Offshore tidal flows peak four times every 24 hours and always will, whatever the weather. This makes offshore tides the only 100% reliable, predictable and sustainable energy source on the planet. So why is it that this immense, inexhaustible solution to arguably the world's greatest challenge, currently plays no meaningful role in the race towards a world powered by carbon free energy? 

 

It is widely quoted that tidal flows around the UK could provide up to 11% of the UK's electricity needs and yet today, no technology is close to delivering that result. Why?

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Until now tidal turbine developers have mostly focused on horizontal axis turbines (HATs) in the limited areas with the strongest tidal flows averaging circa 2.5 m/s (5 Knots) and above. In simple terms HATs can be described as submerged horizontal axis wind turbines and whilst some of these have made good progress, the costs of developing, deploying and maintaining submerged machinery of this type are still very high and they are only efficient in the strongest tides.

 

If the UK and the world are going to realise the true potential of offshore tides, a completely new, less complex, less costly solution must be found that works in the much more prevalent areas with medium energy tidal flows (max. 2.5 m/s) and depths, typically between 30m and 35m. These extensive areas have not been targeted by the existing developers because their technology is designed for the strongest tidal flows, however if offshore tidal energy is to reach huge scale to compare with wind and solar, these are the areas that matter.

 

Tidal Technologies Limited (TTL) was formed in early 2021 to meet this challenge. The result is TT2, a very different and yet very simple design, incorporating vertical axis drive shafts extending above water, driven by submerged vertical foils. Turbines of this type are known as vertical axis turbines (VATs).

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TTL determined from the outset that TT2 must meet certain critical requirements to succeed:

• It must be effective in tidal velocities below 2.5 m/s so that it can be installed across wide areas at scale.

• It must be designed with the flexibility to work in depths of 25m to 35m.

• It must be possible to have large arrays of turbines in close proximity to each other.

• All generating and associated electrical equipment must be well proven, off the shelf products from the wind turbine industry, protected in storm proof containers above water, with no further development required.

• There must be NO moving parts or components that require regular servicing or replacement below water.

• There must be no need to raise the system during its 25+ years lifetime.

• It must be supported on a gravity base capable of sitting on the seabed whilst withstanding the worst storm conditions without the need for a separate anchoring system or piling.

• It must have minimal impact on the seabed.

• The risks to sea life must be negligible.

• It must not pose any greater navigational hazard than offshore wind turbines.

• It must be capable, when fully developed and installed at scale, of delivering electricity at a cost that competes with offshore wind. 

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Following tests of a 1/20th scale model in the Royal Navy's testing facilities in Gosport, Hampshire, we now firmly believe that TT2's vertical axis design with vertical foils can deliver all of these requirements and is the only concept capable of generating competitively priced electricity from offshore tidal flows on a very large scale.

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To understand how it works and see the test, please view our video.

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