|Fig. 1: A Hywind turbine before being towed to sea. (Source: Wikimedia Commons|
When thinking about wind farms, most people imagine a large series of wind turbines on some barren landscape, but few know about the existence of offshore wind farms. While America just built its first offshore wind farm in 2016, there have already been a handful operating for many years in Europe and Asia. [1,2] The wind turbines mounted offshore work similarly to those on land, in which wind spins the turbines and generators convert this mechanical power into electricity, but their larger size (Fig. 1) coupled with higher wind speeds means that offshore wind turbines on average generate more energy per hour.  However, building these large turbines immediately offshore presents problems for "military radar operations, the shipping industries, fisheries, bird life and tourism," writes a reporter from BBC News, and has led to the development of Scotland's Hywind Project farther away from the coast. 
Touted as the world's "first floating wind farm," the Hywind Project involved mounting five Hywind wind turbines twenty-five kilometers off the coast of Scotland mid 2017. Each turbine is twenty-five meters high, with seventy-eight meters submerged underwater, and is anchored to the seafloor by three cables (Fig. 2). To keep the turbines stable, the company behind the project, Norway's Statoil, which surprisingly deals in oil and gas primarily but looking to expand their investments, adapts "spar buoy" technology from said oil and gas industries by using giant cylinders filled with water and ballast (sand, gravel, etc.) as additional support.  These five turbines alone will power 20,000 homes, a little low especially since in total the farm is supposed to generate 30 megawatts. 
|Fig. 2: An illustration of how the turbine is tethered to the sea floor. (Source: Wikimedia Commons)|
The biggest obstacle to the Hywind Project and future floating wind farms is the cost. The Hywind Project cost 250 million USD. Though governments have offered subsidies, initial costs remain high, especially to transport the larger turbines out to sea.  As expensive as it is, moving wind farms farther away from coasts poses huge benefits. As previously mentioned, current offshore wind farms can deter tourists who find the turbines unsightly, interfere with military surveillance systems, kill bird life, and disturb fish habitats and disrupt the fishing industry.  The ability to build in deeper waters opens up possibilities for countries seeking sources of renewable energy that do not have the land to build on or coasts not conducive to traditional offshore farms, like the "steeply shelved coastlines" of western United States or Japan.  It is important to note, though, that the expense of the cables that connect turbines to mainline grids limits is a limiting factor in how far away floating wind farms can be placed. 
Scotland's Hywind Project is an exciting first step, and there are many other floating wind farms, like the Hornsea Wind Farm, being planned. Though high costs are preventing widespread development, there are hopes that there will be improvements in technology, decreases in material cost, and lower costs that come with mass production to help floating wind farms become more prevalent.
© Regina Nguyen. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
 "Offshore Wind Energy," Environmental and Energy Study Institute, October 2010.
 T. Schlossberg, "America's First Offshore Wind Farm Spins to Life," New York Times, 14 Dec 16.
 J. Madslien, "Floating Wind Turbine Launched," BBC News, 5 Jun 09.
 N. Thomas, "World's First Floating Wind Farm Towed to North Sea Base," Financial Times, 2 Aug 17.
 A. Vaughan, "World's First Floating Windfarm to Take Shape Off Coast of Scotland," The Guardian, 27 Jun 17.