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 to 2009. However, from 2010 to 2015 China reduced energy consumption per unit of GDP by 18%, and CO emissions per unit of GDP by 20%. On a per-capita basis, it was the world's 42nd largest emitter of greenhouse gases in 2014. China is also the world's largest renewable energy producer. China is the largest producer of hydroelectricity, solar power and wind power in the world. Energy policymaking in China is largely decentralised. There has been no Ministry of Energy since it was dissolved in 1993, and it was only in 2002–2003 that serious governmental dialogue on re-centralising energy administration