Many experts say that offshore wind must go much deeper into oceans to help hit new climate targets. Massive turbines that float on the sea fit the bill – but the cost is still high. Paul Hockenos has the details. *
“Floating wind power has enormous potential to be a core technology for reaching the climate goals in Europe and around the world,” says Frank Adam, an expert on wind energy technology at Rostock University in Germany. The turbines Frank is referring to are much like conventional offshore turbines but they swim on the sea’s surface rather than being dug into the ocean bed – and thus, say experts, is a technology that heralds a powerful new generation of renewable energy, one now just mature enough to bolster clean energy supplies across the globe.
The ocean space beyond the reach of conventional offshore turbines, namely waters deeper than 150 feet, constitute 80 percent of the world’s ocean space. The Atlantic Ocean, the Mediterranean Sea, and the Sea of Japan, as well as much of the Pacific Ocean, are all too deep for fixed-bottom offshore turbines – but not for the floaters. “In the past few years this technology has made great strides,” says Frank, not only as individual pilot turbines – which now exist in nearly a dozen countries – but even in Scotland as a whole park. “Now the farms have to grow bigger to show governments and investors that they’re feasible on a really large scale,” says Adam.
The giant masts and turbines sit in buoyant concrete-and-steel keels that enable them to stand upright on the water, much like a bobbing fishing lure. The turbines’ nearly 10,000-ton cylindrical bases are held in place, usually in very deep waters, with three taut mooring cables attached to anchors, which lie on the seafloor. In contrast to ordinary offshore rigs, with long towers sunk into the seabed and bolted into place in shallow seas, the asset of floating turbines is that they can access vast swathes of outlying ocean waters, up to half a mile deep, where the world’s fiercest and most consistent winds blow — and pack enough energy to power whole cities.
Parks with floating turbines as large as those of the largest offshore farms are now in the pipeline in deep seas across the globe. The floaters’ turbines could grow even taller since weight actually helps stabilize them – perhaps even with 400-foot blades and towers stretching nearly 300 meters into the air. That’s as high as the Eiffel Tower. These turbines of such dimensions could generate three times the electricity of today’s most advanced onshore turbines.
One example is the WindFloat Atlantic project off Portugal‘s coast that will produce enough power to supply 60,000 homes. France has floating wind power written into its clean energy plans and aims to be the world leader in floating offshore. It has dedicated sites and price supports for farms off of Brittany and two in the Mediterranean. Scotland, which aspires to cover all of its power needs with renewables this year, has new floating parks in the works.
The U.S. states on the Pacific Ocean are prime locations for floating wind parks, according to Walt Musial, an offshore wind energy expert at National Renewable Energy Laboratory, a research institute funded by the federal government. A full 58% of U.S. offshore wind resources accessible to energy development exist at depths greater than 60 meters, he argues in a report.
Experts say that while some of the floaters’ finer mechanics are still being tweaked, the technology of floating turbines is ready to go. The oil and gas industry has used similar marine know-how for decades. And the masts and rotors are identical to those of conventional offshore rigs.
In the European Union’s plans to go climate neutral by 2050, wind energy of all types figure prominently. Onshore wind parks however – though the most cost-effective solution – have met with fierce opposition from NIMBY activists, which has in some countries, such as Germany and Norway, ground their buildout to a halt. As for offshore wind farms, such as those in the North and Baltic Seas, they have dramatically ramped up clean energy production in Europe, and driven down their own price per kilowatt to market-competitive levels. But Europe’s current offshore production is just 5 percent of the wind power supply that the International Energy Agency (IEA) and the EU says Europe should reach by 2050. The problem is that a 20-fold increase in shallow waters alone simply isn’t feasible.
Investors say that the most formidable hurdle to full-scale rollout is recognition from governments, utilities and financiers that floating wind power is a viable technology. So new is the model that the price per kilowatt of generated electricity isn’t currently competitive on energy markets, just as conventional offshore wasn’t ten years ago. Now it is in several European markets.
For all the hype around the swimming parks, there are critics who doubt that the high costs will ever come down far enough to rival onshore wind and solar energy, two of the most cost-effective renewables. “It will always be cheaper to build turbines on land, and that is where the targets are going to have to be reached,” says R. Andreas Kraemer, founder and director emeritus of Ecologic Institute, a Berlin-based think tank.
“Even though the floating parks may be cheaper in some cases than fixed offshore wind power plants, and deployable over a larger sea area, it is still a segment of maritime engineering,” says Kraemer. “That makes it expensive to build, deploy and maintain. Lifespans of the stations are short because of the corrosive nature of the marine environment.”
*Some of these quotations have been taken from a May 2020 article in Yale Environment 360 by the author.
YouTube video of floating turbine in storm. Source: https://www.ideol-offshore.com/en/floatgen-achieves-total-6-gwh-power-production-2019