求翻译…… 当非化石的有机物质经过厌氧腐烂时，会产生富含甲烷的气体，这种气体就被称作生物气（沼气）

【专家解说】：When non fossil organic matter through the anaerobic decay, will produce methane rich gas,this gas is called biogas (methane). The source of biogenic gas include forest and grasslandbetween the marsh and landfill, in sewer sludge, manure, produced by bacteria in anaerobicdecomposition. Biogas also includes flatulence (for example: fart), gastrointestinal gas mostoften from domestic animals such as cattle and sheep.