Holyhead Deep, Wales

Holyhead Deep – the world’s first low-flow tidal stream project


Holyhead Deep marks the starting point of the industrialisation of Minesto’s unique marine energy technology. It is not only Minesto’s first utility-scale project – but also the first low-velocity tidal energy project in the world. Holyhead Deep has been identified as an optimal location for a utility-scale installation. The area matches all the site requirements by providing low-flow tidal velocities (1.5–2 m/s mean peak flow) at a depth of 80–100 metres. The offshore site is only 8 km from the port and town of Holyhead where Minesto UK head offices are located.

Project development process

Developing Holyhead Deep into a commercial tidal energy array is proposed to be carried out in a number of phases. The site is located in an area known as Holyhead Deep. The installation of the kite array will be in accordance with a navigation risk assessment which is undertaken to minimise the impact on other sea users. Stakeholder engagement and multi-disciplinary environmental research work have been ongoing since 2012, and Minesto has worked closely with Bangor University and research organisations in Wales to understand the specific local site environmental issues. The proposed development scenario is as follows:


  • Total tidal array capacity at 80 MW (minimum)
  • In total 60 units at 1.2 MW
  • Extension to the Crown Estate lease
  • Grid connection via the Morlais onshore development
  • Assembly and maintenance of kite systems conducted at Minesto’s Assembly Hall



Commercial array expansion plans

Minesto’s long-term plan is to expand the Holyhead Deep site to a commercial tidal energy array with a total installed capacity of up to 80MW. Minesto intends to develop the site in phases as part of a deploy-and-monitor approach. This gradual expansion would see us taking the technology from demonstrator to full industrial roll-out in North Wales.


Since 2020, Minesto’s state-of-the-art Assembly Hall located in Holyhead, Wales has been fully operational, serving as the hub of Minesto’s engineering and operational activities.

About the Holyhead Deep site

Holyhead Deep is the name of a large depression in the seabed, located west of Anglesey, North Wales. Besides having optimal oceanic requirements, the site also benefits from the proximity of good port facilities at Holyhead Port, onshore grid connection via the Morlais development and good offshore and onshore transport links.

An EU-funded project

In May 2015, Minesto was awarded a €13m grant from the European Regional Development Fund through the Welsh European Funding Office (WEFO), part of the Welsh Government, for the commercial rollout of Minesto’s technology. As part of this contract, Minesto’s U.K. head office was established in Holyhead. In May 2019, the Welsh government announced their continued support for Minesto’s commercial development in Wales following the award of €14.9 million of EU funding through WEFO for the next phase of Minesto’s tidal energy scheme in Wales.


Creating shared value

The vision of the Holyhead Deep project is to contribute to the transition from fossil fuels to renewable energy, making Wales and the UK a global leader of a sustainable energy future. Once fully installed, a 10 MW array will supply local and clean electricity to the equivalent of more than 8 000 Welsh households. The planned increase of the site to 80 MW installed capacity would increase that figure to almost 70 000 households.


The investment linked to building, commissioning, and operating the first commercial-scale array with Minesto’s tidal kites will also make a significant positive contribution to the creation of new employment opportunities and stimulating long-term growth and investment in Anglesey. The establishment of Minesto U.K. head office in Holyhead has seen several full-time jobs created to date and the Holyhead Deep project is already stimulating businesses through the local supply chain.



Environmental Statement & HRA report

Minesto is committed to developing the Holyhead Deep project in a manner where potential environmental impact is minimised as far as practicable. As part of the application for a Marine Licence for the first 0.5MW demonstration project in Holyhead Deep, Minesto carried out a detailed Environmental Impact Assessment (EIA) informed by two years’ of site-specific surveys and various environmental assessment studies. The results are detailed in an Environmental Statement (ES), which was submitted alongside the licence application.


Minesto also commissioned a Habitats Regulations Assessment (HRA) report to provide information on the potential effects of the project of internationally important conservation sites designated under European legislation (known as Natura sites). The ES, Non-Technical Summary (NTS) and HRA report are available to download below:


Download PDF: Non-Technical Summary (NTS) – Welsh language version

Download PDF: Non-Technical Summary (NTS) – English language version

Download PDF: Environmental Statement

Download PDF: Habitats Regulations Assessment (HRA) report


Decommissioning Plan

In addition to the Marine Licence (ORML 1618) which gives Minesto right to construct and operate an offshore renewable energy installation in Holyhead Deep, the company are required to submit a plan (“decommissioning programme”) for decommissioning of the installation to the Department for Business, Energy & Industrial Strategy. This decommissioning plan is available for download below:


Download PDF: DG500 Decommissioning Plan


Why Wales?

In 2015, after an in-depth analysis of sites around the world, U.K. was identified as the most suitable location on the basis that its territorial waters contain approximately half of the European tidal resource and around 10–15 percent of the known global resource. Numerous locations around the U.K. were considered, but Holyhead Deep in Wales was selected as the preferred option due to the highly suitable environmental conditions and government commitment to marine renewable energy, offering significant opportunities to attract support and investment into the project.