Tidal stream energy – poised to start full commercial operations

Britain’s tidal power

Rob Stevens hails the potential of a now-proven, abundant and indigenous source of green energy. All it needs is the kind of government backing Denmark gave to wind power

When Britannia ruled the waves, it was geography that played a big part. Today, that same geographical position offers Britain another – and very different – opportunity for a maritime lead: the development of tidal stream energy.

The tidal streams around our coast have the potential to provide a continuous source of green energy to the UK. The realisation of that power source would also fulfil an immediate strategic need to boost our indigenous supply of electricity as we shift away from fossil fuels and nuclear power in the run into Net Zero by 2050.

We are on the cusp of realising that industrial potential. A hitherto unsung group of British companies have developed tidal technology to the brink of full commercial operations and, with the right backing, are poised to take a global lead in this sector.

British tidal turbine companies such as Simec-Atlantis, Orbital Marine Power, Nova Innovation, Sustainable Marine Energy and others have between them invested over £500m in developing operational tidal turbines. This investment, along with government innovation grants, sees them poised to start full commercial production with their now-proven tidal turbines, the most capable in the world.

These companies have delivered over 35GWh of power to the grid in Scotland. They are also exploring export opportunities in Japan, Canada, France and Indonesia.


A mooring buoy heels in the strong tidal flow at EMEC’s Fall of Warness test site, Orkney. Photo: Colin Keldie

At the heart of the development is another British company, the European Marine Energy Centre (EMEC) in Orkney, which has provided a global test bed for over 30 tidal and wave technologies from all around the world. These all feed into what has become an almost wholly renewable-energy grid in Orkney, the excess power being used to make hydrogen used locally in a variety of fuel, power and heat applications. At the same time they are boosting the local and UK economies to the tune of £306.3m gross value added (GVA) and 452 jobs. All for an initial investment of £36m, as reported in the BiGGAR Economic Assessment of EMEC of January 2021.

On the back of this progress in Scotland, commercial tidal energy sites in the Isle of Wight (Perpetuus Tidal Energy Centre, of which I am chairman) and Wales (Morlais) are on the cusp of gaining environmental consent to start operations, with a view to generating electricity into the grid, some as early as 2025.

They are underpinned by over 20 supply chain companies around the UK, all chafing at the bit to move into full commercialisation in the next round of government energy auctions. The intentions are to deliver the at-scale turbine deployments that will consolidate the UK’s technological lead, continue to reduce the price of tidal energy, and put Britain at the forefront of commercial development.

Once again, the source of this advantageous positioning is our geography. The tidal flows in and out of our coastal regions are sufficiently strong and numerous enough to provide Britain with 50 per cent of Europe’s tidal stream energy capacity, or 10 to 15 per cent of the global resource.

But why is this such an exciting proposition? It gives Britain a new renewable energy industry, where 80 per cent of the manufacturing capability is British, providing new jobs and global export opportunities. All in the very coastal port areas that we are seeking to rejuvenate.

Environmental credentials

Environmentally too, the credentials of tidal stream energy are almost unassailable. This energy source is powered by the gravitational pull of the moon and sun on the waters of our seas, an inexhaustible source of energy for humans.

Water being over 800 times denser than air, tidal streams have a significantly more powerful energy generation capability than that of wind. This gives the system the added advantage of a site ⅛th the size of a wind farm for the same generation capacity. Also, it is at sea, taking up no space on our already overutilised land mass.

Encouragingly, and importantly, it has been shown that the slow-turning tidal turbines do not harm fish or large mammals. In fact, it has been postulated that the tidal sites could even create an artificial reef to protect and enhance the sea life in and around those areas.

The system’s grid credentials are impressive too. The tidal energy flow is predictable out to 100 years ahead, a characteristic which could reduce grid intermittency and wide fluctuations in the renewable energy market price during those cold, cloudy and windless days in winter. All of which could reduce the overall cost of energy.

Going one step further, exploiting the differing times between key tidal locations could provide continuous power to deliver a small but potentially significant element of base load, thus further reducing the need for fossil-fuel-generated reserve power stations.

Strategic advantages

CS Sovereign laying cable off the EMEC test site. Photo: EMEC

There are some compelling strategic advantages too. Britain today is not self-sufficient in electricity. We import around 10 per cent of our electricity through the intercontinental interconnectors, a figure that is likely to increase as we reduce the number of fossil fuel and nuclear power stations over the next few years. But our European counterparts are of course also decarbonising their electrical supplies, and some of them are reducing their reliance on nuclear power. At the same time, we are all seeking to electrify cars and heating, creating a significantly higher demand on the grids. The consequent increase in demand could, as we have seen recently, cause price increases, or supply shortages: an unattractive scenario for the UK, because our gas reserves are amongst the smallest in Europe and we already pay heavily for grid-balancing services to meet winter demand. All of these factors make us vulnerable to political and economic pressures of the kind that France threatened Jersey with recently.

If each of these sites has the same wider potential as is emerging on the PTEC site (300+ MW) then I estimate that the 10 known tidal stream sites would offer an additional generating capacity of  6–17GW per year (and more as technology improves) which is around 20 per cent increase in our indigenous generating capacity. The same amount as we imported last year. It would certainly help to restore grid self-sufficiency.

So why hasn’t the potential value of tidal stream energy been developed earlier? The reason is that up until now it has been too expensive. But the now-proven turbines and the potential environmental and economic advantages have persuaded the government to ‘have another look at tidal’, to quote Kwasi Kwarteng, the Secretary of State for Business.

The Danish example

The decision that we at Perpetuus hope the government will come to is that the wider economic value of tidal stream energy outweighs the short-term cost to the consumer – an argument evidenced by the success of the Danish government investment in wind energy; the £690m they invested in wind energy between 1980 and 2000 had by 2014 generated a turnover of £10.64bn, with exports of £6.4bn, and the creation of 29,000 jobs. By 2016 Denmark’s wind energy exports were higher in value than the UK’s defence industry exports.

The British companies that recognised that potential and have had the tenacity and financial backing to remain in business are now well positioned to capture a significant proportion of the global market share. The cost reductions they have eked out of their small-scale developmental deployments have added a granularity to the Offshore Renewable Energy Catapult (OREC) study of 2018, which predicted that at-scale turbine deployments would make tidal cost competitive by 2030. The next step could place Britain at the forefront of the tidal industry, presenting an industrial opportunity similar to that of the offshore oil industry in the 1970s and wind in 2000s.

Industrial renewal

It would breathe new life into the post-industrial ports around our coasts, bringing opportunities in the manufacture of turbines, underwater structures, moorings and power cables as well as boosting the ports’ maritime support elements. According to the OREC study, UK tidal stream industry could generate a cumulative benefit to the UK by 2030 of £1.4bn and support a total of almost 4,000 jobs. All of this in a marine energy global market with an estimated value of £76bn in 2050.

This is a huge opportunity for Britain: we are ideally placed, by history, geography, experience and a technological lead, to become the international market leaders in marine energy.

Rear Admiral Rob Stevens CB, Chairman of Perpetuus, joined the Royal Navy in 1966 and moved up rapidly, eventually becoming Head of the UK Submarine Service as well as Chief of Staff to the Commander of Naval Forces South. In 2005 he retired from the Navy and became chief executive of the British Marine Federation.