Developers of U.S. offshore wind farms have proposed projects that will require thousands of miles of new underwater transmission lines, Brattle Group economists said in a new report, and linking these into "offshore grids" can reduce the costs and environmental impacts of the offshore farms.
While Deepwater Wind's 29.3-MW Block Island Offshore Wind farm, completed in December 2016, remains the lone operational wind farm in U.S. waters, 28 projects representing roughly 24,000 MW are under development, according to the report. Northeastern states alone have committed to procuring 8,000 MW of new offshore generation.
"Our analysis shows that, at this scale of offshore wind development, the development of offshore transmission grids that can interconnect multiple wind plants can offer significant advantages over reliance on individual generation tie lines," Johannes Pfeifenberger, a Brattle Group principal and study co-author, said in a May 30 new release.
The firm estimates the need for around 600 miles to 1,200 miles of offshore transmission lines to access projects off the coasts of Massachusetts, New York and New Jersey, and a total of approximately 3,000 miles of offshore transmission to integrate the 24,000 MW under development off all U.S. coasts, including nearly 15,000 MW of projects that have acquired site control. Offshore grids integrating numerous projects "would create scale economies and reduce the number of necessary landing points," according to a May 23 Brattle Group presentation at an offshore wind transmission conference in New York City.
Building on the deployment of such offshore grids in Europe, several developers have proposed networked systems in the U.S. The creation of "shared, independent offshore transmission" is the "key to success" for the emerging U.S. offshore wind sector, Edward Krapels, CEO of Anbaric Development Partners, a subsidiary of Anbaric Holding, said in recent testimony before a U.S. House of Representatives committee.
'An anti-competitive, wrong footing'
Policy proposals in Massachusetts, New York and New Jersey, however, "would give generators the exclusive ability to own the transmission lines" and would "get America's offshore undertaking off on an anti-competitive, wrong footing," he said. "It's obviously in their interest to control as much of the access to the onshore grid as possible." But the resulting lack of competition would lead to higher costs, while a "proliferation of cables" would create unnecessary environmental impacts on marine life.
"It will undermine an industry in a vital period of its growth," Krapels told lawmakers. Anbaric's proposed "OceanGrids" off New York and New Jersey would cut the number of subsea cables at least in half, he said.
The Brattle Group found that generation ties to individual projects are "more cost effective for limited wind development and short distances," while offshore grids connecting multiple projects are more suitable for bigger projects further offshore, and in areas with environmentally sensitive shorelines and fewer transmission landing points. "Offshore grids with open access can offer significant cost and competitive advantages for interconnecting large amounts of wind generation," the report concluded.
