Photos: Rance barrage
I was fortunate to visit this site in Brittany a few months ago and while there appears to be some agreement of the benefits in the local area there are also clearly some downsides - the barrage has caused progressive silting and sand-eels and plaice have disappeared. It is very hard to get a real picture from the various studies about it however there is lots written about how it differs from the Severn proposals.
Save Our Severn write comparing the project to the River Severn: "Firstly the Rance River is tiny. The structure there is more like a bridge. And fundamentally, the water is crystal clear and not bit like the magnificent brown Severn. The important thing here and something the pro-barrage scientists continually gloss over is silt. Silt on a massive scale, silt that could render a barrage a dead lump of giant concrete in a stinking life-less river in a matter of decades. If anything has been proven about barrages, it is that they don’t work in silty estuaries. Scientists with years of experience on the Severn and similar estuaries worldwide are trying to warn us, but their voices are being brushed aside by the developers..."
It was an interesting visit and I am glad I have now seen this project as many pro-barrage people have held it up as a good example. I am still stronly in favour of using tidal energy but the barrage is a risk that puts too many eggs in one basket - a vast expense - and what project of that size ever runs to time or budget? Far better to go for a whole series of smaller projects using like tidal lagoons and some turbine technologies. It is vital these now get investment.