The bespoke concrete base for a pioneering underwater renewable energy project is set to be floated across the coast of North Wales.
The structure, which is part of a €30m (£25m) underwater kite project off Anglesey, was constructed by Ruthin-based Jones Bros Civil Engineering UK.
Measuring 21.5m x 12.75m x 5m and comprising 15 hollow sections, it has now been floated in a dry dock at Birkenhead prior to being towed along the North Wales coast to Holyhead.
Called Deep Green, the ground-breaking technology will harness tidal power. The concrete structure has been constructed for a pilot, which will see one 0.5MW generator installed and operated to demonstrate the technology.
Deep Green’s developer, Minesto, is seeking in the long term to generate 80MW at the site, enough to power 70,000 homes.
The technology generates electricity by harnessing underwater currents in kites tethered to the sea floor.
A Jones Bros team of 20 worked on the construction of the base. Project manager Eryl Evans said: “This has been a complex structure with a number of challenges to overcome. We have had to work with very tight tolerances to ensure a balance between buoyancy and weight; for the floatation and delivery of the structure, and its ability to sit on the sea bed.
“Once the structure has been manoeuvred to its location at Holyhead Deep, it will be filled with water to act as ballast to lower it to the sea bed, at which point the Minesto device will be tethered to the structure.”
The structure required 450 m3 of concrete and 180 tonnes of reinforced steel. Once positioned on the sea bed, it will weigh 1,300 tonnes.
It was constructed 12 metres deep inside a dry dock, meaning all materials and plant had to be lifted in by a crane.
Eryl added: “We’ve been building balance of plant for other renewable energy projects such as wind farms for many years, but this involvement with a tidal scheme has been a first for Jones Bros.
“It’s good to expand our experience and be a part of what will be a significant maritime renewable energy project in North Wales.”
Minesto secured a €13m investment from the European Regional Development Fund (ERDF) through the Welsh European Funding Office, for the commercial rollout of its Deep Green technology.Its award-winning technology is the only verified marine power plant that operates cost efficiently in areas with low-velocity currents.
Martin Edlund, CEO of Minesto, said: “The delivery of the gravity base structure marks a milestone for Minesto’s operations in Wales and the upcoming offshore installation in Holyhead Deep. Marine energy has tremendous potential for growth and secure, affordable clean energy supply in Wales and the UK. We look forward to continuing building this industry together with partners and suppliers.”
Founded in the 1950s and employing almost 350 people, Jones Bros has grown rapidly in the last decade. It is currently working on contracts in various sectors including the construction of waste management facilities, highways, flood and marine defence and renewable energy projects around the UK.