Cascade gear system boosts efficiency of wave energy generation

A Swedish company says it has cracked the challenge of scaling up wave energy, with the help of technology from researchers at KTH Royal Institute of Technology.

CorPower Ocean's wave energy system uses a gearbox design that KTH researchers helped to develop. According to the company, the system generates five times more energy per ton of device, at one third of the cost when compared to competing technologies. Energy output is also three to four times higher than traditional wave power systems.

Known as a point absorber, CorPower's converter consists of a buoy that absorbs energy from the waves, plus a drivetrain that converts the buoy's motion into electricity.

CEO Patrik Möller says the CorPower wave energy converter can manage the entire spectrum of waves, unlike competing systems. "Unlike other wave power systems, ours actively controls the timing between the buoy and the incoming wave, with the help of a unique drivetrain. We can ensure that it always works in time with the waves, which greatly enhances the buoy's movement and uses it all the way between the wave crest and wave trough and back in an optimal way, no matter how long or high the waves are."

The system boasts a specially designed rack and pinion gear solution developed in cooperation with the Department of Machine Design at KTH and gear expert Stefan Björklund. The cascade gear provides a robust and efficient way to convert linear motion into rotation, says Möller.

An 8m diameter buoy is said to produce up to 300kW in a typical Atlantic environment, with a 100 buoy wave park generating up to 30MW.