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The Mail’s Misleading Claim About Swansea Bay

January 13, 2017

By Paul Homewood




The Daily Mail has its own take on the Swansea Bay tidal lagoon.

Most of the article just rehashes the points made on other outlets, which mostly seem to have come from Hendry’s report and the Tidal Lagoon Power (TLP) website.

Intriguingly though, the Mail offers a vision of what might follow Swansea:


The ‘pathfinder’ project at Swansea would help with regeneration in South Wales, creating around 2,000 jobs in construction and manufacturing. It could go ahead as soon as 2018, and would take four years to complete.

If successful, further larger projects could be built at: Cardiff Bay; Bridgwater Bay in Somerset; Newport; Colwyn Bay and West Cumbria. If all six projects were built they could have a total capacity of 17.6 gigawatts, equivalent to around 30 per cent of the country’s current electricity capacity.

Cardiff would be more than three times bigger than Swansea and would create around 12,000 jobs and generate more power – around 2.8 gigawatts. This is comparable to the new Hinckley C nuclear power station, which will generate three gigawatts.


I have no idea whether the projected capacities are accurate, as nobody appears to have gone into that sort of detail yet.

But assuming they are reasonable, here are a few comments:



1) The capacity of Swansea Bay is set to be 320MW. Presumably the reference to Cardiff being three times bigger refers to the area of the lagoon. In terms of capacity, Cardiff at 2.8GW would be nearly nine times bigger.


2) A total capacity of 17.6GW would imply the five follow on projects would average 3.5GW.


3) TLP’s website gives a capacity utilisation of about 19%. At this level, six lagoons with a capacity of 17.6GW would generate 29 TWh a year, about 8% of UK’s total generation.

Although the Mail does refer to 30% of electricity capacity in the article itself, the headline 30% of our electricity is highly misleading, not least because very few people realise capacity bears little relation to actual generation.


4) In terms of CAPEX, the Hendry report estimates that follow on projects could work out 8-10% cheaper than Swansea.

(Note that this depends on the right framework! This suggests the government might have to cut lots of corners when it comes to planning, environmental concerns etc)




But assuming a figure of 9%, and bearing in mind Swansea Bay is costing £1.3bn, the next five lagoons could end up costing £64bn.


5) The cost of Hinkley Point is supposedly £18bn, but although it is only rated at 3.2GW, it is capable of generating 24TWh a year.

In other words, the total cost of six tidal lagoons could amount to £65bn, more than triple Hinkley Point, but for only 20% more power.


6) On top of capital costs, there are of course running costs.

The BEIS study, Electricity Generation Costs, published last year, estimates running costs, both fixed and variable, of £21/MWh for nuclear.

Their figure for tidal stream is £64/MWh. This may be well wide of the mark, but it is hard to see the cost of operation, maintenance, replacement of turbines, clearing of silt etc not being very substantial indeed.


7) There may be the opportunity for operational cost reductions in future schemes. But as Dr John Constable points out:

Perhaps, the technology has promise and might improve its productivity.

Unfortunately, this is unlikely. The load factor is principally determined by the character of tidal flows, and the optimal balance of generator size to lagoon capacity, which will not change significantly if at all. Improvements in the longevity and reliability of the materials, and thus reductions in lost output due to maintenance, are conceivable, but are not likely to be major considerations. Consequently, the load factor of future projects is unlikely to differ more than a few percentage points from the current figure of 19%. Furthermore, there is no likelihood that the capital cost of construction can be greatly reduced. While the concept of lagoon is novel, or at least untried, the major elements of the scheme, the turbines, and the impoundment are not. Indeed, the vast majority of the cost is in standard marine civil engineering to build the impoundment, a field several thousand years old, where major cost reductions are not to be expected.


8) Big play is made about the hope that tidal lagoons could last more than a century. However, what might happen in the 22ndC has absolutely no relevance whatsoever for the present or even foreseeable future.

It also has zero impact for the lagoon operators, because earnings so far in the future will be discounted to virtually nothing.

Indeed, one real concern is that they will take their profit in the early years of the project, and then do a disappearing act when things start getting tough.

A relevant point here is that the subsidy scheme TLP have proposed loads a large chunk of it upfront in the early years.


9) On top of all this, there will be the additional costs of providing standby capacity.


I’ll leave the final words to John Constable:


Even a brief review shows that this project is of low productivity and will degrade the productivity of the system of which it is a part. Furthermore, the technology has no realistic prospect of significantly improved productivity. If private investors wish to take the risk, by all means let them, but government should not gamble with consumer bills when the odds are so unfavourable.

  1. Athelstan permalink
    January 13, 2017 8:09 pm

    Once again, how many times? We are discussing the vagaries of some footling scheme and evading the obvious, to not addressing the monster* sitting, sniggering in the corner.

    In terms of energy provision there isn’t an argument to be made, insofar as environmental vandalism is concerned ‘it’ (the Swansea Bay tidal lagoon) is an abomination.

    It’s just pure green bollocks.

    *UK energy policy or, lack thereof.

