In February 2010 we asked the company Niras if they could do an energy calculation on WavePiston. Niras is an engineering company that delivers independent consulting world wide. We had done our own calculations, but were a bit skeptical about the results. The results from Niras Showed that we had not been all wrong. But that we had missed an importent factor - the Froude-Krylov force.

The calculations by Niras proved that each WavePiston wing can harvest more than 5% of the energy contained in a wave.

Conclusion from report is the table above: To evaluate how many units to form the WavePiston system based on the analytical estimates one may compare with a single large modern 5 MW wind turbine. The number of units of the WavePiston system is estimated so that it at least produce 5 MW, as shown in the Table 3. The last column in table 3 gives the ratio between the area of a unit (i.e. two plates), Ap and the water depth times the wave height, h0Hs. Together with the capture width ratio Ceff it is clear to see that the larger the plate is compared with h0Hs the more power from the wave is absorbed by the system. The unit with 1.5x4 m (plate A) requires 60 units with wave case 1 to reach 5 MW while the unit 2x7 m (plate B)

requires 19 units. This means that the assumption of no flow interaction between plates is not realistic as in this case the plates have to be spaced less than than the wave length to have practical dimensions of the WavePiston system. The flow around one plate will affected due to the presence of the nearby plates. The transmitted wave is affected by the presence of the plates and the reflection and scattering of the waves and must be taken into account, as reported by Stiassnie (1986).