The improvement of hydraulic fracturing technologies in the last decade has allowed access to previously uneconomic shale gas resources across North America. Natural gas production is often touted as a way to cut carbon emissions to slow down climate change because gas-fired power plans emit roughly half as much CO2 per unit of energy produced as coal-fired plants. There are some assessments that have been completed, though, that argue that natural gas lifecycle emissions are actually higher than those of coal because of emissions from shale gas production. In line with this latter idea, Mcjeon et al. (2014), show that market-driven increases in unconventional natural gas production does not discernibly reduce the trajectory of greenhouse gas emissions or climate forcing.
The five models used to come to this result integrate energy, economy and climate systems to provide a consistent framework. The models share common natural gas supply curve assumptions but are different in their architecture, geospatial resolution, socioeconomic assumptions, and technology projections. All of the models showed that abundant gas supply leads to additional gas and gas-fired electricity consumption. The five models also consistently showed that additional supply of natural gas in the energy market does not discernibly reduce fossil fuel CO2 emissions, and the authors identified two reasons why. The first is that the gas will substitute for all other primary fuels—such as nuclear and renewables—not just coal. This means that it is not just a substitution between emissions factors of gas and coal. The second is that lower natural gas prices will increase economic activity and reduce any incentive to invest in energy-saving technologies, which ultimately will lead to an expansion of the total energy system, and of fossil fuel use.
These models demonstrate what would happen if the market forces were allowed to work themselves out, however the results would be different if there were policies or laws put into place that limit natural gas’s ability to substitute for low-carbon energy sources. This study highlights the need for future work on the effectiveness of policies that could be implemented to improve the chances of reducing greenhouse gas emissions.
McJeon, H., Edmonds, J., Bauer, N., et al., 2014. Limited Impact on Decadal-scale Climate Change from Increased use of Natural Gas. Doi:10.1038/nature13837