Electric cars are getting the attention of oil companies.

On Wednesday, one of the largest fast-charging networks in the U.S., Greenlots, announced that it had been bought by oil giant Royal Dutch Shell—via the subsidiary Shell New Energies US LLC.

Greenlots supports mainly DC fast charge stations across the U.S., the kind electric cars drivers are meant to visit occasionally when they need a quick charge to complete a long trip—kind of like using a gas station.

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For now, that doesn't mean that DC fast chargers are going to appear at every Shell gas station. Greenlots operates chargers along highways, often at public rest areas, especially up and down the East Coast, in the Pacific Northwest, and California.

The company recently signed an agreement with Volkswagen-subsidiary Electrify America to manage EA's installations along highways. So far, most Greenlots chargers are operated through a cell-phone app were users create an account and put in their credit cards, or via membership. Electrify America has agreed to make all its chargers credit-card accessible.

The initial announcement of the purchase, for an undisclosed amount, did not speculate about what a future Shell charging-station network might look like in the U.S. In a statement, Shell called the purchase the "foundation for Shell's continued expansion of electric mobility solutions in North America." Executive Vice President for New Energies, Mark Gainsborough, said, "This latest investment in meeting the low-carbon energy needs of US drivers today is part of our wider efforts to make a better tomorrow. It is a step towards making EV charging more accessible and more attractive to utilities, businesses and communities."

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Perhaps in part borne of a culture bred in Shell's home country of the Netherlands, the company has long been one of the oil giants most interested in investing in alternative energy sources. Shell already bought the New Motion charging network in Europe and recently bought one of Britain's largest utilities.

The company also operates Shell Recharge Plus, which helps electric-car drivers in California minimize charging during times of peak demand on the power grid, and with the lowest possible fees.

Shell has also been an early investor in developing hydrogen filling stations and supplies for fuel-cell cars in the U.S.