Upper Midwest the worst place to plug in — study 

Source: Katherine Ling, E&E reporter • Posted: Friday, February 27, 2015

If you live in Rochester, Minn., you may want to reconsider buying an electric vehicle, according to a new study from scientists at Carnegie Mellon University.

The colder temperatures in the Upper Midwest can decrease the range of a battery-powered electric vehicle (BEV) by 36 percent compared to one in California and in turn also increase carbon emissions because the region’s generation mix is also the dirtiest, according to the study published in the American Chemical Society journal Environmental Science & Technology.

The study is the first to account for efficiency losses with temperature changes when considering regional differences in energy consumption and emissions of electrified vehicles, according to the researchers.

There is also a penalty for electric vehicles driving in temperatures above 100 degrees Farenheit in places like Phoenix. Researchers found that the range of an electric car can drop from the median 69 miles per charge to as low as 49 miles at 105 F.

The energy consumption differences stem from the temperature’s direct effect on a battery’s chemistry and performance but also the fact that really cold or really hot days cause people to use more heating or air conditioning in the car, which also uses power and drains the battery.

The greater the energy consumption of the vehicle, the more electricity it needs from power plants, producing more emissions depending on the fuel mix. The study found that the West had the lowest average carbon emissions per mile — around 100 grams — while the Midwest had the highest average carbon emissions per mile at more than 300 grams. The other regions with lower carbon emissions per mile were the Texas-Oklahoma region and the Southeast, according to the study.

The combination of these factors showed the best place to have an electric car is the Pacific Coast — more specifically, San Franciso, with a median range of 76 miles and the lowest CO2 emissions per mile, among the six cities the study looked at. The other cities included Portland, Ore., Pittsburgh and Minneapolis.

“These regional differences are large enough to affect adoption patterns and energy and environmental implications of BEVs relative to alternatives,” the study said.

Five out of every 1,000 registered vehicles are electric or hybrid cars in California, and more than half the 70,000 total BEVs in the United States are parked in the state, according to the U.S. Energy Information Administration.

The study was based on aggregated data from more than 7,000 trips in the United States by 87,700 Nissan Leafs, collected by the Canadian vehicle monitoring firm FleetCarma and driving pattern data from a Department of Transportation 2009 survey.

But electric vehicles are not alone in losing range in extreme temperatures, and there is an upside to colder temperatures for EV owners.

Gasoline vehicles also lose a range between 12 and 19 percent at temperatures below freezing, according to a separate analysis FleetCarma released yesterday.

And while electric cars’ average loss in range is between 20 and 29 percent in temperatures below freezing, the energy cost savings actually improve at lower temperatures, the company said.

At 73 degrees Farenheit, the electricity cost savings per mile are 12.4 cents, but at zero degrees Fahrenheit, BEV drivers see a 14.8-cents-per-mile savings, FleetCarma found.

“While the factors that cause the range of a vehicle to shrink differ between electric and gas vehicles, when the costs are analyzed on a cost-per-mile basis the savings improve at lower temperatures,” the study said.

The biggest culprits for decreasing mileage for gasoline cars are excessive idling and less efficient components, the study says. For electric vehicles, power loss mainly comes from heating the cabin and battery.

Both studies note that different vehicle technology, driving style and consumer behavior could change these statistics.