Yesterday came the long-awaited decision as to whether the UK Government would offer any support or subsidy to the Swansea Bay tidal lagoon scheme. There has been widespread criticism of the decision (see #SwanseaBay on twitter) with many people questioning why the Government is rejecting tidal power while at the same time backing nuclear through direct investment, and the expansion of Heathrow airport, which was approved in Parliament yesterday.

“Tories have defied all logic and failed to make the right decision for the people of Wales and the future of our planet”
– Rebecca Long Bailey, Shadow Business Secretary

Commentators complained that the decision was a bad one for Wales given the job creation potential of the tidal scheme – notably, Len McCluskey, leader of the Unite trade union said the decision “deprives the Welsh economy of a £500 million boost and 2,000 jobs”.

Expensive, poor value for money, and no meaningful long-term employment boost

Reading the text of Greg Clarke’s speech, it is clear that the Government feels the £1.3 billion Swansea Bay scheme is simply too expensive and will not deliver the long-term benefits attributed to it by many commentators:

“The same power generated by the lagoon, over 60 years, for £1.3 billion, would cost around £400 million for offshore wind even at today’s prices, which have fallen rapidly, and we expect to be cheaper still in future. At £1.3 billion, the capital cost per unit of electricity generated each year would be 3 times that of the Hinkley Point C nuclear power station.”

Swansea BayThe overall cost of the proposed programme of 6 tidal lagoons was estimated in the Hendry Review to be more than £50 billion – 2.5 times the cost of Hinkley, and £31.5 billion more than an equivalent amount of offshore wind power. This would add around £700 to household electricity bills between 2031 and 2050, or the equivalent of £15,000 for every household in Wales.

In terms of jobs, the Hendry Review found that only 28 jobs would result from operating and maintaining the lagoon in the long term, while saying it would take a “leap of faith to believe that the UK would be the main industrial beneficiary” of any international interest in tidal power, limiting its export potential.

Clarke also highlighted that the expected load factor for the lagoon would be 19% compared to around 50% for offshore wind and 90% for nuclear.

Unsurprisingly, Mark Shorrock, Chief Executive of Tidal Lagoon Power LLP that is behind the scheme disagrees with the Government’s analysis, saying the claims that the lagoon would be 3 times more expensive per unit than Hinkley were “misleading”:

“The offer to the UK government for Swansea is AT THE SAME PRICE as nuclear for a small pathfinder which as he acknowledges is 0.15 per cent of the UK’s energy requirements. The UK’s second proposed tidal lagoon at Cardiff would be 88 times less expensive for consumers than Hinkley. Furthermore, the £1.3bn build cost of Swansea is privately funded. It is NOT a cost to consumers as suggested by Mr Clark.”

Tidal power could increase costs of managing intermittency

Not mentioned by Clarke, but also important, is the wider impact such a scheme would have on the electricity system. Analysis by Euan Mearns in Energy Matters challenges the claims that tidal power could deliver baseload power, and demonstrates that the proposed tidal projects would increase the amount of intermittency in the system.

This is because of the timing of the tides – each tide has two generating opportunities – the 3 hours before high tide and 3 hours before low tide, with periods of no generation in between. Mears examined tidal data for the proposed tidal stations around the UK and found they fall into two groups whose tides are almost exactly 6 hours out of phase, meaning they will all generate or not at the same time.

tidal power

“UK tidal lagoons will produce more intermittent electricity than any other form of renewable generation providing four spikes separated by four periods of zero production each day. It is often claimed that the predictability of tides is a virtue. This also means we can predict with certainty that this energy source will be a disaster for the public as well as the environment.”

Clearly, tidal power as proposed in this case, would further add to the growing costs of balancing the electricity system.

The right decision

Many supporters of the Swansea Bay scheme on social media point to last year’s Hendry Review into tidal power, which was highly positive. However, even at the time, various analysts pointed out shortcomings in the report, particularly around the cost and lifespan assumptions. The arguments against the project were set out very clearly at the time by the thinktank, Policy Exchange, which also pointed out the relative expense of the scheme compared with other renewable technologies, and suggested that the £1.3 billion could be better spent on things like energy efficiency.

“If ever there was a textbook example of how to go about Government lobbying and project development, then it is the Swansea Bay Tidal Lagoon project,”
– Richard Howard, then Director of Development & Head of Environment & Energy Policy Exchange

Tidal power sounds like the perfect solution to the country’s energy needs, and many people, including the Government which indicated it is examining other tidal schemes, would be happy to get behind the idea if it can be delivered at an acceptable cost. Comparisons with the recent announcements on Wylfa Newydd are entirely spurious: Advanced Boiling Water Reactors are an established technology with a proven track record, so the Government can be confident that the project can be delivered broadly on time and budget (unlike the EPR at Hinkley, but that’s a whole other story). Committing £1.3 billion to a “pathfinder” tidal scheme with a low expected utilisation rate and low relative capacity makes no sense and the Government was correct to reject the scheme.

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