Offshore wind turbines are too deep to be economically feasible under most conditions, with fixed-bottom foundations reaching 60 meters or more. However, the goal of normalizing offshore wind is not out of reach. That’s because a whole new generation of floating offshore wind turbines is being used to combat the strongest winds that nature has created.
The engineering behind floating offshore wind power is incredibly complex. Wind turbines are located on floating platforms made of a concrete, steel or hybrid substructure on which the wind turbine is mounted, ensuring its buoyancy and stability. Anchored and propped up on the seabed, they must battle the unfettered forces of stormy seas and arbitrary weather.
Offshore wind energy is a clean and renewable energy source that reaches high and stable speeds due to the lack of obstacles. Its high potential and strategic added value, both at the socio-economic and environmental levels, make it one of the renewable resources that will play a decisive role in the decarbonization process.
According to the Global Wind Energy Council, the global wind industry had its second best year in 2021, with almost 94 GW of capacity added globally, dwarfing 2020’s record growth of just 1.8%. Europe, Latin America, Africa and the Middle East all had record years for new onshore installations. Last year, 21.1 GW of offshore wind capacity was commissioned, 3 times more than in 2020, bringing the best year on record for offshore wind to 22.5% in 2021, gaining market share in global new installations.
Wind power has not reached its full potential as 80% of offshore wind resources in European waters are too deep for current offshore wind turbine technology. Deep water barriers have also prevented the installation of large offshore wind farms on the US west coast.
As engineers look for ways to capture the most reliable high winds, they are moving out into the ocean, into deeper water areas known to experience particularly strong winds. Entirely new technologies are in the design stage to rethink deep water barriers.
The need for stability: Offshore Wind Turbines
Offshore wind turbines have higher load factors than onshore ones and therefore suffer from less intermittent power generation. Away from the coast, they benefit from stronger winds for more production capacity.
Floating turbines can open up vast areas of the ocean to generate electricity. Analysis by the Institut Polytechnique de Paris shows that floating wind turbines hold promise for energy production worldwide: 330,000 TWh per year, or 79% of the total theoretical potential of offshore wind energy. The Global Wind Energy Council predicts that floating wind will become “one of the major game changers” in the industry.
However, the challenges of offshore wind energy projects are significant and include:
- high costs for support structure, operation and maintenance, electrical infrastructure and turbines
- strict environmental standards
- less established construction techniques
- more difficult access to turbines for maintenance
- cables that are longer, larger and deeper than the cable for existing offshore wind farms
- driver uncertainties related to wind speed, turbulence, shear profile, significant wave height, spectral peak period, and wave direction
As noted by , billions of dollars are currently being invested in the floating offshore wind industry Wired. To significantly reduce the cost of a floating turbine, designers are moving away from the tall tower concept to alternative designs that require less steel to eliminate the mechanism that rotates the nacelle. The result should be a simpler design that is easier to set up so that the entire structure can be turned to face the wind.
Norway and Floating Offshore Wind Systems
A variety of floating turbine designs have emerged, intriguing over cost and efficiency.
The Norwegian government has launched a large-scale investment plan to set aside offshore areas to develop 30 GW of offshore wind capacity by 2040. The government said this would facilitate large-scale offshore wind development, enabling the use of a variety of grid solutions. . Cables with two-way power flow, connectors to Europe and connectors to Norway will be considered for each call. The Norwegian Directorate of Water Resources and Energy (NVE) and the Ministry of Petroleum and Energy (MPE) will study the consequences of the alternatives.
Energy scales exponentially with wind speed. Conventional turbines limit the energy output above 11-12 m/s by positioning the blades. Wind Catching Systems (WCS), the originator of floating offshore wind technology, was founded in 2017 with the idea that multiturbines can maximize energy production from a more concentrated area than a single large turbine. Ease of maintenance, durability and simplicity were the guiding principles when the first Windcatcher was designed as a trimaran sail.
WCS’s design for the giant wafer-shaped frame has at least 126 four-rotor wind turbines. Standing as tall as the Eiffel Tower, the entire structure would rest on a floating platform similar to that used by oil rigs. Using full power at higher wind speeds and the multirotor effect, the Windcatcher system produces 2.5 times more annual energy per swept area than a conventional turbine. A wind turbine with twice the sweep area of a conventional 15 MW wind turbine has the potential to increase annual energy production by 5 times.
The company is now involved in a Series A investment round of up to $10 million, and GM Ventures has entered into a strategic agreement or partnership covering technology development, project execution, offshore wind policy and development of sustainable technology applications.
What Else Happens in Offshore Wind Research?
Other offshore wind designs are in the works.
Equinor has developed a new floating wind concept that will enable industry standardization and maximize opportunities for local supply chains. The Wind Semi is designed to enable manufacturing and assembly based on the foundation and local supply chain capabilities of a semi-submersible wind turbine, a floating right triangle type with a turbine positioned at one corner.
Olympic Wind, Washington-based Trident Winds, filed an unsolicited request for a federal lease in late March. The proposal could include up to 2,000 megawatts of electricity, enough for about 800,000 homes, to be generated from turbines mounted on platforms and anchored to the deep ocean floor about 43 miles off the coast of Grays Harbor County, Washington. It will be Washington’s first commercial-scale offshore wind project of 2,000 MW.
Extensive monitoring of new floating wind farms will continue to gather information on their environmental impacts. A study suggests that the installation of floating turbines should be quieter than the installation of fixed-bottom marine machinery, and therefore cause less disturbance to marine mammals, as piling for the foundations would no longer be required.
Although offshore wind turbine technology is less mature than its offshore siblings, current technological advances for offshore floating multi-turbine platforms are the next tool in the renewable energy toolkit to harness abundant offshore wind.
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