The developers of the world’s biggest offshore wind farm — the 3.6-gigawatt Dogger Bank scheme in the UK North Sea — have insisted the project remains on target to deliver its first power to the grid next year as planned, despite delays to the delivery of a key installation vessel.

Some project watchers have raised questions over the ability of SSE Renewables, Equinor and Eni to maintain the schedule of Dogger Bank’s first two phases since a crane accident at a Chinese shipyard in October delayed the delivery of Oslo-listed Seaway 7’s newbuild semi-submersible wind foundation installation vessel Seaway Alfa Lift.

Seaway Alfa Lift had been due to start work at Dogger Bank this year but is now not expected to join Seaway 7’s fleet until the second half of 2023.

Seaway 7 said in a recent trading update that installation work is set to start this year using instead the crane vessel Seaway Strashnov, which will also be deployed for a “full” campaign in 2023.

A spokesperson for the Dogger Bank developers told Upstream this week they “continue to work with Seaway 7 to establish the most optimum vessel options for foundation installation at Dogger Bank”.

They stressed, however, the project “currently remains on programme”.

“First power for Dogger Bank A is scheduled in Summer 2023, with full wind farm operation targeted for spring 2024. The current programme for Dogger Bank remains unchanged,” the spokesperson said.

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SSE and Equinor agreed late in 2020 to invest $8 billion to construct the first two phases of Dogger Bank.

SSE is leading construction, with Equinor in charge of operations, both with 40% interests.

The 1.2 GW first phase, called Dogger Bank A, is expected to start operations in 2023, with Dogger Bank B following about a year later.

Each phase will generate about 6 terawatt hours of electricity annually.

A $4 billion third phase — Dogger Bank C — is expected to begin operations in 2026, taking the wind farm’s total capacity to 3.6 GW. Financial close on Dogger was reached in December.

Italian giant Eni is an industrial partner for all three phases of the wind farm, holding a 20% interest.

SSE and Equjnor selected Norwegian vessel owner OHT in 2019 as their preferred contractor to install foundations on Dogger Bank A and B, using the custom-built Seaway Alfa Lift vessel, with capacity to carry 10 monopiles and transition pieces on her deck per voyage to the wind farm location, about 130 kilometres off the north-east coast of England.

A year ago, OHT combined with the offshore renewables division of offshore contractor Subsea 7 to create Seaway 7 as a stand-alone pure-play offshore wind contractor.

The accident last year at Chinese yard China Merchants Heavy Industry (CMHI) in Jiangsu province involved the folding A-frame on the main crane of the Seaway Alfa Lift.

A recent Upstream report highlighted how government-sponsored research in Norway had come up with the conclusion that Dogger Bank is unlikely to be profitable for Equinor.

Researchers calculated the Dogger Bank project’s expected net present value (NPV) to Equinor at minus £970 million and found that the rate of return on investment does not reach the company’s own benchmark requirements for profitability.

A negative NPV indicates the value of the investment is below the rate of return that the company should require from its investments.

Equinor has not disputed the study’s conclusions but emphasised that it had benefited from selling stakes in the project.

Seaway 7 had not replied to Upstream’s requests for comment by the time of publishing.

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