Plant and forestry waste and dedicated energy crops could sustainably replace nearly a third of gasoline use by the year 2030, according to an in-depth study by the US Sandia National Laboratories and General Motors Corp., which is available on Tuesday.

The goal of the "90-Billion Gallon Biofuel Deployment Study" was to assess whether and how a large volume of cellulosic biofuel could be sustainably produced, assuming technical and scientific progress continues at expected rates. The study was conducted over a period of nine months.

Researchers assessed the feasibility, implications, limitations, and enablers of annually producing 90 billion gallons of ethanol --sufficient to replace more than 60 billion of the estimated 180 billion gallons of gasoline expected to be used annually by 2030. Ninety billion gallons a year exceeds the US Department of Energy's goal for ethanol production established in 2006.

The study assumes 75 billion gallons would be ethanol made from nonfood cellulosic feedstocks and 15 billion gallons from corn-based ethanol. The study examined four sources of biofuels: agricultural residue, such as corn stover and wheat straw; forest residue; dedicated energy crops, including switchgrass; and short rotation woody crops, such as willow and poplar trees. It examines the costs of producing, harvesting, storing and transporting these sources to newly built biorefineries.

Using a newly developed tool known as the Biofuels Deployment Model, or BDM, Sandia researchers determined that 21 billion gallons of cellulosic ethanol could be produced per year by 2022 without displacing current crops. The Renewable Fuels Standard, part of the 2007 Energy Independence and Security Act, calls for ramping up biofuels production to 36 billion gallons a year by 2022.

The study, which focused only on starch-based and cellulosic ethanol, found that an increase to 90 billion gallons of ethanol could be sustainably achieved by 2030 within real-world economic and environmental parameters.

The study concludes that 90 billion gallons per year of biomass-derived ethanol can be produced and distributed with enduring government commitment and continued technological progress.