A European research effort is looking to help cut the cost of floating offshore wind by at least 15%
OCEAN EXPLORATION
Bottom-fixed offshore wind development is limited by the maximum water depth that foundations can access—floating turbines open up huge areas of ocean with near-constant wind resource
COPY AND PASTE
The pursuit of standardised designs will open up cost reduction through economies of scale
KEY QUOTE
We are already seeing that costs are going down with the innovations that we are looking at
Putting turbines onto floating platforms will allow many markets previously closed off to bottom-fixed turbines to benefit from offshore wind. The market is beginning to gain momentum. At the end of 2020, Quest Floating Wind Energy, a market analyst firm, identified 75 floating offshore wind projects in different stages of development across 13 countries. The top emerging markets for the technology are Japan and the west coast of America, each with ten projects in development. France, South Korea and the United Kingdom are not far behind, with nine projects apiece. But because the technology is relatively new, with just a handful of projects in the water, floating offshore wind is still expensive. One current challenge for the industry is that while turbine designs have become standardised, allowing for high levels of manufacturing efficiency, there is still a broad range of different floating foundation concepts. In order to cut costs, the floating offshore wind sector will need to adopt just one or two platform designs for the vast majority of projects, much like the fixed-bottom sector uses either monopiles or jacket foundations. More than a quarter of the 45 planned projects listed by Quest Floating Wind Energy were scheduled to have floating platforms designed by a single company, Principle Power, a United States-based engineering firm. Principle Power’s platforms have already been deployed at the WindFloat project off Portugal’s coastline.
STANDARD RESEARCH
A European Commission-funded project coordinated by the Catalan Energy Research Institute (IREC) is working on standardising other elements of the floating platforms and balance of plants components to bring down the cost of floating offshore wind much faster. Corewind aims to help bring the levelised cost of electricity (LCOE) of floating offshore wind to under €100 per megawatt-hour (/MWh) by around 2023. The project also intends to speed up later cost reduction efforts so that costs can come down to €80/MWh by around 2040, ten years earlier than would be expected under current rates of progress. The Corewind project team has built a modelling tool that involves two types of floating foundation—a spar buoy like the ones used in the earliest floating wind projects, such as the Hywind Scotland project by Equinor, a Norwegian energy company, and a semi-submersible platform akin to Principle Power’s design. The tool assumes the floaters will be built of concrete to reduce the cost, rather than steel as is the case with many designs today. Besides providing open-data models and modelling tools that developers can use to reduce the cost of projects, Corewind aims to carry out simulations and testing on mooring, anchoring and dynamic cable systems. This work will be used to provide guidelines and best-design practices for the industry.
COMPETITIVE PRICES
The average LCOE—or estimated lifetime cost of generating energy—for floating offshore wind is thought to be above €150/MWh, says Jose Luis Domínguez García from IREC. This compares to an average LCOE of less than €90/MWh for fixed-bottom offshore wind, Domínguez says. Depending on location, some fixed-bottom projects may be able to get down to an LCOE of €60/MWh, he adds. But these projects can only be deployed in waters up to around 60 metres in depth. Beyond that, it gets increasingly hard and expensive to install the foundations. Floating wind offers the opportunity to access more areas of the ocean with greater water depths. Many countries are not surrounded by low water depths like those found in the North and Baltic Seas where offshore wind development has been focussed to date. If floating wind can become cost-competitive with other forms of generation, it will allow more markets to replace fossil fuels in their energy mix. Quest Floating Offshore Wind estimates more than 26 gigawatts of floating offshore wind capacity could be commissioned by 2035.
