A massive sea wall built around Swansea Bay, near the South Wales coast, could harness the power of sea tides to provide power to over 100,000 homes. A few weeks ago an environmental assessment of the £650 million ($1.6 billion) project was completed with full public support putting it on track for a completion date sometime in 2017. The 10 kilometer (6.2 mile) long sea wall is designed to be the world’s first tidal lagoon that will completely surround the Swansea Bay with a horseshoe shaped barrier. The colossal coastal structure will capture 11km2 of water as the seas rise and fall to generate 14 gigawatts of electricity and produce 25 terawatt hours of energy each year.
Technically speaking, the idea of harnessing sea tides for their energy actually dates back to 7th century Europe. The tidal wall can capture energy by placing a tide pool inside of the sea wall and separating it with sluice gates as well as an energy-generating turbine. When the seawall opens up during high tide, water will pass through the open sluice gate and turn the turbine as water fills the tide pool. Meanwhile, at low tide the sea wall will open again to release water back into the sea to generate even more electricity.
According to project engineers, the Swansea Bay tidal lagoon will be able to generate energy from the sea’s tides at least four times a day. In the future, lagoons could even be divided into separate pools to generate power on demand, much like pumped storage hydro plants do today. Of course, the best part of using the water to generate electricity is it does not produce any carbon emissions whatsoever.
That said the tidal lagoon won’t be without its trade offs. For one thing, having a sea wall wrap around the coast will have a huge impact on the natural landscape. Building a sea wall will destroy part of the seabed, while cutting off the area from the natural sea could cause a loss of the estuary’s intertidal habitat and lead to significant declines in 13 bird species.
Images © Tidal Lagoon Swansea Bay