The only way to avoid gasoline lines this summer and in summers to come, a leading critic of America's energy policies said today, is to substitute alcohol for gasoline at the nation's pumps and get more cars to run on it.

"The reason for the gas lines is a shortage of unleaded gasoline, in demand because the government has mandated a replacement for lead and an increase in octane levels for fuel efficient cars," Dr. Barry Comoner, director of the Center for the Biology of Natural Systems at Washington University in St. Louis, told the 146th annual meeting of the American Association for the Advancement of Science. "Gasohol is a substitute for high test unleaded gasoline because alcohol is an octane booster. It's the only way to solve the gas line problem into the foreseeable future."

Commoner said it is "a myth" that producing alcohol for cars would take food out of people's mouths. He said American farmers could switch easily from soybeans to sugar beets to increase alcohol production without any impact on the American diet.

"Most of the things farmers grow are fed to livestock, who need carbon for energy and nitrogen [protein] for growth," Commoner said. "You can switch to sugar beets from soybeans and still get enough nitrogen for growth at the same time you increase carbon output by more than 50 percent."

If American farmers move from soybeans to sugar beets, Commoner went on, they would need to till no extra land or use any more energy to feed the nation's people or its livestock. Commoner insisted that switching to sugar beets would cause no more disruption than took place when farmers switched in less than 10 years to soybeans after World War II.

"This year, the soybean acreage in the Midwest exceeded corn acreage for the first time in history," Commoner said. "I think the soybean experience strongly suggests there would be little difficulty introducing the sugar beet crop in the next five years."

Switching to sugar beets would raise the production of carbon for the food chain from 172 million tons to 260 million tons, Commoner said, even increasing slightly the production of nitrogen from 8.5 million to 10 million tons.

"That gives you the same nutritional balance you had to feed the livestock before," Commoner said. "And now you've drawn enough alcohol . . . to replace at least one-third of the gasoline consumption in the U.S."

Commoner said the switch to sugar beets would eliminate the summer gas lines without even moving on to newer technologies to produce alcohol for cars.

"There is already a technology being developed to convert wood cellulose to sugar that can be fermented that's very closed to being commercial," Commoner said. "The moment it goes commercial it will triple the available ethanol from the biomass on the farm, which means that potentially we can replace all gasoline demand without interfering with the production of livestock."