The catch-all term biomass includes all the living organisms in an area. Wood, crops and crop waste, and wastes of plant, mineral, and animal matter are part of the biomass. Much of it is in garbage, which can be burned for heat energy or allowed to decay and produce methane gas. However, some crops are grown specifically for energy, including sugar cane, sorghum, ocean kelp, water hyacinth, and various species of trees. It has been estimated that 90 percent of U.S. waste products could be burned to provide as much energy as 100 million tons of coal (20 percent will not burn, but can be recycled). The use of biomass energy is significantly higher in developing countries where electricity and motor vehicles are scarcer.

In Western Europe, there are over two hundred power plants that burn rubbish to produce electricity. France, Denmark, and Switzerland recover 50, 60, and 80 percent of their municipal waste respectively. Biomass can be converted into biofuels such as biogas or methane, methanol, and ethanol. However, the process has been more costly than the conventional fossil fuel processes. Rubbish buried in the ground can provide methane gas through an aerobic decomposition. One ton of refuse can produce 8,000 cubic feet (227 cubic meters) of methane.