CHICAGO -- Among the most unusual recruits in the fight against greenhouse gases and global warming may be the microbes that live inside termites.

A type of grass called miscanthus may be an optimal source of renewable fuel, suggests research by Stephen P. Long and his colleagues. Related to sugar cane, miscanthus can grow up to 20 feet in a season on land considered marginal for corn or soybeans, said Long, director of the energy biosciences institute at the University of Illinois at Urbana-Champaign.

Planting miscanthus or a hybrid on acres not being used for corn or soybeans theoretically could yield enough fuel to power most of the nation's cars, Long said at an energy symposium sponsored by Northwestern University and Argonne National Laboratory. That assumes that processes to convert cellulose to fuel can be done efficiently, and this is where those termite microbes come into play.

Scientists are studying these critters to learn how the enzymes they produce can break down and convert the cellulose in wood into fuel.

The same process is at the heart of converting biomass to fuel to run our cars and heat our homes, explained Steve Chu, director of Lawrence Berkeley National Laboratory.

"Termites are our friends," said Chu, who in 1997 shared the Nobel Prize in physics.

Despite the recent ethanol push-back since food prices began their worldwide rise, biomass fuels still offer a viable alternative to fossil fuels, Long said.

Prices for rice and wheat have jumped more than for corn, Long said, even though corn is the only grain used to make ethanol. Other factors such as rising energy prices, growing demand for meat in China and bad weather globally play a bigger role in food price increases, he added, while acknowledging that converting corn to ethanol is an inefficient process.

It takes about 80 percent as much energy to make ethanol from corn than the ethanol will yield, Long said. But other fuels extracted from different plants may require only 20 percent of the energy harvested, he said.

"Criticizing biomass fuels on the basis of ethanol made from corn would be like judging the value of railroads based on the original, old steam engines," Long said. "We are at the beginning of developing this technology."