Carnegie Mellon University
September 16, 2011

Press Release: CMU Researchers Find Natural Gas a Better Low Carbon Fuel in Electricity Sector Than Transportation Arena

Contact: Chriss Swaney / 412-268-5776 /

Paulina JaramilloPITTSBURGH—Despite uncertainty issues, Carnegie Mellon University researchers find natural gas may be the fuel of choice when it comes to protecting the environment. Projections of increased domestic supply, low prices and low greenhouse gas (GHG) emissions are supporting the increased use of natural gas in the transportation and electricity sectors.

In a research paper that was published recently in Environmental Science & Technology, Carnegie Mellon doctoral student Aranya Venkatesh and her faculty co-authors report that life cycle GHG emissions from natural gas are uncertain, ranging about 17 percent. Depending on the purpose for which natural gas is used and the fuel it substitutes, the quantity of GHG emissions reductions and the probability of achieving them can vary widely.

The researchers suggest that acknowledging uncertainty in life cycle analysis is becoming more critical, especially when the results of these analyses are used to inform climate policy design. In this paper, they suggest that there is a higher probability of reducing current GHG emissions if natural gas is used to substitute coal for base-load power, instead of using it as compressed natural gas (CNG) for transportation.

"The probability of achieving GHG emission reductions by using natural gas instead of coal in efficient power plants is almost 100 percent. If CNG were used for transportation instead of gasoline and diesel, the emissions reduced would be much lower. There is even a 10 to 35 percent probability that GHG emissions would increase with CNG vehicles," said Paulina Jaramillo, assistant research professor in CMU's Department of Engineering and Public Policy, and one of the paper's co-authors.

Jaramillo also reports that though it is unlikely that all coal power plants can or should be replaced with natural gas plants, there are significant opportunities to increase the use of natural gas for base-load power as old, inefficient and polluting coal plants are decommissioned in the coming years.

Although the researchers have developed an uncertainty framework for GHG emissions only, they acknowledge that other environmental impacts associated with the production of natural gas such as water use are important. Further research on these impacts and strategies to minimize them is required.

This paper is complementary to a recent paper published in Environmental Research Letters by Carnegie Mellon researchers, regarding the life cycle GHG emissions of Marcellus Shale gas.

Pictured above is Paulina Jaramillo, an assistant research professor in engineering and public policy.