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Last week's poll: new surge for tidal energy?

Europe’s largest tidal array has been consented in the Pentand Firth off Orkney, a project that is expected to eventually generate up to 86MW of power. What will it take for tidal energy to make an appreciable contribution to the UK’s energy needs?

The overwhelming majority of respondents to last week’s poll believe much more government investment in tidal technologies is required, with 76 per cent agreeing with this viewpoint.

Only three per cent wrote off tidal entirely, believing it too small to make an appreciable contribution to the UK’s energy mix, whilst nine per cent took the view that the answer lies in large-scale projects to build tidal barrages at several estuary sites.

A wider view was taken by seven per cent who believe a concerted effort should be made to develop renewables rather than shale gas, and five per cent believe tidal will make a credible contribution to the UK’s energy needs through the development of grid-connected energy storage at sites with a high tidal flow, such as Pentland and the Irish Sea.

What will it take for tidal energy to make an appreciable contribution to the UK's energy needs?

As The Engineer reported on September 16, MeyGen will install the tidal array in stages, beginning with a 9MW demonstration project of up to six turbines. Construction starts in early 2014 with turbines set for commissioning in 2015.

This followed an announcement by DECC on February 27, 2013 that Meygen was one of two companies to take a share of £20m under the government’s Marine Energy Array Demonstrator scheme to support the development and testing of pre-commercial marine devices.

Speaking at the time, Greg Barker, energy and climate change minister said, ‘The UK, with its amazing natural resource and outstanding technical know-how is already leading the way on marine power for the rest of the world to follow, and I want to ensure we stay top of this table.’

What do you think? Let us know below.

Readers' comments (31)

  • I think with a bit of planning there are enough small inlets around the coast where smaller turbines could be put instead of looking at massive projects, which will give a faster deployment of resources and return on capital layout, by the way is anybody looking at inland waterways as the rivers(weirs) are still flowing 24 hrs a day and surely technology has leapt forward since our flour mills were invented.

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  • Tidal energy is low head hydropower with a velocity head of 0.25m. Conventional hydropower needs a head of at least 1.2 m to be economic. And this is for one way flow in fresh water!

    I am involved in a 5800 MW tidal energy barrage scheme with 8 m tides. It is uneconomic as is the even more difficult tidal energy schemes.

    They can never compete with shale gas and nuclear power.

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  • I agree totally with Terry Croft. There is a huge number of places where small, modular turbines could be installed, probably at similar cost to solar panels, and with much greater reliability. Being modular would bring economies of scale to manufacturing and help the economy, provided they are not made in China! Small is beautiful.

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  • I am interested by Bryan Leyland's comments, because the River Rance Tidal Power Station in France generates 240 MW and only generates on the outflow of water, that is a capacity factor of 40%. Annual Generation 600 GWh. The project has PAID for itself; built in 1966 the dam should last a minimum of a further 100years, unlike Shale Gas or nuclear that take centuries to decommission (See Calder Hall 1956). It is generating the cheapest electricity in France on an 8 metre head as per Brian Leyland's project. I was wondering if over 120 years it becomes far more economic to use tidal compared to nuclear power-stations that have a life GENERATING life of 30 years. Is the barrage pay back to long? Where presumably on shore power-stations give equivalent powerpower, but cheaper initial capital for a short operating life. The Severn Barrage is equivalent to 4 Nuclear Power Stations in generation capacity - unless the outer barrage is used then equal to 7 nuclear units or 15 GW. With decent maintenance the barrage could last 200 years and become a tourist attraction like the River Rance.

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  • I would love to see our subsidies for wind removed and invested in wave, tidal and nuclear.

    These really do seem to be significantly better options for Britain with its large coast line, fast tides and rough seas.

    Moreover the investment would go in to British universities, British companies and provide jobs for our engineers and manufacturers.

    Wind feels like a complete rip off designed to make land owners and German manufacturers richer at our expense rather than tackling the issue at hand.

