The amount of time it takes to charge an electric car today is one of the main obstacles to wider-spread consumer adoption. Even the quickest DC fast-charging stations generally take around half an hour for an 80-percent charge, which is still much longer than it takes to pump a tankful of gasoline.
Will that ever change? Researchers at Switzerland’s Ecole Polytechnique Federale de Lausanne (EPFL, via Phys.org) believe it might. They’re testing a concept called “intermediate storage” that’s meant to address one of major issue with increased charging speeds: the limitations of power grids. Increasing power flow cuts charging times, but it also puts extra strain on grid infrastructure, EPFL researchers note.
They claim the solution actually involves disconnecting charging stations from the grid for periods of time. A lithium-ion battery pack is consistently charged at a low rate, and when a car plugs in to charge, that stored power is rapidly transferred to the vehicular battery pack. Grid electricity isn’t even needed to directly charge the car, researchers claim.
The EPFL researchers and several partner organizations built a demonstration intermediate-storage battery pack mounted in a trailer. Drawing power from the same type of connection used for residential electricity needs, it can discharge 20 to 30 kilowatt-hours of electricity into an electric-car battery pack in about 15 minutes, researchers say.
The team members behind the intermediate-storage charging station are already so pleased with their concept that they’ve moved on to calculating how much storage capacity will be needed at future commercial stations, even creating an equation for this purpose. They estimate that a station capable of quick-charging 200 cars per day would need storage capacity of 2.2 MWh, or about the same amount of energy consumed by a European household in one year.
That works out to about four shipping containers full of batteries, the researchers say. If that’s true, then future electric-car charging stations may have to set aside a bit of extra real estate.