Wave power challenge

A challenge with wave power is the large variation in size and energy content of waves. Components in the system need to be sized for the peak power while revenue will be in proportion to the average power.

A Wave Energy Converter (WEC) captures power from the waves by applying a damping force against the movements of the buoy. The damping force that captures the most power depends to a large extent on the wave size.

The cost of components in WEC system can be significantly reduced and the efficiency increased if the captured power is smoothed before the generator by an energy storage device, typically hydraulic accumulators. Such devices can however be very expensive and may also compromise the damping force control of the buoys.


OHT solution

OHT offers infrastructure for WEC arrays that enables damping force control in buoys, in combination with hydraulic collection of the captured power.

  • A high pressure fluid collection system for WECs with power smoothing and electricity generation in a central tower.
  • A low-cost and efficient energy storage, in the form of a weight that is lifted with a rack and pinion drive inside the tower, providing constant pressure in the collection system and constant power output.
  • PTO functionality which enables wave-by-wave damping force control in buoys. The hydraulic cylinder is replaced by a rack and pinion connected to a variable/multi displacement pump arrangement.
  • Reduced CAPEX and increased annual yield.

The collection tower is generic. Any WEC buoy can be adapted to connect to the hydraulic collection system. The tower can preliminarily be scaled up to 50-100 MW. A commercial size array will include several towers. 

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Partnering opportunities

OHT is currently developing a system design specification for a 10 MW demonstration array in an open innovation strategy in cooperation with WEC developers, suppliers, test centers and research institutions.

Current cooperation opportunities include:

WEC companies: Evaluation of hydraulic collection, damping force control and gravity storage features for their WECs with hardware in the loop simulations in the test rig.

OEMs and Suppliers: Participation in subsystem
design and integration in hydraulic, mechanic, and electrical systems.

Test centers and Research institutions: Participation in designing test programs, validation and benchmarking.