“SCOTLAND as a whole has definitely the lion’s share of the UK’s tidal stream energy resource, and probably in excess of 25% of Europe’s.”
Oliver Wragg, the commercial director at Orbital Marine Power Ltd, is optimistic about the future of one of the more overlooked renewable resources: the ocean’s tides.
Wragg, who also sits on the board of Ocean Energy Europe, said there is a particular opportunity in Scotland – and Orkney – to take a world-leading role in the development of the emerging green energy technology.
Why Orkney?
“If you’re going to pick the ideal location to go and build out tidal stream energy, it’s there,” Wragg says of the UK’s second most northern archipelago.
The Orkney islands sit between the North Sea and Atlantic Ocean, where the tidal churn is predictable and strong.
“The locations up there are world-leading,” Wragg says. “To put it into context, we estimate globally there is about 100GW of tidal stream energy that can be harnessed. The UK has in the region of about 11GW, so there’s over 10% of the global market based here, and a large percentage of that is [around Orkney].
“You’ve got some sheltered environment, excellent tidal flow, and a really engaged community who understand the benefits of tidal energy.”
Late in February, the SIMEC Atlantis Energy’s MeyGen project – based 20 meters under the waters of the Pentland Firth between Orkney and the mainland – became the first tidal array in the world to generate 50GWh of energy. On a 6MW capacity array, that works out at roughly 1.4GWh per MW per year.
Graham Reid, chief executive of SIMEC Atlantis, said: “These figures might not seem big compared to technologies that have been state-funded for decades, but when they are compared to what they produced at the same stage of their development phase, we are already producing more value for the UK economy, more electricity, and a better price for consumers.”
Orbital’s 2MW O2, “the most powerful tidal turbine in the world” (pictured above), is anchored at the Fall of Warness, west of the North Isle of Eday. Wragg says it is on course to generate 3-3.5GWh per MW per year.
A Scottish knowledge base
The success of the oil and gas industry in Scotland provides a template which tidal energy could follow, Wragg explains.
“The oil and gas fields in the North Sea were some of the easier to access, it’s relatively shallow, relatively sheltered. It’s an ideal stepping stone. We developed this knowledge base with Aberdeen as the epicentre that is now exported globally.
“By having that on your doorstep you’re able to build that domestic market.”
Wragg says that tidal potential on Scotland’s west coast (specifically around Isla) and up in Shetland means there is the chance to develop a world-leading industry, with a new knowledge base ripe for export.
Tidal vs other renewables
“If the sun doesn’t shine and the wind doesn’t blow, the tide still flows,” Wragg (above) says.
The “highly predictable” nature of tidal energy gives it an advantage over other renewables, but the costs involved are much higher, and the technology is “15 or 20 years behind” sources such as wind.
However, many of the internal components for a tidal turbine are similar to those used in wind power, so as the one becomes more advanced and efficient, the other benefits.
While this can give tidal a “head start”, Wragg says that the resource has been left “out in the wilderness in terms of government support” amid an auction system that pushed tidal to the bottom of the pile.
However, ring-fenced funding is looking to turn that around and momentum is building behind tidal as “we’re able to prove that this is something that works, we can maintain it, and we can harness that predictable energy”.
Wragg explained: “Effectively, we are all competing in this auction between tidal stream energy, onshore wind, offshore wind, solar, geothermal, all of these. If it’s just an auction for cheapest cost, you’re going to have zero with tidal energy … because of where we’re at in terms of stages of development.
“Once you go offshore, costs increase by a factor of ten, and once you go sub-sea they increase by a factor of 100. We saw that with early offshore wind. The first generation of tidal turbines were all bottom-mounted … but by being floating, our operating costs are much cheaper, if something goes wrong the team can go out on a small vessel and fix it in minutes or hours.”
The next frontier for tidal technology
Looking towards the future, Wragg points to potential tidal projects across the globe, from the Bay of Fundy (above) in Nova Scotia, Canada, to France’s Normandy coast, to Alaska, Indonesia, and Japan.
And there is still more potential for tidal stream technology.
“There are three large ocean currents, the Gulf Stream, the Agulhas Current, and then the Kuroshio Current, so these are the next frontier,” Wragg says.
“If you imagine offshore wind to floating wind, our bigger picture will see us moving from tidal stream to ocean currents. In some locations, we believe the technology isn’t too far away from that.”
With a knowledge base building in Orkney and elsewhere, there is a chance for Scotland to lead the world.
