Washington, June 4 : Researchers at Beijing University of Chemical Technology have developed a new method that dramatically increases the yield of a clean biogas fuel from rice straw.
Rice straw, a major agricultural by-product in China, is often burnt after each harvesting season, increasing pollution and carbon dioxide emissions.
So far, using the straw to produce ethanol or biogas, a mix of methane and carbon dioxide, by anaerobic digestion with microorganisms has been disappointing.
And that is because the complex structures of the straw's cellulose and lignin components make it hard for the microorganisms to break them down.
Li Xiujin, an environmental engineering professor at Beijing University of Chemical Technology and co-author of the study, explained that researchers soak the straws in alkali to kick-start the breakdown process.
However, that method means recycling chemicals, disposing of waste solutions and heating to a high temperature - involving high facility investment and treatment costs, and a risk of environmental pollution.
Instead of soaking the rice straw, Li's team treated it with a small amount of alkaline solution containing six per cent sodium hydroxide.
They found that this method significantly increased straw biodegradation, and improved biogas output by 64.5 per cent.
The study has provided a boost for biofuels made from waste products - an important factor, given worries over biofuels' impact on food security.
And generating environmentally friendly biogas from farm waste instead of burning it will counter environmental concerns.
Jin Jiaman, director of the Beijing-based Global Environment Institute, said that the new method could help tap biofuels in rural areas.
However, it might not necessarily bring wider use of biogas, which would need government subsidies to install facilities and lay pipelines into rural households.
"The big labour input needed for processing straws could also dampen farmers' zeal to use biofuels," Environmental News Network quoted Jin as telling SciDev.Net.
The study was published online last month in the American Chemical Society's journal Energy and Fuels.