Friday, October 27, 2006
MIT eyes more clever way to use ethanol to improve efficiency
Scientists Eye Ethanol Boost For Gasoline Engines
BOSTON - Injecting small quantities of ethanol into car engines at moments of peak demand -- such as accelerating sharply or climbing a steep hill -- could improve the fuel economy of gasoline engines by 20 percent to 30 percent, a scientist said on Wednesday.
A team of researchers at the Massachusetts Institute of Technology is working on the system, which scientists say would allow carmakers to use smaller engines in their vehicles, reducing weight and improving fuel economy at a lower cost to consumers than by adding a hybrid engine.
"To have a big impact on reducing oil consumption, one needs a low-cost way of improving efficiency, so a lot of people buy the car," said Daniel Cohn, senior research scientist at MIT in Cambridge, Massachusetts.
He estimated that adding the ethanol injection system to a car would cost about $1,000 and that cars using the new system could be in mass production by 2011.
"We view it as a very important near-term way to reduce oil consumption," Cohn said.
Volatile US retail gasoline prices -- which hit a record high above $3 per gallon this summer but have since eased to around $2.20 per gallon -- have piqued consumer interest in fuel-efficient cars.
"It's crucial that the internal combustion engine, whether it's gasoline or advanced diesel, is improved to the point where those improvements are meaningful," said Ron Cogan, editor of the Green Car Journal, a quarterly magazine focused on alternative powertrains.
Much attention has focused on hybrid cars, such as Toyota Motor Corp.'s Prius, which couple an electric motor with a traditional gasoline engine to improve fuel efficiency. But they are pricey -- hybrid engines can add $3,000 or more to a car's cost -- and account for just about 1 percent of new car sales in the United States.
HOW IT WORKS
The U.S's Big Three Detroit automakers -- General Motors Corp., Ford Motor Co. and the Chrysler unit of DaimlerChrysler AG -- as well as the White House have backed the adoption of cars that can burn the 85 percent ethanol-15 percent gasoline blended fuel known as E-85 as an alternative to pure gasoline, which is made from petroleum.
But the limited supply of ethanol, which is made from plant matter, limits its usefulness as a primary fuel source. There are only 900 pumping stations nationwide that sell E-85.
The MIT scientists' plan gets around the ethanol supply issue by using small amounts of it -- so little that Cohn estimated the ethanol tank in cars using the technology would need to be refilled every three months or so.
A turbocharger is added to produce more power. The ethanol injection system with the turbocharger would give a driver more power than a conventional engine of the same size.
The higher pressures and temperatures of a turbocharged engine can lead to a problem known as knock, which occurs when the fuel and air in the engine explode prematurely, hurting performance and potentially damaging the engine.
Cohn said his group's technology avoids that problem by injecting ethanol into the engine when knock is likely to occur. The ethanol vaporizes and cools the fuel-air mixture, keeping it from exploding until the engine is ready.
"This is a very special feature of ethanol," Cohn said.
Story by Scott Malone