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Switchgrass-to-ethanol comes out clean in study

The grass, native to the U.S., gets high marks for energy efficiency and greenhouse gas emissions in Department of Agriculture test.

A large-scale test on the effectiveness of switchgrass to make ethanol gave the native grass high marks on energy production and greenhouse gases.

Switchgrass is a favorite of politicians and cellulosic ethanol advocates who say that the grass, which can grow to nine feet, is a better feedstock than corn--the source of most ethanol made today.

A study published on Monday by the Proceedings of the National Academy of Sciences (PNAS) found that switchgrass contains five times more energy than it takes to grow it, which makes it significantly more cost-effective than corn.

The average greenhouse gas emissions from cellulosic ethanol derived from switchgrass were found to be 94 percent lower than gasoline. By contrast, corn ethanol generates slightly less greenhouse gases in its production than gasoline, according to studies.

Other advantages of switchgrass are that it can grow in a range of climates and it does not require as much water as other processes. It also does not pose the same risk of raising food prices as corn ethanol.

The PNAS study, funded by the U.S. Department of Agriculture, attempted to have a more comprehensive look at growing switchgrass for ethanol than previous studies. Researchers grew the crop across 10 farms in the Midwest with varying precipitation and temperatures.

Although the study echoes other research in concluding that switchgrass is a promising feedstock, it still remains in the research phase of development.

There have been a number of companies seeking to commercialize cellulosic ethanol, but they have chosen more readily available feedstocks such as wood chips or agricultural wastes.