Energy and Climate Change CommitteeWritten evidence submitted by the Environment Agency

Summary

The Government’s Severn Tidal Power (STP) Feasibility Study presented a thorough assessment of the issues of developing tidal energy in the Severn Estuary. Its conclusions on the environmental impact of a Severn Barrage are still valid and we believe merit full consideration by the Select Committee Inquiry.

The Environment Agency supports the development of appropriate energy schemes in the Severn Estuary and elsewhere to help secure the reduction in greenhouse gas emissions required to cut UK emissions by at least 80% from the 1990 level by 2050.

Any proposal must be designed and operated to minimise the adverse impacts on people and the environment. Key to this are:

Considering, the specific needs of, and mitigating the impacts on, species and habitats in the estuary; and

Reducing the exposure of communities to flood risk.

Compliance with the Habitats Directive, with respect to migratory fish and inter-tidal habitats, is probably the most difficult challenge for a proposed Severn Barrage.

We are keen to work with Governments and developers to help identify a project that can generate the maximum sustainable energy from the Severn Estuary whilst meeting the necessary environmental protection identified in legislation.

1. Introduction

The Environment Agency is the Government’s principal environmental regulator and advisor in England and Wales. We play a major role in the sustainable management and protection of estuaries. This includes regulating the abstraction of water and managing migratory fish, flood and coastal erosion risk, and water quality. We also support progress towards a low carbon economy through our regulatory and advisory work.

The Government’s Severn Tidal Power (STP) Feasibility Study presented a detailed and thorough assessment of all aspects of developing energy schemes in the Severn Estuary. We contributed to this work. We believe the conclusions in the report on the environmental impact of a Severn Barrage are still valid and merit full consideration by the Select Committee.

We are aware of media reports of a proposal by Hafren Power for a barrage from Cardiff to Weston-super-Mare. We have not seen details of this proposal. As such our comments here are limited to consideration of a generic barrage from Cardiff to Weston, similar to the one considered in the Government report.

2. What contribution could the Cardiff-Weston Barrage make to UK energy security and climate change objectives?

The Committee on Climate Change has advised that electricity generation must be nearly fully decarbonised by the 2030s if the UK is to meet its carbon budgets and its commitment under the Climate Change Act to cut greenhouse gas emissions by at least 80% from the 1990 level by 2050. We support the development of appropriate energy schemes in the Severn Estuary and elsewhere to help secure the reduction in greenhouse gas emissions required by 2050 and beyond.

Given its particular tidal movement, the Severn Estuary offers clear potential for the development of renewable energy. However the Severn Estuary is also a unique natural environment, with some of its habitats and tributary estuaries being among the most important of their kind and highly protected in Europe. Given the potential impacts on the environment, any proposal must be designed and operated to minimise these impacts. Government must make sure that any energy development in the Severn Estuary is justified by its contribution to greenhouse gas reduction and energy security, taking full account of the environmental impacts.

We will continue to work with Governments and developers to help identify a project that can generate the maximum sustainable energy from the Severn Estuary while meeting the requirements of environmental legislation.

3. What risks and opportunities could it pose with regard to flooding in the Severn Estuary, and how might any risks be mitigated?

The flood risk consequences of any structure that might be developed in the estuary depend very much on its design, construction, location and mode of operation.

The Government report identified that water levels would be affected and that to maintain current flood protection levels in the Severn Estuary, additional flood defences would be required.

Some of the possible impacts would be:

Potential upstream protection from storm surge and tidal flood risk;

Potential to erode existing flood defences upstream of a barrage;

Potential to increase the upstream flood risk due to gravity discharge from rivers and drains being prevented (“tide-locking”); and

Potential increase in coastal flood risk around Wales, North Devon and Ireland from a Severn Barrage.

The management of flood risk must be key in any design. In line with our approach to other developments, we believe there should be no increase in flood risk as a result of a Severn tidal energy scheme.

The total cost of capital works to manage the flood risk for the Severn Estuary communities for the next 100 years is estimated at £600 million, with a Present Value cost of £156 million. This will safeguard 62,700 existing residential properties and 24,800 existing non-residential properties.

If a barrage were constructed, some of these costs would be avoided as the extreme tidal surges would not reach the upper estuary. However, very significant additional costs would be created to manage the effects of a barrage, to address, for example, erosion caused by a higher water table upstream, and to deal with “tide-locking”. A barrage would not protect all the properties that currently receive protection from flood defences. In addition, as a result of a barrage, there would also be potential costs from the downstream and “far-field” effects, for example increasing water levels on the Welsh and Irish coasts.

Our initial assessment is that over 100 years the overall impact on flood risk management costs may be neutral, although further work is required to understand the effects on coastal regions far from the Severn. We believe additional flood mitigation measures should be included in the scheme.

4. What risks and opportunities could it pose to wildlife and habitat in the Severn Estuary, and how might any risks be mitigated?

The Severn Estuary is a unique environment and its habitats and species are protected under national, European and international law. A barrage would result in irreversible changes to the ecology of the estuary.

Of all the options considered, the Government report clearly highlighted that a Cardiff-Weston barrage would have the greatest impact on habitats and bird populations. Of particular concern to the Environment Agency is the impact on migratory fish, an issue for which the Environment Agency is responsible in England and Wales. From media reports, we understand that Hafren Power believe their scheme to be “fish-friendly”. We have many years of experience in this area and employ some of the leading experts in the country. We are not aware of any turbine designs which would allow the safe, repeated passage of fish through a barrage at the scale proposed.

