Are electric vehicles the wave of the future, or expensive toys? This shocking news story–shocking if you live in the North, anyway–suggests the latter.

Cold temperatures can sap electric car batteries, temporarily reducing their range by more than 40 percent when interior heaters are used, a new study found.

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Many owners discovered the range limitations last week when much of the country was in the grips of a polar vortex. Owners of vehicles made by manufacturers including Tesla, the top-selling electric vehicle company in the U.S., complained on social media about reduced range and frozen door handles during the cold snap.

Frozen door handles are an annoyance not unique to electric cars, but reduced range can be life-threatening.

At 20 degrees, the average driving range fell by 12 percent when the car’s cabin heater was not used. When the heater was turned on, the range dropped by 41 percent, AAA said.

Of course, at 20 degrees you pretty much have to turn the heater on. That is a remarkable loss of functionality.

Also, AAA tested the vehicles at 20 degrees above zero, a balmy temperature that we haven’t seen for a while here in the Twin Cities. What happens at 20 below, a temperature we have seen several times in the last week or two? Or eleven below, which it is at this moment where I live? A car whose range is severely compromised at such temperatures could be a death trap.

Advocates of “green” energy say that giant batteries will overcome the intractable problem of the intermittency–i.e., unreliability–of wind and solar energy. Of course, while batteries can power my laptop for six or eight hours, or a vehicle for a relatively short distance, no batteries exist that can power a city for six months, nor is any such technology on the horizon. But I wonder whether green energy advocates who toss around the word “batteries” much as they might say “magic” have considered the impact of cold weather.