Car Care
Alternative Fuel Glossary
Diesel, natural gas, ethanol and hydrogen vie for future dominance
Created by James M. FlammangAlternative fuels have earned plenty of publicity lately. Even so, most unconventional fuel sources and powertrains are in a state of infancy.
Diesel
Essentially fuel oil, diesel has been popular in Europe for decades, but limited mainly to trucks in America. Only Volkswagen and Mercedes-Benz currently offer diesel-powered automobiles.
Modern direct ignition and other control technologies help eliminate the engine knocking and visible exhaust soot that plagued earlier diesel engines.
Diesel is "highly efficient," said Ron Cogan, editor/publisher of Green Car Journal, yielding 30 percent more mileage and 30 percent less greenhouse gases. In California and four northeastern states, diesels don't meet current emissions standards.
"Clean" Diesel
New federal standards for diesel-powered vehicles become effective in 2007. No vehicles meet them now, though Cogan notes that Volkswagen does "expect to meet the standards." By October 2006, cleaner (low-sulphur) diesel fuel is supposed to be on the market.
Ford, among others, is "still working on" a clean diesel, said Paul Kilgore, director of environmental science. Engineers "pretty much know how to deal with particulates," but NOx (nitrous oxides) reduction remains an obstacle.
Kilgore notes two methods to reduce NOx emissions: 1) Precious metal technology, "still in the research stage" and 2) a less-costly method that requires the customer to add an additive every 5,000 to 10,000 miles.
Biodiesel
Domestically produced and renewable, biodiesel can be made from vegetable oils, animal fats, or recycled restaurant greases. Safe and biodegradable, biodiesel reduces such pollutants as particulates, carbon monoxide, hydocarbons, and air toxics.
Some observers have noted that biodiesel vehicles emit an aroma reminiscent of french-fry grease, but that depends on the original source. Biodiesel-powered vehicles "can run seamlessly," Cogan said. "I think biodiesel will be a big thing."
Natural Gas (CNG)
Primarily used in fleets, natural gas is one of the cleanest-burning fuels. It's available through the utility infrastructure.
According to the U.S. Department of Energy, natural gas "produces significantly fewer harmful emissions than reformulated gasoline or diesel." Compared to gasoline, it cuts emissions of carbon monoxide by 90 percent or more, nitrous oxides by 60 percent, and carbon dioxide by 30-40 percent. This fuel can be stored onboard as compressed natural gas (CNG).
Most manufacturers "have pulled out" of natural gas, Cogan said, with one notable exception: the Honda Civic GX. More than 4,000 natural gas Civics are on the road, yielding a $1/gallon equivalent savings over gasoline, according to Stephen Ellis, Honda's manager of fuel-cell vehicle marketing. General Motors offers bi-fuel full-size pickups.
Ethanol
A fully renewable alcohol-based fuel, ethanol can be made from corn, grains, or biomass (such as trees and grasses). Typically, it's sold as a blend of 85 percent ethanol and 15 percent gasoline, dubbed E85. Blends of E95 qualify as alternative fuels to the federal government, while E85 is for "flexible-fuel" vehicles.
Ethanol boosts octane and improves the emissions of gasoline. Not much change to the engine's fuel system is needed. Thousands of "flex-fuel" vehicles can accept E85.
Methanol
An alcohol fuel made from natural gas, methanol is a non-renewable resource. It's also corrosive, requiring special fuel lines and components. Like ethanol, it can be blended with gasoline, but few stations carry M85. Methanol "isn't a player," Cogan said, though it "used to be."
Propane (LPG; Liquid Petroleum Gas)
Propane has been used since the 1920s. About 200,000 propane-powered vehicles are running in America, according to the U.S. Department of Energy, and 9 million worldwide. Many are conversions built for diehard propane enthusiasts.
A clean-burning fuel, propane can produce 60 percent fewer ozone-forming emissions than reformulated gasoline. The reduction of toxic substances is greater yet.
Hydrogen
Many analysts consider hydrogen to be the ultimate solution, especially if it's used in a fuel cell that produces hydrogen with no harmful by-products. "We're on our way to a hydrogen economy," publisher Cogan said. This could be either electrochemical fuel cells, or internal-combustion engines powered by hydrogen. BMW and Ford have been working on the latter.
Honda's Ellis notes that "green" and "brown" hydrogens are both possibilities. One works from renewable energy, the other does not.
Fuel Cells
Nearly all major automakers have fuel-cell development programs, often with demonstration vehicles running. Hydrogen is considered an ideal fuel for this purpose as it creates electricity without combustion to power electric drive motors; heat and water vapors are the only byproducts. Affordability is the main obstacle, along with safe storage and convenient distribution.
In 2004, Ford launched a fleet of 30 fuel-cell Focus models, mostly used by municipalities and institutions. Most experts guess that fuel cells might finally become serious prospects around 2015.
Honda launched its FCX fuel-cell vehicle several years back, in tiny numbers, issued mainly to governmental agencies. Now, 20 are in operation. Honda's Ellis sees a 10-20 year window for expanded availability, depending on cost and the refueling network.
Electric
In the early days of the automobile, electric cars were common. GM revived the idea in the mid-1990s with its EV-1, but that minicar lasted only a few years.
Electric vehicles issue no localized emissions. Short range is their dominant obstacle, followed by long recharge times and lack of charging stations.
Hybrid
Hybrids (gasoline-electric) offer the better of two worlds: gasoline and battery power. Honda and Toyota lead with hybrid powertrains, which operate on gasoline and electricity but need not be plugged in.
"They are a solution," Cogan said, not merely a stopgap. A hybrid powertrain is "viable for virtually every platform." DaimlerChrysler is the only manufacturer with a plug-in hybrid, based on its Sprinter van.
EMISSIONS STANDARDS
Federal standards and those in "green" states differ considerably, but each considers a range of requirements. A ULEV (Ultra Low Emissions Vehicle) model is 50 percent "cleaner" than the average combustion vehicle, and SULEV (Super Ultra Low Emissions Vehicle) is 90 percent cleaner. PZEV (Partial Zero Emissions Vehicle) means emissions are 90 percent cleaner than the average combustion car, along with nearly nonexistent evaporative emissions.