Energy alternatives : Biomass

Biomass was humanity's first source of energy, and until the twentieth century it remained the largest; even today it comes second only to fossil fuels. Wood, crop residues and other biological sources are an important energy source for more than two billion people. Mostly, this fuel is burned in fires and cooking stoves, but over recent years biomass has become a source of fossil-fuel-free electricity. As of 2005, the World Energy Council estimates biomass generating capacity to be at least 40 gigawatts, larger than any renewable resource other than wind and hydropower. Biomass can supplement coal or in some cases gas in conventional power plants. Biomass is also used in many co-generation plants that can capture 85–90% of the available energy by making use of waste heat as well as electric power.