Plug-in electric cars such as Nissan Motor Co.’s Leaf and General Motor Co.’s Volt, could make up 9 percent of U.S. auto sales by 2020 and 22 percent in 2030, Bloomberg New Energy Finance said today.

Achieving that level of growth depends on gasoline prices rising and the cost of batteries coming down, the analysis company said this morning in a CNNMoney.com story. The price of electric cars, higher than three-quarters of autos currently being sold, is the most significant limiting factor, it said.

Bloomberg is more optimistic than J.D. Power and Associates, which last week predicted that just 7.3 percent of passenger cars sold globally will be hybrids or plug-in cars of some kind within the next decade.

On Friday, General Electric Co. CEO Jeffrey Immelt said his company plans to order “tens of thousands” of electric cars within about a week, the largest purchase of its kind in history. Immelt did not specify exactly how many vehicles GE would buy, nor what brands of electric cars would be included in the order.

Next year “will see the launch of a large number of new plug-in hybrid and electric vehicle models around the world,” New Energy Finance CEO Michael Liebreich said in a press release. “It’s not just car companies who have a lot riding on their success. Utilities, oil companies, whole countries will feel the impact if there is rapid uptake.”

General Motors’ Volt and Nissan’s Leaf are due to hit the market later this year. Ford, Toyota, Honda and Mitsubishi also are expected to introduce battery-operated cars within the next few years.

 “We’ve really got to inspire in business a clean energy future,” Immelt said in a speech in London. “Now is exactly the time, because it’s less popular and we’re going to have to go for a while without the government at our back.”