Since 2010, as part of the Pentland Firth and Orkney Waters leasing round, The Crown Estate awarded an agreement for lease to MeyGen plc, granting the option to develop a tidal stream project of up to 398MW at an offshore site between Scotland’s northernmost coast and the island of Stroma, as shown in the map below.
The 3.5km site covers some of the fastest flowing waters in the UK, just 2km from Scotland’s north-east tip. To the north of the site is the uninhabited island of Stroma, which creates a natural channel with the mainland to accelerate the millions of tonnes of water flowing between the North Sea and the Atlantic Ocean every day. This site was originally identified by SAE in 2007, following a global review of tidal resource which concluded that the high flows, medium water depths and proximity to the mainland rendered it a prime location for development.
The MeyGen project is the largest planned tidal stream project in the world. In 2014 the MeyGen project received consent for 86MW.
The project is split into four phases:
MEYGEN PHASE 1 - 6MW
The first phase of the MeyGen project comprises four 1.5MW turbines installed on gravity turbine support structures. The first phase demonstrates that the development of tidal arrays is both commercially viable and technically feasible. Operating since March 2018, the project has delivered over 51GWh of renewable electricity, and the invaluable lessons and experience drawn from the construction, installation, operation and maintenance of this phase will be fed into subsequent phases.
Each turbine has 3 blades with a rotor diameter of 18m. These blades pitch to maintain the machines installed capacity above a rated flow speed. The turbines also include a yaw module which rotates the turbine at each slack tide to face into subsequent ebb or flood tide.
The 150t turbines are mounted on a 1450t gravity foundation that supports the turbines under its own weight in average flow speeds of up to 10 knots. Each turbine has a dedicated quad armoured subsea array cable laid directly on the exposed seabed and brought ashore via a horizontal directionally drilled borehole within the foreshore bedrock.
The turbines feed into the onshore power conversion unit building at the Ness of Quoys, where the 4kV supply passes through an ABB PCS6000 converter to be made grid code compliant at 33kV for export into the local distribution network. Based on average UK annual consumption of 3.1MWh per annum this phase of the tidal array generates sufficient electricity to supply circa 6,000 homes.
The planning consent for Phase 1 includes three power conversion unit buildings, which have been designed in consultation with The Highland Council and Scottish Natural Heritage as modern functional industrial buildings that reflect their landscape and historic environmental context.
Phase 1 incorporates two different turbine technologies (SAE's AR1500 and Andritz Hydro Hammerfest AH1000 MK1), with environmental monitoring equipment installed that assesses the interaction between the tidal turbines and the marine environment, including marine mammals. The results of the monitoring work will be used to inform subsequent phases of the project.
The key milestones achieved to date are:
- Crown Estate Agreement Lease – October 2010
- Marine Licence granted by Marine Scotland – January 2014
- Financial Close/Construction contracts conclude – September 2014
- Construction commences at the Ness of Quoys site – January 2015
- Offshore subsea array cables installed in Inner Sound – October 2015
- Onshore building works complete, and grid connection energised – June 2016
- Offshore installation of foundations and turbines commenced – October 2016
- First electrons exported to grid – November 2016
- ROC and Ofgem accreditation –– March 2017
- 1GWh exported to the grid – August 2017
- MeyGen Phase 1A formally enters 25-year operations phase– April 2018
- Subsea hub installed at MeyGen – September 2020
- Project generates over 51GWh – March 2023
The supply chain for the Phase 1 project is spread across the United Kingdom, Europe and North America; 43% of the project’s capital expenditure was in Scotland and involved companies based in Caithness, and Ross and Cromarty. The operational phase of the project has been run from Nigg Energy Park since 2018 where up to 55% of the project's operational expenditure is sourced locally.
MEYGEN PHASE 2 - 28MW
Status: Awarded CFD
The MeyGen project has been awarded a Contract For Difference (CFD) in Allocation Round 4 for 28MW at a strike price of £178.54/MWh with a target commissioning date of 2027. The project will be transformational for the tidal energy industry, delivering the world's first commercial scale tidal array and securing MeyGen as the home of tidal energy.
MEYGEN PHASE 3 - 52MW
Status: Consented and under development
MeyGen phase 3 will see the remainder of the consented project delivered. Given the award of 28MW in AR4 MeyGen has an additional consent for 52MW which is eligible to be bid into future CFD Allocation Rounds.
MEYGEN PHASE 4 - 312MW
Status: In planning
The MeyGen offshore lease and site resource allows for a capacity out to 398MW to be installed. Phase 4 of the project would seek to expand the consents and build out the remainder of this capacity.