A new report on offshore wind transmission by economic consulting firm The Brattle Group finds electric grid cost savings of more than US$500M and significantly reduced environmental impact and project risks in a multi-user, planned transmission system for offshore wind in New York state.
Elsewhere on the US east coast, however, Massachusetts Department of Energy Resources (Mass DOER) recently rejected a proposal to consider a small-scale independent offshore transmission system for offshore wind that proponents argue would have been an important first step towards the kind of coordinated approach to transmission they believe is necessary.
The Brattle report, Offshore Wind Transmission: An Analysis of Options for New York, evaluates the challenges of connecting individual windfarms to shore separately rather than adopting a planned approach in the form of a high-capacity offshore wind transmission system serving multiple windfarms, an approach that advocates believe would reduce cabling and optimise onshore landing points and substations.
The report was presented in a webinar co-hosted by Anbaric and the New York League of Conservation Voters Education Fund on 6 August 2020, an event co-sponsored by Columbia University’s Sabin Center for Climate Change Law.
Brattle said its research, supported by engineering firms PTerra and Intertec, "underscores the pivotal role of transmission planning in the development of New York’s offshore wind industry."
It said relying on individual generator lead lines would require extensive onshore grid upgrades costing four times as much as a planned approach. By using fewer cable routes and more robust grid connections, a planned transmission system reduces grid congestion and the need for expensive, disruptive onshore transmission upgrades, also reducing the impact on the marine environment and coastal communities.
Brattle principal and study co-author Johannes Pfeifenberger said: “Substantial additional offshore wind development will be necessary to achieve New York’s clean energy goals.
“At the scale considered by New York, a planned approach to offshore transmission will significantly reduce the environmental footprint and the overall costs and feasibility risks of offshore wind generation.”
The report found that planned offshore transmission would reduce cabling by almost 60%; and that planning and procuring transmission separately from generation increases competition and can reduce transmission costs 20-30%. It also found that planned transmission would more fully utilize offshore wind lease areas and more easily reduce offshore wind curtailment.
However, Power Advisory president John Dalton noted that at the end of July, Mass DOER notified the Massachusetts legislature and stakeholders that “the costs and risks of a solicitation for independent offshore wind energy transmission outweigh the potential benefits” and it has therefore decided not to recommend pursuing a solicitation at this time.
The proposal in Massachusetts limited the size of a potential independent offshore wind transmission solicitation to 1,600 MW. Mass DOER found that, at that size, such a solution would not be more beneficial than alternatives.
Mr Dalton said Mass DOER’s decision “reinforces some basic principles” about what it will take to develop independent offshore transmission: the first is a more complete understanding of offshore wind development targets for all states in the region; the second is offshore wind procurement targets that exceed the readily available interconnection capacity; and the third is cooperation between states to establish cost responsibility for transmission facilities.