Clearing the Air With Electric Cars

Colorado's sources for electricity cleaner than in other states

Clearing the Air With Electric Cars


Two of Colorado’s most important political leaders recently adopted plans that encourage greater adoption of electric vehicles (EVs), both as a strategy to help curb climate change and to improve the air that Denverites breath.

Governor John Hickenlooper signed an executive order on climate that includes the development of a statewide EV plan, while Denver Mayor Michael Hancock released a Mobility Action Plan, which calls for multiple steps to encourage EV adoption.

Now, a new report conducted by the Southwest Energy Efficiency Project on behalf of Denver’s Department of Environmental Health (with funding from the Regional Air Quality Council) shows why more EVs on the road –- including affordable models such as the Nissan Leaf and Chevy Volt - will help both metro Denver and the planet.

Simply put, electric vehicles (and soon, electric SUVs and trucks, too) reduce greenhouse gas emissions by 30 percent to 43 percent compared with gasoline powered vehicles. They can cut emissions of nitrous oxide (NOx) – by at least 38 percent and perhaps up to 63 percent and essentially eliminate emissions of volatile organic compounds (VOCs).

These last two pollutants are important because they contribute to the formation of ground-level ozone, or smog, which irritates human lungs and worsens respiratory illnesses.

So, by vastly reducing the amount of ozone’s precursor chemicals in Denver’s air, electric vehicles will help solve one of metro Denver’s most vexing public health concerns.

The findings of this report are important because they dispel the myth that EVs aren’t cleaner than gasoline vehicles.

One source of confusion has been the State of Change report, published by the Union of Concerned Scientists (UCS), which shows how electric vehicles across the country compare to gasoline vehicles regarding life-cycle greenhouse gas emissions. This otherwise great report shows that EVs have major benefits across the country.

Unfortunately, this report consistently undervalues the emissions benefits of EVs in Colorado. Its most recent iteration claims that EVs in Colorado have greenhouse gas emissions equivalent to a gasoline vehicle that gets 38 miles per gallon. But the UCS report looks at electricity mixes on a regional level, lumping renewable energy-friendly Colorado with coal-heavy Wyoming and a coal plant in Northwestern New Mexico.

This oversimplification gives the impression that Colorado’s electricity mix is far dirtier than it really is, leading to some skewed interpretations. For example, a glance at the “State of Charge” map suggests that charging your EV in Louisville, KY would be better than Denver, despite the fact that twice as much of Louisville’s electricity comes from coal. But that’s simply not the case, as revealed by SWEEP’s much more accurate assessment of the benefits of driving an EV in the Denver metro area.

SWEEP’s in-depth Denver study focuses on lifecycle emissions (which accounts for all the upstream emissions). We specifically evaluated EVs that are using electricity from Xcel Energy, Colorado’s largest utility, which serves about half the state’s population and about 70 percent of its EV owners. Xcel’s electricity mix is cleaner than the state of Colorado as a whole, and much cleaner than that of the regional grid.

The 2016 data thus show that when it comes to greenhouse gas emissions, an EV used in Colorado was akin to driving a 47 mpg gasoline vehicle.

There’s even better news: an EV bought today will become cleaner to drive as it gets older. That’s because Xcel Energy plans to retire some coal plants and invest in more wind and solar power, so powering EVs will produce fewer emissions every year.

Based on currently adopted plans, an EV bought in 2016 will become equivalent to driving a 75 mpg gasoline vehicle by 2025! NOx emissions will be 84 percent lower and VOC emissions will remain 99 percent lower.

And Xcel Energy’s latest proposal, announced August 29, will make EVs even cleaner. The proposal forecasts that by 2026, renewables would make over half of the area’s electricity mix. This translates to EVs being like an 88 mpg gasoline vehicle.


Simply put, driving an EV in Denver already brings significant air quality and climate benefits, and it’s only going to get better.

How Much an EV Reduces Greenhouse Gas Emissions Compared to a New Gasoline Vehicle