Google is extending its investment in green technology with a $5bn (£3.2bn) programme to build an undersea, wind energy transmission backbone along 350 miles of the Atlantic seaboard.

The grid project, which stands to serve 1.9m homes from Virginia to New Jersey with up to 6,000 megawatts of electric power from dozens of windfarms 10 miles off the mid-Atlantic coast, is the most ambitious of its kind.

Google announced it is working with Trans-Elect and two other firms, but has not offered a timetable for construction. "This system will act as a superhighway for clean energy," said Rick Needham, Google's green-business operations director.

Investment in both wind energy programmes and the controversial extraction of shale oil from deposits in North Dakota, Montana and Alberta, Canada, has increased since the BP spill over the summer caused US lawmakers to curb permits for offshore oil and gas drilling.

For Google, the Atlantic Wind Connection Project is in line with earlier investments. In May, it put $40m into two North Dakota windfarms, its first clean-energy investment. Two days ago the firm announced it had tested a self-driving electric car on Californian highways.

Today's announcement offers hope that further investment will pour into the lagging US wind-energy programme. Consistent wind through Montana and the Dakotas, off the South Carolina coast and across the Texas panhandle gives the US windfarm industry an opportunity to supply significant amounts of electricity to the grid.

But compared with China, now the leading manufacturer of wind turbines and solar energy equipment, the US had been comparatively slow in adopting the technology. Public opposition to windfarms, including a large project off the presidential holiday island of Martha's Vineyard, has taken years to resolve.

That may now be changing: the Global Wind Energy Council industry group estimates wind-power investment may reach $202bn over the next 20 years.

Charlie Hodges, a wind industry analyst at Bloomberg New Energy Finance, said: "The North American wind industry hasn't had any players involved with the motivation and financial heft to really move this market forward. Google could play that role."