Swedish company SeaTwirl has signed a deal with Westcon to build and deploy a commercial-scale 1-MW turbine in Norway.
Swedish company SeaTwirl was officially founded in 2012. Its first prototype was tested all the way back in 2007. It had a 30-kW test version of its floating turbine technology called the S1 installed off the coast of Lysekil, Sweden in 2015. Rising 13 m (43 ft) above the waterline and reaching down 18 m (59 ft) below, it’s been connected to the grid and making power for seven years and counting and has proven its strength to withstand hurricane-level wind and wave conditions.
SeaTwirl calls its design simple and robust.
Firstly, they can accept and use wind from all directions, so they don’t need heavy, expensive systems to point them into the breeze as HAWTs do. Secondly, they can run their generators at or below the waterline. HAWTs need to mount this heavy gear right up the top of their support towers where the central axle is, creating a top-heavy design that requires extreme tower strength and huge counterweights below the surface to keep them upright. More power equals more materials and more cost.
Thirdly, they can be deployed much closer together than HAWTs, since they create a minimal wake effect downwind. HAWTs need to be spaced further apart, reducing the yield from a given project area.
VAWTs can be spaced much closer to one another than HAWTs in an installation
SeaTwirl’s design rigidly has three VAWT blades on a long, buoyant pole with a low center of gravity and a heavy weight at the bottom acting as a keel. This sits in a static generator ring anchored to the sea floor. The entire pole spins, driven by the blades as they catch the wind, and the generator harvests energy and sends it back to shore via cables.
VAWT designs enable easy and cheap maintenance.
SeaTwirl is now gearing up to build its first 1-MW version, a pilot for its first commercial product. The company has signed a letter of intent, whatever such things are worth, with offshore, energy, and maritime supplier Westcon, to build and deploy its first S2x-model turbine near Bokn, in Norway. It’s expected to be commissioned sometime in 2023, for a test period of around five years.
The S2x will reach a height of some 55 m (180 ft) above the surface, and its weighted central pole will plunge down to 80-m (262-ft) depths. It’ll cut off power if the wind speed rises above 25 m/sec (56 mph, 90 km/h), but it’s designed to withstand extreme wind speeds up to 50 m/s (112 mph, 180 km/h), which would correspond to the upper limits of a category-two hurricane. The company says it should have a service life of around 25-30 years.
“Analyses which have been third-party verified,” reads an investor-focused presentation from at least a couple of years ago, “show that the S2 VAWT will be able to produce energy at a mature LCoE of below €50 (US$50)/MWh.”