The Government report examined the issue of fish migration in detail and recognised that fish would be severely affected with population collapses predicted for species which are protected under law. Indeed, the Government report predicted local extinctions of Atlantic salmon and twaite shad as a result of a Severn tidal scheme.

To mitigate risk, we think more detailed baseline monitoring of the estuary is required to understand the distributions of species and habitats. In particular, further study of fish behaviour and movement within the estuary is essential. If a scheme were to go ahead, it is vital that its environmental impact is monitored.

5. What lessons can be learned from the successful development of La Rance tidal barrage in France and other tidal power projects?

From an environmental perspective, there are only very limited lessons that can be learned from La Rance. This is due to three principal reasons:

La Rance and the Severn are different in nature: they are of a different scale, have different ecologies and support different habitats and species;

La Rance and the Severn have different protections under law; and

There is a lack of baseline environmental data to understand the impact of the La Rance barrage.

6. What risks and opportunities could it pose to local employment and community, and how might any risks be mitigated? In particular, what are the consequences for current ports, fishing and aggregate extraction industries in the estuary?

The Government report highlighted that benefits to the local economy would come at the expense of negative impacts on the current ports and the fishing and aggregate extraction industries in the estuary.

We understand Bristol Port has had their Harbour Revision Order for their new container terminal approved since the Government report concluded. There are considerable implications for the viability of this scheme if the barrage were to be built.

7. Are the proposals in breach of EU legislation, and if so how will this be addressed?

There are two pieces of European Union environmental legislation that would be key in the development of a Severn Barrage: the Habitats Directive and the Water Framework Directive.

Compliance with the Habitats Directive, with respect to migratory fish and inter-tidal habitats, is probably the most difficult challenge for a proposed Severn Barrage. The Government report made good progress in understanding the complexity of the issues in relation to the Habitats Directive. It acknowledged, however, that the scale and impact of a scheme would be unprecedented in a protected area and that there was significant uncertainty on how the regulatory framework would apply.

The Habitats Directive does allow for designated sites to be damaged for imperative reasons of overriding public interest if there are no alternative solutions to the projects. In our experience, these tests can be very difficult and time consuming to apply and may in themselves represent a significant stumbling block. This justification does not remove the need to compensate for damage, which is a prerequisite for any project relying on imperative reasons of overriding public interest to proceed. The Habitats Directive does not stipulate how to provide compensation. However, this is normally done by replacing the protected habitats affected on a “like for like” basis as close as possible to the location of the negative impact.

The report acknowledged that the compensation requirement under the Habitats Directive for projects of this nature would be very challenging but failed to arrive at a mechanism to manage this. It may prove impossible to compensate for any residual damage to fish populations, particularly those using the tributary rivers as spawning areas.

The scale of potential inter-tidal habitat loss will make it very difficult to identify and develop adequate sites for compensation. The Government report identified that a Cardiff-Weston barrage would result in a loss of up to 16,300 hectares of habitat. This, it noted, could require compensation 60 times greater than the largest existing UK compensation scheme.

Moreover, given the scale of the compensatory habitat required, it is unlikely that this could be accommodated within the Severn Estuary. The compensatory habitat areas may consequently be some considerable distance away. The creation of new intertidal habitats may in itself be as controversial as building a barrage.

The report also recognised that land change will be required within the Severn Estuary and probably outside it also. Our experience of managed coastal realignment projects suggests that practical delivery will prove very difficult, contentious and time consuming.

The Water Framework Directive aims to protect and improve the water environment. As required under the Directive, we are undertaking an ambitious programme of work to improve the River Severn and other river basins. The operator of any future barrage would have to ensure that the scheme does not lead to deterioration of the ecology of the River Severn and the rivers and aquifers in the catchment.

There are defences in the Water Framework Directive (Article 4.7) to permit development that causes deterioration, provided the following conditions are met:

All practical steps are taken to mitigate the adverse effect on the status of the body of water;

The reasons are explained in the River Basin Management Plans; and

The reasons for permitting the development are of overriding public interest and/or the benefits to the environment and to society (of achieving the Directive’s objectives) are outweighed by benefits to:

sustainable development;

human health; and

maintaining human safety; and

The benefits of the development cannot (for reasons of technical feasibility or disproportionate cost) be achieved by significantly better environmental options.

8. Are any other proposals for tidal power projects in the Severn Estuary currently under consideration?

We are not aware of other tidal projects coming forward in the Severn Estuary.

9. What could be the wider international implications of the scheme for UK engineering and UK low-carbon industry?

We welcome Government’s commitment to technological innovation in the tidal energy sector. There is a real opportunity for the UK to lead the world in the development of innovative tidal and wave energy technologies, supporting the delivery of the UK’s renewable energy targets and creating green jobs and investment.

10. Conclusions

Given the potential impact of a barrage, the Environment Agency is keen to work with developers to help them understand the environmental and flood risk issues associated with their proposal.

We are also keen to work with the Department of Energy and Climate Change, the Department for Environment, Food and Rural Affairs, the Welsh Government, the Marine Management Organisation and other statutory agencies on the development of guidance and offer expertise where we can.

December 2012