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  • I have been working on a "micro" zero-head device (PowerTube) for four years and have (via scale model tests, calcs, CFD and tests of parts at full scale) got to the point of going as far as I can without building a full scale pre-production model. The unit is the size of a 20 ft ISO container and designed factory built and then moored like a pontoon. The intention is that 1000s can be installed around areas with water flowing at a few knots, both UK and world-wide.

    This is an idea that people have had over the years, and others around the world are working on similar devices in parallel with me. I have a patent granted and two more to be applied for when funds allow. The improvements I have discovered will make this a practical proposition. As with most successful products there appears to be a few key do's and don'ts.

    I have carried out market research and have several customers interested. In addition work with the EA and other planning authorities have informed my marketing brief from which a thorough Product Design Spec has been developed.

    I have sold (my leisure boat to kick things off) and then some equity to small scale investors which gives me half the funds I need and I have applied for the lottery that is the TSB Smart Grant for the balance. Turned down the first time I have just re-applied. I have not found any other funds at all. (MAS has some small grants which would be helpful, but funds in the order of £50k to £100k just don't seem to be around. I believe they were until the change of government (either party may have stopped the programme at the time).

    As a Professional Engineer working full time elsewhere managing the development of new products from concept to manufacture I know how to do this. The lack of help for small businesses and start ups makes life difficult. I don't expect it on a plate, and investors want to see that it works by visiting the prototype in the river. But there must be many good ideas where people can demonstrate good professional research and just can't get the funding to move it forward.

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  • Why should the government be expected to hand out cash to every potty idea that comes along? If your idea has any legs at all you will be able to get a company interested and leverage it from there. That's what we did with TidalStream, we got an investment from a German company and now we are looking with a Scottish utility at a very large deepwater project. For the hydro people, incidentally, you do not need a significant head for tidal stream... we can achieve 40% capacity factor on the same momentum exchange basis as wind energy.

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  • One has only to visually study the rivers Thames, Tyne, and Severn to see the enormous amount of tidal energy available. In addition, way upstream on many rivers throughout the UK where one has energy available from river flow. We should have national scheme to develop this and it is pollution free

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  • I think that a point has been missed with renewables, which is that we can't control availability. They can be switched off, to prevent overloading the grid, but can't be switched on when there is no wind or tide.

    In my opinion there should be more invested in energy storage, so that the available wind and tide energy isn't lost because it happens to occur at the wrong time of day. There are storage ideas out there, and some have been put into place, such as electrolysing water to gain hydrogen, compressing air or cryogenic storage, but nothing that seems to be of large enough scale to use for our generation issues.

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  • In response to Colin Harris - Tidal flow turbines can generate electicity 85% of the time and cant generate at turn of tide as no flow and cant generate either side as insufficient flow just before and just after turn of tide to turn under load driving the generator.

    Not only can we plant turbines in rivers we can plant in tidal races around the coast like the one along the south coast west of the Isle of Wight that Frobisher and Drake used in 1588 to keep out run the Armada and keep it out of the solent

    Tidal Flow Water turbines are reliable as the tides are and equally predictable and an area that UK plc must invest in to provide the majority of renewable energy supporting Nuclear baseload generation. As energy storage facilities increase we can gradually increase the proportion of renewable energy as UK plc energy demands rise like they will do in future.

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  • Bryan, the government has offered double price for nuclear power from the next power stations. Could your barrage be viable if you were offered the same. Also barrages double up as shortcut roads and rail links. Is income from a toll road taken into account?

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  • The government doesn't believe a Severn Barrage would be viable with an energy 'strike' price of less than £100/MWh and believes the current evidence suggests £160/MWh for the first 30 years of operation as more likely.

  • Colin Harris is right to say that energy storage is crucial to the success of renewable energy,especially in controlling the erratic supply from such devices. Bryan Leyland rightly says conventional Hydro requires 1-2 m to be economic, but if a device was capable of utilising 150% of available flow and if the energy were to be capable of being stored 24/7,would this not improve the economic argument. This is not wishfull thinking,it has been done,but you do need to challenge conventional wisdom to get the answers.

