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tidal-turbinesAt the end of 2012, the Select Committee on Energy and Climate Change began an inquiry into a proposal put forward by Hafren Power for a privately-funded, 18km tidal barrage across the Severn estuary.

Last month saw the publication of the Government’s response to the Select Committee’s report, in which it made clear that “more detailed, credible evidence” would be required before the proposal could be considered further.

The need for additional information on the development of the low-head turbines and the impacts of the barrage on ports, navigation and flood risk was highlighted, as was the requirement for more evidence to support claims about job creation and other proposed benefits. Specific reference was also made to the need for an in-depth study of environmental impacts.

The considerable impacts of a barrage on intertidal habitats, fish and bird populations, water quality, and water and sediment dynamics were the subject of much of the evidence provided to the inquiry, including in a submission from NERC, to which both myself and Mel Austen of the Plymouth Marine Laboratory contributed.

The Government’s response went further than simply calling for an Environmental Impact Assessment, in suggesting that a large-scale tidal project in the “sensitive and highly protected Severn” may face “insurmountable obstacles” in complying with requirements under the EU Habitats Directive to mitigate environmental impacts, adding that the high level of public interest provided by renewable energy would not lead to schemes securing automatic approval.

The Government’s position does not inspire confidence that a large-scale barrage will be given the go ahead any time soon, with even supporters of the Hafren Power proposal reportedly stating it was “dead in the water” for the moment.

So far, this latest inquiry suggests that little has changed since the conclusion of the last detailed feasibility study on a Severn Barrage in 2010.  However, there is one key difference, as the Government has given a clear signal that it is willing to consider alternative approaches to harnessing the energy within the Severn estuary, even going as far as to endorse as a “useful framework” the Balanced Technology Approach proposed by RegenSW and its partners.  This approach suggests a combination of tidal range (lagoon and small barrage), tidal stream, wave and offshore wind, that could possibly supply 10-15GW of energy.

There is already interest from developers in taking forward individual tidal lagoon schemes within the Severn, such as Stepping Stones and also the Swansea Bay tidal lagoon, for which stakeholder consultation has been undertaken and preliminary environmental information produced.

Taking a new approach to energy from the Severn estuary brings with it considerable challenges.  One of the attractions of a ‘traditional’ barrage is that it is a proven technique and the likely environmental impacts are comparatively well understood.  The Government has explicitly stated that it will only consider alternative schemes that can provide strong evidence of value for money, economic benefits, energy saving and environmental impact mitigation.

However, as RegenSW note in the Balanced Technology discussion document, there remain many engineering and environmental unknowns and uncertainties around deploying new marine energy technologies at a significant scale, both within individual projects and also in relation to the interactions between them.

Researchers within UKERC’s Energy and Environment theme are already working to help progress our understanding of some of these issues.  Scientists at the Plymouth Marine Laboratory and the Universities of Aberdeen, Southampton and East Anglia, are studying the colocation of marine energy with other coastal activities and public preferences for the attributes of tidal range and offshore wind schemes as well as modelling the cumulative effects of offshore wind farms and comparing the impacts of different energy technologies in full life cycle analysis on national and global ecosystem services.

The feasibility of a Severn Barrage has been considered since the 1920s.  As the need for sustainable energy sources becomes more and more pressing, hopefully we won’t spend another 100 years repeatedly considering the same approach, but will rise to the challenge of developing alternative options for maximising energy from the Bristol Channel while minimising the associated environmental and social impacts.

Tara Hooper is an Environmental Economist at Plymouth Marine Laboratory. Tara’s research is being funded by the UK Energy Research Centre (UKERC).


Dr Mel Austen PMLAs a marine ecologist I have always been interested in complexity and interactions. This started in earnest when I found out that just a handful of estuarine mud contained anything from 20 to 70 species of tiny nematode worms (smaller than a pin head)! Why are there so many species and what do they all do? (In partial answer they all feed on different things and live in minutely defined chemico-physical niches.)

I researched why some marine nematodes were more vulnerable to the things that humans throw at them (i.e. pollutants) than others. I also asked, who feeds on nematodes and how such sedentary organisms are so widely dispersed, given that they can only wriggle or move mere millimetres and they don’t even have a planktonic phase in their lifecycle. Tiny animals are difficult to study and we will probably never know precise answers to these questions.

Then I broadened my research to look at the rest of the animals living in the soft sediments on the seabed. I looked at why they had changed over recent decadal history (early signs of climate change), how they interacted with the whole of the physical, chemical and biological context of the water column above (which moves at different time and spatial scales to what happens in the sediments), what might happen in the future (working with mathematical ecosystem modellers) and considered what this might imply for people.

