A report by consulting firm The Brattle Group says a planned approach to transmission that co-ordinates onshore and offshore transmission investment in New England in order to integrate huge amounts of offshore wind capacity would provide ‘significant benefits’ for industry and customers
The pros and cons of a co-ordinated approach compared with individual lead lines built by generators were discussed in depth by OWJ earlier this month.
Brattle found that a multi-user transmission system of the type advocated by transmission system company Anbaric and by a growing number of analysts would have important advantages compared with the alternative, in which generators install their own grid connections.
The report, Offshore Transmission in New England: The Benefits of a Better-Planned Grid, describes the limitations of connecting each windfarm to shore individually compared to a ‘planned’ approach based on a high-capacity offshore transmission system serving multiple windfarms that would reduce cabling and optimise the use of onshore landing points.
Anbaric, who commissioned the report, said Brattle’s research "underscores the pivotal role of transmission policy in the development of New England’s offshore wind industry."
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 what Brattle said is an estimated cost triple that expected for on-shore upgrades in a planned approach, costing ratepayers an estimated additional US$1.1Bn overall.
By relying on landing points closer to population centres 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, it is claimed.
The report authors said, “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.”
Among the report’s other findings are that planned offshore transmission significantly reduces seabed marine cabling. Planning transmission for the next 3.6 GW of offshore wind would reduce cabling by about 50%.
Planning and procuring transmission separately from generation increases competition and can reduce transmission costs by 20-30%, according to studies of UK offshore transmission and US onshore transmission trends.
The report claims planned transmission can also level the playing field between generators, increase competition and reduce costs for offshore wind, a finding that reflects the experience in Europe.
Brattle said planned transmission could utilise 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,” said the report authors. “A planned transmission approach utilising more efficient direct current technology would reduce losses and deliver more power to shore than alternating current technology utilised to date.”
Anbaric chief executive Ed Krapels said, “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.”
Riviera will host a week of free to attend 45-minute webinars focused on offshore wind commencing 8 June. Register your interest now