Despite rock bottom oil prices slowing electric car sales last year, consumers are expected to buy considerably more electric vehicles over the next few decades.

Electric cars could account for over a third of the new cars sold globally by 2040, according to a new report from Bloomberg New Energy Finance on Thursday. So many electric cars could be on the road by then that they may represent a quarter of the all the world’s vehicles.

The report predicted that falling battery costs, particularly lithium-ion batteries, will help lift sales of battery-powered cars. Government policies, too—in the U.S., China, and Europe—will continue to be a big incentive for consumers to buy electric cars.

By 2022, lower costs and financial incentives could make electric cars cheaper to own and operate than traditional gas-powered cars, the report said. That calculation is based on electricity prices versus gasoline, as well as battery costs.

However the researchers gave themselves wiggle room when it came to predicting oil prices, a notoriously difficult accomplishment, as well as the impossible-to-predict innovation in battery technology.

The report’s authors said their bullish predictions are based on oil prices rising back to $50 to $70 per barrel by 2040 from their current price of around $30 per barrel. If oil prices stay low, like $20 per barrel, electric car sales would likely be slower and account for only around 25% of new cars sales and 14% of all cars on the roads by 2040, the report said.

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Beyond 2030, the report explained that it’s difficult to tell what types of batteries may be dominant and that may affect the overall electric car industry in unknown ways. Will solid state batteries, which use solid polymers instead of liquids, gain traction? Or will lithium-air batteries, which use free air as a key ingredient, break out?

The report says as a disclaimer: “The uncertainty of which of these technologies or developments will occur, and when, means the cost structures and learning rates we have illustrated below could significantly differ in real life in the long term.”

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At a certain point the crystal ball can’t predict companies and technologies that surprisingly emerge out of nowhere and gain massive adoption.

But clearly electric car sales are clearly rising and will likely add dramatically to their current meager market share today. Of the 80 million cars sold globally last year, only 450,000 were electric.