Cardiff-Weston vs Shoots – a comparison of the barrage schemes

Cardiff-Weston barrage The Shoots barrage
Length of barrage 15.9m 6.5m (approx)
Turbine No x runner dia. 216 x 9m 30 x 7.6m
Type of turbine Bulb, fixed distributor, Straflo or rim generator,
No of turbines/Caisson 4 2
Generator capacity 40MW 35MW
Total installed capacity 8,640MW 1,050MW
Annual energy output
with reverse pumping 17TWh (Approx) 2.75TWh
Annual energy, ebb
generation only 16.5TWh(approx) 2.75TWh
Contribution to UK
electricity supply
(2006 data) 4.40% 0.70%
Capital cost (2006) £15B £1.4B-£1.8B
Annual O&m costs £115M £22M-£27M
Unit cost of electricity 3.6-22.3 p/kWh 3-15.4 p/kWh
Annual saving in CO2
based on 0.43kg/kWh 7.3M tonnes 1.2M tonnes
Lifetime carbon saving 877M tonnes 142M tonnes
Environmental aspects Both schemes need to fish passes and injury
look at sedimentation; injury passing through