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How can floating wind costs go down? Evaluating technology challenges and prospects

Patricia Seoane da Silva, Research Associate

Interest in floating wind has sparked during the last couple of years, and the technology is expanding from original markets in Europe to other geographies, particularly in Asia. Taiwan and South Korea are emerging sites for offshore wind generation and Japan is widely perceived as a suitable place for floating wind due to high feed-in tariffs and steeply shelved coastlines.

Although this gain in momentum of interest has barely translated into installed capacity, there is a significant opportunity for floating wind deployments in the long-term. In Europe, the European Commission has set a target of 450 GW of offshore wind capacity by 2050, which considering the current installed capacity (around 20 GW), suggests that about 20% to 30% of the 2050 target could come from floating wind. Additionally, the Japan Wind Power Association expects to install 18 GW of floating wind by 2050 and South Korea has unveiled its 200 MW Donghae 1 floating wind project.

Still, widespread deployment of floating wind continues to be limited by capital costs. Arguably, the key challenges to drive cost reductions involve economies of scale, collaborative innovation, and institutional support.

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Economies of scale and design selection.

Foundations represent around 29% of floating wind capital costs, and thus their mass production would significantly reduce costs. Using the rule of thumb that the cost price decreases by 15% for every doubling of production volume, capital costs for floating wind could decline by nearly 40% if the number of installations increased by an order of magnitude. 

However, in addition to economies of scale the industry would also need to narrow down the wide range of designs and configurations that exist today. The dominant foundation topologies today are:

  • Semi-submersible. This design has taken the lead thanks to simpler installation and maintenance. As opposed to spar-buoy, the relatively shallow drat of semi-submersible platforms enables the entire structure to be mounted onshore and towed to site without expensive heavy-lift operations. This advantage is partly undermined by a rather complex design and longer manufacturing times but has attracted the largest number of industry player thanks to its potential short-term cost reductions.

  • Tension leg platform (TLP). TLP is conceptually similar to semi-submersible, except that the foundation is anchored to the seabed with tensioned mooring lines. This feature results in high horizontal stability, but makes installation and maintenance more complex, as the tensioned tethers require careful installation and risk of compromised operations due to tether failures. While TLP material requirements are lower than semi-submersible, the expensive anchoring has limited technology deployments.

  • Spar-buoy. The early spar concept developed by Equinor favors mass production thanks to its hull geometry, but it is not suited for shallow waters and requires on-site assembly. Despite this disadvantage, Equinor’s offshore oil and gas expertise has resulted in significant technology developments, to the point that spar-buoy is the only floating foundation deployed at commercial-scale today. Recent investments in a 200 MW installation in Spain by Equinor suggests a potential 50% cost reduction compared to earlier projects.

While the three foundation topologies currently dominate the floating wind landscape, there are startups pursuing lower $ per W ratios, such as multi-turbine platforms. Although this is a valid premise, these designs are unlikely to succeed due to its mechanical complexity. Instead, the industry is expected to lean toward semi-submersible and – to a lesser extent – spar-buoy. TLP is already behind and unlikely to see significant deployments in the future.

Collaborative innovation.

Floating wind technology is far from mature, and far-offshore environments need to be widely understood for the technology to grow beyond the interest today to commercial deployment. The industry must gain better understanding of wind and wave interactions, as the natural frequency of floating wind turbines is significantly higher than that of bottom-fixed turbines – more than 100 seconds, as opposed to less than three seconds. This difference makes floating wind turbines more prone to heavy oscillations, which calls for renewed design rules to mitigate the increased effect of structural fatigue. In addition, available wind resource at waters deeper than 60 meters need to be accurately assessed to optimize power production and develop floating wind farm design procedures. Collaborations will be critical, and the industry is beginning to see industry leaders like Equinor partnering with Masdar and ORE Catapult to share floating offshore wind data. Similar formal and informal partnerships will need to be replicated, and collaboration among developers, energy companies, and governments will be essential for the floating wind industry to move forward.

Institutional support.

Ultimately, floating wind remains an expensive form of power generation, and financial support will be key to secure long-term adoption. Combined with decarbonization efforts of countries which may otherwise lack the land resources for conventional wind farms, top-down government initiatives remain a critical third factor for floating wind. The 2050 offshore wind capacity target in Europe is a good example of this challenge, and the EU continues to investigate various forms of financing for floating wind projects to promote the deployment and eventual achievement of this goal. In parallel, research and development support must also happen along with participation from key infrastructure players to enable floating wind turbine assembly and installation. This type of action is starting to occur, for example at the Port of Rotterdam where expansions of offshore wind power generation facilities at the port are progressively being implemented. Cross-cutting institutional support will be paramount by both unlocking existing infrastructure and bringing in together key stakeholders to establish a floating wind supply chain.

Lux Take

There is a broad consensus that the elevated capital costs of floating wind will be the limiting factor for accelerating technology commercialization. Early initiatives in manufacturing scale up and designs, collaborative agreements, and institutional support are worth monitoring to assess the long-term feasibility and outlook for floating wind. However, the industry should not expect broad deployment of floating wind until shallow offshore sites are tapped first. This does not mean that the technology should be ignored, quite the opposite, as floating wind will play a growing role in renewable energy generation build out as land limitations are aggravated. Unlike bottom-fixed offshore wind – whose value propositions lies on a higher wind resource and power output – the business case for floating wind is reinforced by land scarcity. Similar to floating photovoltaics, floating wind has the potential to unlock unused sea resources. As renewable energy targets across the globe become more ambitious, land limitations undoubtedly will become a bigger issue, and floating wind will have the opportunity to step in. In the meantime, the technology will progressively find alternative applications, such as decarbonizing offshore operations.

 

 

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