Siemens has been the latest OEM to join the 8-MW wind turbine club with the introduction of its SWT-8.0-154, so a natural reaction was to nominate it as the Turbine of the Month. But wait. Adwen also announced an 8 with an impressive 180-m rotor earlier this year and, if memory serves, Vestas has two 8-MW units up and running before that and orders for more. So although Vestas gets bragging rights for being first, we nominate these three 8-MW units as our October Turbines of the month.
These 8-MW units are significant developments for several reason. For one, they make it possible to install fewer machines for a required output, which in turn reduces infrastructure costs such as foundations and cabling. In addition, you may recall about six
years ago, at least three companies boasted of having 10-MW turbines in the works. One from Clipper adorned a cover of this fine magazine. That company is no longer with us. The 10-MW turbine has turned into quite a stretch goal for the OEMs so expect a few years to elapse before someone announces a 9-MW unit. For the time being, let’s celebrate the 8 MW designs.
No surprise, all are three-bladed units intended for duty offshore. Not a lot of tech data is available on the Adwen and Siemen’s units, so here’s a little on each.
Vestas installed its first 8 MW prototype in Denmark in early 2014, and now has orders for 32 machines for the 258-MW Burbo Bank Extension project off the coast of Liverpool Bay in the UK.
The company says the design includes strategies to mitigate risk with features such as:
• A failure-tolerant mode to run with reduced output should unexpected issues arise
• Aircraft-inspired component redundancy to avoid unnecessary interventions between scheduled service and to ensure a continuous normal output
• A medium-speed gearbox for reliable operations
• All equipment and components are evolutions of proven existing technology.
The Adwen AD 8-180 turbine has the largest rotor in the industry which has led the developer to claim the largest annual energy production. The turbine is planned for 90-m towers.
The company, a collaboration of Gamesa and Areva, has commissioned and started testing the AD 8-180 drivetrain at IWES Dynamic Nacelle Testing Laboratory (DyNaLab) in Bremerhaven, Germany where it is undergoing tests that will last until the end of 2016. The validation will cover mechanical and electrical tests on the drivetrain and main tower components.
The tests will simulate operational conditions for extreme and fatigue loads, and validate key components. The simulations will also allow validating individual and fully integrated subsystems as well as the complete drivetrain operation at full power. These tests are needed to shorten a field test campaign and shorten the turbine’s time to certification.
Adwen started tests at the end of 2015 with the assembly and commissioning of the electrical system. In April 2016 the drivetrain was transported to DyNaLab to start the mechanical assembly as well as assembly of auxiliary structures for sensors, lubrication systems, and the set-up and fine tuning of more than 350 sensors that will be used during this verification process.
When this first part of the full drivetrain test campaign concludes, a complete AD 8-180 nacelle will be installed in the prototype, currently being assembled in Bremerhaven.
Siemens’ direct drive wind turbine intended for duty offshore and on has reached its next development milestone. The company says this latest addition to its offshore platform, the SWT-8.0-154, takes a significant step towards grid parity for offshore wind. The 8-MW turbine is based on the existing offshore direct-drive platform, incorporating only smaller evolutions.
The first SWT-8.0-154 will be installed in early 2017, and will allow for up to 10% higher annual energy production under offshore wind conditions as compared to the 7-MW model. According to the company, the offshore platform enables a significant reduction in the Levelized Cost of Energy at low risk. Type certification for the 8-MW turbine is expected in early 2018.
Upgrading the Siemens 7-MW offshore direct drive wind turbine to eight MW is made possible through the introduction of new magnet technology with an even higher grade than that introduced in the SWT-7.0-154. This allows a rated power increase of more than 14% from 7.0 to 8.0 MW. Similar to the previous upgrade from 6.0 to 7.0 MW, the company says, the 8-MW turbine will benefit from the established supply chain and proven components of offshore direct drive technology. These components include the B75 blade and the medium-voltage transformer of the SWT-8.0-154. The higher rating will come from only a few component upgrades.
The company says about 150, 6-MW direct-drive wind turbines have been commissioned for offshore work. Two SWT-7.0-154 prototypes, installed at the Østerild test site in Northwestern Denmark, are performing above expectations, according to Siemens. The SWT-8.0-154 prototype is planned for install by early 2017.