Tidal Lagoons

This page offers useful information about one of the newest forms of renewable energy, tidal power. You can download a printable PDF of this briefing here. View our template letter for writing to your MP about tidal power here. If you have any further questions please contact us

What is a tidal lagoon?

A tidal lagoon is a power station that generates electricity from the natural rise and fall of the tide - they capture a large volume of water behind a man made structure which is then released to drive the turbines and generate electricity. As the tide rises and falls naturally, with no requirement for fuel, tidal power is truly renewable and unlike other forms of renewable energy it is entirely predictable as there are always 2 high and 2 low tides a day. The height and time of the tides can be predicted years in advance to a high degree of accuracy.

Tidal lagoons can act as a barrier to potentially damaging and disruptive storm surges and waves that threaten the infrastructure of coastal communities in the face of climate change, predicted to cause more flooding and coastal erosion. Tidal lagoons can be designed to withstand 1 in 500 year storm surges and waves. They are also designed for future increases in sea level. Lagoons have an asset life of 120 years, making ‘future-proofing’ in this way necessary. There is also scope to increase the wall height if future adaptation is needed, so that tidal lagoons can increase the resilience of local communities. In turn, this will reduce emergency public spending on the damage from coastal flooding.

Case study: Swansea Bay Tidal Lagoon

Swansea Bay tidal lagoon will be the world’s first tidal lagoon power plant.

  • Due to the incredible tides on the West coast of Britain, by keeping the turbine shut for just 3 hours, there will already be a 14ft height difference in water between the inside and outside of the lagoon.
  • The lagoon will include 16 turbines and a 6 mile breakwater wall, generating electricity for 155,000 homes for the next 120 years
  • The lagoon would see 236,000 tonnes of carbon savings each year that the lagoon is in operation
  • 2,232 construction and manufacturing jobs will be directly sustained by the build, supporting thousands of further jobs in the Welsh/UK economy
  • The project is expected to contribute £316 million in Gross Value Added to the Welsh economy during construction, then £76 million in each of its 120 years of operation
  • The project will be so much more than a power station. The lagoon will encourage healthy living and engagement with the outdoors, with the seawall being free access to the public as well as being a playground, beach and rock pools.
  • The tidal lagoon will be used for local, national and international sports including sailing, canoeing and open water swimming, as well as cycling and running around the sea wall.
  • The lagoon will provide the venue for conservation and biodiversity schemes; there will be a lobster and oyster hatchery and the lagoon offers the prospect of restoring the native Swansea oyster population, a former Swansea industry that provided 500 local jobs
  • The ambition is to work with all 176 schools, colleges and universities in Swansea Bay, to inspire students and develop skills and knowledge around themes of tidal energy, coastal engineering and marine conservation.
  • We expect the tidal lagoon to become a major tourist attraction, with around 100,000 visitors per year, generating trade for local businesses
  • The Welsh and UK industry has the opportunity to secure a primary position in the global tidal lagoon sector, leading the way in tidal energy.

After Swansea Bay Tidal Lagoon (the Pathfinder Project) there are proposals for other sites, which for many are at the design stage. They include:

  • Cardiff
  • Newport
  • Colwyn Bay
  • West Cumbria
  • Bridgewater Bay
  • Orkney

Economies of scale apply so that the larger projects could generate the cheapest electricity of all the new power stations in the UK.