Siemens has installed the prototype of its towering 8-MW offshore direct-drive wind turbine at a national test center in Østerild, Denmark, marking the company’s foray into the global race to develop mega–wind turbines.
The new offshore turbine was installed on a steel tower at a hub height of 120 meters (m) in late January (Figure 4). The final type certificate is expected in 2018. The prototype is based on Siemens’ 7-MW model, which already has first orders to be installed in early 2018 in the Walney Extension East project in the UK.
According to the Global Wind Energy Association (GWEA), relatively higher costs and installation complexity compared to onshore wind have posed barriers for widespread offshore wind development. Turbine makers are working to reduce costs by deploying larger turbines to increase energy capture, along with keeping volumes up and tackling supply-chain challenges. While GWEA notes, citing a 2011 study, that wind turbines of up to 20 MW could be constructed using existing materials, “such behemoths are not yet economic,” it says. “[It] will probably not be long before we’ll see 10, 12 and 15 MW machines—and if there are fundamental limits, they’re not yet clear. As materials science continues to advance, who knows how large offshore machines will be in 20 years’ time?” it says.
For now, the largest offshore wind turbines hover over the 7-MW to 8-MW range. However, MHI Vestas—a joint venture between Vestas Wind Systems and Mitsubishi Heavy Industries—on January 26 unveiled an uprated version of its 8-MW medium-speed geared commercial turbine. The company said the prototype installed at Østerild produced 216,000 kWh over a 24-hour period—a record for a commercially available offshore wind turbine—on December 1. Like the original model, the V164 prototype weighs about 35 metric tons and has 80-m-long blades, but it is about 35 m taller with a hub height of 140 m, and it can reach a rated power of 9 MW depending on specific site conditions. MHI Vestas began commercial operation of the first V164-8.0-MW machine in September 2016 at the 258-MW Burbo Bank Extension, a wind farm owned by DONG Energy, PKA, and KIRKBI A/S, 7 kilometers off the coast of Liverpool in the UK (Figure 5). MHI Vestas also noted that it has a “firm order book” of more than 1.6 GW for the turbine model.
Other notable prototypes include Gamesa and AREVA’s jointly developed 8-MW Adwen AD-180, which is undergoing testing in Bremerhaven, Germany. Meanwhile, Enercon’s E-126 model, a 7.5-MW onshore model, has been installed at the Noordoostpolder site in the Netherlands.
—Sonal Patel is a POWER associate editor.