New research from Purdue University in the US suggests that methane emissions from gas power plants may be significantly higher than accounted for in current inventories. Methane is a greenhuse gas that contributes to global warming.
The report estimates average hourly methane emissions 21 to 120 times higher for gas power plants than those calculated from data provided by facility operators to the US Environmental Protection Agency’s (EPA) Greenhouse Gas Reporting Program (recently abandoned under the Trump administration).
By multiplying total CO2 emitted annually by all US gas power plants and refineries (as tallied by EPA) by the methane-to-CO2 emission ratio determined in the study, the authors estimate yearly methane emissions from the nation’s refineries and gas-fired power plants are twenty times higher than currently reported.
However, the results also show that gas-fired power plants still have lower greenhouse gas emissions than coal-fired power plants, even when accounting for these higher rates of methane emissions. Methane has especially high climate forcing effects in the short term, but is then absorbed or broken down relatively quickly into the environment.
Most of the methane emissions were associated not with the CO2 plumes from the combustion stacks, but rather from other parts of the facilities (such as compressors, steam turbines, stream boilers and condensers), which indicates that natural gas is leaking before it is burned to generate power. The combustion stack sources, which the EPA GHG Inventory currently estimates to have only minor emissions, may actually contribute only about 10- to 20% of the total methane emissions from the facility.
The research would be greatly enhanced by further research in collaboration with power generators. To that end, EDF is inviting leaders in the power and refinery sectors to collaborate in gathering more data in the wake of this research, according to Joe Rudek and David Lyon – who were among the report’s authors - writing on EDF’s Energy Exchange Blog.