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
Carbon dioxide and microbial fermentation. In 1772, English chemist Joseph Priestley published a paper entitled "Impregnating Water with Fixed Air" in which he described a process of dripping sulfuric acid (or "oil of vitriol" as Priestley knew it) on chalk in order to produce carbon dioxide, and forcing the gas to dissolve by agitating a bowl of water in contact with the gas. Carbon dioxide was first liquefied (at elevated pressures) in 1823 by Humphry Davy and Michael Faraday. The earliest description of solid carbon dioxide was given by Adrien-Jean-Pierre Thilorier, who in 1835 opened a pressurized container of liquid carbon dioxide,