Wood and sugar cane have traditionally been used as biomass energy sources by burning them to produce heat. Biomass power stations now also convert various organic wastes through combustion into steam to drive turbines and generate electricity. Examples of biomass fuels include rubbish, manure, woodchips, and agricultural waste. While biomass is a renewable source of energy, its large-scale use for fuel risks competition with land needed for food production and still produces greenhouse gases like fossil fuels.