Project Blue: 400mw from Tidal Power

The sea has always played an important part in British history, and as the technology necessary to recover some of the vast amount of energy swirling around our coasts in the form of tidal currents improves, it looks as if it will continue to shape our lives in the future too.

There is an estimated 18 terawatt hours (TWh) per year of technically recoverable power in our waters – a staggeringly huge total, equivalent to the whole world’s average energy consumption for a day – and some of this enormous potential is now about to be harnessed.

Fastest Tides in the World

Around 40 percent of the UK’s tidal energy bonanza is located in the treacherous waters of the Pentland Firth, the narrow strait that separates the Orkney Islands from the northern Scottish mainland. It’s not hard to understand why so much energy is concentrated in such a small area. Twice a day, the North Sea fills and empties through this slender channel, generating some of the fastest tides in the world as up to an incredible 3 million tonnes of water per second pass through the gap, at speeds of 15 knots or more. All that adds up to an awful lot of kinetic energy!

Generating Capacity

Like much of the UK coastline, this stretch of sea-bed is owned by the Crown Estate, which has entered into lease agreements with a total of seven renewable energy companies for a range of projects with a total potential generating capacity of up to 1,600 mega watts (MW).

MeyGen is one of that seven, a joint venture consortium comprising Morgan Stanley Bank, International Power and Atlantis Resources, the British-based leader in the field, responsible for producing the AK1000 – the largest bladed tidal turbine in the world. In October 2010, they were awarded a 25 year operation lease to develop their project in the Firth’s Inner Sound, between the mainland and the island of Stroma, which is one of the area’s most energetic tidal stretches. With a capacity to provide up to 400 MW, the finished facility will be one of the largest ever undertaken anywhere on the planet

An Epic Scale

Everything about the project is on an epic scale, and completing it will ultimately involve installing up to 400 submerged tidal turbines on the sea bed, along with all the necessary ancillary equipment and infrastructure to allow the generated power to be used. By the time the phased programme of construction is finished in 2020, it is set to be producing enough power to supply 400,000 homes, having generated some 700 jobs in the local area in the process.

Even the first phase, which is intended as little more than a demonstration of the scheme’s potential, will deploy 10MW of capacity, using a mixture of TGL Rolls-Royce 500kW turbines and Atlantis’ own giant AK1000 1MW units – each one of which stands 22.5 metres tall and weighs 1,300 tonnes.

Flagship Project

Dan Pearson, MeyGen’s chief executive has described it as “the crown jewel” of projects in the Firth, largely due to the enormous tidal resource present, and the close proximity to the Scottish mainland, which facilitates connecting into the grid. It has, he says, “the potential to be a flagship marine energy project”, although he acknowledges that turning that potential into a reality is not without its challenges. The North Sea is, after all, a difficult environment to work in at the best of times, and any structure facing tracing tides and corrosive seawater needs to be very robust and reliable; maintenance is hardly going to be a simple matter on the bottom of the Pentland.

Never-the-less, all the omens seem to be good, and before long the dream of commercial scale tidal turbines installed beneath the sea to provide a significant proportion of the UK’s future energy needs will at last become a reality.

It looks as if Britannia really does rule the waves!