MARGINAL GAINS
Floating offshore wind—much like its fixed-bottom counterpart—expects to see LCOE fall by roughly 5% purely through the use of bigger turbines that have better average energy production rates and lower balance-of-plant costs. The largest floating offshore wind turbines in the water today, at Energias de Portugal’s WindFloat Atlantic three-turbine project, are capable of delivering up to 8.4 megawatts (MW) of energy each. In the short term, Corewind envisages this capacity almost doubling, to 15 MW. GE Renewable Energy already sells a 14 MW machine and Vestas is readying a 15 MW product for serial production in 2024. Bigger turbines will require larger floating foundations, which again would help to deliver a cheaper LCOE through economies of scale. It also means fewer turbines are needed for utility-scale capacity, meaning less balance of plant components such as platforms and cables. Beyond the development of turbine technology, the Corewind research project is focusing on areas of cost that will not necessarily come down without further research. This includes the moorings and anchors attaching the floating platforms to the ocean floor, and the cables used to export electricity back to shore. The cost of these elements is highly dependent on project-specific factors such as water depth, distance from shore and turbine layout. Deep waters could add significantly to cable costs. One cost-saving technique that Corewind will look at is to see if cables from the platforms can double up as moorings. The research project believes mooring and anchoring improvements and standardisation could help cut LCOE by between 3% and 5%.
PREVENTIVE MAINTENANCE
An extra 3% to 6% reduction could come from better operations and maintenance (O&M) strategies. To do this, O&M practices will need to minimise the amount of corrective maintenance required at the wind farm, which is made more difficult if the project is far out at sea. Faults can lead to significant losses. The O&M programme should focus on getting most of the fixing done in a planned fashion, known as preventive maintenance. Preventive maintenance is helped by the growing digitisation of wind turbine models. This allows wind farm owners to monitor signals coming from each turbine and to schedule maintenance if something seems to be going amiss—before there is a breakage and the losses are even greater. Domínguez says it might also be possible to use building information modelling, a tool developed for the construction industry, to create a digital twin of a floating offshore wind farm that can be used for troubleshooting. Another strategy might be to reduce the output of some turbines to avoid damage. “In that way we are providing some protection to the wind turbine,” Domínguez says. Techniques such as these might be able to reduce the level of reactive maintenance by half, he adds. One final area of potential cost reduction is standardisation and industrialisation, not just of the floating platforms but also of components such as cables. This is likely to emerge naturally as the floating offshore wind industry expands. Although the Corewind project still has a couple of years to run, the early results are encouraging. “We are already seeing that costs are going down with the innovations that we are looking at,” says Sabina Potestio of WindEurope, the European wind industry trade association and one of the project partners. The Corewind modelling tools will be made available to the industry to help cut floating wind LCOE across all these markets, Domínguez says.
COST REDUCTIONS
If the project can achieve its aims, then it could lead to cost reductions well beyond the expectations of most sector experts, based on independent research carried out by Ryan Wiser of Lawrence Berkeley National Laboratory in the United States. Wiser surveyed 140 wind industry experts and found that they expected floating technologies to fall by 17% compared to 2019 levels—but not until the mid-2030s. “Clearly, there is a lot of uncertainty about future costs,” says Wiser. “The experts anticipate that the Capex [capital expenditure] of floating in 2035 will be higher than the Capex for fixed-bottom in 2019,” he says. “However, capacity factors will be much higher, and there will be improvements in design life and Opex [operational expenses] as well.” As much as a quarter of all new offshore wind projects could use floating turbines in 2035. And “in 2035, there was a view that floating would be generally less expensive in water depths over 60 metres,” says Wiser. Elsewhere, though, there is a view that the momentum building behind floating offshore wind could lead to faster-than-expected cost reductions. “[We] see sub-$100 [per megawatt-hour] feasible for some of the announced projects and sub-$80 around 2025 for individual projects, provided developments go as planned,” says Quest’s market development and strategy director, Erik Rijkers. Further LCOE reductions could be gained through an extension in the lifespan of the projects. The design life of offshore wind projects has traditionally been assumed to be 20 years but improved technology design could still see projects functioning after 30 years. Extending the expected lifetime production of a floating wind project also helps to bring down pricing significantly.
TEXT Jason Deign PHOTO EDP Renováveis