New research shows that prairie grasses grown using only moderate amounts of fertilizer on marginal land can produce significant amounts of ethanol.

The five-year study of switch grass done by the University of Nebraska and the U.S. Department of Agriculture's Agricultural Research Service was published this week by the National Academy of Sciences.

Researcher Ken Vogel said he estimates that an acre of switch grass would produce an average of 300 gallons of ethanol based on the study of grass grown on marginal land on farms in Nebraska, South Dakota and North Dakota.

An acre of corn grown in those same states produces about 350 gallons of ethanol on average.

The latest study adds to the evidence supporting the development of cellulosic ethanol, Renewable Fuels Association spokesman Matt Hartwig said.

"It underscores that cellulosic ethanol production is not only feasible, it is essential," said Hartwig, whose group represents ethanol producers.

Nebraska Ethanol Board Projects Manager Steve Sorum said the industry is excited about the prospects for cellulosic ethanol because the feedstocks for it, such as switch grass, are cheaper to grow. Also, some of the byproducts created in the process can be burned to generate electricity.

The key will be developing an economic way to break down the cell walls of cellulose-based fuel sources, Sorum said.

Both cellulosic and grain-based ethanol will likely be used to meet the new federal standard for biofuel use. The energy bill Congress passed last month requires a massive increase in the production of ethanol to 36 billion gallons a year by 2022.

The energy bill will emphasize cellulosic ethanol, made from feedstocks such as switch grass and wood chips, after 2015, when about two-thirds of the nation's ethanol is supposed to come from such non-corn sources.

Hartwig said there is general agreement that 15 billion gallons a year is about the most ethanol that can be produced from grain with current technology without hurting grain markets. That makes it important to develop other sources for the renewable fuel, he said.

Vogel said comparing the amount of ethanol produced by corn with the amount that could be produced by switch grass is a bit unfair because the method of converting switch grass to fuel is still being perfected.

Last year, the Department of Energy announced plans to invest $385 million in six ethanol refineries across the country to jump-start ethanol production from cellulose-based sources - a process that has not yet proven commercially viable.

But Vogel and the other researchers did develop an estimate of how much energy switch grass would produce based on current conversion rates. Switch grass produces more than five times as much energy as the amount consumed by growing the crop and converting it to ethanol, according to the report.

Vogel, a U.S. Department of Agriculture geneticist and University of Nebraska-Lincoln professor, said the switch grass research is the most extensive to date.