It won national exposure in 1725 when John Gow, reckoned to be Britain's last pirate, was captured there after his ship Revenge ran aground.

At only eight miles long and home to some 120 people, the island of Eday is famous for its seabirds, hilly moorland, and sweeping beaches.

The least fertile of the northern isles of Orkney, it was long noted as a major exporter of peat for fuel for the rest of the archipelago.

Now Eday could be supplying fuel again, this time from the waves round its shores where the tides run at eight knots or four metres every second. Such power could easily drive turbines for electricity generation and it is this potential that has thrown the island into the forefront of Scotland's renewable energy industry.

First Minister Alex Salmond was on Eday yesterday to open the testing centre for tidal energy, which is part of the European Marine Energy Centre (Emec).

The site consists of five berths for tidal energy converters, located off the south-west tip of the island. Each berth is connected by a subsea cable to an electrical substation at Caldale.

The power is taken ashore where it is made ready for transmission to the national grid, while the movement of the tide is constantly monitored. When all five cables are utilised to full capacity, there will be enough power generated for 1500 houses, but Eday is really about developing prototypes.

One company is already on site and the Dublin-based OpenHydro will be the first tidal generator to be connected to the UK grid from Orkney. A queue of other developers is forming, including Danish company Hilleke Power.

As Bent Hilleke yesterday looked out on the tide flows from the Fall of Warness at the southern end of Eday, he told The Herald: "We plan to come here because we really have no tide to speak of in Denmark, perhaps one metre off the west coast.

"It is a bit difficult to test a tidal generator when there is no tide but it is different here. I like that tide."

It was music to the ears of Emec's funders such as Highlands and Islands Enterprise. Chief executive Sandy Cumming said: "Strong tides, high waves, and winds used to be seen as a disadvantage for communities like Orkney but today they are an asset, helping propel Orkney to the forefront of an emerging industry of global importance.

"HIE, together with its partners, is delighted that Emec is becoming established as a world leader in marine energy and that this phase will consolidate its international reputation.

"No other facilities of this kind exist anywhere in the world. Scotland is currently at the forefront of research and commercialisation of wave and tidal energy generation."

There was enormous local pride that an island of around 120 people has been chosen for such a pioneering role. Council convener Stephen Hagan said: "We welcome the opening of this new stage in Emec's development. Orkney's abundance of renewable resources, especially wave and tidal streams, gives it an advantage in marine renewables.

"These resources support a growing cluster of public and private sector, and academic, activity in renewables in the islands."

The Orkney islands will also become home to the world's largest generating capacity wave farm, off the coast of Stromness, it was confirmed yesterday.

The development by CRE Energy, a ScottishPower offshoot, is expected to use four 750-kilowatt Pelamis wave energy converters to generate enough energy for around 2000 homes.

Mr Salmond said: "This project is another step towards fulfilling Scotland's huge renewable energy potential. Our natural resources mean we can be a world leader in new wave and tidal energy technologies."