农村的旧式炉灶,用秸秆作燃料,一般五口之家一日三餐,至少要烧掉20～30斤秸秆和柴草,能量利用率仅为10％。如果用秸秆和柴草发酵成为沼气,经过有机物质的厌氧消化过程,热能利用率可达到60％,比直接燃烧热效率提高五倍。据试验,在碳氮比25:1的条件下,每2斤秸秆可产生0.3立方米沼气。7斤秸秆就可 Old rural stoves, straw fuel, the general family of three meals a day, at least to burn 20 to 30 pounds of straw and firewood, the energy utilization rate of only 10%. If biogas is fermented with straw and firewood, the utilization rate of heat energy can reach 60% through anaerobic digestion of organic substances, which is five times higher than that of direct combustion. According to the test, at a ratio of 25: 1 of carbon to nitrogen ratio, 0.3 cubic meters of biogas can be produced per 2 kg of straw. 7 kg straw can be