The proposition that the merits of Offshore Wave Energy can be judged according to the performance of primary deployments of three Pelamis vessels - well to call it hasty would be an understatement.

Moreover, to compare the very first Pelamis' performance with that of the massively deployed Onshore Wind turbines in terms of finance & energy returns further indicates a strange partisanship, particularly as embedded carbon-emissions and public opposition are excluded from comparison.

Outright errors, such as the guess of wave being even more intermittent than wind, when even basic experience of the sea teaches that waves continue long after wind has died away (and sometimes they even arrive from afar without their causative winds) and the mistaken past capital pricing of Onshore Windpower, further diminish the credibility of the critique Luis has attempted.

This is a pity, for Pelamis needs critique as being a cheap & cheerful expedient response to political funding constraints, rather than an efficient converter of a very major energy resource. [Back in the '80s the EU15 commissioned research into the wave energy resource which reported that it could potentially supply 80% of EU15 power requirements].

Pelamis, by its tiny frontage (5ms) compared with its length (450ms) and required sea-space (notionally 2x450 x 2x450 = 810,000 m2 = 0.81 km2) takes up a very large area of sea and length of wavefront per metre of wavefront processed. The latter ratio is around 5 : 900 or 1 : 180. Thus it makes rather poor use of the resource, and would need many serried ranks of vessels (& their moorings) to start getting even a minor fraction of the resource harnessed.

The wave energy tech that has attracted most research worldwide is called OWC (Oscillating Water Column), wherein passing waves are made to rise and fall within a chamber. This allows air above the water to be driven through turbines, with the advantages both of compressibility and of relatively minor containment stresses compared to those of using seawater as the working fluid.
The potential is for many wave chambers to be set in a matrix under a V-shaped floating platform to receive waves sequentially, thus providing high-pressure air in some chambers at the same time as low-pressure air in others, thereby greatly enhancing the air-pressure differential across the turbines and thus their conversion efficiency, while also multiplying many-fold the wave-frontage that is being swept.

Needless to say, this is a proposed concept, not a prototype being launched next week, but I hope that its outline gives some idea of the potential future importance of batteries of Offshore Wave Energy vessels as being one of very few sustainable energies to offer city-scale power supply.
Thus the idea that wave energy should be dismissed on TOD as merely a dubious niche-market option is plainly nonsense, but it may perhaps be of interest for the established "renewable" energy lobbies to try to promote.

In assuming that Luis has been misled by such partisan arguments against Offshore Wave, it is to be hoped that he'll now reconsider.

Regards,

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