Reading beyond the headlines, a new study by researchers at the University of Minnesota actually supports what most studies have shown: electric vehicles (EVs) can substantially reduce carbon and smog forming pollution. So why the confusion? The media headlines, unfortunately, chose to focus on the worst case scenarios where EVs are charged exclusively or substantially on coal-fired power. For the reasons discussed below, these scenarios are overly pessimistic, especially in light of new national pollution standards. And they don’t reflect the reality of EV charging today.
When examining which power plants will be used to meet new energy demands (like EVs), multiple factors have to be considered including the region (right now, EV markets are clustered in coastal states with cleaner grids) and the actual air pollution regulations the utilities are subject to (even if excess coal generation exists, it doesn't mean it can be used due to pollution limits). This type of detailed analysis is very complicated and very expensive so sometimes researchers choose to develop ‘what if’ cases. This approach is reasonable but it leaves it to the reader (or the media) to sort out the real story.
At NRDC, we teamed up with the Electric Power Research Institute (EPRI) in 2007 to do the exhaustive analysis of what power plants will likely be dispatched with the addition of EV load. EPA recently did a similar analysis as part of the clean car and fuel economy regulations. The results are similar: today’s EVs are predominately powered by gas power plants, with a growing amount of renewables, and a shrinking amount of coal. So we'd expect in the real world EV charging would be closest to the Minnesota researchers’ natural gas scenario, which shows that EVs are less polluting than gasoline. And they can and should get 100% clean as new renewable energy projects come on line across the country.
NRDC is continuing to evaluate EV and power grid interactions and their environmental impact. What we are finding is that incorporating projections of the latest regulations on the books now makes a big difference in emissions, especially for nitrogen oxides, sulfur dioxide and fine particles that lead to on-the-ground air pollution like smog. Incorporating the impacts of these new regulations is complex and current standard models like the DOE's GREET, which the Minnesota researchers used, don't appear to have the latest emission factors. We are currently investigating this and look forward to working with the researchers to understand this better.
The media loves controversy so we are not surprised at all they chose to focus on the worst case scenarios. The study makes it abundantly clear that cleaner EVs go hand-in-hand with a cleaner grid. Fortunately, when realistic scenarios of the power mix to charge EVs are considered the study confirms: EVs are cleaner than gasoline and only getting cleaner.