The U.S. offshore wind industry got a boost last week when Interior Secretary Ken Salazar signed the lease for Cape Wind. Today brings word of a big new project that also could help jump-start the industry–a 350-mile offshore transmission line, running about 10 to 15 miles off the Atlantic coast from New Jersey to Virginia.

The Atlantic Wind Connection, as it's being called, will grab attention because it has backing from Google. Google previously invested in North Dakota wind farms and backed a startup called Makani Power that is developing airborne wind turbines.

Trans-Elect Development Co., an independent developer of transmission lines, will announce the project today. Besides Google, its investors include Good Energies, a global investment firm that focuses on renewable energy and energy efficiency, and Marubeni, a publicly-traded Japanese conglomerate. Google and Good Energies will each take a 37.5 percent equity stake, according to this report by Matt Wald in The New York Times.

The first stage of the project alone will cost $1.3 to $1.4 billion to build, says Bob Mitchell, the CEO of Trans-Elect, who briefed me yesterday on the idea. That doesn't include another $300 million or more in financing, legal and regulatory costs. Overall costs could top $5 billion. Construction could begin by 2013, and the entire 350-mile line would not be completed until 2020 at the earliest.

The project will require federal, state and local regulatory approvals. The PJM Interconnection, which operates the electricity grid in the mid-Atlantic states, and the Federal Energy Regulatory Commission (FERC) will both take a close look–since the costs would ultimately be passed along to electricity consumers.

Assuming all the regulatory hurdles are cleared, the project could have a big impact. A major obstacle to the growth of  wind power (as I wrote recently in this story in Wired) is that the strongest wind resources tend to exist in rural areas like the Dakotas, Iowa and west Texas, which are far from cities, where electricity is needed, or offshore. In both instances, transmission is badly need to link supply and demand.

Mitchell says the construction of  a high-capacity backbone transmission line offshore would lower the costs and speed the development of offshore wind. It's a bold "if-you-build-it-they-will-come" approach.

"This will remove the biggest barrier that offshore wind faces," Mitchell told me, "by enabling wind farms to connect to shore in the most efficient way possible. Rather than having every individual wind farm build its own transmission line to shore, and link up at several places up and down the cost—they're affectionately referred to as spaghetti lines—this will enable them to enter the transmission grid through a superhighway."

"We want to create a super grid that will be in place and simulate the development of wind farms far faster than if they would each have to solve their own transmission issues," he said.

Because the wind usually blows somewhere off the coast, if not everywhere at once, Mitchell said the transmission line also would help solve what's known as the intermittency problem with wind or solar power–that is, the fact that wind and solar plants can't be counted on to generate electricity round the clock, as coal, nuclear and natural gas plants do.

When complete, the Atlantic Wind Connection project would be able to connect 6,000 MW of offshore wind, enough power to serve approximately 1.9 million households. The developers said the concept from a Washington lawyer named Markian Melnyk, while researching a book on offshore power.  The project will use High Voltage Direct Current which, its backers say,

allows for easier integration and control of multiple wind farms while avoiding the electrical losses associated with more typical High Voltage Alternating Current (HVAC) lines. With this strong backbone in place, larger and more energy efficient wind farms can connect to offshore power hubs further out to sea.  These power hubs will in turn be connected via sub-sea cables to the strongest, highest capacity parts of the land-based transmission system.

Launched in 1999, Trans-Elect previously acquired and sold transmission lines in Michigan and in Alberta, Canada, and it built a new transmission line in California This would be by far the biggest undertaking for Trans-Elect, which is based in Bethesda, Md.  Mitchell previously worked as chief of staff for Alaska Sen. Mike Gravel and in the cabinet of James Blanchard, Michigan's governor from 1983 to 1991.

Google became involved after Mitchell arranged a meeting with Dan Reicher, a former Clinton administration official and energy investor who is now director of climate change and energy initiatives at Google. "They very quickly came to see the impact on renewable energy that a transmission line like this could have," Mitchell said. To reduce global greenhouse gas emissions, Google.org, the company's philanthropic arm,  is working on developing utility-scale renewable energy that is cheaper than coal.

Two final observations…

Just last week, the U.S. energy department released a comprehensive report on offshore wind power that found that

harnessing even a fraction of the Nation's potential offshore wind resource, estimated to be more than 4,000 gigawatts, could create thousands of jobs and help revitalize America's manufacturing sector, reduce greenhouse gas emissions, diversify U.S. energy supplies, and provide cost-competitive electricity to key coastal regions.

You can download the the Executive Summary and the full NREL report.

What's more, if offshore wind ever becomes a big business in the U.S., it will likely be concentrated off the Atlantic Coast, as Matt Wald explains in the Times:

The Atlantic Ocean is relatively shallow even tens of miles from shore, unlike the Pacific, where the sea floor drops away steeply. Construction is also difficult on the Great Lakes because their waters are deep and they freeze, raising the prospect of moving ice sheets that could damage a tower.

Besides, many more people live along the Atlantic Coast than along the Pacific or the Great Lakes. Demand for electricity in the northeast and mid-Atlantic regions is already stressing the transmission lines that carry it.