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OES-Environmental distributes metadata forms (questionnaires) to solicit information from developers involved in environmental monitoring around marine renewable energy project sites around the world. This page provides project descriptions, baseline assessment, post-installation monitoring, and links to available data and reports. Content is updated on an annual basis.

MeyGen Tidal Energy Project

Description

The MeyGen tidal stream energy project is owned by SAE Renewables (SAE) previously known as SIMEC Atlantis Energy Ltd, a global developer of sustainable development projects. MeyGen was awarded an Agreement for Lease for the Inner Sound tidal development site on 21 October 2010 by The Crown Estate. The Inner Sound Agreement for Lease is for 398MW of installed tidal stream energy capacity and will be consented in a phased approach. Phase 1 is currently operational while Phase 2 and 3 have been awarded at this stage.

Phase 1 is an operational 6MW demonstration array, which comprises four 1.5MW turbines installed as part of MeyGen’s “deploy and monitor strategy” and entered into the 25-year operational phase in April 2018. All the turbines are upstream, three-bladed, horizontal-axis machines, fully submerged and mounted on gravity-base foundations resting on the seabed:

  • 1 x Atlantis Resources Limited AR1500: with a rated capacity of 1.5MW at 3.0 m/s, a rotor diameter of 18 m, and is designed to withstand the extreme environmental conditions expected to be encountered in the Pentland Firth in Scotland and the Bay of Fundy in Canada. The detailed design of this cutting-edge turbine was completed by Lockheed Martin Corporation during 2014. The AR1500 system has pitching blades and full nacelle yaw rotation capability to facilitate operation in highly energetic deployment locations.
  • 3 x Andritz Hydro Hammerfest HS1500: consisting of a horizontal axis rotor (18 m rotor diameter), pitched blades and yaw feeding a variable speed conventional generator via a gearbox and reaches rated power at current speeds of 3 m/s. Automatic control software governing a sensor-driven monitoring system adjusts the leading edge to capture optimum output from a given tidal environment. It is designed to handle flows between 1 and well above 4 m/s, in water depths down to 100m.

Another milestone of Phase1 is Project Stroma which comprises a subsea hub installed in September 2020. This allows multiple turbines to be connected to a single power export cable. This will significantly reduce the costs associated with grid connection. The length of power export cable as well as the amount of onshore conversion equipment required for grid connection will be significantly reduced, as will the amount of horizontal directional drilling and the amount of vessel time required for cable installation. Project Stroma will connect two additional Atlantis AR2000 turbines via the new subsea hub to a single power export cable which will then be connected via the MeyGen substation to the National Grid. 

Phase 2 has recently been awarded a total of 59MW from the three latest allocation rounds for Contracts for Difference (CfD) (Allocation Rounds 4,5 and 6) with a target commissioning date of 2027, 2028 and 2029 respectively. Overall, the Meygen lease and site resource allows for a capacity out to 398MW, therefore future phases of the project would seek to expand the consents and build out the remainder of this capacity.

SAE are also exploring the opportunity to collocate the tidal stream project alongside storage solutions, based upon prior experience at Uskmouth Energy Park. This is called the Meygen Sustainable Energy Park.

Export Cables: Each turbine requires its own cable to shore. Each cable was brought to shore via horizontal directional drilled (HDD) bores through the bedrock which terminate in a Power Conversion Centre (PCC). This subsea cable installation was carried out in September 2015 (see below).

Onshore Infrastructure: MeyGen requires an onshore PCC, cable landfall and cable routes from the PCC to the grid connection location.  At the PCC, the electricity is transformed up to higher voltages for export to the national transmission grid.  A further connection to the high voltage transmission network with Scottish Hydro Electric Transmission Ltd. has been secured, providing enough capacity to cover a large proportion of the remainder of the Project. The onshore infrastructure for the project was completed in early 2016 (see below).

Vessel Spread: The following vessels were utilised during construction and operation:

 

Vessel type

Activity

Comment

DP installation vessel

Installation of  turbine support structures

Smaller vessels were present for support services.

During year 1 and 2 of installation, only one DP vessel was onsite at any one time.  During year 3, two DP vessels were on site during support structure installation. 

Installation of export cables

DP installation vessel (or tug)

Install turbines onto support structures

Location

Inner Sound, Pentland Firth, Scotland.

Licensing Information

Consent was granted in 2013 by the Scottish Ministers under Section 36 of the Electricity Act for the construction and operation of Phase 1, consisting of up to 61 turbines with a permitted capacity of up to 86MW.  The consent was conditional upon SAE deploying the turbines in stages, with Phase 1A limited to a maximum of 6 turbines (only 4 turbines were installed), with all subsequent stages of the development being subject to the prior written approval of the Scottish Ministers. 

