Writing at The Energy Collective blog, Steve Everley reviews the scientific evidence to support the idea that gas wells produce significant leaks of fugitive methane and finds that it is vastly outweighed by evidence that they don't.
- Cornell Univ.: “Using more reasonable leakage rates and bases of comparison, shale gas has a GHG footprint that is half and perhaps a third that of coal.”
- Univ. of Maryland: “GHG impacts of shale gas are…only 56% that of coal.… [A]rguments that shale gas is more polluting than coal are largely unjustified.”
- Carnegie Mellon Univ.: “Natural gas from the Marcellus shale has generally lower life cycle GHG emissions than coal for production of electricity in the absence of any effective carbon capture and storage processes, by 20-50% depending upon plant efficiencies and natural gas emissions variability.”
- *NOTE: Study partially funded by the Sierra Club
- Mass. Institute of Technology: “Although fugitive emissions from the overall natural gas sector are a proper concern, it is incorrect to suggest that shale gas-related hydraulic fracturing has substantially altered the overall GHG intensityof natural gas production.”
- *NOTE: Coauthor is a lead author of the forthcoming Fifth Assessment Report for the IPCC
- National Energy Technology Laboratory (U.S. DOE): “Natural gas-fired baseload power production has life cycle greenhouse gas emissions 42 to 53 percent lower than those for coal-fired baseload electricity, after accounting for a wide range of variability and compared across different assumptions of climate impact timing.”
- Joint Institute for Strategic Energy Analysis/NREL: “Based on analysis of more than 16,000 sources of air-pollutant emissions reported in a state inventory of upstream and midstream natural gas industry, life cycle greenhouse gas emissions associated with electricity generated from Barnett Shale gas extracted in 2009 were found to be very similar to conventional natural gas and less than half those of coal-fired electricity generation.”
- AEA Technology (for the European Commission): “In our analysis, emissions from shale gas generation are significantly lower (41% to 49%) than emissions from electricity generated from coal. This is on the basis of methane having a 100 year GWP of 25. This finding is consistent [with] most other studies into the GHG emissions arising from shale gas.”
- Worldwatch Institute: “[W]e conclude that on average, U.S. natural gas-fired electricity generation still emitted 47 percent less GHGs than coal from source to use using the IPCC’s 100-year global warming potential for methane of 25.”
- The Breakthrough Institute: “The climate benefits of natural gas are real and are significant. Recent lifecycle assessments studies confirm that natural gas has just half as much global warming potential as coal.”