soybean or rapeseed oil, with an alcohol, often methanol. It is often mixed with diesel in heavy-duty vehicle applications at a ratio of 20% biodiesel to 80% diesel fuel (B20).
Although biodiesel has the same properties as conventional diesel, it produces fewer unburned HC, CO, and PM levels. In addition, its use requires no modifications to the existing engine.
Biodiesel`s disadvantages lie in higher NOx-emissions results in some tests and its costs. According to the U.S. Department of Energy (DOE), production costs for biodiesel are about three times that of conventional diesel.6
Alternative vehicles
Along with alternative fuels, alternative vehicles were born in an attempt to reduce emissions from transportation. In Europe and the U.S., several automobile companies have developed fuel-cell vehicles.
Although alternative vehicles receive much attention because they are different, improvements in conventional-fueled cars cannot be ignored. Car companies have developed direct-injection diesel and gasoline engines, which greatly increase vehicle efficiencies. Increasing efficiencies, in turn, reduces NOx.
Generally, alternative-fueled vehicles have found their place in niche markets (see DOE article in this special report). Applications which allow for structured driving schedules or low mileage allow alternative-fueled vehicles to predict when they need to refuel in this limited infrastructure market.
Transit buses are particularly popular for these new fuels. In 1996, the EIA estimated that one out of every five new transit buses on order was an alternative-fuel capable bus.2
Fuel-cell vehicles
Fuel-cell applications use several alternative fuels, which include hydrogen, methanol, natural gas, and even conventional fuels.
These cells convert hydrogen to electrical energy. Hydrogen in fuel-cell cars can be directly stored or made from other fuel sources.
Fuel cell-powered cars are expected to be 2-3 times more efficient than the internal combustion and diesel engines and have near zero emissions. Based on current technology, however, the energy efficiency and the level of CO2 emissions remains like that of the optimized thermal engine route.7
Issues that need to be improved for automotive fuel cells are size, weight, start-up time, and cost.
There is intense competition among automobile manufacturers to develop the fuel cell that will become the standard of the future. Most popular is the proton-exchange membrane (PEM) fuel cell.
In March 1999, DaimlerChrysler AG unveiled its newest fuel-cell vehicle, Necar 4 (New electric car). For the first time, engineers have mounted the fuel-cell system in the floor of the car, which minimizes the encroachment of passenger room. Necar 4 is powered by liquid hydrogen, which is stored in a cryogenic cylinder in the rear of the car.
DaimlerChrysler plans to place fuel-cell vehicles in limited production by 2004.
According to Bob Eaton, DaimlerChrysler chairman, costs and fuel infrastructure remain the key challenges to successfully commercializing fuel-cell vehicles. "With Necar 4, we`ve already proven that fuel cell technology is viable. Now, we are working to make the technology affordable for every consumer."
To address fuel infrastructure, in April 1999, DaimlerChrysler, the California Air Resources Board (CARB), the California Energy Commission, Ballard Power Systems Inc., Ford Motor Co., ARCO, Shell, and Texaco created the "California Fuel Cell Partnership" to advance further automotive fuel-cell technology. The partnership aims to place about 50 fuel-cell passenger cars and electric buses on the road between 2000 and 2003.
Other leaders in fuel-cell vehicle development include Toyota Motor Corp., General Motors Corp. (GM), Nissan Motor Corp., Honda Motor Corp., Volkswagen, Volvo Cars, and International Fuel Cells.
Electric vehicles
Although some fuel-cell cars claim to have zero emissions, the electric vehicle more surely fits this category. Although the vehicles themselves may produce zero emissions, power plants where the electricity is made may often emit pollutants that are not taken into account when evaluating electric vehicles.
The main disadvantage of electric vehicles resides in the limitations of the battery. The battery takes weight and space. Also, the battery limits the range of each road trip. Some manufacturers claim a range of 200 km and a recharging time of 1 hr.7
The electric vehicles have been slow to take off. First, as a result of low demand, California postponed target-goal dates for its Low Emission Vehicle Program (LEVP).
The future of electric vehicles was further temporarily shaken by Honda Motor Co.`s decisions to halt the production of electric cars. Honda claims, however, it is still committed to electric vehicle development but is taking time to focus on customer satisfaction and understand the future of electric vehicles.
The LEVP, originated by California, set sales mandates for three categories of reduced-emission vehicles: low-emission vehicles (LEVs), ultra-low emission vehicles (ULEVs), and zero emission vehicles (ZEVs). Only electric vehicles were certified as ZEVs by the CARB.
The LEVP was originally scheduled to begin in 1998 with a requirement that 2% of the state`s vehicle sales be ZEVs, increasing to 5% in 2001 and 10% in 2003. The beginning of mandated ZEV sales was rolled back to 2003 because it was determined that ZEVs would not be commercially available in sufficient numbers or at sufficiently competitive costs.2
Several automobile companies have produced hybrid vehicles that use both batteries and a small gasoline or diesel engine. Hybrid-electric vehicles combine the advantages of existing gasoline and diesel infrastructure with the benefits of a battery.
Toyota has sold its hybrid electric vehicle, called Prius, since 1998 in Japan. Honda, Nissan, GM, Isuzu, and Ford are among those involved in developing hybrid electric vehicles.
References
- "Alternative to Traditional Transportation Fuels 1997," Energy Information Administration, Oct. 22,1998.
- "Annual Energy Outlook 1999," Energy Information Administration, DOE/EIA-0383(99), December 1998. -
- "Environmental Fact Sheet: Partnership for a New Generation of Vehicles and the Environment," U.S. EPA, EPA420-F-98-007, April 1998.
- Lorenzetti, M.S., Alternative Motor Fuels, A Nontechnical Guide, PennWell Publishing Co., Tulsa, 1996.
- "The Chemical Conversion of Natural Gas: Players, Recent Developments and Outlook," Institut Fran?ais du P?trole, Panorama 99, Jan. 28, 1999.
- http://www.afdc.doe.gov/altfuel/bio general.html
- "Recent Developments in Automotive Engines (Performance, Unit Consumption, Emissions)," Institut Fran?ais du P?trole, Panorama 99, Jan. 28, 1999.
