Scotland launches the world’s largest tidal power project

Scotland is beginning the installation of what will ultimately become the world’s largest tidal power station in the Pentland Firth near the Orkney Islands.

“The focus here is very much on creating a new, clean, no-carbon source of electricity that we can develop both for Scotland [and for] the rest of the world,” says Calum Davidson, the director of Energy and Low Carbon at the Highlands and Islands Enterprise, a Scottish government agency.

The project will ultimately anchor 300 or more enormous underwater turbines on the seabed over the next ten years, generating 400 to 500 megawatts of energy, creating jobs and helping Scotland reach its renewable energy goals.

Scotland has been a leader in wave and tidal energy for about 15 years, Davidson says. Most of the world's main manufacturers of tidal energy equipment have tested and developed their devices in Scotland. Prototypes have been generating small amounts of electricity to sell to the grid for three or four years. Now, they are moving into the next phase: putting four 1.5 megawatt turbines into the fast-moving waters off Scotland's northern coast.

A private company, Atlantis Resources, originally from Singapore and now based in Scotland, helped put together a £50 million (about $80 million) financing package for this first phase, which will be built during 2014 and 2015.

“Then,” Davidson says, “there's going to be what we call a ‘fallow year’ in 2016, where there's going to be a lot of monitoring to make sure there are no adverse impact on the environment. By the end of this decade, in 2020, 60 turbines will have been built.”

Because this is a brand new technology, a huge amount of work has gone into studying the possible environmental impacts, Davidson says. The financial closure last week came only after completing nearly four years of environmental studies.

“Nobody has done this before, to any great extent,” Davidson says, “so 2016 will be very much focused on monitoring the impact on things like marine mammals, the seabed, diving birds and fisheries.”

Because the tidal currents are so strong in that part of Scotland, Davidson expects the presence of the turbines will cause few problems. “The waters in that area can move as fast as four to five meters per second, which is really quite enormous,” Davidson says. “So the seabed actually doesn't have a huge amount going on in it — it's pretty much bare rock.”

In addition, seabed turbine blades turn much more slowly than, for example, offshore wind turbines. “Some major studies have shown that the effects are quite minimal and quite acceptable,” he notes.

Most importantly, the carbon savings could be very dramatic. “If we're looking at this very first, very modest six megawatts, it's going to save 14,000 tons of CO2 per year compared to coal,” Davidson says. “Once the big power station has been built, it's going to save a million tons of carbon per year.”

A concern often expressed about renewable energy is that it doesn’t operate all the time. Davidson says tidal power, unlike wind and solar, is “completely predictable and completely reliable.” A waterway like the Pentland Firth can generate energy about 20 hours a day.

“Tides are on a 13-hour cycle,” he explains. “There's only about one hour of the day when the tide doesn't move. The tide is moving fastest in the middle of those cycles and that's when you get the most power. … The expectation is some of these [turbines] will be working at maybe 30, 40 percent efficiency.”

For Davidson himself, the project has a personal dimension. “I come from the part of Scotland where this is being built out, so it's very, very satisfying to know that the very small part of the world where you come from is right at the heart of creating a whole new global industry based around no-carbon, underwater tidal power.”

This story is based on an interview that aired on PRI's Living on Earth with Steve Curwood