Carnegie Mellon University
March 17, 2011

Press Release: Carnegie Mellon Researchers Study Impact Hybrid Cars Have on Global Environment

Outstanding Research Supports New View of Hybrid Success


Contacts: Chriss Swaney / 412-268-5776 /
Mark Burd / 412-268-3486 /

PITTSBURGH—Every major U.S. automaker will have a hybrid vehicle model available on the market by 2012, and a few of these models will be plug-in electric hybrids. As crude oil prices spike past $100 a barrel, Carnegie Mellon University researchers are studying how increased reliance on vehicles powered by electricity will impact the environment.

"We studied driving patterns and electricity production in multiple electricity markets to predict the net emission changes  — total changes in emission from reduced gas but increased use of fuels to produce electricity — associated with driving plug-in-hybrid electric vehicles (PHEV) instead of a regular vehicle," said Scott B. Peterson, a Ph.D. student in CMU's Department of Engineering and Public Policy.

Peterson, working with Carnegie Mellon's J.F. Whitacre, a professor of materials science and engineering and engineering and public policy, and Jay Apt, a professor of technology at the Tepper School of Business and the Department of Engineering and Public Policy, reveal in a recent paper in the prestigious Environmental Science & Technology — and highlighted as Editor's Choice in the Feb. 18 edition of Science — that the net emissions in switching from gasoline to electric generation for running cars are reduced for carbon dioxide (CO2) and nitrogen oxide, but that sulfur dioxide (SO2  — a precursor of acid rain) can increase. They also found that a carbon price on electricity alone would not make PHEVs more effective at reducing emissions.

"PHEV's were not likely to result in net decreases of SO2 emissions without additional investment in scrubbing technology by the electric power generation sector," Peterson said.

The Carnegie Mellon researchers also found that charging PHEVs during periods of low demand using almost entirely coal still resulted in CO2 reduction of 4 percent. If the Environmental Protection Agency's Clean Air Transport Rule comes into effect, SO2 emissions will be on the way to declining from 18 million tons in 1990 to four to five million tons in just a few years.
Carnegie Mellon researchers report that their research is helping inform consumers about the benefits of low carbon products in a way that directly highlights the ultimate benefit of meeting the world's commitment for improved climate change targets.