By Ivan Penn and Stanley Reed

New York Times News Service

LOS ANGELES — California’s aggressive pursuit of an electric grid fully powered by renewable energy sources is heading in a new direction: offshore.

On Friday, the U.S. Interior Department took the first steps to enable companies to lease waters in Central and Northern California for wind projects. If all goes as the state’s regulators and utilities expect, floating windmills could begin producing power within six years.

Such ambitions were precluded until now because of the depths of the Pacific near its shore, which made it difficult to anchor the huge towers that support massive wind turbines.

“They would be in much deeper water than anything that has been built in the world so far,” said Karen Douglas, a member of the California Energy Commission.

Several contenders are expected to enter the bidding, equipped with technology that has been tested in Europe. California’s determination to fully rely on carbon-free electricity by 2045, mandated in a bill signed by Gov. Jerry Brown in September, is forcing the state to look beyond solar power and land-based wind farms to meet the goal.

“We are early in the process here,” Douglas said, “but offshore wind has potential to help with our renewable energy goals.”

The potential rewards from offshore wind development are not without potential downsides, however, and will almost certainly not come without conflict. Development along California’s coast has long been a sensitive and highly regulated issue. As has happened elsewhere, there will surely be objections from those who feel their ocean views are being blighted. And the potential impact on birds, fisheries and marine mammals will be closely scrutinized.

California would not be the first place to develop floating wind turbines in the United States. The University of Maine, with $40 million from the Department of Energy, designed its own floating wind platform and produced a test version that it plans to develop as a commercial project to power 8,000 to 14,000 homes by 2021.

California is a particularly opportune spot for such a project, given the length of its coast and the size of its population. And the coast offers an added advantage: Winds over the ocean tend to pick up strength as the sun sets, just when the contribution of solar power is done for the day.

“California has very good offshore wind,” said Walt Musial, a principal engineer and manager of offshore wind efforts at the National Renewable Energy Laboratory.

The Bureau of Ocean Energy Management, part of the Interior Department, identified three areas for leases: a parcel off Humboldt County in Northern California, and two sites in the Morro Bay area on the central coast, near Hearst Castle and Diablo Canyon, the location of the state’s last operating nuclear plant.

Offshore wind projects in California will largely benefit from existing power lines to keep costs down. Several power plants along the coast have closed or will be retired because of pollution and other environmental concerns.

And power lines on the state’s western side are less congested than those on the eastern side.

In addition to undergoing the federal reviews, the wind projects must be cleared by several state agencies, including the California Coastal Commission for impact on federal and state waters; the California State Lands Commission; and the Department of Fish and Wildlife because of concern about protected species.

It is expected the wind farms would be about 15 to 30 miles off the coast, making them less visible from land and less of hazard to seals and migratory birds.

Even at that distance, other marine life could be threatened, including sea birds and whales migrating through the channels. In addition to towers hundreds of feet tall, there would be streams of cables connecting the windmills to the electric grid on shore.

“I would have some questions whether those cables would mean that whales would not use the area the same way as they have,” said Francine Kershaw, a marine mammal scientist at the Natural Resources Defense Council, which supports wind power, including offshore development. “But collisions with sea birds is probably the major concern.”

Much will depend on the size of the projects. Proposals are expected from the Redwood Coast Energy Authority in Humboldt County, which is seeking developers for 10 to 15 floating wind units that can help it meet the carbon-free mandate.

Redwood Coast, a government-run utility serving 60,000 customers in a mostly rural area, expects to spend about $500 million for the wind farm.

“That level of generation would be a significant chunk of our energy load,” said Matthew Marshall, Redwood Coast’s executive director. “Offshore wind is really the big untapped resource.”