The Severn Estuary Commission led by Dr Andrew Garrad and backed by the Western Gateway Partnership, consulted over 200 local organisations about possible tidal projects in the area. It concluded that ‘a commercially viable lagoon should be developed - a Commercial Demonstration Project. It should use the Regulated Asset Base funding approach. Initial development would be undertaken by a predominantly public sector delivery vehicle followed by privately financed construction.’
The Commission says ‘it would be the world’s first tidal range lagoon, would create economic growth, and provide a better understanding of tidal range energy. Its environmental impact would need to be carefully monitored, and that knowledge should be used to determine whether future developments should take place. A parallel environmental monitoring programme should be implemented to fill broader data gaps.’
This report follows on from a long chain of studies of possible tidal projects on the Severn and also elsewhere in the UK. Tidal range barrage projects, utilising the vertical rise and fall of the tides, were the first to get studied, but progress on the giant Severn estuary idea came to a halt a while ago, although some smaller to medium scale barrage projects are still being pushed. But smaller tidal stream systems, using the horizontal flow of the tides, have of late prospered more, mostly so far in Scotland, but are also viable in many other locations. In theory, multiple units of these could be spread over a range of sites with differing peak tides, so resolving a key problem with large barrages- peak tides only occur twice every 24 hours.
However, tidal stream technology was not followed up in this new study, since it was not seen as so relevant at this location, given its low tidal flow rates (as opposed to the very high tidal range), although the report noted that 120MW of tidal stream projects are planned to be in place by 2030 elsewhere in the country, aided by the Contract for Difference (CfD) system, and the total tidal stream potential was put at 11GW. Instead, for the Severn, it focuses on tidal lagoons- purposes built structures in the sea being linked to and impounding some coast line. Fully offshore lagoons were also seen as possible, but were thought likely to be much more expensive since you had to build all the impoundment.
The old tidal range favourite of some, a large tidal barrage on the Severn, was seen as too invasive, very environmentally damaging and very expensive, much as had been concluded by an earlier government review- but not as had been concluded by a review in 2007 by the Sustainable Development Commission, led by Jonathon Porritt. He has now disagreed with the conclusions of the new study, and claims that the environmental impacts of the barrage have been overstated.
He says that ‘the Severn Estuary is indeed a very special place, including a designated Ramsar Site, a Special Protected Area, a Special Area of Conservation, and several sites of Special Scientific Interest…The potential damage to all that (particularly to the estuary’s intertidal areas) has been judged historically to be so significant as to make it all but impossible to compensate for that damage, as required by Habitats Directive regulations & (latterly, here in the UK) by Biodiversity Net Gain requirements. Infeasibly huge sums of money have been suggested as the cost of creating compensatory new habitats’.
However, he also says that ‘the Estuary is also an extraordinarily hostile environment, with tides racing in and out twice a day, scouring those ‘precious’ intertidal areas so brutally that not much invertebrate life that can survive, and that means there’s a lot less food for birds. It’s different higher up the Estuary (especially by the time one gets up to Slimbridge), but the further down one goes, the more impoverished those intertidal areas become. Heretical though this will sound to a lot of environmentalists, much of the Severn Estuary is far from being the kind of ‘biological wonderland’ that NGOs make it out to be.’ The Royal Society for the Protection of Birds (RSPB) is not going to like that! But he does back lagoons…anything rather than nuclear, which he sees as a massive mistake.
The problem though is that, so far, all the various tidal options have come out as expensive to build- big invasive barrages most of all. It can be argued that major costly infrastructure projects like this should not be assessed on a short-term economic basis. It is interesting, in this context, that the government is now looking to fund large high-cost nuclear projects, like the proposed Sizewell C, using the Regulated Asset Base (RAB) financing approach. The new Severn tidal report clearly spotted that! It says ‘Projects with RAB funding can attract 50+ year investment, and RAB can offer better long-term value than other schemes by reducing overall financing costs’. However, it added, RAB ‘requires consumers to start paying for the asset before construction is completed and introduces greater regulatory complexity compared to other schemes’. And it says ‘there are elements of the CfD funding structure that can be incorporated advantageously into a RAB funded project’. But it also says ‘the CfD model is not currently seen as appropriate for assets with a long operating life, particularly as it does not permit investor cash-flow during construction’.
I think it meant ‘consumer’ there, not ‘investor’. Either way, I am not sure it is a very good principle to try to pass on the risk to the customer via RAB, whatever the technology. As it is, tidal stream projects got a £172/MWh strike price in the sixth round of the CfD last year- a big drop from earlier, so hopefully the CfD will help this type of small-scale modular tidal tech to follow the success of offshore wind, with ever falling costs. Whether it can do the same for larger lagoons, much less big barrages, is less clear.
So, what happens next? The Commission is a bit vague on details. It says that the UK and Welsh Governments should ‘provide policy support for tidal range energy to ensure private sector investor confidence and public sector engagement in environmental research and monitoring. A Tidal Range Energy National Policy Statement would then be needed to further establish clear policy backing. Alongside this statement NESO should revise its Strategic Spatial Energy Plan to include tidal range potential’. But it does also outline something a bit more solid- a Commercial Demonstration Project (CDP). It says ‘As well as generating a substantial amount of low-carbon electricity, its purpose would be to understand the energy and socio-economic benefits of such a project and to provide a platform for full scale evaluation of its environmental impact’.
Well, the next round of the CfD is due soon, and although tidal stream project are likely to do well again, there are evidently also some players out there pushing ahead with lagoons. For example, the team behind proposals for a £10.9bn Somerset tidal lagoon near Bridgewater, with 2,500MW capacity….Will they and /or others apply for a CfD. Or try for a RAB? Watch this space!
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