Wave-energy device adapts its set-up from calm to rough seas

The Weptos device expands on the ‘Salter’s Duck’ principle of wave generation, devised in the 1970s by the eponymous Scottish engineer, which uses ‘bobbing’ tear-shaped buoys.

Back then, the original idea was to have single double-decker-sized buoys, but Weptos uses an array of 20 buoys — or rotors — facing perpendicularly along two arms joined at the ends to create a V-shaped set-up.

The 20 rotors of each arm drive a single axis and, with the use of a ratchet mechanism, are collectively able to keep the axle turning at a speed of 30–94rev/min.

‘The power is fed in on the upstroke to achieve a relatively constant rotation on the common axle,’ said Prof Jens Peter Kofoed of Aalborg University, which is a partner in the project along with Danish companies Energinet and Zacco.

A gearing mechanism then increases the torque to around 90Nm, which is utilised by generators at the intersection between the arms.