How does tidal lagoon power work?

There’s a little wave of interest in tidal lagoon power this week, as the Tidal Lagoon Power company has announced plans for a further five possible projects, after their ambitious pilot scheme in Swansea.

As you may remember, the Swansea project entails a five mile wall built around Swansea Bay. It would contain the tide and channel it through turbines, generating electricity on the way in and the way out. Being the first in the world and highly experimental, it’s not cheap – but the infrastructure is expected to last 120 years. Along with that century of clean power comes a host of new leisure opportunities around the wall and its path, and a major learning opportunity for future tidal schemes.

The Swansea project is already in planning, and has broad support. We will know in June if it is to go ahead. The other five are speculative, a series of places that could be similarly transformed if the environmental assessments go well. If all of them were built, they could provide 8% of Britain’s electricity. The proposed Cardiff Bay lagoon would be the second project and the first large scale tidal lagoon power station, generating enough to power every home in Wales.

It’s not uncontroversial, but this is a major technology to watch, as it could provide some of the heavy lifting in a future renewable energy power system. Here’s a useful video that sums up how it works:


  1. Maybe but I can foresee problems. Silting. Aquatic growths on the equipment. On the other hand the lagoons might be used for fish farming. This needs to be looked at holistically

    1. Yes, an aquatic farm is part of the plan, along with a visitor centre, art, and sports venues. Ideally it would bring long-term benefits and employment as well as clean energy.

      not sure about silting + aquatic growth. I presume they’ve thought about that.

  2. It is very expensive, nuclear is far cheaper.

    That said unless you develop it costs would never come down so building the Swansea one is probably worth the extra money single mums on minimum wage will have to pay for their ‘lecy. But we shouldn’t rush to build any more till this one has proved itself.

    1. Exactly, and someone had to build the first nuclear power station too. It’s got to be tried somewhere, at some point, and Swansea bay is a perfect place to pilot the technology.

      They have full costings, and admit that the first lagoon would be very expensive. They estimate that by the third they would be on a par with nuclear.

  3. As these projects become more common place, hopefully resistance will subside. We see wind turbines all over the place now.
    In my city they wanted to put up a turbine at the local school. People complained so much that they had to reduce the height by 50′.
    Now everyone says, “have you seen my wind turbine?” They are all proud of it even though it is less efficient than if they had allowed it to be built at the original height.
    I’d love to get a unit for my yard.

  4. When I was a student in Swansea there always seemed to be a dredger taking silt out of the shipping lanes, and every low tide there were giant tankers lurking out at sea waiting to make their way inshore. What I really enjoyed was walking along the sea front to and from my student residence and watching the thousands of salt flat wading birds scuttling about on the vast expanse of sand in the winter sunshine. Enchanting! I hope that the tidal lagoon will not change that.

    1. The lagoon delays the tide in order to get a difference in water heights, but otherwise they will come and go as usual. Hopefully that should leave the wading birds to go about their business uninterrupted. The designers expect the rocky lagoon wall to provide new habitats for birds, fish and other creatures, meaning it would be positive for biodiversity overall.

      As I understand it, the environmental impacts of lagoons are different from the Severn Barrage and other schemes. The barrage raised water levels inland and destroyed bird habitats, changed water salinity and was generally much more disruptive.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: