Energy is released from biomass when it is heated or gas is extracted from it. After this process is complete, the energy from it can be converted into useable fuel. An example of this process is what occurs on some farms. The waste from farm animals is collected and placed into a covered bin. As a natural process, methane gas is emitted. Using special machinery, the gas is harvested and converted into useable fuel. A growing number of farms use this fuel instead of energy from electric companies. The methane can then be used to heat stoves, furnaces, or other household appliances resulting in less natural resources being used and as a natural method of reusing waste. Excess methane can also be sold by farmers to utility companies.