The water use of the UK electricity sector and its vulnerability to drought

Abstract

The majority (80%) of global electricity generation comes from thermal power stations, most of which use large volumes of water for cooling. Population growth and climate change are likely to increase water scarcity, whilst many countries are exploring pathways to low-carbon electricity systems. Thermal power stations, both with and without carbon capture and storage (CCS), are likely to continue using water for cooling where possible for the foreseeable future. This thesis investigates the dependency on water for cooling of multiple low-carbon pathways for the UK put forward by Government and academia. An analytical framework that combines generation technologies, cooling systems and sources, water use factors and regional water availability is applied at national and regional scales. Whilst most decarbonisation pathways reduce freshwater use for a variety of reasons, high levels of CCS are likely to increase freshwater demands due to the increased water intensity of CCS generation. Furthermore, higher demands will be locally concentrated, given Government’s strategy to cluster CCS facilities. Subsequently, UKCP09 Weather Generator climate timeseries and a hydrological model of the River Trent are used to simulate the effects of hydroclimatic variability on licensed water availability. The impacts are tested on a CCS cluster operating with different cooling systems and under two Government-proposed abstraction regimes. Capacity availability is impacted by low flows, but this can be mitigated through increased use of hybrid cooling and prioritisation of more water-efficient capacity. Other innovative solutions may reduce freshwater dependency, however these are not facilitated by the current policy and regulatory arrangements. In some cases, reducing water use and carbon emissions are in direct conflict. To ensure both energy and water security, this thesis proposes strategies that take into account the planning of CCS clusters, increasing competition for and scarcity of water, and the already challenging economics of CCS.