The United States could replace nearly a third of gasoline consumption with ethanol mainly made from plant waste and special energy crops in about 20 years, according to a study released Feb. 10.

Some 75 billion gallons of ethanol per year could be made from non-food cellulosic feedstocks, like wood waste and fast-growing grasses, and 15 billion gallons would come from traditional corn-based ethanol by 2030, according to the study by Sandia National Laboratories and General Motors (GM).

“If what you truly want to do is impact imported oil quickly… there’s no play more attractive than biofuels in the automotive sector,” Larry Burns, the research chief for GM, said in an interview.

The estimated increase in ethanol output would mean a nearly ninefold jump from the 10.2 billion gallons per year the U. S. currently makes.

But the oil market would have to change for the extra ethanol to be affordable. The price of oil would have to rise to about US$90 a barrel, from about US$42 today, to make cellulosic ethanol competitive.

Cellulosic, which can be made with the use of enzymes, chemicals or heat and pressure to break down the tough woody bits of plants, is more expensive to make than traditional ethanol made from grains.