生物燃料（英语：Biofuel）、生质燃料或生态燃料，泛指由生物质组成或萃取而成的固体、液体或气体。生物质可以用三种不同的转化方法转化为易于利用、含有能量的物质，包含：热转化，化学转化，和生物化学转化。此生物质转换可能会产生固体，液体或气体的形式，而这种新的生物质可用作生物燃料。所谓的生物质系指有机活体或者有机活体新陈代谢的产物，例如牛粪。不同于石油、煤炭、核能等传统燃料，这种新兴燃料是可再生燃料。因为油价上涨和能源安全的需要，生物燃料越来越受欢迎。然而，根据欧洲环境署，生物燃料并不一定能减缓全球变暖。

A biofuel is a fuel that is produced through contemporary biological processes, such as agriculture and anaerobic digestion, rather than a fuel produced by geological processes such as those involved in the formation of fossil fuels, such as coal and petroleum, from prehistoric biological matter. Biofuels can be derived directly from plants, or indirectly from agricultural, commercial, domestic, and/or industrial wastes. Renewable biofuels generally involve contemporary carbon fixation, such as those that occur in plants or microalgae through the process of photosynthesis. Other renewable biofuels are made through the use or conversion of biomass (referring to recently living organisms, most often referring to plants or plant-derived materials). This biomass can be converted to convenient energy containing substances in three different ways: thermal conversion, chemical conversion, and biochemical conversion. This biomass conversion can result in fuel in solid, liquid, or gas form. This new biomass can also be used directly for biofuels.