Finding energy in the Shetland tide

There are few things as regular and predictable as the tide. It’s possible to pick a beach and know exactly when high tide will be, a hundred or a thousand years from now. Dictated by the Moon and the Sun, these gravitational pulls are as regular as clockwork.

In Bluemull Sound, the stretch of water between the Shetland North Isles of Yell and Unst, the world’s first offshore tidal energy array is turning this great daily rhythm into electricity. While boats travel across this beautiful stretch of water to the fishing grounds to the north of Shetland, three turbines have been spinning away 20 metres under the surface since 2016.

Installed and run by Edinburgh-based Nova Innovation, a higher performance fourth turbine was added in the autumn of 2020, as part of the EU’s €20 million EnFAIT development project.

“We believe this is the next big thing in clean energy,” says Nova Innovation’s Engineering Director Gary Connor, who has a PhD in power generation and co-founded the business with CEO Simon Forrest in 2010. “In the UK, mistakes were made with the strategy for developing wind turbine technology. The UK has the largest offshore wind capacity in the world, but most of the turbines are made in Denmark and Germany. This is a chance for Britain to be a world leader in tapping a virtually unlimited energy source, making tidal energy mainstream.”

It has been estimated that tidal energy has the potential to supply at least 10% of the UK’s electricity needs. The reasons there are still so few tidal energy arrays around the world is largely down to the early development stage of the technology and the challenges of operating and maintaining equipment in a harsh marine environment . But, compared to wind, tidal energy has the advantage of being completely predictable, and with minimal visual or environmental impact.

With the tidal energy array in Bluemull Sound, Nova has intentionally started small, with the first three nine-metre, 100 kilowatt turbines able to power around a hundred homes in total. These were installed in partnership with Belgian renewable energy developer IDETA (ELSA), with support from Scottish Enterprise, and a supply chain that was 80 per cent Scottish. In 2018, the Bluemull turbines were linked to a Tesla battery, effectively creating the world’s first grid-connected tidal energy power station able to deliver baseload electricity.

“We’re starting small, and walking before we start running,” says Connor. “In the UK, a lot of wind turbines started out very big, but weren’t financially viable, so investors lost confidence. We’re making sure everything works properly before we scale up.”

Part of the EnFAIT funding is about studying tidal energy in action, analysing everything from its cost-effectiveness to its impact on the environment. Using a direct drive generator instead of a gearbox, the new 100kW turbine installed at Bluemull in the autumn reduces the cost of generating energy by 30 per cent, a big step in making tidal energy commercially viable. According to Connor, Nova’s tidal arrays are already more cost-efficient than the diesel power stations used in many remote areas around the world. “And the more we do this, and scale up, the more those costs will come down.”

With the turbines held down by their mass alone, Connor says that the impact of the Bluemull turbines on the seabed is minimal, and that they’ve analysed more than 20,000 hours of footage and not seen any fish struck by blades, which tend to avoid the area when the tide is running strongly.

Nova Innovation isn’t just focused on Shetland. They are developing a 1.5 megawatt array in Petit Passage – a beautiful corner of Nova Scotia, Canada – starting with five turbines in the next 18 months. There are also early-stage plans to build an installation at Bardsey Island, off North Wales’s Llŷn Peninsula, and Connor says that Nova Innovation is in talks with countries like Japan and Indonesia to build tidal arrays in areas which have traditionally had diesel power stations.

Meanwhile, in Orkney, home to the European Marine Energy Centre, more than 30 tidal energy devices have been tested since 2003, including a larger 2 Megawatt turbine developed by Orbital Marine, another Edinburgh-based firm, which is now planning a new 4MW tidal energy farm, with plans to be operational in early 2021.

But Shetland was the first to have an array of turbines, and for a number of reasons. One is that the Bluemull Sound tides are perfect for a small-scale project like this: strong and consistent, but with enough let-up that turbines can be installed relatively easily. Perhaps more importantly, Nova were initially drawn by the islands’ receptiveness to a project like this, especially the North Yell Development Group, which was involved in the initial installation in 2014.

“We wish everywhere was like Shetland,” says Connor. “It’s an incredibly resourceful place where, if you go away in the evening with a problem, someone will have come up with a solution by the morning. For us, it’s been a combination of things that have been so helpful: there’s the engineering know-how, with so many reliable and experienced people to call on from working so long with maritime and oil industries, but also this sense of community where peoples’ natural inclination is to help each other out.”

Meanwhile, Shetland has wider plans to become a hub for renewable energy, with the 103-turbine Viking Energy wind farm the most notable new development in a broader plan to provide five per cent of the UK’s clean energy needs by 2050.

“It’s really just the beginning,” says Tom Wills, Nova Innovation’s Shetland-based Offshore Manager, who ran as a candidate in the Shetland by-election last year. “I grew up surfing, sailing and windsurfing here, and was always fascinated by this idea of creating our own clean energy from the natural resources we have. We need to make sure we scale up in a way that creates sustainable jobs and benefits the local community, but it’s so exciting to think of Shetland as a centre of clean energy. We’re hoping that tidal energy becomes an even bigger part of that.”

For more on Nova Innovation, visit their website.