Increased use of biogas, a mixture of methane and carbon dioxide produced by decomposing organic matter, is expected to fuel China's drive to advance ecological agriculture and protect its environment, officials and experts agreed at an international meeting that ended over the weekend in Beijing. In addition to being piped through to kitchen ranges and lamp-stands, biogas is now being used to treat sewage in an increasing number of towns, according to Wang Xiwu, a senior expert on biogas.