Contrary to some previous reports, natural gas offers greenhouse gas (GHG) emissions advantages compared with coal-fired power generation, according to a recent study by Worldwatch Institute and Deutsche Bank Climate Change Advisors. Earlier this year the U.S. Environmental Protection Agency updated its methodology for estimating methane (CH4) emissions from natural gas systems, but gas-fired generation still releases 47% less GHGs than coal from source to use, the researchers said. A controversial study by Cornell University earlier this year reported that CH4 leaks were a particular concern for gas produced from shale formations using hydraulic fracturing (see Shale Daily, April 13). But even counting higher estimated emissions of CH4 from shale gas production activities, gas-fired power generation still beats coal-fired power by a wide margin when it comes to overall GHG emissions, according to a subsequent study published by the gas-friendly American Clean Skies Foundation (see Shale Daily, April 21). IHS Cambridge Energy Research Associates in August said GHG emissions from shale gas production likely are "significantly overstated" (see Shale Daily, Aug. 25). Another recent study by the National Center for Atmospheric Research found that burning natural gas emits "far less" carbon dioxide than coal but even so, more reliance on gas won't significantly slow climate change.