Swansea Bay: tidal power’s £1.3bn experiment

Can tidal lagoon energy be both clean and green?

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Seven thousand years ago, a group of Mesolithic children and adults made their way across marshland near what is now the Gower Peninsula in Wales. The estuary they looked out on was around 16m lower than its present level and nearby Swansea Bay was still completely dry. Even though the Ice Age was over, enough water remained locked up in ice to keep sea levels low – allowing the group’s footprints to sink into mud and survive the centuries. Today, however, it is feared that rising sea levels will drive communities away from the coast. By 2100, human-induced climate change threatens to raise temperatures by 2-4C and push up tide-lines by 4-6m. In Wales alone, 220,000 households are at risk of flooding.

The government has promised to help counter this global trend by reducing UK carbon emissions 80 per cent from 1990 levels by 2050.  And with the second largest tidal range in the world, British marine energy could play an important role in this shift. But harnessing the power of the tides is not without consequence. In 2013, plans to construct a £34bn barrage across the Severn estuary were rejected after concerns were raised about its effect on local ecosystems; wildlife groups worried the structure would block the safe migration of fish and impact the river’s thousands of species of wintering birds.

So can tidal technology be both clean and green? A company called Tidal Lagoon Power (TLP) believes it has the answer. Instead of entirely dissecting estuaries with a row of turbines, the company proposes building U-shaped breakwaters out from the coast. At a proposed pathfinder project in Swansea Bay, 16 gated turbines installed inside a 9.5km breakwater wall would generate regular electricity each time the tides go in and out.

The project promises to supply clean energy to 155,000 homes and to enhance the local environment for nature and humans alike. Its eco-minded plans include turning the breakwater into an artificial reef, as well as creating a roost for birds, and new areas of saltmarsh, grassland and dunescape. Wardens will be employed to keep an eye on activity above ground and underwater acoustic camera technology will monitor happenings beneath. A hatchery and ponds for baby oysters will even attempt to restore and conserve native species.

At £1.3bn, this green scheme does not come cheap and the company is seeking government support through a Contract for Difference subsidy. But TLP also views the Swansea project as a “pathfinder” for a series of larger plants. The company claims these subsequent schemes would improve the technology’s cost-efficiency and create further employment, both directly and across a UK-focused supply chain. It is estimated that Swansea development could support 2,260 jobs during its construction and operation alone.

A recent independent review agrees and has found in favour of the pilot. According to the review’s author, the former energy minister Charles Hendry, the long life-span of tidal lagoons makes them an attractive and cost-competitive complement to other low-carbon options, as well as a potential asset to Britain’s wider economy. “As Britain moves into a post-Brexit world, we need to ask if we want to be leaders or followers. If the answer is that we should be leaders, as mine unequivocally is, then tidal lagoons offer an early, achievable and long-term opportunity,” the report advises.

Major environmental organisations have also given the Swansea pathfinder scheme their qualified support. Doug Parr, Chief Scientist at Greenpeace UK, told the New Statesman: “If environmental concerns can be addressed the government should get on with it because it could be the first of a wave of tidal lagoons across the  UK, and even internationally. We can lead the world in providing a new, renewable innovation to meet our clean energy needs.”

But some large green question-marks still remain. The lagoon at Swansea has already received development consent but has yet to obtain a Marine Licence from Natural Resources Wales. And plans for larger tidal projects to come will require further permissions under EU law. According to NRW the process of examining the application has been both “challenging and instructive”. Concerns from wildlife groups include the build-up of silt and unforeseen changes to the movement of floodwaters, as well as the impact on marine and bird life.

Joan Edwards, the Head of Living Seas at the Wildlife Trusts, fears that the lagoon may interrupt the homing instinct of salmon, which migrate upstream close to the coast using smell. She is also concerned about the effects of the estuary flow. “When you build sandcastles on the beach, the sea comes in and you don’t know exactly where the water will go – what channels it will choose to flow through.”

Ultimately, there is still too little information to make accurate predictions. In evidence submitted to the review by the Environment Agency, the following caution was issued: “We currently have little knowledge of, and low confidence in, the modeling proposals for some of the schemes being proposed.” Objections are also being raised to TLP’s plans to source building material for the project from a disused quarry on the Cornish coast, which the company’s CEO, Mark Shorrock, has recently purchased. Alison McGregor of Cornwall Against Dean Superquarry doesn’t think Shorrock, “is as green as he makes out to be.” She is particularly fearful for the impact the re-opened quarry would have on the adjacent Manacles Marine Conservation Zone.

Such concerns prompted the review to call for the adoption of careful monitoring systems. Hendry recommends that if tidal lagoons are built, “the government should require a high level of ongoing monitoring of environmental impacts”. He also suggests the adoption of a National Policy Statement and a Tidal Power Authority, to provide all-round support and oversight for any future industry.

What is harder to settle on is how much monitoring at Swansea should conducted before further lagoons are green-lit. The review recommends that no larger projects should be approved before the Swansea pathfinder is operational. While according to NRW, monitoring the effects of such a project “could take many years to complete given the complex life cycles  of many species.”

So how much monitoring is enough? Even if the impacts at Swansea are deemed manageable, the cumulative impact on multiple lagoons in the same estuary would still be unknown. On the other hand, the economic and environmental case for action is compelling. The government’s decision on whether or not to support the Swansea scheme – and the wider technology – thus faces a deep challenge: of having to commit to a path forward in the face of constant change. Not just the changes that the Swansea pilot scheme will bring to the estuary, but those brought by climate change itself, as well as continuing developments in competing forms of marine and renewable energy.

At least here the government is in ancient company. When the Mesolithic peoples of early Wales inhabited the region, they did so in the face of constantly moving tides and climate. Most likely travelling in response to flood and resource shift, they made adaptation and flexibility central to their success. Now the government must do the same.

India Bourke is an environment writer and editorial assistant at the New Statesman.