Mechanical energy nonconservative forces, like frictional forces, will be present, but often they are of negligible values and the mechanical energy's being constant can therefore be a useful approximation. In elastic collisions, the mechanical energy is conserved but in inelastic collisions, some mechanical energy is converted into heat. The equivalence between lost mechanical energy (dissipation) and an increase in temperature was discovered by James Prescott Joule. Many devices are used to convert mechanical energy to or from other forms of energy, e.g. an electric motor converts electrical energy to mechanical energy, an electric generator converts mechanical energy into electrical energy and a
Energy policy of China provide renewable electricity to 3.5 million households in 10,000 villages by 2010. This is to be followed by full rural electrification using renewable energy by 2015. Although a majority of the renewable energy in China is from hydropower, other renewable energy sources are in rapid development. In 2006, a total of 10 billion US dollars had been invested in renewable energy, second only to Germany. In 2006, 16 million tons of corn have been used to produce ethanol. However, because food prices in China rose sharply during 2007, China has decided to ban the further expansion of the corn ethanol