Toyota, General Motors and virtually every other major automobile manufacturer are tinkering with a technology called Homogeneous Charge Compression Ignition (HCCI), which could boost fuel economy in cars by about 20 percent and generate fewer polluting hydrocarbons. Research projects are also under way at national labs and universities.
Automobile industry researchers and observers gathered recently to discuss fuel efficiency and alternatives to the internal combustion gasoline engine. They didn't always agree on what the best alternatives might be, but all acknowledged that current gas prices are adding urgency to the debate.
Diesel-powered cars and cars with gas-electric hybrid engines are likely to become much more common. Researchers also are exploring an internal combustion technology called Homogeneous Charge Compression Ignition, or HCCI, which could increase fuel efficiency by 20 percent and produce less pollution.
In HCCI, the combustion process occurs by moderating the pressure and temperature inside the cylinder. Igniting the fuel with a spark is not required, said John Pinson, group manager of diesel engine research at the General Motors Research and Development Center, said during a one-day symposium sponsored by Infineon Technologies. A similar, but slightly different and slightly less effective, combustion process takes place in diesel engines.
"It is more efficient and less far-fetched than it sounds," Pinson said of HCCI. "In this decade you are going to see incremental introduction of it."
Other near-term ideas include use of gasoline-electric hybrid engines and engines fueled by hydrogen, diesel and/or ethanol. All these options have their critics.
On one end of the spectrum, Karina Morley, director of powertrain control electronics at automotive-systems supplier Visteon, says that the gas burning engine's days are numbered.
"Within 10 years, you are going to see the transition to alternative fuel sources," she said. "Eventually internal combustion engines will die off, but it'll take 20 to 30 years."
Dave Hermance, executive engineer for advanced technology vehicles at Toyota USA, disagrees with that assessment. Internal combustion engines will probably still be going quite strong for 20 years, he said, and oil companies will still be producing petroleum products. Nonetheless, the rising cost of these products is going to make the alternatives attractive.
"The break-even point used to be $30 a barrel for alternative fuels. We're way past that," he said.
For its part, GM is one of the primary backers of diesel fuel. Diesel provides about 12 percent more energy than standard gasoline, said Pinson. Improved engines will also likely make it possible for diesel cars to meet emission standards already laid out by the federal government in a cost-efficient way, he said.
Another advantage of diesel is that one of the basic elements of the fuel-supply infrastructure--gas stations--already exists. Diesel is already popular in Europe. While it's tougher to find diesel in the U.S., its popularity could grow. DaimlerChrysler's Mercedes has had excellent sales of its diesel cars, which it reintroduced to the U.S. market in 2004, said John McElroy, an automotive journalist who hosts the TV show American Driver. Audi also has committed to bringing diesel vehicles to the U.S.
Ultimately, GM would like to marry full-fledged HCCI to diesel for a higher level of fuel efficiency, according to Pinson. Some aspects of HCCI will come to cars sold in Europe in 2007, he said.
HCCI, with regular gas or diesel, will take quite a bit of work, Pinson acknowledged. The pressure and temperature inside the cylinder need to be minutely calibrated. Gas from different stations may differ slightly in composition and performance, and could turn a smooth-running HCCI engine into a pinging, coughing machine.
Since the quality of gas and other environmental factors can't be controlled, the solution is to control the pressure/temperature inside the cylinders with sensors that can send data to a microprocessor controlling the engine. To raise the temperature, for instance, the microprocessor can send signals to the engine that will cause it to retain some of the hot gases from previous combustions in the cylinder.
The microprocessor, however, has to adjust the environment in the cylinder constantly, and the sensors would have to cost only a few bucks.
"HCCI is probably one of the most complex control architectures you can have," said Christopher Cook, vice president of automotive, industrial and multimedia business group at Infineon North America.
From hybrids to biofuels
While Toyota doesn't see a strong future for diesel, it likes HCCI for gas engines and hybrids. Currently, Toyota's hybrids combine a gas engine with an electric one. Ultimately, hybrids could pave the way for fuel cell cars. In fuel cells, energy is produced from a chemical reaction when a molecule passes through a reactive membrane. Combustion engines create energy by igniting fuel via flame or heat.
All-electric cars that can be charged at home, however, are going to be tough to market. Batteries just don't provide enough power for the price that gas does. The guys turning their Toyota Prius gas-electric cars into all-electric vehicles are spending $9,000 on the batteries, Cook said.
Ethanol, a combination of gas and alcohol derived from plants, could also become feasible further out. "If you can make it renewable and manage the cost, it could become viable," said Cook.
Some scientists, along with some recent studies, have thrown cold water on the prospects for biofuels such as ethanol, claiming that it takes more energy to make a gallon of ethanol than the gallon of ethanol can provide. Toyota USA's Hermance, however, said those studies failed to take into account the energy and/or economic value of the byproducts.
"You've got to make use of every part of the process," Hermance said. "If you don't do that, it certainly looks bad."
Liquifaction of coal could also catch on someday, he speculated. Methanol, the stuff inside Indy racers, has been suggested as a fuel source. Unfortunately, it's corrosive.
Even if technically feasible, alternative-fuel cars will also have to win over the public to succeed. Though fuel economy became a big selling point during the first oil crisis in the 1970s, arguments for fuel efficiency have lost power in the era of the SUV.
Despite their disagreements, both Pinson and Hermance asserted that cars with internal compression engines running on hydrogen will face a lot of challenges.
Producing hydrogen remains expensive, and putting enough of it in a tank that can go on a car will likely prove impractical. It's more suited to stationary applications, such as home heating, said Hermance.
"If it goes that way, we will catch up" on hydrogen combustion engines, Hermance said. Toyota does have hydrogen fuel cell projects under way, although they face some of the same cost and design problems.
Both Ford and BMW have plans for cars with hydrogen internal combustion engines, noted American Driver's McElroy. BMW, however, has an upscale service to go along with it.
"They will have mobile refilling stations that bring the hydrogen to you," he said.