Wednesday, January 21, 2015

Tidal Lagoons in south Wales

Last night, I went to a presentation given by Tidal Lagoon Power at the Penarth Pier Pavilion. This was part of an evening organised by Gwyrddio Penarth Greening (PGP). I will give a short briefing here on tidal lagoon developments in south Wales.

Joanna Lane, the Wales Public Affairs Manager of Tidal Lagoon Power Ltd, talking about the proposed Swansea Bay Tidal Lagoon and plans for further tidal lagoons in four areas around the coast of the UK (Severn, Thames, west coast of NE England into Scotland, and The Wash), including a proposed tidal lagoon between Cardiff and Newport.

The final planning decision on the Swansea Tidal Lagoon will be made this summer (June 2015). If successful, work on site will begin this September, with a two-and-a-half year build envisaged. The technology is ingenious (see the video:, but both the turbine and construction techniques are well-tried and tested elsewhere (e.g. the Netherlands). At Swansea, a 9.5 km breakwater wall will enclose a tidal area of around 11.5 km2. Water will be held in the lagoon on the outgoing tide and kept out on the incoming tide. Given two tides, electricity will be generated four times a day as the water released in both directions drives 26 low-head bulb turbines. The power generated will be equivalent to 90% of Swansea’s domestic use. The lagoon infrastructure is designed to generate this power for at least 120 years. The proposal incorporates plans for 10 km of marine ecosystem restoration and mariculture (e.g. mussels, oyster, samphire, seaweed, and possibly algae for biofuel in collaboration with Swansea University).

Tidal Lagoon Power’s business model depends on the eventual completion of six tidal lagoons, which will generate around 8% of the UK’s electricity. Locations around the UK enable differences in the timings of the tides to be exploited, so that demand can be met around the clock. The other lagoons will be considerably bigger than the one in Swansea, as this first UK tidal lagoon is also acting as a demonstration project for future developments and a starting point for a new tidal power industry. Different considerations will come into play at each proposed site. At Swansea, for instance, no rivers enter the lagoon, it backs onto a brownfield site (Swansea University is building its new campus on part of this site), and there is a focus on providing public access and civic amenities (e.g. sports).

The proposed tidal lagoon between Cardiff and Newport (tidal range 9.2 m) will have a breakwater wall running for around 20-25 km, enclosing a tidal area of around 70 to 80 km2. The tidal range will be converted to electrical power using 60 or 65 turbines. It is likely to extend from the coast around 2 km from Cardiff Bay to around 2 km from the mouth of the River Usk in Newport. This lagoon is likely to be more problematic from the environmental impact assessment point of view than the one in Swansea, because the river Rhymney may flow into it and it will incorporate wetlands. Some of this area is of conservation importance at the European level, which will oblige Tidal Lagoon Power to create compensatory habitats in collaboration with Natural Resources Wales. The company acknowledges that this is a “new science”, and that importance lessons can be learned from the Cardiff Barrage experience.

A pre-application for the Cardiff and Newport Tidal Lagoon has just been submitted (November 2014), with a full planning application expected around 2017 and a goal of generating power around 2021. There is an opportunity for the Cardiff Naturalists' Society and similar stakeholder organisations to get involved at an early stage of this proposal.

Stephen Nottingham

1 comment:

  1. Hi Stephen.

    Thanks for sharing.

    Very interesting and a lot to think about

    The Swansea project sounds a sensible scale for this new technology and in many ways I wish that project well.

    I agree with you that a massive lagoon of 20-25 km is much more problematic. in my opinion the science of understanding the impact of the smaller one should be much better understood before a huge one like that is given the go ahead.

    The Cardiff Bay barrage has had problems with water quality and needs oxygenation and whilst the proposed lagoons do have flow in and out it will no doubt be reduced and it would be interesting to know what studies have been done on that

    Also interesting re the Swansea proposal is the proposal to seed oyster beds. Of course they were destroyed in Swansea by the pollution from the copper plate industry that contaminated the sea bed amongst other things and I'm interested to know would they be dredging that pollution out from within the lagoon and what would stop copper coming back in and effecting the oysters, also What would stop it being stirred up and effecting the River Severn during construction?

    re the Cardiff plan. of course "compensation" means many things to many people and I remember the upset that the Newport Wet Lands caused to the family of the farm where land was being flooded. I personally felt that the wetlands should have been developed closer to the damage and that the people of Cardiff should have had a major wildlife reserve created with facilities such as are in the Newport site

    I do think that we as CNS should ask to be informed and consulted along the way


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