A technology assessment of the proposed Cardiff-Weston tidal barrage, UK

Several tidal power schemes have been proposed for the River Severn Estuary between the South West of England and Wales. Here the so-called ‘Cardiff-Weston’ Barrage has been evaluated using various sustainability appraisal techniques to determine its net energy output, carbon footprint and financial investment criteria, alongside various critical technical and environmental issues. The barrage would be located seaward of the Severn road crossings, involve an estimated cost of £20.9 bn to construct, and could potentially generate some 16.8 Tera Watt hours per year [or about 4.4% of UK electricity demand]. An indicative energy technology assessment has been undertaken in order to evaluate this tidal power scheme over its foreseen lifespan of 120 years in terms of its cradle-to-site, operation and maintenance requirements. The present analysis suggests that the proposed Cardiff-Weston Barrage would yield relatively attractive ‘figures of merit’ in terms of its net energy and carbon emissions, although its financial performance is poorer than alternative power generators. Comparisons are also made with the much smaller, ‘Shoots Barrage’ scheme that would be located up-river of the Severn road crossings, and which is favoured by environmental groups, because to its more benign ecological and environmental impacts.