Electric cars can save lots of lives from air pollution, but only if they're powered by renewable energy, not energy from coal or ethanol, a new study finds.
The study, published Monday, Dec. 15, 2014, in the Proceedings of the National Academy of Sciences, found that deaths from air pollution could be cut by 70% if electric cars use only renewable-source electricity. But if they use energy from "dirty" sources like coal, they could actually make matters worse and could increase the number of deaths by 80% or more.
“These findings demonstrate the importance of clean electricity, such as from natural gas or renewables, in substantially reducing the negative health impacts of transportation,” said Chris Tessum, co-author on the study and a researcher in the Department of Civil, Environmental, and Geo- Engineering in the University of Minnesota’s College of Science and Engineering.
The University of Minnesota team estimated how concentrations of two important pollutants — particulate matter and ground-level ozone — change as a result of using various options for powering vehicles. Air pollution is the largest environmental health hazard in the U.S., in total killing more than 100,000 people per year. Air pollution increases rates of heart attack, stroke, and respiratory disease.
Full life cycle
The authors looked at liquid biofuels, diesel, compressed natural gas, and electricity from a range of conventional and renewable sources. Their analysis included not only the pollution from vehicles, but also emissions generated during production of the fuels or electricity that power them. With ethanol, for example, air pollution is released from tractors on farms, from soils after fertilizers are applied, and to supply the energy for fermenting and distilling corn into ethanol.
“Our work highlights the importance of looking at the full life cycle of energy production and use, not just at what comes out of tailpipes,” said Bioproducts and Biosystems Engineering Assistant Professor Jason Hill, co-author of the study. “We greatly underestimate transportation’s impacts on air quality if we ignore the upstream emissions from producing fuels or electricity.”
The researchers also point out that whereas recent studies on life cycle environmental impacts of transportation have focused mainly on greenhouse gas emissions, it is also important to consider air pollution and health.
“Air pollution has enormous health impacts, including increasing death rates across the U.S.,” said Civil, Environmental and Geo- Engineering Associate Professor Julian Marshall, co-author on this study. “This study provides valuable new information on how some transportation options would improve or worsen those health impacts.”