Energy accounting of river severn tidal power schemes

An energy accounting exercise has been carried out, using data currently available from the main contractors, for three alternative Severn Tidal Power schemes--Line 5s Lavernock to Brean Down; Line 5s plus second stage bund enclosing Bridgewater Bay and Line 2.5, Minehead to Aberthaw. The energy ratios, GJe/GJt, obtained for these three schemes fall respectively within the following bands--12:1 to 16:1, 10:1 to 14:1 and 12:1 to 16:1. Thus, in no case is the energy ratio less than 10:1, the highest possible value being 16:1. Solely on the basis of energy accounting, and using the best data available at the time of the exercise, the straightforward schemes based on Lines 5s and 2·5 look equally attractive, and would be preferred to Line 5s plus second stage bund. The total initial energy requirement for these various schemes would not be unduly sensitive to limited changes in individual inputs. On the basis of energy accounting assessment only, the Severn Barrage power schemes appear to be very attractive indeed; certainly at least as good an investment as a large wind power programme, attractive though the latter has already been shown to be.