New doubts have been raised about ambitious proposals to build a massive electricity-generating tidal lagoon off the foreshores of Penarth and Cardiff.
A similar – but much smaller – scheme for Swansea Bay has now been criticised by a mechanical engineer and former University of California professor Roger Griffiths. Professor Griffiths says no one can be sure the 16 turbines planned for Swansea (66 are planned for Penarth) will work efficiently in both directions (i.e. on the flood tide and the ebb tide).
He says there have been no measurements of the performance of these turbines in reverse flow – when the tide is coming in – nor have they been tested under difficult conditions at the lowest depth of water . Professor Griffiths’s view is backed by tidal engineer Dr Bob Allen, who claims there has been an assumption the turbines would work to the same efficiency with the tide flowing in both directions – an assumption yet to be proved.
Tidal Lagoon Power has now issued a New Year update on the much larger tidal lagoon it proposes to build out in the Bristol Channel off the foreshores of Penarth and Cardiff .
In a press release redolent with planning jargon, Tidal Lagoon Power says it has submitted a report for the Planning Inspectorate’s “Environmental Impact Assessment”. This document is intended to protect the environment by making sure all potential detrimental effects on the environment are taken into consideration – and is also to identify what are called “mitigation measures” for situations where “adverse impacts cannot be avoided” .
Tidal Power says it is compiling historical data spanning the past 20 years from “all Severn Estuary survey work” and will include information on dredging and dumping areas in the Bristol Channel . It is also carrying “modelling” of tidal flows, movements of sediment and “water quality” – but does not say whether this is being done in real-time with scale models or is just a computer desk-top exercise.
Tidal Power says it is carrying out “geophysical and oceanographic surveys”, “a Habitats Regulation Assessment”, “Water Framework Directive screening” and bird and fish surveys. It has also formed a “Fisheries Peer Review Group” to be chaired by Chris Mills, the former Director of Environment Agency, Wales – but doesn’t say if it has any local fishermen on it.
The academics who have criticised the Swansea project also express concerns about the ‘jet’ effect’ of the discharge from the 16 Swansea turbines which will be a hazard for any small boats nearby. The 66 turbines planned for the Cardiff/Penarth barrage are all concentrated in two areas – both with outflows directed towards Penarth (see top illustration) and at right angles to the course vessels take when leaving and entering Cardiff Bay.
Meanwhile there are continuing concerns about the very high “strike price” being envisaged for the project – the price which the power companies (and ultimately the consumers) – would have to pay for electricity generated by tidal lagoons over something like a 35-year life of a lagoon project.
The Prime Minister has said “The problem with tidal power, simply put, is that at the moment we have not seen any ideas come forward that can hit a strike price in terms of pounds per megawatt-hour that is very attractive.”