Last week, an influential House of Commons committee announced serious concerns over Hafren Power’s proposed Severn barrage. It has been claimed that the facility could provide up to 5% of Britain’s electricity demand but critics warn that wildlife could be deeply affected. What does this mean for the future of tidal energy in the UK?
In theory, tidal energy offers huge potential for the UK’s power mix. Tides are incredibly predictable, more so than wind energy and solar power. But the sheer power contained in Britain’s seas come at a cost. The damage that seawater causes to materials and machinery makes maintenance an issue.
Tidal projects have always been difficult to fund, despite the fact that the UK has great locations for wave and tidal energy projects. The upfront cost of constructing these renewable energy projects has put many off. The other major downside to tidal barrages is the somewhat unpredictable ecological impact.
Peter Hain, former Welsh Secretary of State, has been a strong advocate of the Severn Barrage. Hain’s website states: ‘The barrage makes sense environmentally’. But is this really the case?
The current proposal is a 18km fixed tidal barrage across the Severn estuary. MPs on the energy and climate change parliamentary select committee have been examining the proposal. The report said that while a barrage might help tackle climate change, the environmental and economic case is not strong enough. The committee did however urge the Government to consider developing smaller tidal facilities.
Hafren Power responded to the report by saying ‘We believe the environmental and economic issues can be solved with everyone working together’. They claim that the Severn Barrage will protect against storm surges and save the UK billions in flooding costs. Critics, such as RSPB and WWF, fear that it will endanger the ecosystem, particularly birds and fish.
Peter Hain claims ‘the Rance Barrage in France suggests that there would be a significant increase in faunal abundance and biodiversity. The barrage would slow down the fearsome Severn tide, introducing more light and oxygen and therefore improving the water quality, attracting more fish which will support greater and more diverse birdlife.’
The Rance Barrage is one of the biggest tidal power stations in the world. Development costs were extremely high but these have now been recovered and it produces around 600 GWh a year.
Research shows that the dam has clearly modified the currents of the estuary and caused progressive silting. Sand-eels and plaice have all but disappeared, though sea bass and cuttlefish have returned. There have been large changes to the aquatic ecosystem of the Rance estuary but it continues to be varied.
So what about alternative schemes in the UK?
The Swansea Bay tidal lagoon is one such project. An ambitious tidal power station, it is seeking £10m of funding from the public. The scheme claims it could power 107,000 homes and generate 250MW of renewable energy. Small-scale investors have being offered a 55% stake in the company.
Traditional barrage designs consist of two different types. Ebb generation allows water to fill an enclosed area until full tide. Once the sea level has fallen enough, to create sufficient head, turbines generate power from the water leaving the enclosed area. Two-way generation allows water to flow through the turbines as the tide goes in and out. This energy produced is usually less than ebb generation but electricity is produced over a longer period.
The Zero Carbon Britain report recommends that tidal and hydro should supply 4% of the UK’s energy.
Tidal energy is still in its infancy compared with wind and solar, which have a proven track record. But with the crown estate investing £20m in the UK’s wave and tidal energy, this industry could soon begin to contribute. Ongoing advances in designs like SeaGen and VIVACE mean that the UK could be on the crest of a new wave of possibilities.