  2. mothcatcher permalink
    January 13, 2017 8:53 pm

    From what I can glean of the Swansea project. Paul, there is absolutely no new technology involved. So it won’t be hard for the UK to be the ‘world leader’ in this stuff.

    The prospectus relies merely upon the scale of the project to generate (in the prospectus anyway) numbers sufficiently large that they don’t look too embarrassingly pathetic for the people who sign our cheques to notice they are being had.

    But they don’t seem to mind being had in the slightest, it seems.

    By the way – that NI biomass thing is a cracker, isn’t it? Funny that the BBC seems only concerned with its political consequences, not with the scheme itself (which, in a slightly different form, runs in Britain also)

    • January 14, 2017 5:00 pm

      The BBC have strained mightily to contain the NI RHI fiasco. I was compartmentalized on the NI part of their website for several months.

      I just wonder at what point does this tidal barrage bollox count as advertising? I’ve the complaint already drafted.

  3. martinbrumby permalink
    January 13, 2017 9:33 pm

    If serious consideration is to be given to this ridiculous proposal, why not dust off the scheme for a Severn Barrier? By having a two compartment enclosed lagoons it should be possible to generate continually except in unusually protracted dry weather.
    The old scheme had a number of other claimed benefits.
    The environment / environmentalists? Tell ’em to get lost. The environment would be different but still of some value. Look at the (now quite ancient but still effective) Rance Tidal Power Station.
    Of course, you’d have to repeal some environmental legislation and act a bit like the Chinese Communist Party. The greens would welcome that, surely.
    Yes but a lot more sensible than this pathetic proposal.

  4. Graeme No.3 permalink
    January 13, 2017 10:01 pm

    I sincerely hope that this scheme doesn’t go ahead because it will result in another outbreak of green hysteria about a tidal scheme in the Kimberleys (far north west of Western Australia). The tidal range there can be 14 metres on occasion but averages much less, down to 4 metres. Any ‘power station’ would have to include the cost of 3300km (2,000 miles) of high voltage transmission lines to the nearest market. The sites are mostly in National parks but then greenies are never bothered by destroying sites of natural beauty.

    I was in St. Malo last year near the Rance River tidal station, and noted the big tidal range; I read that it averages 8 metres peaking to 14 metres. I was told by a (definitely left wing) chap who had visited it in 2015, that they were having problems with weeds in the turbines. Whether this is true I cannot say but I am inclined to believe him.

    As the Rance River station has been generating since 1967 it seems a little parochial for The Mail to claim this would be the FIRST and that it was Revolutionary. Indeed tidal mills hae been around almost as long as windmills.

    • Graeme No.3 permalink
      January 14, 2017 8:53 am

      I note by the way that Rance Tidal supplies 0.012% of France’s consumption.

    • January 14, 2017 12:10 pm

      The minimum tide seldom gets a mention in marketing propaganda, when the sun and moon are on opposite sides of the earth, much lower tides than when they are on the same side.

      • January 14, 2017 12:17 pm

        Oops, minimum (neap) tides when the sun and moon are at a right angle.

    • January 14, 2017 4:14 pm

      Graeme no3
      You are absolutely correct about the Rance Barrage. It is inefficient – with an hours slack water at the high and low ends of the tide. I hadnt heard about the weeds in the turbines but it’s not surprising.
      And, if it had been successful, would one not have expected other barrages all along the coast?

      • January 14, 2017 5:03 pm

        There will be barnacles and mussels too….

      • It doesn't add up... permalink
        January 14, 2017 6:12 pm

        The reason La Rance was built was they only needed a 750m dam to enclose a 22.5km^2 section of river estuary with a good tidal range. Other prospective sites in the area require very ex(t)(p)ensive sea walls. You can see a map of proposals in the Rance presentation here:

  5. January 13, 2017 10:50 pm

    Points about 100 year life
    – Greenblob pushes the 5m sealevel rise by 2100 Hansen pushed.
    – Longterm value is offset by chance that time will bring CO2 free Fusion or guilt free CCS.

  6. Graeme No.3 permalink
    January 14, 2017 8:52 am

    I hope for the latter. Since ‘carbon’ is burnt to gain energy then storing it will involve energy (compression/cooling etc.). So the net result at the moment is loss of energy.
    The best, cheapest most efficient way of ‘capturing carbon’ is letting plants (and algae) do it, so ‘guilt free’ means the end of the ‘Global warming/freezing Climate Change in different directions’ scheme and in future we would then be mature enough to let nature take its course.

  7. It doesn't add up... permalink
    January 14, 2017 11:14 am

    Hendry’s full report contains the allegation to which the Mail refers:

    A number of illustrative portfolios for an optimal programme were analysed.
    These were compared with TLP’s proposed programme of six tidal lagoons. This
    analysis indicated that a programme of the top seven schemes (in terms of
    comparative cost per annual energy production) would provide 30 TWh of low
    carbon electricity per year from, a total installed capacity of 18 GW.
    In preparing these assessments, out technical advisers ITP have grouped together a
    number of tidal lagoons with certain characteristics, to assess which grouping might
    be optimum.

    p 16 ( or p 21 of the pdf)

    The currently proposed tidal lagoon at Cardiff would have an installed capacity of c.3 GW and an annual output of around 5.5 TWh, while the proposed tidal lagoon at
    Newport would have an installed capacity of between 1.4-1.8 GW and an annual output of between 2 TWh and 3 TWh.

