Shared Grid Offshore New England Saves Over USD 1 Billion Onshore – Report

A multi-user, planned transmission system to harness wind power off New England’s coast could result in onshore electric grid cost savings of over USD 1 billion and significantly reduce environmental impacts, a report prepared for transmission developer Anbaric shows.

The report, Offshore Transmission in New England: The Benefits of a Better-Planned Grid, describes the limitations of connecting each wind farm to shore individually in comparison to a “planned” approach – a high-capacity offshore transmission system serving multiple wind farms, reducing marine cabling and optimizing onshore landing points.

The report found that a planned transmission approach “is likely to result in lower costs in both the near- and longer-term, by lowering risks and costs of onshore upgrades and increasing competition for both offshore transmission and generation.”

The current approach of relying on individual generator lead lines would require extensive on-shore grid upgrades at an estimated cost that is triple expected for on-shore upgrades in a planned approach, costing ratepayers an estimated additional USD 1.1 billion overall, the report states. By relying on landing points closer to population centers and at robust onshore grid locations, a planned system is said to reduce grid congestion and the need for expensive, disruptive onshore transmission projects that could hinder the growth of offshore wind.

“Substantial additional offshore wind development will be necessary to achieve the New England states’ clean energy goals,” said Walter Graf, one of the study’s co-authors.

“At the necessary scale, a planned approach to offshore transmission will significantly reduce the environmental footprint and the overall costs of offshore wind generation.”

The report has also found that planned offshore transmission significantly reduces seabed marine cabling. Planning transmission for the next 3,600 MW of offshore wind would reduce cabling by about 50 per cent, preventing 356 miles of seabed disturbance and significantly reducing impact on fisheries and marine ecosystems.

This approach could also reduce transmission costs by up to 30 per cent, as well as increase competition and reduce costs for offshore wind.

Planned transmission would also utilize offshore wind lease areas more fully, the report said. In an unplanned system, after each developer interconnects the bulk of their lease site, it may be cost-prohibitive to interconnect the residual areas in the lease, forfeiting potential wind power. A planned transmission approach utilizing more efficient direct current technology would reduce losses and deliver more power to shore than alternating current technology utilized to date.

“Developing a shared ocean grid is the most effective way to scale offshore wind,” said Edward N. Krapels, CEO of Anbaric.

“The next phase in achieving states’ goals depends on building transmission infrastructure in a way that reduces overall costs, protects fisheries and the environment, and enables continuing growth of New England’s best energy resource.”

The report was prepared by the consulting firm The Brattle Group.