This post was written by Rosa Dominquez-Faus, post-doctorial researcher at the Institute of Transportation Studies, UC Davis.
Author Michael Levi in his new book Power Surge argues that renewable energy and the shale revolution are complementary rather than competing energy strategies for the United States. Indeed, analysis shows that CO2 emissions from the power sector have dropped by 15% since 2005 due to a combination of flat demand, increased efficiency and fuel shifting to both natural gas and renewables.
The rise in natural gas use in the power sector reflects both utilities substituting low-priced natural gas for coal and petroleum as well as the use of natural gas to back up renewable power during intermittency lows. Since 2005, the US power sector has seen a net loss of 30 coal power plants and a reduction of 500 TWh of coal-fired electricity generation, 138 new TWh of renewable electricity added with the installation of 813 new renewable power plants, and 470 additional TWh of gas-fired electricity despite a net reduction in the number of natural gas plants.
But in other sectors such as the industrial sector, the residential sector and the transportation sector, natural gas’s contribution since 2005 to lower CO2 emissions has been limited. The transportation sector contributes to a third of total CO2 emission and has also seen an improvement in emissions since 2005. With a moderate growth from 2 to 3% of the total transportation fuel share, natural gas has slightly contributed to the 9% reduction in transportation-related CO2 emissions. Those are rather attributable to 10% reduction in petroleum fuels use, matching 8% reduction in total vehicle miles traveled, and growth in biomass energy from 1 to 4% as results of the renewable mandate. The impact of shale in transportation will be more prominent in the next few years, as natural gas fueling infrastructure is expanded and we see trucks and fleets switching from diesel and gasoline to natural gas.
But then CO2 emissions aren’t the whole picture. Methane is a more potent greenhouse gas and natural gas systems leak methane (disclaimer: oil and coal systems also leak some methane). At leakage rates below 2% during production, natural gas offers carbon emissions improvements over other fossil fuels, most analyses find. Oil companies say that “green completions” can limit methane emissions from production activities to 2 percent or lower in most instances, but initial studies are showing that some 10% to 15% of drillers are not using the most advanced procedures to limit venting of CO2 from shale gas operations. Studies to determine the leakage rates in transmission and urban distribution and delivery systems are being undertaken in several locations including Boston and New York City and preliminary data shows a highly variable range of ambient methane concentrations, requiring further analysis to determine the sources.
In the long run, growth in domestic shale gas use will make more oil and coal available to international markets, dropping the prices of those commodities and incentivizing their use, which could result in overall net increase of global GHG emissions, according to research by the Institute of Transportation Studies (ITS) at University of California Davis. In this context, U.S. LNG exports might indeed be more carbon friendly than an export ban, which encourages higher oil and coal use in other parts of the globe.
The bottom line: the Shale Revolution is probably helping the United States reduce its domestic carbon footprint but climate is a global issue and the impact of the U.S. shale revolution on global markets will also have to be considered and addressed.