Offshore wind turbines, with their solid-bottom foundations reaching up to 60 meters or so, are too deep to be economically feasible in most environments. But the goal of normalizing offshore winds is not out of reach. This is because a whole new generation of floating offshore wind turbines is being deployed to tackle the most powerful winds that nature produces.
The engineering behind floating offshore wind energy is incredibly sophisticated. Wind turbines are located on floating platforms made of a concrete, steel or hybrid substructure on which the wind turbine is installed, which provides it with propulsion and stability. Anchored and moored on the seabed, they must fight the uncontrolled forces of stormy seas and arbitrary weather.
Foreign wind energy is a source of clean and renewable energy that reaches a high and constant speed due to the lack of obstacles. Its high potential and strategic added value, both at a socio-economic and environmental level, make it one of the renewable resources that will play a crucial role in the decarburization process.
The global wind industry had its second best year in 2021, with nearly 94 GW of capacity added globally, which according to the Global Wind Energy Council lags behind the record growth of 2020 by only 1.8%. Europe, Latin America, and Africa and the Middle East have had record years for new onshore installations. 21.1 GW of offshore wind capacity was commissioned last year, 3 times more than in 2020, making the best year in foreign wind history a market share in global new installations up to 22.5% in 2021.
Yet wind power could not reach its full potential, as 80% of offshore wind resources in European waters are in places too deep for existing offshore wind turbine technology. Deep-water barriers also prevented the installation of large offshore wind farms on the U.S. west coast.
While engineers look for ways to capture the most reliable strong winds, they move further out into the sea to areas of deeper water where especially strong winds are known to blow. Completely new technology is in the design stage to reconsider deepwater barriers.
The need for stability: Foreign wind turbines
Foreign wind turbines have higher load factors than land-based wind turbines and therefore suffer from less intermittent energy production. Further from the coast, they benefit from stronger winds for greater production capacity.
Floating turbines can open large parts of the ocean for electricity generation. Analysis by the Institut Polytechnique de Paris indicates that floating wind turbines worldwide hold promise for energy production: 330 000 TWh per year, or 79% of the total theoretical potential of foreign wind power. The Global Wind Energy Council predicts that floating wind will become “one of the key game changers” in the industry.
Nevertheless, the challenges of foreign 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
- cabling that is longer, larger and deeper than the cabling for existing offshore wind farms
- driving uncertainties related to wind speed, turbulence, shear profile, significant wave height, spectral peak period and wave direction
Billions of dollars are currently being invested in the floating offshore wind industry, as explained by wired. To significantly reduce the cost of a floating turbine, designers are moving away from the long tower concept to alternative designs that require less steel to eliminate the mechanism that causes the gondola to rotate. The result should be a simpler design that is easier to build so that the entire structure rotates to show the wind.
Norway and floating offshore wind systems
Several floating turbine designs have emerged that generate intrigue about cost and efficiency.
The Government of Norway has launched a large-scale investment plan aimed at allocating sea areas to develop 30 GW of offshore wind capacity by 2040. The government said it would facilitate large-scale offshore wind development that would allow the use of various network solutions. . Cables with bidirectional power flow, interconnections to Europe, and interconnections to Norway will be considered for each call. The Norwegian Directorate of Water Resources and Energy (NPA) and the Ministry of Petroleum and Energy (MPE) will study the implications of the alternatives.
Energy scales exponentially with wind speed. Conventional turbines limit energy output above 11-12 m / s by protruding the blades. Wind Catching Systems (WCS), the developer of floating offshore wind technology, was founded in 2017 with the idea that multi-turbines can maximize power generation from a concentrated area rather than a large turbine. Easy maintenance, durability and simplicity were the guiding principles when the first Windcatcher was designed as a sail on a trimaran.
WCS’s design for a giant wafer-shaped frame includes at least 126 four-rotor wind turbines. The entire structure, as high as the Eiffel Tower, would sit on top of a floating platform, similar to that used by oil rigs. By utilizing the full energy in higher wind speeds and the multi-rotor effect, the Windcatcher system generates 2.5 times more annual energy per swept area than a conventional turbine. With twice the swept surface area of a conventional 15 MW wind turbine, one wind trap unit has the potential to generate 5x the annual energy production.
The company is now engaged in a Series A investment round of up to $ 10 million, and GM Ventures has entered into a strategic agreement with or collaboration covering technology development, project execution, foreign wind policy and the promotion of sustainable technology applications.
What else is happening in offshore floating wind R&D?
Other offshore floating wind designs are in the works.
Equinor has designed a new floating wind concept that will enable industry standardization and maximize opportunities for local supply chains. The Wind Semi, a semi-submersible wind turbine foundation with a type of floating flat triangle with a turbine positioned at one angle and intended to provide for manufacturing and assembly based on local supply chain capabilities.
Olympic Wind, Trident Winds in Washington, issued 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, built from turbines mounted on platforms and moored to the deep seabed about 43 miles off the coast of Grays Harbor County, Washington. It would be the first commercial-scale offshore wind project in Washington at 2,000 MW.
Extensive monitoring of new floating wind farms to collect data on their ecological impacts will continue. One study suggests that the erection of floating turbines should be much quieter than the installation of fixed-bottom offshore machines, and therefore less disruptive to marine mammals, as piling driving for the foundations would no longer be necessary.
Although offshore wind turbine technology is less mature than its established siblings, the current technological advancement for offshore floating multi-turbine platforms is the next tool in the renewable energy toolkit to harness abundant offshore wind.
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