There are some environmental debates which seem to be come and go with the same frequency as England taking part in penalty shoot-outs. Some, however, like last night’s drama in Russia, have happy endings or at least give us an opportunity to learn some lessons.

The debate about how to harness the tidal power from the Severn Estuary has raged for decades, most recently after Rt Hon Charles Hendry was commissioned by the then Prime Minister, David Cameron, to review the potential of tidal lagoons.

My last blog on the subject was 18 months ago. I said then that we saw potential value in a Swansea lagoon as a ‘pathfinder’ to learn more about the environmental impacts of this untried technology – if outstanding environmental issues notably the impact on fish could be resolved.

We now have an answer from the Westminster Government that tidal lagoons are not value for money and it will not support any of the programme of 6 lagoons promoted by Tidal Lagoon Power (TLP) including Swansea.

Shelduck: one of the species for which the Severn Estuary is designated as a Special Protection Area (Ben Hall,

In many ways this reinforced the position of the previous Westminster Coalition Government who concluded the 2006-10 review of Severn tidal power by saying that there was no strategic case for government to support a tidal power project and it would not reopen the debate unless or until the strategic context changed (ie if the need grew or the cost of technology reduced).

Well, they did, of course reopen the debate but it now appears they’ve closed it again.

So what can we learn this time?

Once again, missing from the reasons for not proceeding this time is any reference to the environment. We saw tidal lagoon energy as high risk for nature and argued that a precautionary and evidence-based approach was therefore needed. However, this seemed to be overlooked as rhetoric hardened into an all or nothing position that pre-judged the outcome of a demonstrator project. So, while we can live with the decision, it is disappointing that the environmental consequences of our energy policy choices don’t get a mention in the reasons for not proceeding.

The RSPB’s 2050 Energy Vision Report published in 2016 shows how a transition to sustainable energy can be made in harmony with nature. This depends on the choice of technologies and on proper consideration of environmental impact in their siting and design. This found that we can meet our energy and carbon targets with less risk to wildlife and nature than with large scale tidal lagoons. But tidal range energy remains a compelling idea. With partners we published the Severn Vision which includes a goal of developing in harmony with nature, tidal renewable energy. The challenge then is whether there could be a solution that is value for money and environmentally sustainable.

The best places for tidal range energy include some of our most important wildlife sites. The Severn Estuary is not only the location of 4 of the 6 lagoons promoted by TLP, but is also a wildlife wonder. Its mudflat and saltmarsh habitats are natural carbon stores that support over 80,000 wintering waterfowl and wading birds. In its waters are 110 species of fish including seven migratory species which are internationally important not just in the Severn but in the designated rivers that flow into it. That is why we saw a case for Swansea Bay lagoon as a test site, to learn more about the environmental impacts of this untried technology, if - and only if - it was well researched and met environmental standards. We were not satisfied on either of these points.

We also question whether current lagoon technology can be scaled up as envisaged by the Hendry Review while still protecting our marine and coastal wildlife. Evidence shows that a fleet of tidal lagoons will have large scale and complex wildlife impacts. The Welsh Government’s own assessment of a policy supporting multiple tidal lagoons around Wales could not rule out adverse effects on 70+ of the most highly protected wildlife sites (SPA, SAC and Ramsar). This includes sites in all four countries of the UK and some in France and the Republic of Ireland. There are lessons relevant to the debate about our future relationship with the EU as clearly our wildlife crosses borders and we need co-operative approaches across geo-political boundaries to protect it. We know about these risks because of the environmental assessment that is required by EU legislation, so it is vital to maintain this requirement into the future.

History and experience suggests that, like England taking part in future penalty shoot-outs, government will look again at tidal range energy. Much more thinking and research now needs to go into understanding the complex estuary environments in the UK and whether tidal energy could be developed in harmony with nature. We were pleased that in 2010 as part of its Severn Tidal Power Study the Government published a review of alternative tidal range concepts. One of these concepts has now been developed and adapted into an operational river hydropower scheme. So, if there is a next time, we should start with the premise of finding a solution that not only generates large amounts of renewable energy at a cost that is attractive to the tax-payer but also one that has the least impact on the environment.

A good starting point would be to revisit and extend the 2010 study.