Will-they-won’t-they: the government and the Swansea tidal lagoon

Swansea tidal lagoon is the project that wants to bring a new type of clean power into the UK’s energy mix. The government have carbon cutting targets that they need to hit. A match made in heaven? With this story hitting the headlines again as Greg Clarke says the government “are not closing the door” on the project, we investigate.

What is a tidal lagoon when it’s at home?

A tidal lagoon is a power station that generates electricity from the natural rise and fall of the tides. Here’s how it works.

A lagoon is created by what basically looks like a massive sea wall. The lagoon captures water as the tides come in, and holds it back as the tide goes out. Then the water is released back into the sea to drive turbines and generate electricity.

Let’s break that down into a little more detail.

Both the incoming and outgoing tides generate electricity. When the tide is coming in, the turbine gates hold back the sea water. This means the seawater builds up outside the lagoon, getting higher and higher, while the water in the lagoon stays the same. Once the sea water is high enough, the gates open and water pours into the lagoon through turbines. The water turns the turbines, and generates electricity.

When the tide goes back out, the process is basically reversed. The gates hold the sea water inside the lagoon, while the water level outside gets lower and lower. Eventually, the gates release the water back into the sea - it flows through turbines, generating more electricity.

There are always two high and two low tides a day, and we can predict the height and time of these tides years in advance. The company behind the Swansea tidal lagoon, Tidal Lagoon Power, say this will mean it is generating energy for up to 14 hours in any 24 hour period.

The benefits

The Swansea lagoon promises to save the UK 236,000 tonnes of carbon each year that it operates. Speaking of which, it should keep churning out energy for at least 120 years. The 320MW generator should reliably supply an impressive 11% of Welsh domestic electricity consumption - that’s 155,000 Welsh homes each year. That’s a whole lot of carbon kept out of our atmosphere - about the equivalent of taking 46,275 cars off the road every single year.  No biggie.

The project is wildly popular with Swansea Bay locals. During the community consultation, 86% of local people and businesses came forward in support of it. This may have something to do with the whopping 2,232 construction and manufacturing jobs that would be sustained by the project.

So… why the hold up?

Well, the government and the Swansea tidal lagoon go way back. In 2015, the government made the big move of featuring the Swansea tidal lagoon in the Conservative party general election manifesto. It was all going so well. Sunshine, rainbows and big tidal lagoons.

Then, in 2016, the government commissioned an extensive and independent review of tidal energy. In 2017, this review came back to the government, and described the project as the ‘no-regrets’ option. But more than a year on, they are yet to respond to the review.

There are claims that some senior figures in Whitehall want to stop the project going ahead. But ex-Conservative minister Chris Hendry - who conducted the review - has said this January that the project is “still the right thing to do”, and that delays can be put down to the general election and Brexit.

But what are the main criticisms of the project?

The two most prominent concerns are the cost, and the potential effect on wildlife.

Keeping count

At £1.3bn, the construction cost is not to be scoffed at. Whilst it’s undeniably a lot of money, the development costs pale in comparison to the £19.6bn price tag for the now infamous Hinkley nuclear power station.

Tidal Lagoon Power have asked the government for a 90 year contract with an average price of £89.90/MWh over the 90 years (MWh = megawatt hour, a unit used to measure energy produced by big generators). For comparison, Hinkley has signed a contract with the government for £92.50/MWh over 35 years.

In January, Welsh First Minister, Carwyn Jones, sent a letter to Theresa May offering to fund a substantial chunk of the project from the Welsh government’s purse. The figure offered is said to be somewhere in the £100 million to £250 million range.

But the government has not approved the lagoon, which one minister described as “eye-wateringly” expensive.

It’s fair to say that this is an expensive project, but Tidal Lagoon Power argue that after this initial investment the costs for future tidal lagoons would come down. It’s a similar story for offshore wind. Back in 2015 the price for offshore wind power was an average of £117.14/MWh, but last September this dropped to as low as £57.50/MWh.

So giving this project the go-ahead could be the first step towards making tidal power a newly viable source of the clean energy for the UK.


What effect would the tidal lagoon have on birdlife, marine mammals and tiny invertebrates living in the bay? There are concerns that the project could negatively affect fish in the area, but models have shown the effect to be very small. Plus, experts believe the project could even have a positive impact on birds.

Taking a step back, it’s generally accepted that climate change is the biggest threat to wildlife, and we need to make the transition to renewable power sources as swiftly as possible. So with that in mind, environmental experts are cautiously supportive, but want the effects of the project to be carefully monitored.

So, what now?

The leader of the local council, Rob Stewart, insists that the project is too important to be shelved. He wants to ensure the project happens with or without the support of central government. Tidal power is very popular with the general public, and the guys with the money like it too: FTSE 100 insurer Prudential, and energy company Good Energy are both backing it.

With Tidal Lagoon Power, the Swansea Bay locals and the Welsh government anxious to get things moving, there is growing (and understandable) impatience with Westminster. With a decision always just around the corner, we’ll have to wait and see whether this exciting project finally gets the go-ahead.

Banner photo: Tidal Lagoon Power