One Floating Wind Turbine Good, Two Floating Wind Turbines Better

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The floating wind turbine industry is sure coming up with some interesting twists these days, and that’s good news for President Joe Biden’s decarbonization plan. Here in the US, the offshore wind pipeline is already humming along the Atlantic coast, but the waters of the Pacific coast are too deep for regular old offshore wind turbines. Floating is the way to go. The challenge now is how to get costs down, and a firm called Hexicon has come up with a rather unusual solution.

Two Floating Wind Turbines Are Better Than One

The Hexicon solution may seem simple at first glance. The idea is to pitch two wind turbines onto the same floating platform, instead of just one.

However, the devil is in the details. If you know your wind farms, you know that turbines in proximity to each other can interfere with each others’ share of the available wind, leading to reduced efficiency.

That issue can be resolved by carefully calibrating the location of turbines in a wind farm. The Hexicon two-turbine solution also helps to offset any potential loss by floating their floating platforms out into deep water, where average wind speeds are higher.

As an added bonus, deeper waters are generally farther offshore. That reduces the chance of ruffling feathers among onshore communities when a new proposal for an offshore wind farm comes around, and that’s important. The ill-fated 468-megawatt Cape Wind project off the coast of Massachusetts in the US is one example of an ambitious early-on offshore wind project gone bad, in part due to objections from onshore property owners.

Well, one property in particular. Whose family has a large stake in the US fossil energy industry. Go figure!

Cape Wind’s developers battled for years until the project finally bit the dust in 2017. Somewhat ironically, that helped clear the way for bigger projects, and last week Massachusetts nailed down bragging rights to the first world class commercial offshore wind farm in the US, the Vineyard Wind project, which weighs in at 800 megawatts.

Two Floating Wind Turbines Better

Where were we? Oh right, Hexicon. The company is not new to the CleanTechnica radar, having popped up in 2012 with a hexagonal floating wind turbine platform festooned with 46 turbines for a total capacity of 54 megawatts.

We lost track of the goings-on over at Hexicon for about nine years, but it appears that it has been busy all this time, and has refined the initial concept down to pairs of floating wind turbines.

The company’s CoensHexicon branch cites a more compact footprint for offshore wind farms in comparison to single-turbine platforms. Among other advantages, the firm lists reduced costs for towing, mooring, turbine installation, cable hookups, and maintenance.

In a 2018 overview, Hexicon AB estimated that its two-turbine solution provides for up to 75% more electricity per area than a comparable one-turbine setup, and requires about 45% less cable.

The firm also points out that floating wind turbine platforms can be fully built at shore-based shipyards and towed out to sea. That reduces at-sea labor and other construction costs to a minimum.

In addition, Hexicon is not wedded to any particular turbine, which would enable it to quickly pivot into new, improved turbine technology on the market. Wind turbine efficiency is already improving so quickly that some wind farms developers are upgrading their plans on the fly, so that’s an important consideration.

The TwinWay Floating Wind Turbine Project

Hexicon already has several projects under way around the globe. The latest one, announced last week, is a demonstration project located off the coast of Norway in an offshore test bed claimed by the Marine Energy Test Centre, aka METCentre.

That puts Hexicon firmly in good company. METCentre administers the Norwegian Offshore Wind Cluster, which includes 270-plus corporate members.

METCentre launched with an initial focus on conventional, fixed-platform offshore wind turbines. Now it is carving out a name for itself in the budding field of floating wind turbines. “Equinor installed the world’s very first floating wind turbine, Hywind Demo, here in 2009, Google Makani was tested at the centre in 2019 and the demonstration of the first 10+MW floating concept (Flagship) will commence in 2022,” METCentre notes.

METCentre has an upgrade and expansion plan in the works, just in time to accommodate the Hexicon project. The expansion will boost METCenter’s capacity to 85 megwatts, of which Hexicon will reserve six.

Dubbed TwinWay, Hexicon’s demonstration-scale offshore wind project  aims to affix firm numbers onto the performance of the two-turbine mashup in a setting with specific water depth, currents, and wind characteristics.

“With this project we can demonstrate the clear benefits with offshore floating wind compared to onshore as well as bottom fixed offshore wind power, and how it is set to become a highly relevant part of the future renewable energy mix,” enthuses Hexicon CEO Marcus Thor.

Where Offshore Wind Turbines Float, Green Hydrogen Lurks

Of course, no mention of Norway and offshore wind turbines would be complete without mentioning the green hydrogen angle, considering that Norway is already angling to use its hydropower resources to produce green hydrogen. Norway is also home to a newly porposed offshore wind plus green hydrogen project called Deep Purple.

It’s possible that Hexicon’s double-turbine configuration could provide a more cost-effective platform for piggybacking electrolysis systems onto offshore wind turbine arrays.

Hexicon may already be drifting in that direction through CoensHexicon, which has partnered with Shell on the floating offshore wind farm in South Korea. For that project, CoensHexicon has floated (so to speak) a number of co-development idea including wave tidal energy, solar arrays, desalination, and aquaculture aimed at bringing down the cost of the wind farm compared to other energy sources.

Shell is also involved in a wind, solar, energy storage, and green hydrogen mashup with The Netherlands, so CoensHexicon’s partnership with Shell could ripple into its METCentre project in Norway.

What About The US?

Yes, what about it? The failed insurrection of January 6 is still snaking out across the US in the form of state-based voter suppression bills but apparently the Biden administration can fight fascism and chew offshore wind gum at the same time.

Even as the Department of Justice rounds up the usual suspects, the Biden administration has been tooting the offshore wind horn.

The Vineyard Wind project is a case in point, and its significance is gigawatt-scale. The project got the green light from the Biden administration last week after nearly being sunk by the Trump administration. As this is the first US wind farm to maneuver through the streamlined regulatory system established by the Interior Department’s Bureau of Ocean Energy Management, other projects seeking approval now have a more reliable pathway to approval.

For those of you keeping score at home, the nation’s only commercial scale pipeline in operation now is Rhode Island’s 30-megawatt Block Island wind farm, which slipped through during the Obama administration, before the BOEM pipeline took shape.

As for a whole offshore wind farm full of floating wind turbines, the US is still a long way off. However, in addition to the Pacific coast states, the Atlantic states of Maine and New Hampshire are already eyeballing turbines that float to provide them with access to offshore wind resources, so stay tuned for more on that.

Follow me on Twitter @TinaMCasey.

Image: Floating offshore wind turbines courtesy of Hexicon.

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Tina Casey

Tina specializes in advanced energy technology, military sustainability, emerging materials, biofuels, ESG and related policy and political matters. Views expressed are her own. Follow her on LinkedIn, Threads, or Bluesky.

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