Advances in technologies for extracting oil and gas from shale formations have dramatically increased production in the United States. Shale gas in particular has grown rapidly, from less than one percent of US production in 2000 to 34% in 2012, and projections show strong production growth continuing for the foreseeable future. … With this abundance of natural gas comes a variety of questions. These questions include how shale gas will affect the national and global economy, local environments and communities, global energy markets, geopolitics, and more. In this paper, we focus on the implications of growing shale gas production for the climate.

—Newell and Raimi

If natural gas is abundant and less expensive, it will encourage greater natural gas consumption and less consumption of fuels such as coal, renewables and nuclear power. The net effect on the climate will depend on whether the greenhouse emissions from natural gas—including carbon dioxide and methane —are lower or higher than emissions avoided by reducing the use of those other energy sources.

Most evidence indicates that natural gas as a substitute for coal in electricity production, gasoline in transport, and electricity in buildings decreases greenhouse gases. But natural gas production and consumption has higher emissions than renewables and nuclear power.

Over the range of scenarios that we examine, abundant natural gas by itself is neither a climate hero nor a climate villain.

—Richard Newell, Gendell Professor of Energy and Environmental Economics and director of the Duke University Energy Initiative

We find that so far increased natural gas has mostly taken the place of coal, but looking forward there also may be increased consumption for sectors such as industry, as well as some degree of displacement of zero-emission sources such as renewables and nuclear. The net effect on US greenhouse gas emissions appears likely to be small in the absence of policies specifically directed at greenhouse gas mitigation.

—Daniel Raimi, associate in research at the Energy Initiative

Newell and Raimi modeled two scenarios: one in which natural gas production and prices follow a “reference case” scenario, and another in which increased shale gas production lowers prices and encourages increased consumption. They also account for a range of methane emissions scenarios, ranging from 25% below to 50% above the levels estimated by the US Environmental Production Agency.

The climate benefits of natural gas are reduced if there are a lot of methane emissions, but while “recent evidence suggests methane emissions may be higher than the EPA currently estimates, it’s not clear how this new information will affect those estimates,” Raimi said. “Reducing methane emissions is important, but even if methane emissions from natural gas systems are significantly higher than current EPA estimates, we did not find this significantly alters the impact of abundant natural gas on long-term national or global greenhouse gas emissions pathways.”

Newell and Raimi suggest that additional research is needed in a number of related areas. Key areas include methane emissions from natural gas systems and other sources; the emissions profiles of natural gas versus electricity and oil-based heating systems; the GHG implications of changes in international trade patterns due to shale gas growth; and the likely magnitude of substitution of natural gas for coal versus zero-carbon electricity, both in the United States and internationally.

Resources

• Richard G. Newell and Daniel Raimi (2014) “Implications of Shale Gas Development for Climate Change,” Environmental Science & Technology doi: 10.1021/es4046154