The Evolution of Wind Turbines
Commercial wind turbines evolve-
While commercial wind turbines of 30 Kilowatts (KW) output were turning at Tehachapi Pass in California in 1981, NASA and the U.S. Department of Energy completed the first megawatt-scale wind farm in the nation at Goodnoe Hills, Washington. That wind farm contained three two-blade turbine units, each capable of 2.5 Megawatts (MW). (That’s 2,500,000 watts continuous output at 17 rpm.) This blogger was privileged to visit them in 1982 and recalls that the scale of a 300-foot diameter swept area was impressive. The development path had been arduous, and a number of designs had been built as prototypes along the way.
Fast forward to December, 2016. These days, wind turbines have gone to sea, serving as the next great utilization of renewable energy. Wind is generated by differential heating on land and across oceans, and in-between them as well. This force is due solely from solar radiation striking the earth. Having solved the turbine anchorage challenge in water, we now see manufacturing giants such as Siemens and Vestas leading the way. Vestas and Mitsubishi Heavy Industries recently collaborated to produce a new record breaking turbine with a capacity of 9MW, more than three times the size of what I visited at Goodnoe Hills.
This three-bladed monster is an upgrade from a Vestas 8MW version and during a 24-hour period in December, ’16, it generated 216,000 kilowatthours. The turbine is 722 feet tall, with 38-ton blades that each measure 263 feet in length. It’s blades have a total swept area of 227,377 square feet, which is larger than the London Eye ferris wheel, according to a press release.
This turbine resides off Østerild, Denmark and joins a mature offshore wind technology in Europe. Construction of long-delayed U.S. offshore wind farms began off the southern coast of Massachusetts in 2016. Additional deployment in deeper water off the Pacific coast is expected in the future. Undersea cabling has been deployed for 150 years, and undersea anchoring for large wind turbines has been engineered and solved.
Offshore wind development is attractive because the winds there are more frequent than terrestrial sites (the best of which are already tapped). They are steady in direction for long periods of time, and there are no conflicts with other land uses as there is with new industrial development on land.