You might be interested in this paper: Jaramillo, P., W. M. Griffin, and H.S. Matthews. 2007. Comparative life-cycle air emissions of coal, domestic natural gas, LNG, and SNG for electricity generation. Environmental Science & Technology, Vol. 41, No. 17, 6290-6296 You can download it here: http://www.desertrockenergyproject.com/Griffin%20-%20Final%20LNG%20GHG%20analysis%20(2006).pdf" [Broken] It analyzes the total GHG life cycle emissions for power from natural gas and coal. The numbers they come with are that NG isn't that much better than coal and LNG is actually much worse than coal. This set off my BS detector, but when I checked it, the paper is actually pretty good. They account for things like the release of NG during the production process. Since NG is 96% methane and methane is 20 times worse than CO2 as a GHG, that is a big difference right there. I'd always assumed that natural gas emitted about half the CO2 as coal, which is true, but incomplete.