The Brattle Group’s new report on offshore wind transmission details onshore electric grid cost savings of over $1 billion and significantly reduced environmental impacts in adopting a multi-user, planned transmission system to harness wind power off New England’s coast.

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.

Brattle’s research underscores the role of transmission policy in the development of New England’s offshore wind industry. The report, prepared for transmission developer Anbaric, 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 onshore grid upgrades at an estimated cost that is triple expected for onshore upgrades in a planned approach, costing ratepayers an estimated additional $1.1 billion overall. By relying on landing points closer to population centers and at robust onshore grid locations, a planned system reduces 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. At the necessary scale, a planned approach to offshore transmission will significantly reduce the environmental footprint and the overall costs of offshore wind generation.”

Walter Graf, one of the study’s co-authors.

Among the report’s other findings are:

• Planned offshore transmission significantly reduces seabed marine cabling. Planning transmission for the next 3,600 megawatts of offshore wind would reduce cabling by about 50%, preventing 356 miles of seabed disturbance and significantly reducing impact on fisheries and marine ecosystems.
• Planning and procuring transmission separately from generation increases competition and can reduce transmission costs 20%-30%, according to studies of UK offshore transmission and US onshore transmission trends.
• Planned transmission can level the playing field between generators, increase competition and reduce costs for offshore wind, a finding that reflects the experience in Europe.
• Planned transmission would utilize offshore wind lease areas more fully. 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. 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.”

Edward N. Krapels, CEO of Anbaric.

“Transmission is vital for achieving Massachusetts’ offshore wind goals. We can green the grid, create jobs, and efficiently reuse coastal power plant sites by developing transmission first, and this study shows why that’s a good approach for Massachusetts and New England.”

,Patricia A. Haddad, speaker Pro Tempore of the Massachusetts House of Representatives.