A proposal for a tidal power generating lagoon in Swansea Bay, South Wales was given the nod in the 2015 budget. The project is estimated to cost about one billion pounds, but proponents argue that the experience gained here will make future projects cheaper. Tidal Lagoon Power’s founder and CEO Mark Shorrock said that: “Economies of scale bring immediate advantage. A second lagoon will require a lower level of support than offshore wind, for a renewable power supply that is both long-lived and certain.”
In simple terms the project involved building a massive sea wall to complete enclose an area of Swansea Bay almost the size of the City of Swansea itself, encompassing an area of 4.4 Sq miles (11.5 Sq km). The rising tide will flow into this basin through turbines generating electricity as it does so. Then, as the tide falls the captured water will flow back through the same turbines and out to sea. It is expected that this process will have a generating capacity of 320MW delivering 420GWh per annum. The design life of the project is 120 years.
Once built the development plans a range of social, cultural and scientific programmes and developments. There will be public access to the whole breakwater for walking, cycling or travel by mini tram. The lagoon itself will host boating and water sport activities as well as providing an area for scientific research and aquaculture.
The development however is not without issues. The technical challenges are not particularly difficult, we have after all been throwing stones in the ocean for many years now and the processes required to build the wall are well understood and the expertise and equipment is available. The biggest challenge will be from public opinion. The project website gives some very nice graphics and imagery (though I could not get the 3D fly-through to work in any browser), but the scale of the project with a 12 – 13 metre high seawall exposed at low tide, which, to a viewer from the shore may eclipse the horizon will change forever the visual impact of Swansea Bay. Public objections will come forth at planning meetings and they will all need to be countered or mitigated.
That public opinion may well be swayed by the financial concerns surrounding the project, the highest amongst them being the level of government fiscal involvement required. It is reported that this projects will require some of the highest levels of energy subsidies yet given to renewable energy projects. It will need a subsidy input of £150 per megawatt hour (MWh) make it viable compared with £98 agreed for the Hinkley nuclear power station, the £100 for wind farms and £95 for solar. It will also require a wholesale electricity price of £50 per MWh, the current wholesale rate (March 2015) being £42.62. At the end of the day subsidies come out of the taxpayers pocket and if they are asked to subsidise as well as pay more for the resultant power, that could be an issue that sways their vote at council planning meetings.
It is hoped that this first tidal lagoon is will open the door to more projects where that economy of scale Mr Shorrock is looking for will become evident. Plans are in hand for four lagoon larger than Swansea Bay with a capacity of 7,300MW, that is 10% of the United Kingdom’s electrical energy needs. Colwyn Bay is earmarked for the second project at an estimated cost of £2.3bn and with a third in the be based in the Severn Estuary costing £4bn. Projects four and five at locations yet to be disclosed but estimated at a cost of £4.5bn would follow these initial projects, but all this hinges on the successful implementation of the Swansea Bay project.