Aquamarine wave energy generator connected to the grid.

Alex Salmond will today switch on Aquamarines Power's Oyster wave energy generator, connecting it to the grid for the first time.

The device, just offshore from Billia Croo, Near Stromness in Orkney, will pump high pressure water to an onshore electric turbine.

This electricity will be fed into the National Grid to power homes in Orkney and beyond. A farm of 20 Oysters, claims the firm, will provide enough energy to power 9,000 three bedroom family homes.

The Oyster is designed to operate in water depths between 10 and 16 metres.