The notion that sitting miles offshore, bobbing on platforms anchored to the seabed by chains borrowed from oil and gas engineers, could be the answer to Europe’s energy crisis seems almost paradoxical. However, an increasing number of businesses are essentially placing their bets on that. The idea of floating offshore wind is no longer novel, and the commercial trials currently taking place in deep Atlantic and North Sea waters may prove to be far more significant than most people think.
The fundamental engineering reasoning is fairly simple. Only in locations where the seabed is sufficiently near the surface can fixed-foundation wind turbines—the ones you see standing in comparatively shallow coastal waters—be planted. That restricts ambition as well as geography. Floating platforms completely alter the situation. They can be placed in waters that are 80, 90, or even 150 meters deep, where the winds are stronger and more reliable. According to José Pinheiro, project director at EDP Renewables, wind typically increases with distance from the coast. Although that observation seems straightforward, it has significant implications for the production of energy.
This reasoning has found some quiet testing ground in the WindFloat Atlantic project, which is anchored off the northern coast of Portugal. An 8.4 megawatt turbine is carried by a three-column, semi-submersible platform that floats in about 85 to 95 meters of water. It is secured at three mooring points using a technique that anyone who has worked on offshore oil rigs is familiar with. The European Investment Bank provided a €60 million loan, which enabled it to progress from a demonstration concept to something close to commercial scale. The signals are more positive than they were even five years ago, but it is still genuinely unclear if that scale can be reached quickly enough to matter for Europe’s energy ambitions.
The variety of strategies being tested concurrently is what makes this moment especially fascinating. In order to maintain stability without requiring extremely deep submersion, Ocean Flow Energy in northeast England has created a hybrid design called Starfloat that combines a deep-water spar structure with a buoyancy collar close to the waterline. Their engineers put it together at already-existing onshore shipyards, in part to cut expenses and in part to restore the kind of industrial capacity that has been quietly dwindling for decades in British coastal communities. The floating wind industry seems to have some insight into its own political future, realizing that it must be perceived as producing both energy offshore and jobs onshore.
With a twin-hull design that rotates on a single mooring point to always face the wind, Spain’s SATH project has taken yet another route, constructing platforms mostly of concrete rather than steel. A mechanical bearing facilitates the rotation, and a rotating electrical connector transfers power. When you describe it, it sounds a little improvised, but the engineering is intentional and the objective is clear: quicker installation, less sensitivity to inclement weather, and the capacity to mass-produce parts close to deployment locations instead of transporting bulky steel structures across oceans.
A noteworthy commitment to reducing their impact on marine life is shared by all three projects. The noise levels underwater during installation are significantly lower than those required for fixed foundations because the majority of construction and assembly takes place onshore. There is no significant disturbance of the seabed or pile-driving. The floating wind industry has paid unusually close attention to underwater noise, which has long been identified by researchers as a major issue for marine mammals. This is likely due in part to genuine concern and in part to the fact that environmental opposition can kill a project more quickly than any engineering issue.
The financial situation is still difficult. It is necessary to build these platforms at significant production volumes rather than as individual demonstration units in order to achieve about 60 euros per megawatt-hour, which is competitive with established inshore wind farms. Over the years, many European clean energy technologies have quietly perished in that gap between demonstration and full commercial deployment. It is known as the “valley of death,” and it has previously engulfed promising initiatives. Money by itself cannot bridge the gap, but the European Commission and the European Investment Bank have both taken steps to address this with specialized financing instruments. Time, operational data, and persistent political will are required.
Europe may have 150 gigawatts of offshore wind power by 2030, which could supply about 14% of the continent’s electricity needs. The floating wind’s ability to deliver on its promise in deeper waters is crucial to those figures. It’s difficult not to feel that the stakes are exceptionally high as these projects move forward through the winter waters off Portugal and Scotland, both commercially and in terms of the longer question of how much energy independence Europe can actually achieve for itself.
