Offshore Wind Power Coming to California

1 Mar 2021

Offshore wind power is heading the Golden State’s way, first to serve the Redwood Coast Energy Authority, a panel of energy experts at a California Community Choice Association webinar said Feb. 26. This renewable technology has already gained favor in Europe, Asia, and on the East Coast of the U.S.

The Redwood Coast authority project is expected to be operational as early as 2027. It will supply 120-150 MW of wind power from floating turbines that will be moored about 25 miles off the coast of Eureka.

Technology that allows the mooring of large floating turbines to California’s deep seafloor is “now available,” Matthew Marshall, Redwood Coast Energy Authority executive director, said.

Currently, a lease application for the project, expected to be California’s first offshore wind facility, is pending with the federal Bureau of Ocean Energy Management, according to Marshall.

Other areas off the California Coast also have world class wind resources. That includes off Morro Bay and San Luis Obispo County, where coastal power plants linked to the state’s power grid by transmissions lines are slated to close.

West Ocean Winds is developing the Humboldt project, along with other companies, including Aker Offshore Wind. Aker is a San Francisco-based firm that builds floating platforms for offshore wind turbines in the Bay Area.

The platforms would be towed from San Francisco Bay to Humboldt Bay in Eureka, where turbine towers would be mounted before towing them out to sea, Tyler Studds, head of project development for West Ocean Winds, said.

Floating turbines to be attached to deep seafloor

Once the floating turbines arrive at their location, they will be moored to the seabed in water up to 1,000 meters deep and then linked together with electrical cables, he said. The turbines will be placed about a mile apart.

Next, they will be tied into the grid onshore with an undersea transmission cable.

Studds said it’s unclear what size turbines will be used, though they could span 90 meters across and produce as much as 15 MW of power apiece.

Development details are due at the end of the year, he said, to be followed by up to five years of data collection needed to analyze the potential environmental impacts and determine what, if any, mitigation measures to protect marine life and birds may be needed.

Once fully approved, it will take about one year to build the project, according to Studds. The turbines then would operate from 25 to 30 years.

The cost of the power depends upon the final development plan. However, Walt Musial, National Renewable Energy Laboratory offshore wind manager, said a recent lab study shows that the cost of offshore wind power in California is expected to fall from about $100 to $120/MWh if it was operating today to near or below $60/MWh by 2032.

While the planned project will meet the Authority’s limited needs for power along the sparsely populated Redwood Coast, the offshore area in that region could provide much more power, according to the panelists.

Steady wind energy could fill solar void

Since the wind in the outer waters along the coast is fairly steady it could easily fill in the void that occurs in California’s grid when solar production falls in the late afternoon, observed Marshall.

Currently, however, the Redwood Coast region lacks the needed transmission facilities to distribute all of its potential offshore wind power to urban areas. Marshall suggested the most economical way to develop transmission to fully tap the Redwood Coast’s wind resource would be to build a line over the Coast Range to link into existing high capacity transmission paths in the Central Valley. He estimated that would cost about $1 billion.

The other option would be to run an undersea cable system to the Bay area, but that would easily double the cost, according to Marshall.

The Redwood Coast project is advancing as lawmakers in Sacramento are considering a bill by Assemblymember David Chiu (D-San Francisco) to encourage offshore wind projects.

Chiu’s measure, AB 525, would require state energy agencies to develop a plan for developing 3 GW of offshore wind power by 2030 and 10 GW by 2040. The plan would outline needed transmission facilities, port upgrades, and workforce training.

Both the State Building & Construction Trades Council and Environment California back AB 525.

—William J. Kelly

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