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  • Too much is made of the problem of Energy Storage! We have very little capacity at present and it is NOT a problem. Wind may be unpredictable but it is versatile. Wave and Tidal are entirely predictable. Nuclear will continue to make up a significant Proportion of our Power Requirements. If 20% came from Renewables (that is Ambitious so perhaps 15% is more realistic) and 40% from Nuclear then that still leaves 40 to 45% from "Other" sources !! That's a LOT !!

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  • Barrages across estuaries suffer silting which reduces the amount of useable water unless expensive dredging is done. Tidal barrages should be restricted only to inlets and bays that are not also estuaries. Estuaries should use free mounted flow generators that do not abstruct water movement or natural silt flow. A small loss in generated power should be recovered by lower initial build costs, lower and maintenance costs and as a bonus does not disrupt wildlife.

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  • Tidal generation does not work between tides, but tides are both predictable and there is lag along coastlines.

    If smaller generating systems are viable, more of them producing a distributed sytem along a coastline would ensure that a continuous supply is available.

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  • Jon, during neap tides all will generate very little indeed.

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  • I am in agreement with Rodney Harrap, not Brian Leyland.

    Combining a long investment horizon with other potential payback sources such as :
    Pumped storage options and maybe Road and rail links,
    and maybe
    Additional onshore wind turbines built on the surfaces of the Severn barrage or other barrages, these ideas could change the economics over the longer term.

    No- one seems to have an open mind about other potential benefits form schemes such as these.

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  • What people are nearly saying is, that tidal energy is the ONLY dependable and predictable source of green energy that exists and will continue to to do so whilst the sun and moon continue to exist.

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  • Whilst storage will be useful, it is not absolutely critical at this stage. So we should not make the deployment of tidal dependent upon storage.

    Last week we saw how this can work when wind delivered >13% of UK electricity supply (6GW). To accommodate this a number of gas stations were turned down, so saving the gas for another day. We are fortunate we have gas and we need to make the most of the opportunity it provides for a flexible supply to fill in around the harvested renewables.

    Now of course this affects the business model of the gas generators, because they cannot get guaranteed access (and therefore income) for their product, but that can be adjusted over time.

    So turning back to tide; it will be a useful and dependable contributor, but its scale (estimated by the Carbon Trust to be around 5% of UK supply) should be able to be accommodated into the networks using conventional scheduling processes.

    The thing that we DO need to concentrate on with tide (and wave energy) is the present shortcomings with the grid. Quite reasonably no one planned the grid to have large connections on the beach near the resource (with the possible exception of Anglesey... who are about to put another nuclear station up, so the grid may not be readily available there too).

    We ARE going to have to face the challenges of getting the wires to the beach. The size of the wires could be affected by storage, but frankly I'd not worry for the moment. Just get SOME wires in and lets see what we can do. We can optimise them for storage as we get towards maximising the harvestable resource.

    Wind link:

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  • There is also a propsal for a tidal lagoon in Swansea Bay. The key to these projects is storing the energy generated when its not needed and in this respect we have the leading technology provided by a UK company ITM PLC for converting this surplus to Hydrogen which can be pumped into the gas grid.

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  • We should think big. Use the whole Irish sea for tidal energy. It might need several dams extending to Ireland. The total energy present should exceed our needs if it can be harvested. So it must be worth some research on methods.

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  • Many of the coorespondents are talking of dams and heads as the means of quantifying the energy, missing the point that the major influence on the energy is the lunar and solar phases. I can tell from personal experience of fishing in the Thames estuary that the tidal stream energy is vast. I had nearly 1kg of lead on my line and it wouldn't hold on the seabed. My fishing line was strung out at about 45°. Surely then, as has been used in Scottish waters, is to use underwater turbines, without using the dams that are highly damaging to river and estuary natural enviroments.

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  • Finally a posting on wave power its got to be the way to go. wind is so unreliable & having the electricity utilities pay for them to be turned off is madness Im all for wave power the tide never fails unlike the wind.
    just need the government to support its development instead of all these eyesore windmills.

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  • Please don't mix tidal power and wave power.

    Tidal power is predicatable.

