Offshore Wind Farms Connected By an Underwater Power Grid for Transmission Could Revolutionize How the East Coast Gets Its Electricity

Coordinated offshore transmission can avoid many of those costs with what the Department of Energy calls “meshed” or “backbone” designs.

Rather than individual connections to land, many offshore wind farms would be connected to a shared transmission line, which would connect to the onshore grid through strategically placed “points of interconnection.” This way, electricity produced by an offshore wind farm would be transmitted to where it is most needed, up and down the East Coast.

Even better, electricity generated onshore could also be transmitted through these shared lines to move energy to where it is needed. This could improve the resilience of power grids and reduce the need for new transmission lines over land, which have been notoriously difficult to gain approval for, especially on the East Coast.

Coordinated offshore transmission was part of early U.S. discussions on offshore wind planning and development. In the late 2000s when Google and partners first proposed the Atlantic Wind Connection, an offshore transmission project, the benefits in both offshore renewables and the entire energy system were intriguing. At the time, the U.S. had just one utility-scale offshore wind project in the pipeline, and it ultimately failed.

Today, the U.S. has 53 GW of offshore wind projects being planned or developed. As energy researchers, we believe coordinated offshore transmission is important for the industry to succeed at scale.

Offshore Grid Could Save Money, Reduce Impacts
By enabling power from offshore wind farms and onshore electricity generators to travel to more places, coordinated transmission can enhance grid reliability and enable electricity to get to where it is most needed. This reduces the need for more expensive and often more polluting power plants.

A 2024 report from the National Renewable Energy Lab found the benefits of a coordinated design are nearly three times higher than the costs when compared with a standard point-to-point design.

Studies from Europe, the U.K. and Brattle have pointed to additional benefits, including reducing planet-warming carbon emissions, cutting the number of beach crossings by a third and reducing the miles of transmission cables needed by 35% to 60%.

In the U.S., offshore transmission lines would be almost entirely in federal waters, potentially avoiding many of the conflicts associated with onshore projects, though it would still face challenges.

Challenges and Next Steps
Building an offshore grid will require some important changes.

First is changing government incentives. The federal investment tax credit for offshore wind, which covers at least 30% of the upfront capital cost of a project, does not currently help pay for coordinated transmission designs.

Second, planning needs to take everyone’s concerns into account from the beginning. While the overall benefits of coordinated transmission designs outweigh overall costs, who receives the benefits and who bears the costs matters. For example, more expensive power generators could earn less, and some communities feel threatened by offshore development.

Third, greater coordination will be needed among everyone involved to dispatch power to and from the regional grids. The Federal Energy Regulatory Commission’s recent Order 1920, requiring power providers to plan for future needs, may serve as a blueprint, but it does not apply to interregional projects, such as an offshore transmission backbone connecting over a dozen states across three regions.

The U.S. reached an important milestone in March 2024 with the completion of South Fork Wind, the country’s first utility-scale wind farm, bringing U.S. offshore wind power capacity to nearly 200 megawatts. Eight more projects are under construction or approved for construction. Once built, they would bring installed capacity to over 13 gigawatts, roughly the same as three dozen coal-fired power plants.

An offshore transmission backbone could support offshore wind development and the East Coast’s energy needs for generations to come.

Tyler Hansen is Research Associate in Environmental Studies, Dartmouth College. Abraham Silverman is Research Scholar, Ralph O’Connor Sustainable Energy Institute, Johns Hopkins University. Elizabeth J. Wilson is Professor of Environmental Studies, Dartmouth College. Erin Baker is Professor of Industrial Engineering Applied to Energy Policy, UMass Amherst. This article was updated 31 July 2024, to clarify that the states formalized the memorandum of understanding, and it  is published courtesy of The Conversation.