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Swansea Bay Tidal Lagoon Criticised As Too Expensive

February 24, 2015

By Paul Homewood  




The Telegraph report:


Plans to build the world’s first ‘tidal lagoon’ in Swansea Bay have suffered a setback after influential consumer charity Citizens Advice said the project was “appalling value for money” and should not receive subsidies.

Ministers are preparing to begin formal bilateral negotiations with developers over the proposed green energy scheme – a £1bn, six-mile sea wall with turbines to harness the power of the tide, which has already been included in the National Infrastructure Plan.

Tidal Lagoon Swansea Bay is thought to be seeking a guaranteed subsidised price of about £168 for every megawatt-hour (MWh) of electricity it generates over a 35-year period – almost four times the current market price of power.

But Citizens Advice has said that the plan would “squander” billpayers’ cash, leaving them paying a higher price for electricity than from any other major UK green project to date.

New offshore wind farms are offered about £140/MWh while onshore wind gets about £90/MWh, both for 15-year periods.

The planned £24.5bn nuclear plant at Hinkley Point has been offered £92.50/MWh for 35 years. If built, the tidal lagoon would be “per unit of output, the most expensive significant renewable energy project in Britain”, Citizens Advice said.

It urged ministers to allocate the finite green energy subsidy budget to the most cost-effective projects.

In its response to a Government consultation on the planned negotiations, the charity said the process would repeat mistakes made in talks over Hinkley, with an “opaque negotiating process, lack of scrutiny of cost effectiveness and excessive politicisation of the decision”.

It suggested both projects were “boondoggles” that were in favour due to “skilful lobbying and political friends”, with “worrying implications for the consumers who will be obliged to pay for it all”.


Artist’s impression of the proposed tidal lagoon in Swansea Bay



Tidal Lagoon Swansea Bay has previously said it would require less than 1pc of the Government’s annual subsidy budget, implying a total of less than £60m a year, and that the subsidy price for a second, larger lagoon could call significantly to be on a par with Hinkley.

A spokesman for the company said: “It makes complete sense for an island nation with high tidal range to embrace the emergence of tidal lagoons. In a single step, this project takes us to a place where electricity from the tides can be cost competitive with nuclear and gas. And it kick-starts an industry that will deliver tens of billions to the national economy.”

A DECC spokesman said it would consider Citizens Advice’s consultation response. 


The figure quoted of £168/MWh seems realistic. A report last by energy consultants, Poyry, came to the same figure, although it went on to add that future bigger sites would come in cheaper.

The real attraction of tidal is its long life span. Poyry estimate that a tidal lagoon should remain operational for 120 years.  

What is maybe most surprising though is just how little power Swansea will provide. According to the National Infrastructure Plan, which has approved it, the lagoon is nominally rated at 240MW. The company seems rather coy about telling us how much electricity will be produced, though the BBC say it will supply 155,000 homes. This would amount to roughly 600GWh, or 0.2% of UK total output.

The Poyry report offers another hint, when it compares the Swansea Bay lagoon with a 140MW offshore windfarm, in terms of energy output. Since offshore wind produces at around 35% capacity, we can glean that the tidal lagoon would run at only about 15%. (The Poyry report is based on the tidal lagoon being rated at 320MW. According to the company video, there would be 26 turbines, all rated at 16MW, which equals 416MW). 

Based on this 140MW offshore comparison, we could only expect 429GWh/year. To put this into perspective, the new 880MW gas power station being constructed at Carrington will be capable of producing about 14 times as much electricity.

  1. February 24, 2015 2:15 pm

    The problem is that politicians seem to have no clue as to whose money they are spending. The fact that this sort of thing isn’t getting more coverage in the MSM is a scandal.

  2. February 24, 2015 2:19 pm

    To summarise your summary:

    “Based on this 140MW offshore comparison, we could only expect 429GWh/year. To put this into perspective, the new 880MW gas power station being constructed at Carrington will be capable of producing about 14 times as much electricity.”

    The Tidal Lagoon Swansea Bay would require an annual subsidy of nearly £60m pa, whereas Carrington requires zilch.

    • February 24, 2015 4:14 pm

      Your last sentence is most pertinent, I noticed that too. It would improve the article if that was made clear by amending the last line. Not everyone reading this may be aware.

    • February 24, 2015 4:14 pm

      But its, Green, it’s green, no body cares how much green energy costs, because in their mind it’s from nature so it’s “free.” After all, they can always tax the people more, the politicians aren’t spending their own money, and eventually they view the money as “monopoly” play money.

  3. February 24, 2015 4:25 pm

    I went to a presentation on the proposed scheme. A geologist there suspected that the lagoon would silt up inside a few years. They would need continuous dredging.

    Of course this is only the first of several such schemes. The follow on ones proposed are much much bigger and would have a massive impact on the south side of the Severn Estuary.

    Madness is the only description.

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