    Wave power, like wind, is not, being subject to the elements.

    Note: Tides around the UK are phased, so while it's turning at one place, it's running hard somewhere else. Sure, there is a (predicatable) difference in strength between neap and spring tides.

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  • I'm working designing tensile kite network structures for the harder problem of airborne wind energy... it's ace fun.
    Thing is the open source hardware designs we are producing are almost exactly analogous to a quality upside down solution for tidal or ocean current flows.
    Basically string a hexagonal tensed net across a flow. From each cell centre set a tensed twisting net tube of quasi 2d kite structures.
    Ropes and rags are so the way for lightweight flow to energy conversion.

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  • In regard to energy from the flow of water in rivers there are comments about energy storage. If we take the River Thames as an example, there are a number of weirs and locks that are used to control flow. These could be used also to maintain a variable flow through turbines to meet the variable demand. A 300mm rise in the river level causes no problems but is a great deal of stored energy. The same approach could be used throughout many rivers in the land. I am tasked at the moment to design a small hydro scheme using a 200 year old mill pond. The pond is large so we will use this to control the flow to when needed.

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  • I am all in favour of using tides as a way of generating electricity. At the same time the possibility of the West Antarctic ice cap melting and increasing sea levels cannot be ignored. Does anybody know what would happen if this occurred?

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  • Alternative power generation is essential for the future in the UK.
    Its development should be encouraged by government grants to develop its potential for local generation and consumption.

    However, the continual clamour for wind, tidal and hydro schemes, has become a distraction from the business of bulk electrical supply for, today, next week, next year and for the next decade at least.

    The UK’s electrical supplier’s policy for the reinvestment of the decaying UK electrical generation of base load power is based on the Nero fiddling, whilst Rome burns approach.

    The secure supply of base load electricity into the UK is nearing a tipping point.
    Where in order to maintain the electrical grid, wide scale power cuts will have to be made, and these will be at the maximum consumption periods, when consumers want and need to use electricity.

    We will all suffer serious social disfunctionality and great economic loss.

    ALTERNATIVE projects talk in MW mega watts, whilst what the UK base load needs, is GIGA WATTS, a thousand fold difference!

    The biggest tidal schemes of 90 MW and wind farm schemes of 300 MW, (subject to the if, buts and when they get up to their predicted outputs), is insignificant to a single 500 MW generator.

    What the UK needs is 36 x 500 MW generators to compensate for the fading out of the 60-70’s nuclear and coal fired builds.

    Assuming the UK’s electrical suppliers policy is allowed to remain in self denial.

    Then by 2024, the UK will be left with a wide variety of ALTERNATIVE generators running on hydro, wind, tidal, and thermal generators.

    A 1000+ highly dispersed localised generators operating 5MW – 10MW offering electricity at rates which will require a 2nd mortgage if you lucky enough to be connected.
    A scenario much like the market in the 1920-40’s before privatisation.

    The failure by the existing cartel of corporate suppliers to invest in the replacement of Nuclear heated generation and their abuse and dependency on the fast growing Network of International interconnectors, is taking the worlds best electrical generation system, to 3rd World supply system in less than 40 years of selfish corporate greed.

    When are we going to stop talking ALTERNATIVE and start talking electrical generation sense?

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  • there ia a constant flow of water over the weirs on the navigable inland waterways, surely it is feesable to use this to drive a small turbine, lo the lock byewash on the narrow canals could be tapped

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  • It's not just feasible, it's already being done. But often it's just not economic.

  • Sir, I have for many years maintained that we could and should generate power from wave & surge movement, we have in Briton one of the longest shorelines in Europe with some of the highest tides, I have submitted Ideas for underwater generators in the past & I'm sure there are many others out there with ideas to do the same, it needs the Government to step up & throw some of the billions they waste supporting Countries that have Nuclear programs, or sending aid to Countries with a space program.

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  • We are still waiting for the huge potential for power generation from the Bristol Channel, the worlds second largest tidal range and free source of power to the country. I am sure I.K. Brunnel would have jumped at the opportunity to build it.

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