Environmental impact of the energy industry to virtually all aspects of present society, especially for transportation and heating for both homes and for commercial activities. Natural gas is often described as the cleanest fossil fuel, producing less carbon dioxide per joule delivered than either coal or oil., and far fewer pollutants than other fossil fuels. However, in absolute terms it does contribute substantially to global carbon emissions, and this contribution is projected to grow. According to the IPCC Fourth Assessment Report, in 2004 natural gas produced about 5,300 Mt/yr of CO emissions, while coal and oil produced 10,600 and 10,200 respectively (Figure 4.4); but by 2030,
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,