Offshore Wind

Swedish Offshore Wind Farm Could Use 30-MW Turbines

A Sweden-based company that develops deepwater wind power projects has joined with a global renewable energy group in a partnership to develop an offshore wind farm that could feature turbines as large as 30 MW.

Freja Offshore, a joint venture (JV) between Sweden’s Hexicon and Mainstream Renewable Power, part of Norway’s Akers Horizon group, on June 22 said it has submitted an application for an offshore wind farm in Sweden that could have between 2,000 MW and 2,500 MW of installed capacity. The companies in a report on the project for Swedish officials said the installation would feature turbines of at least 15 MW, with an eye toward using turbines as large as 30 MW.

Turbines of 30 MW in size are not yet available, but the developers said they expect such units will be manufactured by 2030. The JV said that expectation aligns with the project’s development timeline. The largest known offshore wind turbine built to date is an 18-MW model from China State Shipbuilding Corp.

IberBlue Wind, a JV formed between groups based in Ireland and Spain, in April said it planned two offshore wind farms using 18-MW turbines in waters between Spain and Portugal.

Germany-based developer BayWa r.e. late last year announced it planned to build a 600-MW offshore wind farm near Portugal using 20-MW turbines. The company said the installation could be in service in 2028, subject to permitting.

Project Sited in Baltic Sea

The Freja Offshore project announced Thursday, called Cirrus, would be the second formally announced by Hexicon and Mainstream Renewable Power in Sweden. The groups’ JV in April submitted a planning application under the Swedish Economic Zone Act (SEZ) for a 2.5-GW offshore wind project, called Mareld, located in the North Sea. That installation would use floating wind turbines; expectations are that the project would be online around 2028.

The JV earlier this year said it could develop as many as four offshore wind projects over the next several years to serve Sweden.

The Cirrus project would be built in the Baltic Sea off the south coast of Sweden, about 31 miles south of Karlskrona and Öland in the SEZ. Developers said the location was chosen because energy demand in the southern part of Sweden is expected to rise substantially over the next several years. Freja Offshore in its application said the wind farm could deliver as much as 10 TWh of power each year.

“We are excited about the immense potential the Cirrus project holds in terms of providing affordable electricity, generating job opportunities in the region, and in advancing our business objectives in our domestic market,” said Marcus Thor, CEO of Hexicon, in a statement.

“Freja Offshore has ambitious plans for developing Sweden’s nascent offshore wind industry and we are confident that the Cirrus application and the Mareld application we submitted back in April this year can play important roles in creating local benefits and help Sweden achieve its renewable energy ambitions,” said Sebastian Bringsværd, head of Norway and Sweden at Mainstream Renewable Power.

Between 85 and 133 Turbines

Freja Offshore in a consultation document said the project would have at least 85 wind turbines and could accommodate as many as 133, depending on turbine size and capacity. A project capacity of about 2,500 MW is based on the use of 85 30-MW units. A capacity of about 2,000 MW is based on installation of 133 15-MW turbines.

The group said a 30-MW wind turbine would likely have a height of 370 meters, or about 1,200 feet. The rotor would have a diameter of 340 meters (about 1,100 feet).

Officials said the size comparisons were based on the evolution of wind turbines since 2011, when an 8-MW turbine had a rotor diameter of 164 meters (540 feet). They also calculated prospective size increases from 2021, when they said a 15-MW turbine had a rotor diameter of 236 meters (775 feet).

Freja Offshore in its application wrote, “As a result of this development, it is expected that 30-MW turbines with a rotor diameter of 330 meters will be launched between 2025 and 2030.”

Fixed-Bottom and Floating Technology

The JV also said the project could use a combination of fixed-bottom and floating wind turbines.

“Cirrus is planned to be an offshore wind farm with bottom-fixed turbines, but Freja Offshore will also investigate the potential use of floating wind turbines for the deepest sections,” officials said in Thursday’s announcement. “The offshore wind farm will however still be beyond the horizon and just barely visible during clear weather conditions as it will be situated 50 kilometers [31 miles] off the coastline.”

The groups said the Cirrus project will bring several benefits to the southern region of Sweden.

“Increasing electricity production is imperative, but there are other important factors as well: defense interests, residential considerations, fishing, and natural values, to name a few,” said Magnus Hallman, CEO of Freja Offshore. “That is why we have chosen to place the wind farm as far out at sea as possible, as well as to capitalize on the extremely favorable wind location. The proximity to Karlskrona is also viewed as positive as it has been a maritime technology hub for over 300 years. We will collaborate with all relevant stakeholders in the region to leverage the expertise available to progress the project and we are also prepared to adapt the design of the park to coexist with other interests, should this be necessary.”

The consultation document for the project said Cirrus also could include a floating offshore substation in addition to floating turbines.

Freja Offshore also addressed regional concerns in its project outline, writing that the wind farm site had been “meticulously designed” to minimize disturbances in the surrounding area. That includes co-existing with marine exercises performed by the Swedish Armed Forces.

The application submitted to the Swedish Ministry of Climate and Business relates to construction and operation of the offshore wind farm. It must be built in accordance with the rules for the SEZ, and also co-exist with an internal cable network under the auspices of the Continental Shelf Act, which governs use of the seabed around Sweden.

Darrell Proctor is a senior associate editor for POWER (@POWERmagazine).

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