More info on this at
https://en.wikipedia.org/wiki/Pelamis_Wave_Energy_Converter .
The company was bought by E.ON and the project was killed. At that time, there were working 450 Kilowatt prototypes (see the video). 450 Kilowatt is a power volume that took wind power plants over three decades (about from 1970 to 2000) to achieve.
The technology was then apparently copied by a Chinese company.
The other, extremely brilliant idea in this specific concept is that it limits the force of the elements which the machine is exposed to.
Wave energy converters have the general problem that in storms and high waves, the immense forces tend to destroy the machine.
This device solves that problem by using a mechanical coupling to the ocean surface, a kind of mechanical oscillator. The waves are an oscillation and they couple to the mechanical dimensions of the device, which couples to specific wave lenghts - like an amateur radio receiver. Differently from electromagnetic waves, the power in surface waves increases with longer wave lenghts. If the waves become strong in a storm, their wavelengths become larger, and therefore the mechanical coupling of the device becomes weaker. It just floats on the very big waves.
This protects the device.