This seems like a practical item and they seem to have done enough test work on the unit for it to have a chance to actually work. The first unit has now been installed on the seabed and real time trials will soon be underway. This fall should be 'make or break' for the concept.
It is simple and seems to be heavy duty (required for the ocean application). There will be some damage to the sea floor during installation but that will heal.
From the Aquamarine web site http://www.aquamarinepower.com/technologies/
Oyster® is a hydro-electric Wave Energy Converter, designed to convert renewable energy harnessed from ocean waves into usable electricity.
Oyster® consists of an Oscillator fitted with pistons and fixed to the nearshore sea bed. Each passing wave activates the Oscillator, pumping high pressure water through a sub-sea pipeline to the shore. Onshore, conventional hydro-electric generators convert this high-pressure water into electrical power.Oyster® is designed to be deployed in multi-MW arrays. With a peak power of 300-600kW per Oyster®, a commercial farm of just ten devices could provide
clean renewable energy to a town of 3,000 homes.