压缩天然气(CNG)主要成份是甲烷,开采后能立刻用于燃烧,几乎不用精炼,储量很大,但比液体燃料难销售和储运.排放的有毒物质非常少.液化石油气(LPG)是提炼石油的副产品,有害物质排放量比汽油和柴油少.沼气 类似天然气,大部分由甲烷组成.它是有机废弃物的产品,如从污水处理厂或腐烂的农作物中产生.将其用于燃烧会产生相当的环境效益. Compressed natural gas (CNG) is mainly composed of methane, which can be used immediately for combustion after mining, almost without refining, large reserves, but difficult to sell and storage than liquid fuels. Very few toxic substances are emitted. LPG is As a by-product of petroleum refining, emissions of hazardous substances are less than gasoline and diesel, and biogas, similar to natural gas, is mostly methane. It is a product of organic waste, such as from sewage treatment plants or decayed crops. Will have a considerable environmental benefits.