The government plans to build a series of tidal lagoon power plants in the UK – here's everything you need to know

Sarah Spickernell
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The first lagoon would be built at Swansea Bay in Wales (Source: Tidal Lagoon Power)

The government is considering building the world's first tidal lagoon power plants in the UK.

There would be six of them – four in Wales and two in England, and the energy generated would be used to power as many as eight per cent of the UK's homes.
The company behind the idea is Tidal Lagoon Power, and a full planning application will be submitted in 2017. Government responses have been positive so far, with energy secretary Ed Davey saying he wants to back the project.
Each lagoon would work by allowing water to build up on one side of a set of turbines, so that when they open the water surges through with such force that a huge amount of energy is generated.
The plan is to build the first one in Swansea Bay for £1bn. It would consist of 90 turbines in a 14 mile breakwater, and over the next 120 years it would supply energy for 1.5m homes.

The lagoon would cost £1bn to build (Source: Tidal Lagoon Power)

Barriers would open and close to generate energy (Source: Tidal Lagoon Power)

For some, the plan represents a step towards the UK becoming a leader in green energy, since it would be a long-term investment in powering homes without releasing pollutants. Mark Shorrock, chief executive of Tidal Lagoon Power, said:
Full-scale tidal lagoon infrastructure gives the UK an opportunity to generate electricity from our amazing tidal range at a cost comparable to fossil fuel or nuclear generation.
Others are less sure of its benefits, mainly because of the large sums of money involved at the beginning. Here is an overview of some of the main reasons for building versus ditching the project.

Reasons to Build

  • The method would be completely renewable and would release no harmful gases into the atmosphere.
  • Being surrounded by coast means the UK has some of the best access to tidal power in the world
  • Although the first would be expensive, Tidal Lagoon Power says subsequent ones would be much less expensive once the capital costs have been paid off.
  • Waves are a much more predictable source of energy than the sun or the wind.

Reasons not to build

  • It would be very expensive to get the project going, and Tidal Lagoon Power is thought to be requesting £168 per megawatt-hour of energy the Swansea Bay lagoon generates. This is almost four times the market price of power.
  • The consumer charity Citizens Advice told The Telegraph it was “appalling value for money”, arguing it would require bill-payers to pay a higher price for electricity than from any other green energy project to date.
  • Although the environmental implications are mostly positive, some anglers say it will have a negative impact on fish migrating to spawn in local rivers. These, they say, are only now recovering from long-term pollution. According to the BBC, the firm has acknowledged that some fish might stray into the turbines, but insisted the numbers would be small.

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