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Scientists from the Cornell University in the United States, together with Tompkins Consolidated Area Transit (TCAT), found that electric vehicles consume significantly more energy in cold weather.
Specialists from TCAT tested seven battery-powered electric buses in 2021 as part of a pilot program funded by the U.S. government. For two years, the buses operated on 41 routes in Tompkins County.
In the cold season, electric buses had problems, especially on road sections that passed through hills and in areas with severe weather conditions. In low temperature conditions, the buses’ range and performance were significantly reduced.
The «optimal temperature zone» models, created by the researchers, showed, how much energy these buses would consume at ideal temperatures between 16°C and 30°C. At temperatures between -4°C and 0°C, the buses consumed about 48% more energy, including the power required to keep the bus moving and the energy regenerated during braking. Even in the wider range of -12°C to 10°C, energy consumption still increased by 28.6%.
Half of this energy was spent on heating the batteries themselves. These batteries work best at a temperature of 24°C. In the cold season, they need additional energy to warm up before the bus can move. Another important factor was the interior heating system. On urban routes, the doors are often opened and closed, letting cold air into the cabin.
The study also showed that regenerative braking — a process that allows the battery to charge slightly while the bus slows down — does not work as effectively in cold conditions. This is partly due to the fact that bus batteries are about 8 times larger than those of cars, installed in electric cars. This makes it harder for them to maintain the same temperature in all cells.
Researchers recommend parking electric buses indoors during the cold season. They also advise charging the batteries while they are still warm and reducing the time that doors are left open at stops. More broadly, cities may need to rethink the way they approach transportation infrastructure. This means checking how many charging stations they have, whether they can keep buses in heated garages, and how to adjust routes and schedules.
The researchers also found that rural routes, which have fewer stops, consume less additional energy in cold weather than urban routes. This could help transportation agencies decide which routes are best suited for electric buses during the colder months.
The results of the study are published in the journal ScienceDirect
Source: Neowin