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UK's marine energy reserves are too promising to be ignored

Marine energy – such as energy from tidal and ocean currents – is the ‘best of the best’ amongst green energy sources: it has the greatest potential (in theory, the planet’s oceans could supply the entire world with renewable energy), tidal and ocean current  power plants are under water and therefore completely invisible, they produce electricity from 100 per cent renewable energy sources (the water in the globe’s oceans will always move around, well, at least until the sun swallows the moon), they are safe, and the icing on the cake is that they actually have positive environmental effects. Positive? Yes, studies have shown that marine life thrive in marine energy parks. 

The UK and Irish waters are especially promising for marine energy, due to the islands’ geographical location. UK and Ireland can provide 25-50 per cent of total European marine energy, according to a new report from RenewableUK. The marine energy industry has been forecast to be worth £6.1 billion to the UK economy by 2035, and displacing up to half a million tons of CO2every year by 2020.

The total amount of wave and tidal stream energy in UK and Irish waters is estimated at 935 TWh/year. Of this, some 98 TWh/year of marine energy resource has been assessed as being economically recoverable with today’s technologies. The current UK annual electricity demand is about 350 TWh/year. No wonder the UK and Ireland are frequently called “the Saudi Arabia of marine energy”. Other countries with great marine energy potential and political or commercial marine programmes already under way are the USA, Canada, China, France, Portugal, Spain, Chile, New Zealand, Japan, China, South Korea and South Africa.

Deep Green

MInesto’s ‘Deep Green’ underwater kite technology is designed to extract energy from low-velocity water flows

So why isn’t marine energy more developed and used, and more talked about amongst politicians, decision-makers, environmental movements and the general public? Well, as with all emerging technologies, there are a series of obstacles to harvesting cost-efficient marine energy:

·        Capital costs of marine energy projects are currently relatively high compared with e.g. wind projects.

·        Lack of funding for research, development and demonstration on technology, to both academies and private companies (many of them start-ups). The development of marine energy needs support from both private investors and governments.

·        Regulatory issues. For instance, it can take up to two years to get a site permit for offshore testing.

·        Market challenges like long development timescales, grid connections (or lack thereof), and lack of performance assessment standards.

·        Challenges in offshore operations: the sea is a tough environment in which to install, operate and maintain marine energy power plants. In many tidal energy sites the currents rarely go below 1m/s.

·        Limited locations where tidal and ocean currents are strong enough to be technologically and economically viable to harvest.

Let us take a look at the last two of these obstacles. They can be overcome with new developments in marine energy technology. The fact that most marine energy power plants developed so far can only operate efficiently in currents that are really strong reduces the number of good locations for marine energy parks and complicates offshore operations for installation, service and maintenance. After all, it is not easy to work in strong currents.

Just recently, Minesto launched an ‘underwater kite’ in the waters off Strangford Lough, Northern Ireland. The ‘kite’ consists of a wing and a turbine which is secured to the seabed with a tether and moves fast in an 8-shaped path in the tidal or ocean current. The hydrodynamic principle on which this technology is based allows for the kite to move at speeds of up to ten times that of the flow of water it is operating in. This marine power plant is the only available solution to cost-efficiently produce electricity from slow tidal currents.

There are many more sites with low velocity tidal and ocean currents than there are with strong currents. So the possibility to operate cost-efficiently in slow currents extends the total potential for renewable marine energy significantly. In the UK, the amount of energy which is possible to harvest from tidal currents is doubled when low velocity currents are included.

Slow currents are also much easier and less costly to work in; installation and maintenance can be carried out with small Multicat vessels as the ‘kite’ only weighs seven tonnes for a 500kW turbine. The kite’s robust anchorage system means that no tower is needed. Only attachment and detachment of the kite needs to be done offshore. All this reduces maintenance costs and operating expenses, and results in a cost-efficiency that is comparable with conventional energy sources.

Even sheer physics is on the underwater kite’s side: it operates 30-60 meters above the seabed, i.e. higher above the seabed than a power plant fixed on the seabed. 75 per cent of the marine energy is in the upper 50 per cent of the water column (and only 25 per cent is in the lower half). So a power plant that operates higher up in the water will capture more energy than a conventional marine energy power plant.

In conclusion, many or all of the obstacles to efficient marine energy can, and will be, overcome given enough time and funding. New power plants that can operate cost-efficiently in slow currents is one big step forward. There will be other important steps. Marine energy is simply too clean and too potentially beneficial to the planet and its inhabitants to be ignored by politicians, investors and the global energy industry.


Anders Janssen is chief executive of Minesto, a Swedish energy technology company in the field of marine energy. Minesto has a patented and proven technology (Deep Green) to harvest energy from low velocity tidal and ocean currents. See

Readers' comments (7)

  • A much better idea for government to invest in marine energy generation that will be used and a benefit to everyone than a high speed rail link used by less than 4% of the population!

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  • What the UK needs is a low-cost and reliable power supply that is available when needed. It can get this from nuclear, coal or shale gas.

    Wind power, solar power and marine power only exist because of huge subsidies based on the mistaken belief that man-made carbon dioxide causes dangerous global warming. Even if it did, it would be cheaper and better to convert from coal to gas or to build nuclear stations than to waste money on intermittent and maintenance intensive new energy technologies.

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  • There`s been a generator off la Rochelle since the late seventies so there`s much to be learned from their experience, as well as any new tech. What I cannot understand is that the government always drags its heels on projects like this that would really help our power needs and create an industry to sell on around the world.

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  • Whilst I'm greatly in favour of trying to exploit this wonderful natural gift that we seem to be sat in, there's a bit of me that still thinks "if it sounds too good to be true, then it probably is"! Might there be a danger that if we get too good / efficient at extracting energy from undersea currents, we'll upset something else?

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  • We need to differentiate between that of a tidal barrages and that of a tidal turbine.

    Tidal barrages, such as that proposed in the past for the Severn, will yield extremely high amounts of energy. However the high environmental impacts need to be reconciled. The UK has a total of 8 of the 20 global barrage sites in its waters.

    Turbine technology is expensive, yields a fraction of that of wind farms and has a high maintenance burden. Unless significant advances in technology can be made it will remain unviable as a wide-ranging solution to our energy problems.

    Bearing in mind off-shore wind farms remain comparatively expensive I see no reason why an underwater turbine can be any better an investment unless very heavily subsidised by generation tariffs.

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  • The biggest difference between wind and tidal energy is that tidal energy is constant and predictable.

    Correct me if I'm wrong but didn't I see a report recently saying that one large off shore wind array had only produced 7% of its predicted output in the 3 years it had been in operation?

    We need a mix of technologies to give us energy security, which certainly is not the case at the moment with our reliance on imports of gas, coal and oil.

    We also need a predictable energy source to take up the base load of our generating capacity and wind certainly will not do that.

    Why is this and previous government so obsessed with wind power? We don't manufacture it or I suspect install or maintain it, so the taxpayer subsidy simply leaves the UK to benefit other country's economies.

    The future despite the sceptics still lies with fusion, but in the meantime other technologies need to take up the slack and it would be immensely beneficial if the subsidy money found its way into British engineering companies, not only for them but the UK economy as well

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  • Wave Energy, just think about how much a 3metre wave weighs! Just look at our website for a brief outline on how our device uses that power.
    It sits on the bottom of the ocean has no moving parts (except for a turbine) a life time of at least 40 years'

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