  8. January 14, 2017 11:24 am

    “Although the Mail does refer to 30% of electricity capacity in the article itself, the headline 30% of our electricity is highly misleading, not least because very few people realise capacity bears little relation to actual generation.”

    True – which is why, of course, Brown and other AGW poltroons and crooks always refer to capacity as though it was the same thing as actual output.

  9. January 14, 2017 11:34 am

    If Swansea Bay lagoon needs 5 million tons of rock, imagine what all the larger schemes would add up to. It has to come from somewhere.

  10. It doesn't add up... permalink
    January 14, 2017 11:50 am

    Hendry doesn’t seem to understand the basic physics of tidal hydro:Following the tidal cycle, tidal lagoons would be capable of delivering the greatest output shortly after high and low tide (p 24/29)

    No: the power generated depend on the head – that is the difference between the levels, which will be at a maximum much later in the cycle.

  11. It doesn't add up... permalink
    January 14, 2017 12:01 pm


    The isolation of the generator from the fluctuations in sale price of power
    in the electricity market through the provision of a guaranteed CFD strike price would
    mean that there would be little economic benefit to the operator to generate during
    periods of high electricity demand based on the market price alone. Demand-based
    dispatch (where possible) will not be a feature of tidal lagoon operations unless
    operators are provided with an incentive to do so under an alternative regulatory

    So even more subsidies will be required? Something that was identified in the Trip Around Swansea Bay (which is still perhaps the best source for an evaluation of these schemes).

    Another Oops:

    It has been put to the Review that while tidal lagoons may not be able to provide
    dispatchable power, a number of tidal lagoons operated together as a portfolio could
    come close to providing a consistent level of generation throughout the day.

    While I believe that such a smoother output profile could have advantages, advice
    from our technical consultants is that operating tidal lagoons in a portfolio like this
    would still leave periods of the day when there was no output, particularly at neap
    tides. This is, in part, a matter of geography: the areas of the coastline that offer
    suitable locations for tidal lagoons do not offer a perfectly smooth output profile as
    their tidal cycles do not align

    Also covered in the Trip Around Swansea Bay.

  12. January 14, 2017 12:48 pm

    Here are some simple sums that show how futile and costly the idea of the Swansea bay tidal scheme really is:

    Scheme cost estimated £1.3 billion
    Scheme size 0.32 Gigawatts

    Equivalent capital cost per Gigawatt. £4.06 billion / GW overnight capital costs

    Gas Fired Generation assessed by US EIA £0.75 billion / GW overnight capital costs

    Comparative ratio of capital costs ~5.4 times
    So the proposed tidal barrage scheme is in any event some 5+ times more expensive to build.

    However if that was not poor enough as a prospect the announced capacity factors, (actual output / nameplate generation) are:

    Tidal scheme output achieved because of maintenance and tidal change over the day. The assessment that the barrage should produce electricity 14 hours out of 24 that can never be at full output so the net capacity figure for generation = ~19% of nameplate generation
    Gas firing is fully dispatchable with a maintenance estimate =~90% of nameplate generation

    So the actual costs / Gigawatt generated
    Tidal: £4.06/19% = ~£21.4 billion
    Gas Fired: £0.75/90% = ~£0.83 billion

    Comparative ratio of generation costs ~26 times

    So the overall effectiveness of a Tidal barrage scheme is even worse when its capacity percentage is taken into account.

    The same sort of simple analysis can be applied to all weather dependent renewable energy technologies where in the UK the measured capacity figures are as follows:

    On-shore wind max ~22%
    Off-shore wind ~30%
    Solar power ~9%

    Seeing how the use of fracking in the USA has reduced their CO2 output overall by ~25% in the last 10 years it would seem a very high price to pay to avoid CO2 emissions when compared to a consistent and reliable means of relatively low level CO2 emissions for electricity generation.

    • January 14, 2017 1:39 pm

      The renewables percentages show what a joke the term ‘back-up’ is in relation to their output. It’s more a case of the renewables backing up everything else, except at intermittent times and with variable success.

    • It doesn't add up... permalink
      January 14, 2017 2:31 pm

      A simpler sum: at £50/MWh (a high estimate of current annualised market price), the payback period is over 45 years without financing cost or maintenance costs. At any interest rate above 2% the project loses money consistently even if maintenance cost is zero.

      Incidentally, you left out the cost of gas in your calculation. It’s about £38/MWhe at the moment.

  13. January 14, 2017 5:51 pm

    All such engineering projects have preliminary reports on cost, results and profits. They are signed by PEngs. The assumptions are clearly defined. I wonder what they look like?

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