A new tidal fence equals a nuclear reactor?
Initially a Severn tidal barrage was proposed that would stretch across the Bristol Channel from lower Cardiff in Wales to Weston-super-Mare in England. This project would have produced 5% of the energy needed for the UK, but had the potential for damaging shipping and wildlife. An alternative proposal to build a Severn tidal fence in the same area would produce less energy but allow shipping to continue unimpeded and would be better for the local wildlife. The tidal fence would still produce more energy than the Sizewell B nuclear power plant.
The tidal barrage, similar to a dam, would have stretched the entire width of the Bristol Channel with potentially negative consequences for wildlife caught on either side of the barrage. Shipping from Cardiff and Bristol would have been negatively affected as well.
Although the tidal fence would provide less energy, only 1.3 GW or 1% of the Country’s needs, the advantages could well outweigh the impact of producing less energy. This alternative idea would be a compromise between the need to provide energy and the preservation of wildlife and commercial interests.
The tidal fence would leave a gap that would allow shipping to continue uninterrupted while also being safer for local wildlife. Salmon would still be able to migrate and most of the mudflats, essential to migrating birds, would be preserved.
As part of the tidal fence proposal a smaller area would contain a barrage or lagoon that would provide energy during certain times of the day. The tidal fence is expected to provide the most energy during the middle of the tidal cycle while the lagoon would provide the most energy at high and low tides.
The original idea for a tidal barrage was researched in 1981 and in 1989, but shelved at the time. With the increasing emphasis on meeting the Kyoto standards and on renewable energy, the idea for generating energy in this area has resurfaced.
A number of organizations have come together to promote the Severn tidal fence over the Severn tidal barrage including the World Wildlife Fund (WWF), Amec, Marubeni Europe, Edinburgh University, IT Power, Ecconect, BMT, naREC, and pulse tidal. A fairly impressive group of researchers, engineering companies, renewable energy resources and wildlife groups.
Research into the environmental effects of both plans is currently underway. Hopefully, the tidal energy plan that is eventually adopted, will provide the least impact for every interest affected while providing the most energy for the Country.
As it is, there are so many different tidal and wind projects that are proposed for different parts of the UK, that a less invasive plan here may not matter.
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