Adding ‘people’ created a whole new dimension of research. How do marine ecosystems function from a totally anthropocentric perspective, beyond the obvious provision of fish for us to eat? And how and why do we value the different services provided to us by the sea? Which brings me at last to energy.

From some people’s perspectives (and many of them are involved with UKERC) it seems that the ONLY thing of any importance is energy. Marine renewable energy supply is now even viewed by some as being an ecosystem service (although this ignores the definition of an ecosystem which embraces the interaction of both living and non-living components of the environment). However, the key thing for me is that the marine environment provides more than just energy.

It is a vital source of food, both directly from the sea through capture and also through aquaculture. It is a place to undertake leisure and recreation (I am a keen sailor and used to do a lot of scuba diving). It is a medium for transport (around 95% of goods entering or leaving the UK go by sea). We also take our seas for granted when we use them to discharge wastewater, like treated sewage, fertiliser/pesticide run-off from our highly intensive and much needed agriculture, and road surface water run-off – including all the chemicals released from the tyres and oils associated with transport. And of course the seas are a massive sink for our greenhouse gas emissions. I could go on still further about what the marine environment provides for us.

In recognition of this and of EU policy (The Maritime Directive, The Marine Strategy Framework Directive), the UK enacted legislation (Marine and Coastal Access Act 2009, Marine (Scotland) Act 2010) which introduced marine planning. This recognises that not only are the resources we exploit from our seas increasing, our seas are also becoming increasingly busy.

UK marine planners, who are based in the Marine Management Organisation and in Marine Scotland, have to consider the trade-offs between all the different services and resources that the marine environment provides. And of course they do this from a very anthropocentric perspective. When they look at the sea they have to weigh up not just the UK’s renewable energy targets, but also inter alia the need for food security, the need for security of transport, the need for local businesses and industry to sustain their local tourist and leisure income, the appreciation by the general public of the marine environment, and the legislative demands to protect and preserve aspects of the marine environment through creation of a network of protected areas (Marine Conservation Zones, Special Areas of Conservation).

Marine planners would be failing in their responsibilities if they only considered the need for a secure supply of energy to satisfy our demand. Similarly, we fail in our responsibilities as researchers if we consider low carbon energy supply in isolation, ignoring its interactions with the living and non-living aspects of the sea and with other users of the sea.

Some of these interactions can be positive – established wind-farms can potentially be areas of protection for marine life, for the enhancement of fish stocks and for local aquaculture to provide food. Some can be negative – wind farm arrays can interfere with the navigation of ships potentially endangering lives in the event of a collision, as well as increasing fuel consumption and costs to avoid the newly installed shipping hazards.

Also to be considered are the cumulative and interactive impacts on marine ecosystems of increasing deployment of offshore wind turbines, and in the future of wave and tidal energy devices, both with each other and with other uses of our seas. And then there can be the unanticipated public response to the deployment of energy infrastructure (fracking comes to mind here), where we still have little primary data to understand the motivations that lead to negative responses.

It doesn’t help that researchers consider the positive and negative impacts of marine renewable energy through the blurry lens of our limited information on this fast developing seascape. Our key source of knowledge of environmental impacts should be statutory monitoring, but much of it is inadequate and/or the results are not freely available for researchers, such that our rate of gain in knowledge of impacts is much slower than the speed of deployment.

Our clarity of understanding the impacts of renewable energy on marine ecosystems, on different industries and on the public, is not unlike the clarity of view you get when you stick your head underwater in the sea, open your eyes and try to make out the details of the different fish and seaweed that are all about you.

I have always loved complex problems and issues, and I have always loved the sea and its marine life. For me the research challenges associated with marine renewable energy are complex and important. Energy security and increasing the proportion of low-carbon energy supply are vital, but so are many of the other services provided by our seas.

Marine planners are rising to these challenges and so must the research community to support them, ensuring that the decisions they, and others, must make are based on the best available evidence and understanding.

Dr Melanie Austen is Head of Science for ‘Sea and Society’ at Plymouth Marine Laboratory. She is also a Co-Director at the UK Energy Research Centre (UKERC), leading the Energy and Environment theme.

Charlie WilsonWhat comes to mind when you read the word ‘home’? A feeling? A sense of place? An aesthetic? Switching off, a to do list, family, work, goings on, peace and quiet, mayhem, order, clutter, tidiness, gadgets, possessions, relaxing, stress, safety, tensions … ?

