With around 60 sunny days per year, “the UK” and “solar power” do not make for a natural co-location. And although we are not short of wind, many see it as an unreliable energy source.
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But Britain does have something else in its favour. With roughly 17,820km of coastline, it has an energy source that the government thinks could provide 50% of Europe’s tidal power resources. It is entirely renewable and, unlike wind and solar energy, it is completely reliable.
“As long as we have a moon in a sky, we’ll always have tides and we can predict 1,000 years ahead exactly when our tides will be,” says Tidal Lagoon Power (TLP) director of engineering and construction Mike Unsworth.
TLP aims to capitalise on our country’s high tidal ranges – the Severn Estuary has the second highest tidal ranges in the world, beaten only by the Bay of Fundy in Canada. This natural advantage puts the UK in a strong position to develop world-leading expertise in a new tidal power industry.
10 to 12 UK hotspots
The Tidal Lagoon team has identified between 10 and 12 tidal hotspots around the UK that are perfectly placed for tidal power plants. It has projects in the pipeline for six of those, but Unsworth stresses that if other developers take an interest, the potential is great.
“We think if 10 of those 12 projects were built over, say, the next 20 years, then that would contribute 12% of UK electricity demand,” he says.
Back in 2011, TLP began plans for a pathfinder project in Swansea, a chance to prove the technology and the market potential for tidal power.
Once complete, the £1.3bn Swansea Bay Tidal Lagoon will power around 155,000 homes – equivalent to 90% of Swansea Bay’s domestic energy use, or around 11% of Wales’ needs.
The Swansea concept is being scaled up for a much bigger barrage at Cardiff. This project had its first formal planning document submitted in 2015 and is estimated to produce enough electricity to power more than 1.3M homes – putting its installed capacity on a par with Hinkley Point C.
“It is a nuclear scale power station, but clearly it’s acting on the tides so it’s purely renewable, 100% renewable,” says Unsworth.
There is another advantage to a tidal power plant – it has double the lifespan of a nuclear plant at 120 years compared to 60. In comparison, solar photovoltaic power sources have a life expectancy of 25 years and offshore wind turbines, a mere 22 years.
Of course, the technology planned for the Swansea Bay tidal lagoon project is not new. Tidal barrages are well established. French energy company EDF – also the client behind Hinkley’s expansion – completed the tidal barrage across the Rance river in Brittany, in 1966, achieving a world first.
The Sihwa tidal barrage in South Korea has since overtaken it, becoming the world’s biggest tidal barrage plant in 2010 with a capacity of 254MW compared to the Rance barrage’s 240MW.
Tidal barrages create a breakwater, across a river or estuary. Turbines are housed inside the breakwater and as the tide comes in, water is funnelled through them, creating energy.
But the 320MW Swansea Bay project is different. Although the breakwater will span from one spot of land to another, it has less impact as it creates a lagoon rather than cutting across a water flow.
First of a kind
“While the technology associated with building breakwaters and the technology associated with the turbines is not novel, it’s not new, bringing those aspects together into a lagoon is the first of a kind element,” says Unsworth.
The 9.5km breakwater consists of a mixture of sand and gravels protected by rock armour. In its mid-section, a concrete housing holds 16 conventional hydro turbines.
The turbines are bi-directional, and their blades can be positioned according to the direction of water flow. It means the cycle can be repeated four times a day with each tide, and the tidal lagoon can generate electricity for 14 hours out of 24.
But before it can begin construction, the TLP team has a few barriers to overcome. It has already received planning permission but is now waiting for a Contract for Difference (CfD) from government.
At the same time, the Hendry Review, which has been examining the potential for tidal power in the UK since May 2016 could give the project a boost.
It is led by industry expert and former energy minister Charles Hendry with a brief to decide whether there should be a pathfinder tidal power scheme. A decision that there should be one and that it should be Swansea would give the project a further boost.
Contract for Difference
The Contract for Difference is expected to be agreed shortly, as is the outcome of the review. In the meantime, Laing O’Rouke has been named as preferred bidder for the civils structures, and a JV between General Electric and Andritz Hydro is in place for electrical work.
But the team has retendered the marine works after deselecting its preferred bidder, Chinese company China Harbour Engineering.
“We felt that the solutions, and the designs, and the methodologies of how you would build the breakwaters – they weren’t delivering us with what we considered to be value for money,” explains Unsworth.
So does this present new opportunities for the UK? According to Unsworth, the top four marine dredging companies in the world are in Europe and each has subsidiaries in the UK. The team at Tidal Lagoon Power has set a benchmark for their projects to create 65% of spending on the project in the UK supply chain. If they achieve it, this could be a massive boost to British business, making it a world leader in a technology still in its infancy.
“We are really keen that the technology and the knowledge, the design, the intellectual property, the expertise, is all developed within the UK, on the UK projects, using a UK-focused supply chain, ” says Unsworth. As he explains, there are several key places around the world – including France, China, and India – which have similar tidal ranges to the UK.
If a British supply chain can establish itself on home-grown projects, it has a good chance of exporting its world-leading design and capability successfully.
Unsworth stresses that “the time has come” for innovative renewable technology, and points to the Paris Agreement on emissions reduction as evidence that climate change is a global priority. Developing technologies like tidal lagoons will also create jobs in a low carbon economy – a popular prospect for any career-minded politician.
“The renewables sector – be it wind farms, be it floating wind, be it tidal lagoons – they will continue to thrive as more and more reliance is placed on low carbon and renewable technologies,” says Unsworth.