System Operation

SurfPower is designed to optimally recover both potential and kinetic energy from waves. The buoyant  wings uniquely engage waves over a wide front, thereby maximizing energy recovery.

Seawater water is the energy transport medium used by SurfPower, thereby eliminating all risk of pollution due to accidental spills. Pressurized seawater is collected via a high pressure seabed main from the buoyant wing /pump and assemblies and is delivered onshore where it is used to drive a pelton/ turbine generator and/or a reverse osmosis desalination plant. The system is operated essentially at a constant hydraulic pressure in an open loop configuration (the discharge from the pelton turbine is simply returned to the sea).

SurfPower buoyant wings move vertically and laterally in response to wave action when the buoyancy force generated by an oncoming wave is sufficient to overcome the pressure in the seabed main. The buoyant wings are optimally configured to have just sufficient buoyancy to overcome the restraint provided by the piston pump working against main’s pressure. Ideally, the buoyant wings will be almost totally submerged as the wave advances on to the pontoon. After passage of the wave crest, the pontoon breaks out on the backside of the wave. The weight of the pontoon and attached pump provides a force component that drives the pontoon back to its initial starting position in the next wave trough.

The piston pump is attached to the pontoon at a point approximately 3.5 meters below the center of buoyancy. The distance between the point of attachment and the center of buoyancy provides stability to the pontoon under aggressive wave conditions, i.e. when the pontoon is approached by a steep-fronted breaking wave and/or when the pontoon is totally submerged by a wave that overtops it. It is not economically viable to provide hydraulic cylinder extension sufficient to handle all wave heights that may be encountered. Optimal cost of energy will be realized if the cylinder stroke length is limited, so that the pontoon is overtopped in all wave conditions exceeding 4 meters. Buoyant wings are designed to withstand total submergence when they are overtopped by waves higher than 4 meters. Extra piston pump stroke length is provided to accommodate changes in the mean water level due to tidal action.

SurfPower has a unique ability to assume a storm mode of operation that reduces energy production and structural loading by several times below that encountered under normal conditions. Further forces on the buoyant wings under extreme storm conditions can also be mitigated by increasing the operating pressure of the system (constricting the pelton nozzle orifices). In this condition, the buoyancy of the wings is not sufficient to overcome the resistance provided by the piston pump. The buoyant wings therefore remain submerged for most of the wave cycle, allowing the high energy wave crest to move over the pontoon without impact (as shown by the video on the home page CLICK HERE).

Scientific readers are encouraged to click on Parametric Design Study and SurfPower Computer Modeling Phase III for a detailed analysis of system energy recovery performance and storm survival strategy.