Cooling water for

ions from rivers will decrease in the coming decades, unless there is widespread uptake of carbon dioxide capture and storage (CCS). CCS may prove to be essential if the UK is to achieve its carbon dioxide and greenhouse gas emission targets. ‘Decarbonisation’ strategies that rely on CCS are therefore potentially at risk of not having sufficient cooling water in periods of low river flows. In this paper, regional freshwater demands for cooling water are assessed against regional freshwater availability at low flows in a scenario of medium climate change. In the strategy with high CCS, demands for water greatly exceed current and future availability in the north-west (NW) England, Humber, East (E) Midlands and Thames regions. These risks can be mitigated by increasing the penetration of hybrid cooling systems or shifting generating capacity to estuaries or the coast. The former could reduce national water use by up to 35%, whereas applying the latter in the NW England, Humber and E Midlands regions offers nationwide reductions from 30 to 50%. Notation A95 abstraction sensitivity band factor (%) for Q95 flows i river Qe licensed flow (m /s) available to the electricity sector Qe95 available flow for abstraction by the electricity sector at a Q95 flow Qe99 available flow for abstraction by the electricity sector at a Q99 flow QL flow (m /s) that is licensable from the whole flow in the river Q95 flow (m /s) of the river exceeded 95% of the time in the period under consideration (typically historical), a low flow Q99 flow (m /s) of the river exceeded 99% of the time in the period under consideration (typically historical), a very low flow Q95.min minimum flow required at Q95 to support the design size of power station Se proportion (%) of the total licensable flow that is available to the electricity sector, determined by the licences held by the sector