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Oscillating surge converter mounted on a railway system.

What if we could maintain wave energy converters more easily

Authors: Pekka Koivukunnas and Jukka Mikkonen, Elomatic Oy

Harnessing energy from ocean waves has gained more and more interest during last decades. Ocean waves contain lot of sustainable energy, but it is still not widely utilized. It has proved out to be challenging task to harvest energy from ocean waves. Environment is very harsh. Several different approaches are under development but no breakthrough solution exists so far. 

What are the state of the art technologies? What are the biggest challenges they are facing? How could we contribute to find solutions to those challenges?

Near shore wave converters 

For near shore applications, different kind of oscillating wave surge converters (OWSC, oscillating flaps) has been developed. The common feature is that they are hinged in a fixed position to the seabed.

Picture 1. Operating principle of an OWSC

The main challenge in existing designs is, that they are difficult to maintain. Everything must be performed underwater by divers in heavily moving water. Underwater service work is very expensive. Design must be very reliable and robust (long maintenance interwall) , which means high costs. But if it anyhow fails, some down time is inevitable.  An other problem is that every now and then, very big waves occur. Who knows if in the future, we will see even more of those extreme waves, due to the climate change? In those situations, there is a risk of damage, if the converter is not protected somehow.

Could there be some alternatives

If the problem is underwater maintenance, how could we avoid that? What if we would bring the device on the shore for the service? How could we do that?

One option would be to use rails which lead from main land into the sea. In shipyards it is common practice to have a rail system to take up and launch ships. See picture 2.

Picture 2. An example of existing railway system.

The possibility to take the wave converter out of water when needed, would enable much lighter, simpler and cheaper construction of the device.

What if we would use, instead of one massive unit, several smaller units. The whole production would not be down, even if one unit would be in maintenance.

Picture 3. Oscillating surge converter mounted on a railway system.

Could this kind of approach work? What are the drawbacks? Has someone already proposed this kind of solution? How would you develop this idea? What are the challenges with this idea? Would you like to develop it with us? Are there some other alternatives or ideas? Would this kind of arrangement enable broader use of OWSC type devices? Please, leave Your comments in comment field or e-mail us.

Next steps

We will continue analyzing this challenge and refining the idea of taking the converter out of the sea, with a systematic innovative and open approach. We will post our new ideas as soon as we can. If you like to join us in developing this idea, please let us know.