A Marine Licence under the Marine (Scotland) Act 2010 was granted for Phase 1 in 2014. A Marine Licence Variation was issued in 2017 with a revised Turbine Deployment Area (to include an additional area to the north-west of the site and to remove a similar sized area from the eastern side of the site). Following this, in 2019 a Section 36 Consent Variation was granted to ensure that the Turbine Deployment Area specified in Annex 3 of the s.36 consent is consistent with the revised Phase 1 Marine Licence area shown in Part 4 of the Schedule to Marine Licence (ref: ML 04577/17/1).

Licencing documentation can be accessed on Marine Scotland Information: https://marine.gov.scot/ml/meygen-tidal-energy-project

Licence Competent Authority Reference Date issued Expiry date
Section 36 (Electricity Act) Consent Scottish Ministers   9 October 2013  
Section 36 Consent Variation Scottish Ministers   29 August 2019  
Marine Licence (Marine (Scotland) Act) Consent – Construction, Operation and Deposit of a Tidal Stream Electricity Generating Station Marine Scotland 04577/14/0 31 January 2014 31 December 2020
Marine Licence (Marine (Scotland) Act) Consent (variation) – Construction, Operation and Deposit of a Tidal Stream Electricity Generating Station Marine Scotland 04577/17/1 11 September 2017 1 January 2041
European Protected Species Licence Marine Scotland MS EPS 19/2016/00 4 November 2016 4 November 2018
Marine Licence Variation Marine Scotland 04577/15/0 17 September 2015 31 December 2020
Marine Licence Variation Marine Scotland 04577/16/0 29 July 2016 1 January 2041
Marine Licence - Seabed Preparation Marine Scotland 06045/16/0 29 July 2016 1 January 2041
Marine Licence - Cable stability measures for the 4 turbine subsea cables Marine Scotland 06234/17/0 18 January 2017 1 January 2041
MeyGen Tidal Energy Project - Marine Licence Marine Scotland 06978/19/0 1 October 2019 30 November 2036
Marine Licence Variation - Cable stability measures for the 4 turbine subsea cables Marine Scotland MS-00009804 6 May 2022 1 January 2041
Marine Licence Variation - Construction, Operation and Deposit of a Tidal Stream Electricity Generating Station Marine Scotland MS-00009802 6 May 2022 1 January 2041

Project Progress

MeyGen secured an Agreement for Lease (AfL) from the Crown Estate for the Inner Sound tidal development site in 2010.  This AfL is for a tidal stream development with an installed capacity of up to 398 MW.

In 2013, MeyGen was awarded consent from the Scottish Government for the installation and operation of Phase 1 (up to 86MW).  Phase 2 will take place following the ‘deploy and monitor strategy’ on Phase 1 turbines and will see the build out of the remainder of the project subject to a separate consent application .

Onshore construction of the development commenced in 2015, beginning with the creation of a 340 m access road to the onshore site in Caithness. Completion of the access route was expected to take three months, with all onshore construction work being finished by the end of 2015. A press release in spring 2016 confirmed that the foundations, steelwork and cladding for the onshore infrastructure were complete, and the onshore project was ready to start electrical ¬fit out works. Works on the building included installing power conversion equipment for the turbines, 33kV switchgear for grid connection and a control centre for controlling the tidal turbine array off shore, as well as an indoor substation for SSE grid connection equipment and offices for MeyGen project operations team.

Scottish Hydro Electric Power Distribution Ltd. completed a 17km onshore cable installation campaign with the final section of cable brought into the MeyGen onshore building in February 2016. MeyGen is classifi¬ed as a Large Power Station by National Grid and hence has a requirement to satisfy the stringent UK grid code. This was the fi¬rst tidal energy project to go through this diligence process and demonstrates the scale of this project.

In September 2015, 11km of submarine cable was successfully installed at the MeyGen off¬shore site. A specifi¬c neap-tidal window was selected in September to provide enough time for the vessel to install one of the four turbine cables every 12 hours. While ambitious, this schedule was achieved, and the offshore operation took just 2.5 days. The next phase of the project’s offshore works carried out in summer 2016 involved the installation of the four Turbine Support Structures. Following this, the four Tidal Turbine Generators were installed in late 2016 and early 2017.

The project announced the completion of its construction phase and the start of its 25-year operational phase in April 2018.  During 2018, several MeyGen tidal power turbines were inspected and underwent maintenance.  All the turbines were redeployed and re-connected towards the end of 2018. 

