The 12-tonne device was lowered into 55 metres of water, 16 kilometres off the coast of Cornwall.

Wave-power machines can be connected to the £42m ($64.5m) hub for evaluation of their performance.

Wave Hub was lowered to the seabed on 3 September, following problems laying the project's power export cable last month.

Four 300-metre ‘tails’ which serve the berths of the hub were then positioned on the seabed by contractor CTC Marine.

The ship Tideway Rollingstone is now placing the first of 80,000 tonnes of rock on top of the 25-kilometre cable connecting Wave Hub to the shore to hold it in place.

UK Science Minister David Willetts says: “This ground breaking project will strengthen the UK’s position at the forefront of the wave energy sector."

He adds: “This is a huge opportunity for UK business – the sector could be worth £2bn by 2050 and it has the potential to create up to 16,000 jobs by 2040.”

Maria McCaffery MBE, chief executive of Renewable UK, says: “Wave Hub will focus global industry attention on the UK and put the South West firmly on the map in terms of marine energy research and development.”

Wave Hub is being funded by £12.5m from the South West RDA, £20m from the European Regional Development Fund Convergence Programme and £9.5m from the UK government.