The tidal power mining machine resembles a giant screw

British company Spiralis Energy’s screw-like tidal energy harvester is moving closer to practical deployment after computational fluid dynamics (CFD) analysis of the prototype showed good results, Interesting Engineering reported on October 15. Cape Horn Engineering, a UK-based marine technology consultancy, conducted this analysis.

Previously, Spiralis Energy installed a test machine at Poole port, England. This version is about 6 meters long, 1/3 the size of the machine that Spiralis Energy plans to deploy in the future. Using computational fluid dynamics, Cape Horn Engineering has predicted a peak power output of 2.59 kW. Actual measurements showed a peak power of 2.50 kW at a speed of 21 revolutions per minute. Considering the friction of the machine, these two data are within 1.5% deviation, demonstrating high accuracy.

“With this validation completed, we are more confident in predicting that the full-size machine will surpass the 250 kW threshold,” said Rodrigo Azcueta, director at Cape Horn Engineering.

Spiralis Energy will move into the next phase of testing with the full-size machine, which is 16 meters long and 5 meters in diameter. Another interesting point is that it is made from plastic waste instead of exploiting new resources.

Spiralis Energy plans to install two such machines in the English Channel to test performance in colder winters. Cape Horn Engineering’s CFD analysis will help the company determine structural loads and optimize the machine’s geometry for maximum performance.

The screw-shaped machine needs to be submerged in water, but electricity production takes place above water, in dry conditions. The spiral structure is 3D printed in modular form. So when a part breaks, it can be printed and repaired at the nearest facility instead of having to wait for the company to provide a replacement part.

“Our technology can provide a renewable energy source that is not harmful to marine life and is within the framework of a circular economy,” said Guy Levene, CEO of Spiralis Energy. The company aims to supply 11% of the UK’s annual energy needs with electricity from the sea.