Tidal Power Resource

Tidal Power Resource

What is tidal energy?

Tidal energy is the production of energy using the natural rise and fall of tides. Using the tides for energy is 100% renewable – there is no danger of the tidal cycle stopping any time soon! In order to capture the energy of the tides, the rising or falling water is funnelled through turbines or paddles, causing them to move and generate electricity with their rotation. This is similar to using wind turbines in the air, though tidal energy is much more reliable in that it occurs twice a day.  

The UK has a large potential to develop tidal energy, as it has a large tidal range. A tidal range describes the difference between the high tide mark and low tide mark. The bigger the range, the more water can be forced through the turbines, and the more energy is generated. 

Swansea tidal barrage concept

Tidal energy in the Severn Estuary

The unique shape of the Bristol Channel and Severn Estuary act as a natural funnel, channelling water up the coast inland. This creates one of the largest tidal ranges in Europe, ranging from 7 meters in the outer reaches to 14 metres at Avonmouth1. This shifting of the tides has the potential to generate huge amounts of energy. This energy potential has made the Severn a hotspot of interest for tidal power proposals.  

Since the UK Government has committed to reaching net zero emissions by 2050, tidal power in the Severn Estuary could contribute significantly to this target. However, any schemes are inevitably going to have a range of impacts, from those on habitats and wildlife to those on shipping and ports. 

Previous tidal power proposals

The tidal potential has attracted a range of tidal power proposals, including various barrages, tidal lagoons and other schemes, debated at both national and local levels. Proposed schemes have included the Cardiff-Weston Barrage, the Swansea Bay Tidal Lagoon2, and the Bridgewater Bay Lagoon. Barrages act to dam sections of water, which flow into and out of the lagoons via underwater turbines. The force of the water moving through the turbines generates electricity, which will occur with the daily tides. After extensive assessment, the proposals put forward to date were abandoned due to their cost and potential impact on marine life. Assessments like this, termed Environmental Impact Assessment (EIA)3, play a role in ensuring that developments can minimise their impact on ecosystems as much as possible. 

Previous proposed tidal barrages across the Severn Estuary (Photo credit Burnham-on-Sea.com)

The future of tidal power

After the Swansea Bay Tidal Lagoon project was scrapped in 2018, there were no plans for tidal schemes of any sort within the Severn Estuary. However, in 2021, a different proposal for a tidal lagoon in Swansea was put forward. As well as using underwater turbines to generate 320 megawatts of renewable energy, the proposal includes a floating solar farm and a number of affordable eco-homes4. Termed the ‘Blue Eden Project’ construction is set to begin in 2023, starting with the construction/development? of high-tech batteries for energy storage. This will then be followed by the construction of the floating solar farm, situated in the Queen’s dock area, which will power a data centre. It is the intention of the proposal that no energy is wasted from the data centre either, as the excess heat produced will be used to heat 5000 new eco-homes on the waterfront.  

For more information about the Swansea project, click here

Scale and layout of the proposed Blue Eden project at Swansea (Photo credit DST Innovations)

It is clear that more tidal schemes like this will pop up across the UK, fighting climate change and allowing us to meet our Net Zero targets. This is especially relevant post COP 26, spurring on more research into tidal energy generation technology. 

References

1 – NRW Marine Character Areas: Bristol Channel (Wales) https://naturalresources.wales/media/674506/mca-28-bristol-channel-wales-_-final.pdf  

2 – Tidal Lagoon Power: Swansea Bay http://www.tidallagoonpower.com/projects/swansea-bay/  

3 – SOAS: What is Environmental Impact Assessment https://www.soas.ac.uk/cedep-demos/000_P507_EA_K3736-Demo/unit1/page_08.htm  

4 – ITV News: Swansea tidal lagoon: £1.7bn renewable energy project promises thousands of jobs https://www.itv.com/news/wales/2021-10-25/swansea-tidal-lagoon-17bn-renewable-energy-project-promises-thousands-of-jobs  

5 – Hydro-environmental modelling of proposed Severn Barrage, UK (Lin et al, 2010) DOI: http://dx.doi.org/10.1680/ener.2010.163.3.107  

Explore

The Severn Estuary is one of the largest estuaries in Britain and has the second highest tidal range in the world.

Proposed location of the Cardiff-Weston Barrage, a proposal which has since been dropped (Photo credit Lin et al, 20105)
Design of the proposed waterfront eco-homes (Photo credit Blue 21)

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