Supplying the UK National Grid with tidal power

UK-based tidal energy developer Spiralis Energy is aiming to power up to 11% of the National Grid using its tidal energy technology. The company, an Earthshot Prize 2024 nominee, is on a mission to transform the renewable energy sector by harnessing the yet untapped power of tidal currents.

Tidal energy, unlike other forms of renewable energy such as wind and solar, offers a round-the-clock, stable and predictable baseload of power that is essential for national grids.

Spiralis is to test two of its ‘Axial Skelter’ power generating screws in the untapped waters off Alderney in the Channel Islands. Alderney has some of the strongest tidal currents in Europe, and thanks to its unique seabed ownership, the island is able to facilitate rapid project development.

In comparison with existing renewable energy solutions, whilst the individual energy output of an Axial Skelter is lower than that of an offshore wind turbine, they can be manufactured and maintained at a fraction of the cost (circa £1m per Axial Skelter with predicted annual maintenance costs of around £100k), which allows for a far lower cost per megawatt.

Installation and transportation of a single offshore wind turbine is around £2m, with annual maintenance costs up to £300,000 per turbine. Longer-term, maintenance costs for offshore wind can accumulate significantly due to the requirement of more regular inspections.

Axial Skelters have been designed for easy maintenance and have a standard servicing schedule. The modular design of the entire system means that repairs can take place rapidly, where components can be quickly swapped during slack tide periods, like a racing car pit stop, but at sea. Additionally, the Axial Skelters are manufactured from recycled materials and are completely end-of-life recyclable, whilst also posing minimal risk to marine life. 

The primary advantage of tidal power over other forms of renewable energy is its predictability – tide times are accurately forecast to within six minutes, up to 100 years in advance. This enables significantly improved power management planning. Currently, solar and wind contracts are subject to buying energy from an unpredictable source as the output is entirely dependent on the weather. With climate volatility set to increase, Spiralis will provide a reliable energy source to combat ongoing energy concerns.

Spiralis will be bidding for a 15-year contract with the UK Government as part of Contracts for Difference 2025 in order to integrate into the national grid, and has already identified a useable site in Wales should it be successful in its bid. Basing its manufacturing and array operations in Wales will also create significant opportunities for jobs and apprenticeships that sit within the standard coastal industrial and maritime skillset.

Chief Executive of Spiralis Energy, Guy Levene OBE says: “The UK has the best tidal knowledge in the world. Our technology can deliver a renewable energy source that doesn’t harm sea life and sits within the circular economy framework.

What makes Spiralis easy-to-scale is that our units have a modular design to enable them to fit into a standard shipping container for affordable transportation anywhere in the world.  It’s really quite straightforward – we’re offering a simple, more affordable, more reliable and sustainable energy solution; our technology simply works.”

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