When industrial-scale floating wind power units first started sea-trials a decade ago, investor pushback against designs built around anything but field-proven offshore technologies sank a large number of concepts deemed too commercially risky for their combinations of ‘experimental’ elements – resulting in oil & gas engineering-inspired platforms finding favour as developers began scoping out gigascale deepwater deployments around the world.
But the explosive growth forecast now for the sector – from the 120MW of plant currently turning toward the more than 150GW in the global pipeline, according to latest industry figures – is priming the market for a new wave of designs to join the semisubmersibles, spars and TLPs heading into mass production, along with several front-running new-look technologies today being piloted.
For Brita Osmundsvaag Formato, CEO of US start-up T-Omega Wind (TOW), the leap beyond designs that mate “onshore wind turbines with floating oil platforms” is long overdue. Her company’s eponymous TOW concept has been engineered “from the water up”, she underlines, “not the other way around”, with its sights trained on what she sees as the “three problems with existing technology: cost, the inability to deploy in the deep water that is typical across the globe, and crippling supply-chain/manufacturing bottlenecks”.
“Our mission is to develop what we believe is a disruptive technology that will democratise floating wind around the world,” she states, speaking with Recharge. “And [for TOW] that started with our considering what would be optimal for the oceans, not how technologies developed on land or for other industries might work offshore.
“When you look at existing [floating] offshore [wind] technologies you see serious supply chain issues, the need for specialised fabrication infrastructure and often deepwater ports,” says Osmundsvaag Formato, a 25-year veteran of the international energy industry, including senior roles at ExxonMobil, Duke and Equinor.
“Our solution instead of being based on land [wind] turbines is designed first for the harshest offshore environments and instead of being wave-resistant as with so many of the [offshore oil & gas style] concepts’ heavy [platform] structures, ours is designed to ‘ride’ on the surface of the ocean so it is a lot lighter and [as it uses less steel] lower-cost.”
This would mean TOW – engineered to use a standard horizontal-axis rotor and generator fitted to the apex of a floating four-legged steel platform that is anchored to the seabed via a single mooring line – would weigh-in several classes below the current 3,000-tonne-plus steel hulls used for the 6-10MW units now in operation off northern Europe. T-Omega calculates a levelised cost of energy (LCOE) for a full-size TOW unit of less than $50/MWh, “cheaper still if we could make our frames out of carbon-fibre”, says Osmundsvaag Formato.
“The TOW system floats in shallow or deep water, rides on top of the waves rather than resisting them, resists wave-induced motions with a rotor held firmly on both sides [by the four-legged tower structure], and aligns to the wind by weathervaning,” she outlines.
“While using a standard horizontal-axis rotor, it eliminates a large percentage of material cost for the support structure and platform [and] is suitable for manufacture in modest boatyards across the globe.”
The magnitudinous weight-savings of the design, adds Jim Papadopoulos, who with Northeastern University engineering colleague Andy Myers devised the TOW concept, is key to its commercial promise. “Existing designs range from 500-1,000t/MW, so our concept is 75-80% lighter than the others now being proposed [and means] we will be able to have a draft of 5-6 metres” making launch in shallow-water ports and harbours possible, he says.
Being lightweight, adds Osmundsvaag Formato, also improves the “serviceability” of the design, as units could be “rapidly swapped out and brought to shore for maintenance and repair” at a cost she quantified as “one-third to one-half” of the first-gen technologies now coming to market.
Modelled on the industry benchmark ‘DTU 10’ – the Danish Technology University’s 10MW reference turbine – a full-scale TOW would fly a 178-metre-diameter rotor atop a trussed tower with a 70 x 70-metre base mounted on 14-metre-wide pontoons.
A part-scale model of the concept, in the process of being reviewed by classification body DNV, recently sailed through maiden wave-tank tests at the University of Strathclyde in Scotland, including weathering simulated North Sea storm sea-states with waves cresting at heights equivalent to 30 metres. Digital modelling of TOW load-cases, meanwhile, is underway at the US National Renewable Energy Laboratory.
Though its ambitions are “very much global”, Osmundsvaag Formato says its home US market is “hugely exciting and all the more since the Biden administration’s recent announcement of its Floating Wind Shot”, which set a target of 70% LCOE reduction – equal to $45/MWh – by 2035 with the construction of 15GW of deepwater arrays.
“East Coast some day hopefully soon but of course the West Coast has world-class wind resources and now has a first auction set for December,” she says.
Closed-door discussions are currently underway with several unnamed “multinational energy industry strategics” to take TOW into prototyping,
Flying in the face of the wind industry’s historically Olympian industrial culture, which has led to the high-speed scale-up of turbines to now 15MW-plus units, with still larger on the horizon, T-Omega is rebelliously approaching its design “to help reverse this gigantism trend”, says Osmundsvaag Formato.
“While the floating wind turbine industry players are now focusing on ever-increasing size to achieve economies of scales, we don't really believe that bigger is necessarily better – the technologies we need are those that really solve for cheaper installation and maintenance cost per megawatt.”
Papadopoulos, addressing views expressed in a recent LinkedIn debate as to how the sector might best ‘balance’ innovation and industrialisation as floating wind commercialises, adds: “It’s already a good argument to say, ‘Let’s get on with the 10MWer’ [rather than be always scaling up for the ‘next’ nameplate platform] and in fact you could say that once you leave behind the installation and manintenace costs, going much bigger than 10MW [turbines] only hurts you with the overall LCOE.
“This is a system we are devising, not just the turbine in the water, but also how it’s manufactured, how it operates, how it gets fixed... . Our ‘rapid replacement philosophy’ informs our repair strategy: bring it to shore quickly and once there, it’s easy to disassemble and reassemble – pull off the blades, pull out the generator, replace the legs – [which are] operations very difficult to do at sea because you’ve got a moving base and a heavy construction vessel waiting for weather-windows and so on.”
Beyond the ambitions to bring the TOW technology to market internationally, Osmundsvaag Formato returns to the higher calling of developing a low-cost floating wind power concept: as a an engine in a just energy transition. As the World Bank latest numbers elucidate, of offshore wind’s 71TW global technical potential, 71% is in water too deep for bottom-fixed projects.
Many tens of gigawatts of commerciallisable wind power could be available to ‘emerging’ floating wind markets from Brazil through South Africa and India and Southeast Asia’s numerous islands nations, via floating wind farms, at a stroke creating a local industry in the fabrication and operations of the projects.
“Your think about offshore wind and how great a source of power it could be around the world and how it coincides in many locations with the greatest population centres and the greatest electricity usage. But that's not where all of the current clean energy technologies are viable,” says Osmundsvaag Formato.
“So, there are great resources out there that cannot be harvested today with the current technologies and, as we know, how much of the world’s richest wind resource is over deepwater. And with floating we can go almost anywhere.”