Four 1.5-MW tidal stream turbines that will make up the first phase of the massive MeyGen project proposed for installation in the Pentland Firth, have been fully assembled.
Three of the turbines were built by Andritz Hydro Hammerfest. Tidal power generation firm Atlantis Resources, which owns 85% of the MeyGen project, built the remaining one, an AR1500 model. The turbines will be installed in the Pentland Firth, a strait that separates the Orkney Islands from Caithness in the far north of Scotland, as part of the demonstration phase (Phase 1A).
The project has extensive backing from the Scottish government. It was financed using a combination of debt, equity, and grants from a funding syndicate that includes the Crown Estate, the Scottish Executive, the UK’s climate department, and the Highlands and Islands Enterprise.
The Pentland Firth reportedly has a technical resource of 11 TWh per year available in tidal currents—which is exceptional when compared to the UK’s total technical resource of 29 TWh. Atlantis and partners GDF Suez (now ENGIE) and Morgan Stanley in 2010 snapped up an agreement for lease of the inner sound of the Pentland Firth (in the UK’s first competitive seabed leasing round for wave and tidal projects) to develop up to 398 MW of tidal stream power generation. The Crown Estate has agreements for 11 sites in the area with a potential capacity of 1,600 MW.
In 2013, Atlantis acquired its partners’ stakes in the project, but on financial close, the Scottish government committed to a 14% stake in the MeyGen holding company, Tidal Power Scotland Holding Ltd. MeyGen has since achieved financial closure, obtained environmental approvals, and received all other consent needed for the first 86 MW of capacity at the site. It has also secured transmission and distribution capacity that would support several phases of the project. This June, the project successfully connected to a 33-kV network following installation of one of the longest underground 33 kV power export cables in the UK by network operator Scottish Hydro Electric Power Distribution.
While Atlantis has extensively tested prototypes of its turbine in the ocean, MeyGen said that it selected Andritz Hydro Hammerfest as its preferred third-party turbine supplier because the company’s turbines could satisfy the MeyGen technical specifications and had accumulated a significant operating record—first with a 300-kW prototype in Norway and subsequently with a 1-MW unit at European Marine Energy Centre. Also, MeyGen noted: “Additionally, [Andritz Hydro] was prepared to commit to limited turbine warranties backed by an Andritz parent company guarantee.”
The turbine sizes (each 1.5 MW) were chosen “after extensive resource modelling and financial optimisation in order to provide the lowest possible cost of energy for the project,” MeyGen said.
The two models are similar. Each 200-metric ton turbine (Figure 1) has three blades, a pitching system, and a yaw mechanism to turn the turbine about 180 degrees when the tide changes direction. The nacelles contain a generator and gearbox, but the power conditioning equipment is housed in the onshore facilities.
The turbines will be positioned on top of their foundation structures on the quayside at the Nigg Energy Park in Scotland, ready for deployment to the site later this year. The turbines and their foundations will then be transported to the site by the Neptune jack-up vessel operated by Geoseas, a subsidiary of the DEME Group.
—Sonal Patel, associate editor (@POWERmagazine, @sonalcpatel)