"People who own all-electric cars where coal generates the power may think they are helping the environment. But a new study finds their vehicles actually make the air dirtier, worsening global warming.
Ethanol isn't so green, either.
"It's kind of hard to beat gasoline" for public and environmental health, said study co-author Julian Marshall, an engineering professor at the University of Minnesota. "A lot of the technologies that we think of as being clean ... are not better than gasoline."
The key is where the source of the electricity all-electric cars. If it comes from coal, the electric cars produce 3.6 times more soot and smog deaths than gas, because of the pollution made in generating the electricity, according to the study that is published Monday by the Proceedings of the National Academy of Sciences. They also are significantly worse at heat-trapping carbon dioxide that worsens global warming, it found.
The study examines environmental costs for cars' entire life cycle, including where power comes from and the environmental effects of building batteries..
"Unfortunately, when a wire is connected to an electric vehicle at one end and a coal-fired power plant at the other end, the environmental consequences are worse than driving a normal gasoline-powered car," said Ken Caldeira of the Carnegie Institution for Science, who wasn't part of the study but praised it.
The states with the highest percentage of electricity coming from coal, according to the Department of Energy, are West Virginia, Wyoming, Ohio, North Dakota, and Illinois.
Still, there's something to be said for the idea of helping foster a cleaner technology that will be better once it is connected to a cleaner grid, said study co-author Jason Hill, another University of Minnesota engineering professor.
The study finds all-electric vehicles cause 86 percent more deaths from air pollution than do cars powered by regular gasoline. Coal produces 39 percent of the country's electricity, according to the Department of Energy.
But if the power supply comes from natural gas, the all-electric car produces half as many air pollution health problems as gas-powered cars do. And if the power comes from wind, water or wave energy, it produces about one-quarter of the air pollution deaths.
Hybrids and diesel engines are cleaner than gas, causing fewer air pollution deaths and spewing less heat-trapping gas.
But ethanol isn't, with 80 percent more air pollution mortality, according to the study.
"If we're using ethanol for environmental benefits, for air quality and climate change, we're going down the wrong path," Hill said.
12/15/14, "Life cycle air quality impacts of conventional and alternative light-duty transportation in the United States," pnas.org
"Edited by Douglas J. Arent, National Renewable Energy Laboratory, Golden, CO, and accepted by the Editorial Board November 8, 2014 (received for review April 15, 2014)"
"Commonly considered strategies for reducing the environmental impact of light-duty transportation include using alternative fuels and improving vehicle fuel economy. We evaluate the air quality-related human health impacts of 10 such options, including the use of liquid biofuels, diesel, and compressed natural gas (CNG) in internal combustion engines; the use of electricity from a range of conventional and renewable sources to power electric vehicles (EVs); and the use of hybrid EV technology. Our approach combines spatially, temporally, and chemically detailed life cycle emission inventories; comprehensive, fine-scale state-of-the-science chemical transport modeling; and exposure, concentration–response, and economic health impact modeling for ozone (O3) and fine particulate matter (PM2.5). We find that powering vehicles with corn ethanol or with coal-based or “grid average” electricity increases monetized environmental health impacts by 80% or more relative to using conventional gasoline. Conversely, EVs powered by low-emitting electricity from natural gas, wind, water, or solar power reduce environmental health impacts by 50% or more. Consideration of potential climate change impacts alongside the human health outcomes described here further reinforces the environmental preferability of EVs powered by low-emitting electricity relative to gasoline vehicles."