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

Abstract

Several tidal power schemes have been proposed for the Severn estuary between south-west England and Wales, UK. In this paper the so-called Cardiff-Weston barrage is evaluated using various sustainability appraisal techniques to determine its net energy output, carbon dioxide 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 £21 billion to construct and could potentially generate some 16·8 TWh/year -about 4·4% of the UK electricity demand. An indicative energy technology assessment is undertaken 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 dioxide emissions, although its financial performance is poorer than that of alternative power generators. Comparisons are also made with the much smaller Shoots barrage scheme proposed upstream of the Severn Road crossings, which is favoured by environmental groups due to its more benign ecological and environmental impacts. NotationE con,L total process energy invested in construction of the tidal barrage E dec,L energy required to decommission the tidal barrage at the end of its life (L) E mat,L total primary energy invested in materials used to construct the tidal barrage E n,L net electrical energy produced over the lifetime (L) of the tidal barrage E op,L energy required to operate the hydro-turbines over the lifetime (L) of the tidal barrage L lifetime of the tidal barrage (in years) R t net receipts (income less costs) from sale of electricity produced by a power generator t time in years of the total foreseen life (L) of a power generator

Realising transition pathways for a more electric, low-carbon energy system in the United Kingdom: Challenges, insights and opportunities

“…46 Two other large-scale power generators that could be available to help secure a low-carbon future for the United Kingdom are nuclear power plants 42 and tidal barrages. 43 The lives of existing nuclear plant has typically been extended to around 40 years (e.g. Hunterston B was financed for 25 years with an expectation of 35 years, and subsequently extended by 7 years).…”

“…42 The adoption of either shortor medium-term technologies would obviously be critically dependent on public attitudes to nuclear power in Britain and elsewhere. 1,11,42 Both the Cardiff-Weston and the smaller Shoots barrages on the River Severn between Somerset and south Wales have been evaluated by Hammond et al 43 using various ETA techniques to determine their net energy output, carbon footprint and financial investment criteria, alongside various critical technical and environmental issues. These tidal power schemes were assessed over their foreseen lifespan of 120 years in terms of its cradle-to-site, operation and maintenance requirements.…”

“…A tidal barrage built across the Severn Estuary would inevitably give rise to significant ecological modifications to the aquatic environment. 43 . The suitability of ARBT have been evaluated for different applications.…”

Socio-technical transitions in UK electricity: part 2 – technologies and sustainability

“…These studies have sought to identify the components of a balance sheet of technological credits and debits in order to evaluate their societal impacts, and to determine whether they are compatible with Britain's move towards a low carbon future in 2050 and beyond. Indicative energy technology assessments (ETAs) have therefore been carried out for a variety of energy technologies, e.g., UK shale gas extraction (Hammond and O'Grady, 2014), carbon capture and storage (CCS) (Hammond, 2013;Hammond and Spargo, 2014), advanced rechargeable batteries (Hammond and Hazeldine, 2015), Rare Earth Elements (REE) as a constraint on clean energy technologies (Hammond and Mitchell, 2014), nuclear power plants (Hammond, 2011), and tidal power barrages (Hammond et al, 2018). These ETAs were all indicative in the sense of being a simplified evaluation and illustration of the performance of state-of-the-art devices.…”

“…The Severn Estuary, which empties into the Bristol Channel, is seen as one of the premium international tidal power locations because it has the second largest tidal range in the world (15 m). It would involve the construction of a 10 mile long barrage (dam) between Lavernock Point (south of Cardiff, Wales), and Brean Down on the Somerset coast, England The use of technology that utilises the tidal range is well-established, and typically has an estimated lifetime of 120 years (Barton et al, 2018;Hammond et al, 2018). Both the Cardiff-Weston and the smaller Shoots barrages on the River Severn have been evaluated by Hammond et al (2018) using various ETA techniques to determine their net energy output, carbon footprint and financial investment criteria, alongside various critical technical and environmental issues.…”