The list could go on and on, and likely as not you’ll have your own associations to add. What homes mean to their occupants varies enormously, but in all cases, it’s likely to be complex.

So it follows that deciding to make major structural changes to our homes, often costing thousands if not tens of thousands of pounds, will similarly be complex, influenced by all sorts of different considerations. Right?

Well, not according to most of the policy and market activity to support and deliver energy efficient renovations. Look at how the government communicates policies like the Green Deal or how service providers market their insulation or efficient window products.

You’ll generally find the home represented as a set of financial outgoings (energy bills) and useful services (thermal comfort) that you are motivated to improve upon by investing in efficiency measures. So renovating your home is more like buying a flight, choosing a DVD player, or even deciding where to get a cup of coffee … it’s a fairly standardised product or service so you want to minimize costs and associated hassle, and get value for money.

So, have you renovated energy efficiently? If you’re a fairly typical UK household, then probably a bit, but not nearly as much as you could do, nor as much as financial common sense would dictate. Keep following the dominant thinking about energy efficient renovations, and you’ll also know the reasons why.


Your motivations to save on energy bills, make your home more (thermally) comfortable, and maybe even reduce your carbon emissions, are like a strong and wide river flowing downhill. But a large dam is blocking its advance. This is the barrier of upfront costs.

Smaller dams reinforce it and further restrict the river. Access to capital, distrust in contractors, disruption to home life, and uncertainty about how long you might stay in your home all mean that your motivations to renovate don’t actually lead to renovations.

This ‘motivations and barriers’ framing of the problem is clear and understandable. It directly informs policies like the Green Deal designed to remove the cost and trust barriers. And it makes sense to us in that it shows us (with our homeowner hats on) as being broadly rational or motivated by beneficial outcomes.

It’s also largely wrong, because it doesn’t relate to how we think about homes. Renovating, after all, is the process of making major, often irreversible changes to our homes, those complex and deeply personal places where we live.

The VERD project at the University of East Anglia has been looking for the last two years at the whys and wherefores of home renovations: not just energy efficiency, but also what we call ‘amenity’ renovations such as a kitchen remodelling, a loft or garage conversion, or a new bathroom. Our research has found almost no evidence that efficiency is regarded differently from amenity renovations.

In all cases, renovation decisions begin as an adaptive response to tensions, imbalances or issues at home that are created by certain conditions of domestic life. Households are more likely to be considering renovations if they face competing commitments in how to use available space at home, if they face or expect to face physical issues with home life, if they see a mismatch between their home and their vision for an ideal living space,or if they find ideas and inspiration for the home from external sources.

In about one in four cases, households decide to renovate because they more or less have to. The boiler breaks down, a window or door gets damaged, the family can no longer fit in the kitchen to eat. These ‘triggers’ precipitate action.

Renovating as a response to imbalances in certain conditions of domestic life or as a response to to external triggers both explain why we decide to renovate. This holds for both efficiency and amenity renovations.

Subsequent decisions to renovate are drawn out processes, often stretching on for many months if not years. They’re cumulatively reinforced, with intentions strengthening, plans changing, information being processed, options being explored … and eventually, in some cases, a renovation being carried out, a renovation that is far more likely to involve changes to the amenity features of a home. If efficiency measures are involved, they are four times as likely to be done together with amenity measures than to be done alone.

In other words, efficiency renovations are not distinctive, and it is a mistake to treat them as such. Efficiency renovations are as much about changing a home as any other kind of home renovation. So action on efficiency needs to start from a clear understanding of homes and what they mean to their owners and occupants. This view of renovation decisions – based on the data and analysis of the VERD project team – is clearly very different from the received wisdom.

Rendering renovators as cost-savers or comfort-improvers with motivations blocked by cost and other barriers is unhelpfully simplistic. It also misses a vast unexploited opportunity to think about and deliver energy efficiency in to homes. Rather than relying exclusively on a specialist efficiency industry backed by dedicated policy institutions, we should be talking to and working with the home improvement industry at large: the kitchen installers, the loft converters, and the conservatory builders on whom homeowners up and down the country are willingly and happily spending their money.

Dr. Charlie Wilson will be launching the findings of the VERD Project at a free morning event on Wednesday 16 October at Church House Conference Centre in London. Details available here:

Read the full report at

Dr Charlie Wilson is a Lecturer in the School of Environmental Sciences at UEA and is part of the team responsible for the VERD project, which stands for Value propositions for Energy efficient Renovation Decisions. VERD is a research project funded by the UK Energy Research Centre (UKERC) in collaboration with B&Q, Adapt Commercial, and Broadland District Council.

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