By February 2019, the MeyGen tidal array had exported more than 12 GWh of tidal energy to the grid in Scotland.  During Phase 1A the tidal array generated 6GWh of energy and saw monthly production of 1,400 MWh a month of tidal energy.  This was quickly surpassed by a new record with MeyGen exporting more than 15 GWH to the grid in May 2019.

2020 saw Phase 1 of the Group’s flagship MeyGen tidal energy project continue to break records, delivering over 37GWh of clean and predictable electricity to the grid.

In March 2020, the MeyGen project was awarded £1.5 million in grant funding from the Scottish Government’s Saltire Tidal Energy Challenge Fund to develop a subsea tidal turbine connection hub for the next phase of development of the MeyGen tidal power array, Project Stroma. The subsea hub was successfully installed in September 2020 and is said to be a key part of the overall cost reduction strategy for tidal power generation.

A press release in August 2021 announced that both the AR1500 and the Andritz turbine number one have been retrieved for planned quarter-life maintenance at the company’s tidal turbine workshop at Nigg Energy Park. Whilst in the workshop, the turbines have undergone basic routine maintenance, including oil and filter changes, and will soon be ready for reinstallation at the MeyGen site in Caithness. Currently, there is very limited availability for suitable offshore vessels. The plan will be to install both turbines in one offshore operation, reducing overall costs when compared to two separate vessel hires.

In July 2022, SAE achieved the first contractual milestone in Phase 2 for the delivery of additional 28MW of tidal power capacity for the project. 

In October 2022, SAE deployed an acoustic Doppler current profiler (ADCP), a tidal flow measurement device, at the MeyGen site. 

In September 2023, MeyGen Phase 2 secured multiple CFDs totalling 22 MW during Allocation Round 5, at a significantly higher strike price compared to Allocation Round 4. This total was further increased by an additional 9 MW from Allocation Round 6 in September 2024, bringing the overall total for Phase 2 to 59 MW.

In December 2024, the final turbine of the four turbines for Phase 1 were deployed, and therefore the site is now fully operational. This means that the site is delivering 6 MW of power.

Key Environmental Issues

There were a number of potential impacts that have been identified in the Environmental Statement, however only the following were deemed to be potentially significant:

  • Collisions between marine mammals and installation vessels; and
  • Disturbance to fish due to EMFs from subsea cables.

The following mitigation and best practice measures were outlined in the Environmental Statement and Environmental Management Plan: 

  • Where cables are not within boreholes they will be laid where possible within natural crevices and cracks within the seabed ensuring that the majority of the cable is below the seabed.
  • The length of the drilled boreholes for the cable will, as far as possible, increase the length of cable under the seabed.
  • Cables will be bundled into groups of 3 minimising the magnetic field by placing the cables close together, allowing the field vectors to cancel each other out.
  • Ongoing research by Marine Scotland and their advisors will be monitored for further indications of successful mitigation strategies.
  • MeyGen commit to undertaking frequent reviews of the literature regarding spiral injuries in seals and ducted propellers and to regularly discuss advances in understanding of this topic with relevant regulatory and advisory bodies. MeyGen will apply appropriate mitigation, as deemed necessary in consultation with Marine Scotland and SNH, should vessels with ducted propellers be used, to avoid any significant impacts[1].
  • The turbines have been subjected to engineering design and third-party verification to ensure they are suitable for deployment in the Inner Sound.
  • The Project will be using tried and tested equipment and techniques to minimise the risks associated with the high tidal flow environment.
  • Turbine nacelle designs that use buoyancy as part of the installation and maintenance strategy have failsafe locking systems for the connection between the nacelle and the Turbine Support Structures (TSSs) to prevent accidental release.
  • On-site monitoring via SCADA (Supervisory Control and Data Acquisition) will alert the 24-hour control room operations team of turbine failure or an object hitting the turbine.
  • An Emergency Response Cooperation Plan (ERCoP) will be prepared for the Project following the template provided by the MCA in Marine Guidance Note (MGN) 371. This will be submitted to the MCA for comment and approval. Emergency response would include informing HM Coastguard, Royal National Lifeboat Institution (RNLI), Harbours and local users (e.g., Pentland Ferries) so that vessels in the area are alerted to the potential hazard.
  • Multicat type vessels will be used for some of the activities to reduce ship strike and propeller collision due to the lack of ducted propellers and and a fixed seabed anchor system on these types of vessels.

[1]   A large majority of spiral injuries are now understood to be caused by aggressive interactions from other grey seals, based on observations of lethal attacks by adult male grey seals (Sea Mammal Research Unit, 2015): http://www.smru.st-andrews.ac.uk/files/2015/10/USD1and-6_addendum_repor…