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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)

  • 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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