Exciting news: It looks like the UK is going to have its first tidal lagoon power station in Swansea bay, capable of generating 240MW. Now why is such a large scale project so exciting? Tidal lagoon energy is a relatively new way of generating renewable energy on a large scale, making it an excellent way to start using one of the UK’s best resources: its tides.

The UK has one of the largest tides in the world, with the Severn Estuary being the third highest in the world, and we are not using it enough. There is a lot of great work being done in Orkney on tidal stream technology, but exploring a mix of technologies is important if we want a clean energy UK.

So, what is it? To simplify, it is building a large man-made lagoon using sand and rocks mostly for the walls, with gates housing large turbines. When the tide is at its highest, the gates are opened to allow the water to surge through the turbines. The gates are then shut until the tide’s lowest point, when the gates are then opened again to allow the tide to surge through the other way. What is so brilliant about this method of energy generation, is that by looking at a local tide table, you can see how much energy you will generate and at what time far into the future. This means you get very consistent energy production and can adapt to it. For example, if the tide changes are in the middle of the night, when we don’t need as much energy, it could be stored instead via pumping water into large tanks, to be released when we need it. Energy storage techniques are always advancing and I would hope further developments will be implemented in this project.

Looking at this specific project, it is impressive to see how much this could genuinely generate. The lagoon itself covers an area of 11.5kmsq and is rated at 240MW (megawatts) for a 4.5m tidal head. This means that its net yearly output would be 400GWh (gigawatt hours). For some perspective, the average electricity usage of a UK house is around 3,300kWh (kilowatt hours). So that would be over 100,000 houses a year. The idea is to have several of these lagoons in suitable areas around the UK, all generating a lot more than the Swansea lagoon, most having proposed ratings between 1000 and 2000MW.

There are concerns over environmental impacts of projects such as this one, and these should always be studied and taken into account to cause as little damage as possible. One important factor is that the proposed lagoons are not the same, and are instead of, a Severn Barrage (a proposed idea to build a large dam across the Severn Estuary). Whereas a barrage would cause mass flooding to the surrounding environment and destroy habitats, a lagoon would actually have the opposite affect. As it is nearly completely walled there is no external flooding outside of this wall. Another interesting aspect of it is that it creates a large new area of calm water, thus creating new habitable ground for a lot of animals – think of it as a giant rock pool. There are other things to consider, such as the site the walls are being built on, and where it is connected to the mainland, but things are looking optimistic. Both RSPB and Friends of the Earth will show support if all their questions are answered.

It is exciting to see innovative projects in the UK and considering our energy industry at this moment, it is great to be able to report some positive news. Jacob Williams