NCPA - National Center for Policy Analysis


February 27, 2008

The expected introduction of plug-in hybrid electric vehicles, called PHEVs, could cut U.S. gasoline use but increase deadly air pollution, due to the fact that their tailpipe emissions may be offset by smokestack emissions, according to reports by the Minnesota Pollution Control Agency and National Resources Defense Council (NRDC).

According the Minnesota study's authors:

  • Use of PHEVs could result in more sulfur dioxide (SO2) emissions -- a component of corrosive acid rain - at levels more than double those of gasoline engines and about 3 or 4 times greater than hybrids.
  • In addition, PHEVs would emit more carbon dioxide (CO2) than driving a conventional hybrid.

In addition:

  • The big jump in SO2 would likely occur even if 40 percent of Minnesota's electricity were generated by wind power (about 4 percent is now) not coal or other polluting fuels.
  • That's because a PHEV's lower tailpipe emissions may be offset by smokestack emissions from the utility generating plants supplying electricity to recharge the big batteries that allow plug-ins to run up to 40 miles without kicking on their gasoline engines.
  • Plug-ins, are partly powered, in effect, by the fuel used to generate the electricity.

The NRDC calculus shows that a plug-in charged from a power plant burning the dirtiest type of coal still has an overall pollution level less than a conventional gasoline car.  But it would produce 11 percent more greenhouse gas emissions than a regular, non-plug-in hybrid, according to Luke Tonachel, vehicles analyst at the NRDC and co-author of the group's report on plug-ins.

Source: James R. Healey, "Plug-in cars could actually increase air pollution," USA Today, February 26, 2008.

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