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Tidal energy: the silent giants of the Pentland Firth

  • Written by  Matt Maynard
  • Published in Energy
Tidal energy: the silent giants of the Pentland Firth (Image: SIMEC Atlantis)
30 Aug
A Scottish tidal power project in the Pentland Firth has the potential to supply enough energy to power 175,000 Scottish homes

Hidden under the churning waters of the Pentland Firth tidal race between the Orkney Islands and Mainland Scotland, are the four silent giants of the MeyGen project. The 1.5MW turbines placed on the seabed convert the kinetic energy of tides into electricity. The now operational project already has the capacity to supply electricity to 2,600 homes across Scotland and is classed as the world’s largest tidal stream array project in the world. Plans are afoot to potentially deploy 265 more turbines, but are dependent on the sector’s ability to compete with offshore wind.

Tidal race for energy

‘The big thing the tidal energy sector has – that potentially other sectors don’t – is we are entirely predictable,’ explains project development officer Cameron Smith. ‘Tides can be predicted years ahead.’

Shoreline wave and tidal energy accounted for only 0.04 per cent of the UK energy mix in the first quarter of 2018. Recent developments in tidal technology, as well as the improved ability to store the electrical energy generated, mean that statistic could be about to change.

Unlike solar or wind energy that are affected by atmospheric conditions – tidal energy generation is answerable to the Moon. Coal power plants have traditionally been used to provide reliable ‘base load’ power to the grid. While pressure is mounting to phase out coal due to its heavy C02 emissions, Smith believes tidal power is ‘coming of age’ and could plug the reliability issue of the renewable energy market.

Scotland is the place to do it. SIMEC Atlantis Energy, the company behind the MeyGen project, estimates that 25 per cent of Europe’s potential tidal energy is tied up in the powerful Scottish currents. A 2013 government study found that wave and tidal stream energy had the potential to meet up to 20 per cent of the UK’s electricity demand.

One of the four MeyGen turbines installed in the Scottish waters (Image: SIMEC Atlantis)One of the four MeyGen turbines installed in the Scottish waters (Image: SIMEC Atlantis)

Across Europe, tidal energy is estimated to meet up to ten per cent of electricity demand by 2050, according to Ocean Energy Europe. Plans to deploy 100GW of production capacity would power 76 million European households and create 400,000 jobs.

Visual impact of tidal projects is minimal. ‘A major scale off-shore wind farm close to the shore would be quite difficult for people to get their heads around,’ Smith explains. While the MeyGen project is close to land, he adds that ‘we are entirely sub-sea. The turbines themselves are quite small in diameter compared to off-shore wind projects. Water is much denser than air. You get a much higher power density when the blades are sub-sea. They work quietly away under water, causing nobody any harm.’

Employment of the local community by Atlantis is the main reason the MeyGen project has received strong local support, according to Smith. ‘Genuinely you have got the opportunity to create high quality, skilled jobs in a remote location.’ As the tidal industry develops into something that can be exported, MeyGen’s project development officer believes employment opportunities will continue to grow. Smith draws a comparison to the historical increase in jobs and skillsets created by the British oil and gas industry.

The MeyGen turbine being installed (Image: SIMEC Atlantis)A MeyGen turbine being installed (Image: SIMEC Atlantis)

Shifting tides of offshore energy

The Crown Estate owns British seabeds. MeyGen obtained a lease lasting 25 years for its operations. ‘We are good at this stuff,’ Smith says of the British auction process and regulation governing offshore development. ‘We’ve learned from oil and gas leasing. We (the UK) have been doing it for a very long time.’

Now the tide seems to be turning from fossil-fuel to renewable energy generation in the North Sea. Atlantis is benefiting from both the labour market and the facilities established by the legacy of the oil and gas industry in the area. ‘An established supply chain, experienced in working the harsh conditions of these waters,’ is cited as essential by Atlantis in developing the MeyGen project. Nor is Smith a detractor of the role the fossil fuel industry continues to play in the increasingly varied North Sea energy mix.

‘You have got off-shore wind being built,’ Smith explains of Scotland’s biggest offshore wind farm, the Beatrice project, soon to be completed near the MeyGen site. ‘You’ve (also) got oil and gas decommissioning and recommissioning. Tidal can be complementary… to other offshore activities, providing similar types of employment. When there is a downturn in oil [employees] can move to our sector, and vice versa. Once we are established, there is the opportunity to export machinery, potentially to export expertise, and to do project development and take joint ownership in other geographical locations.’

Smith won’t be drawn on the threat that tidal power’s increasing market share could have on competing industries however. ‘The oil and gas industry has been nothing but helpful,’ he assures. But as more turbines are installed, and economies of scale are reached, Shell will surely be feeling the pressure on its traditional extractive industries.

The waters of the Pentland FirthThe waters of the Pentland Firth

The future of North Sea energy generation

It’s choppy waters currently for North Sea oil and gas investment with big players exiting, and others entering and acquiring assets. Shell claimed in August that its productivity problems were now things of the past, while celebrating 50 years of extraction in the area. Instead of slow-down, it doubled down, claiming it will be extracting fossil fuel products from the North Sea for 50 more years. Elsewhere it was criticised for 50 years of climate change denial; its anniversary announcement scorned for its complete oversight in curbing C02 emissions.

MeyGen tidal power project is not without its own problems. Of the four different turbines deployed at the Pentland Firth site, its Atlantis Resources turbine has continued functioning. Two of the three German Andritz Hydro Hammerfest machines, however, reported problems with their generators in July, and are being retrieved for unscheduled repairs.

The industry as a whole suffered a setback at the end of July when marine renewable energy giant and innovator, Naval Energies, announced it was stopping investment in all tidal-turbine projects. The French company cited uncompetitive costs of energy creation, and an inability for the sector to compete with the more mature technology of fixed bottom offshore wind projects. In the UK, the £1.3billion Swansea Bay tidal lagoon proposal was rejected in June. A government assessment concluded that other low carbon alternatives could provide electricity at lower cost.

With offshore wind projects being preferred in a recent round of government subsidies, MeyGen and the tidal energy sector will need to continue to lower energy production costs and bolster confidence in the nascent technology before installing more turbines. If they get it right, the potential of the UK’s underwater giants is enormous.

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