Liquefied petroleum gas Commercially available LPG is currently derived mainly from fossil fuels. Burning LPG releases carbon dioxide, a greenhouse gas. The reaction also produces some carbon monoxide. LPG does, however, release less per unit of energy than does coal or oil. It emits 81% of the per kWh produced by oil, 70% of that of coal, and less than 50% of that emitted by coal-generated electricity distributed via the grid. Being a mix of propane and butane, LPG emits less carbon per joule than butane but more carbon per joule than propane. LPG burns more cleanly than higher molecular weight hydrocarbons because
Supercritical carbon dioxide heat pumps are commercially marketed in Asia. EcoCute systems from Japan, developed by Mayekawa, develop high temperature domestic water with small inputs of electric power by moving heat into the system from the surroundings. Supercritical has been used since the 1980s to enhance recovery in mature oil fields. "Clean coal" technologies are emerging that could combine such enhanced recovery methods with carbon sequestration. Using gasifiers instead of conventional furnaces, coal and water is reduced to hydrogen gas, carbon dioxide and ash. This hydrogen gas can be used to produce electrical power In combined cycle gas turbines, is captured, compressed to