Innovative pre-tension solution reduces InfinityWEC electricity production cost

Source: press release, 23 November 2022

The InfinityWEC wave energy converter
The InfinityWEC wave energy converter (illustration: Ocean Harvesting)

The InfinityWEC wave energy converter has been upgraded with an innovative solution which uses hydrostatic pressure to provide a constant pre-tension force in the power take-off (PTO), reducing size, weight, complexity, and ultimately cost of electricity production (LCoE).

In the upgraded InfinityWEC design, the PTO hull is split into two halves, with the top half moving up and down with the buoy, while the bottom half is fixed to the anchor. Similar solutions have been used by pressure-modulating wave energy converters, to extract energy from the variation in pressure below waves, close to the surface. InfinityWEC however, is a point-absorbing wave energy converter, with a buoy on the surface driving the PTO positioned close to the seabed. At 70 m depth, the high pressure of the water provides a 100-ton pre-tension force with only a 1.6-metre diameter PTO hull. A patent application has been filed for the innovation.

“The new pre-tension solution is a further improvement of the InfinityWEC wave energy converter, reducing the weight of the PTO by approximately 40%,” says CEO Mikael Sidenmark. “We take advantage of the water pressure outside the PTO to generate the constant pre-tension force, which in combination with ball screw actuators provides instant force control with very high efficiency. This enables wave-by-wave tuned force control, improving the annual energy production by up to 30% compared to sea-state tuned control.”

Ocean Harvesting is preparing for sea trials of InfinityWEC at scale 1:3, to be performed off the west coast of Sweden. The sea trial project, to validate the performance in a real sea environment, will be conducted between February 2023 – June 2025. Results will be used to further develop and improve the full-scale system with regards to energy yield, system efficiency, availability, and ultimately affordability.

On 14 November, Ocean Harvesting was awarded a EUR 2 million grant from the Swedish Energy Agency for the project. To complete the project financing, the Company is now raising EUR 3 million in equity investment at a pre-money valuation of EUR 7 million.