Matthew A. Lackner, a professor in the Mechanical and Industrial Engineering Department and associate director of the UMass Amherst Wind Energy Center, authored an informative article about floating wind farms in the July 20 edition of Offshore Engineer, as republished from his earlier article in The Conversation. The headline in the Offshore Engineer piece reads, “California is Planning Floating Wind Farms to Boost its Power Supply – Here’s How They Work.”
As Lackner writes, “Northern California has some of the strongest offshore winds in the U.S., with immense potential to produce clean energy. But it has a problem. Its continental shelf drops off quickly, making building traditional wind turbines directly on the seafloor costly if not impossible.”
According to Lackner, “Once water gets more than about 200 feet deep – roughly the height of an 18-story building – these ‘monopile’ structures are pretty much out of the question. A solution has emerged that’s being tested in several locations around the world: making wind turbines that float. In fact, in California, where drought is putting pressure on the hydropower supply and fires have threatened electricity imports from the Pacific Northwest, the state is moving forward on plans to develop the nation’s first floating offshore wind farms as we speak.”
In his article, Lackner writes that a floating wind turbine works just like other wind turbines. “Wind pushes on the blades, causing the rotor to turn, which drives a generator that creates electricity. But instead of having its tower embedded directly into the ground or the sea floor, a floating wind turbine sits on a platform with mooring lines, such as chains or ropes, that connect to anchors in the seabed below.”
As Lackner explains, “These mooring lines hold the turbine in place against the wind and keep it connected to the cable that sends its electricity back to shore. Most of the stability is provided by the floating platform itself. The trick is to design the platform so the turbine doesn’t tip too far in strong winds or storms.”
In this context, there is still plenty of work needed to be done by researchers such as Lackner and his colleagues in the UMass Wind Energy Center.
“While floating offshore wind farms are becoming a commercial technology,” he writes in the Offshore Engineer article, “there are still technical challenges that need to be solved. The platform motion may cause higher forces on the blades and tower, and more complicated and unsteady aerodynamics. Also, as water depths get very deep, the cost of the mooring lines, anchors, and electrical cabling may become very high, so cheaper but still reliable technologies will be needed.”
As Lackner concludes, “Expect to see more offshore turbines supported by floating structures in the near future.” (August 2021)