Scotland’s floating wind farm is showing how powerful offshore wind can be
The turbines withstood some serious gusts.
Ars Technica, March 4, 2018
The world’s first commercial floating offshore wind farm, called Hywind, started sending electricity to the grid last October. Since then, the six-turbine, 30MW installation has been working well. Really well. In fact, Hywind has had a 65-percent capacity factor over the last three months according to Statoil, the Norwegian mega-corporation that built the wind farm off the coast of Scotland. (Capacity factor measures a generation unit’s actual output against its theoretical maximum output. A capacity factor of 100 percent means the wind farm would be sending 30MW of power to the grid every minute of every day since it has been in operation.)
Hywind in particular was built much like a floating offshore oil drilling rig, with the platform anchored down to the seabed using suction anchors. These eliminate the need to construct expensive fixed structures under water and allow Statoil and others to site the turbines farther out to sea in deeper waters. Hywind specifically is 15.5 miles out from Aberdeenshire, Scotland. At maximum capacity, it can power 20,000 homes.
Despite its “floating” moniker, Hywind is well-equipped to withstand violent storms without capsizing. The system performed as expected during the extreme storms that hit it over the winter. In October, the proximity of Hurricane Ophelia exposed Hywind to wind speeds of 125km/h (80mph), and, later in December, another storm delivered “gusts in excess of 160km/h (100mph) and waves in excess of 8.2m (27ft).”
“Whilst the wind turbines shut down for safety reasons during the worst of these winds, they automatically resumed operation promptly afterwards,” Statoil wrote. “A pitch motion controller is integrated with the Hywind turbine’s control system and will adjust the angle of the turbine blades during heavy winds, which mitigates excessive motions of the structure.”
Statoil and its partner Masdar are aiming to build more of these as costs come down and wind turbines get more efficient. By 2030, Statoil says, it hopes to bring the cost of floating offshore wind down to €40-60 per MWh ($50-74 per MWh).