Electric car buyers, beware of extreme weather

Should you buy an electric car? The answer might depend on whether you live on the balmy California coast or in the freezing Midwest. According to a new study, the regional climate can make a big difference in an electric vehicle’s energy consumption.

Many environmentally-minded consumers are drawn to the idea of buying an electric car. But some people shy away from the purchase because of “range anxiety,” or the fear that their car battery will peter out while they’re on the road.

The study authors point out an important factor that influences battery life: temperature. Batteries are less efficient in cold conditions, and they degrade more quickly in hot conditions. Not only that, but people may crank up the heat or air-conditioning in their cars on cold or hot days, using even more energy.

The team decided to find out how temperature affected electric car efficiency in different parts of the country. The researchers analyzed data from the company FleetCarma on more than 7,000 Nissan LEAF trips in North America. They also studied ambient temperature data taken at 1,011 US locations from 1976-2005 and driving pattern data for 87,777 vehicles in 2009. Armed with these numbers, the team estimated the daily average driving range — the distance an electric car can travel with a fully charged battery — and the average electricity consumption per mile in various regions.

Cars in cities with extreme temperatures showed bigger fluctuations in driving range, the authors found. For example, the median range in San Francisco, Phoenix, and Rochester, Minnesota was roughly 70-75 miles. But in Phoenix and Rochester, the range could fall by as much as 29 and 36 percent, respectively, below the median. In contrast, San Francisco drivers rarely saw the range drop below 70 miles. Similarly, an electric car in the Upper Midwest consumed an average of about 15 percent more electricity per mile than one on the Pacific Coast.

The researchers note that they analyzed data only for the Nissan LEAF, and other models might behave differently. Still, potential electric vehicle owners would be well-advised to consider the effects of scorching or frigid weather on their trips. Roberta Kwok | 5 March 2015

Source: Yuksel, T. and J.J. Michalek. 2015. Effects of regional temperature on electric vehicle efficiency, range, and emissions in the United States. Environmental Science & Technology doi: 10.1021/es505621s.

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