The generation sector’s reliance on water

Matthew Aylott sets out the uncompromising facts around the generation sector’s reliance on water and how this could soon turn into a crippling vulnerability.

Electricity generation in the UK is dependent on water. Huge amounts are needed to cool thermal power stations and fuel hydro-electric plants. But the system is under strain and we need to build resilience to ensure this dependence does not become a vulnerability.

Freshwater abstraction by electricity generators is higher than for public water supply. Government data suggests that in England and Wales alone the energy industry is responsible for abstracting 5.7 billion cubic metres of water from non-tidal sources, which is over 40 per cent of the total amount of water abstracted every year.

In Scotland most thermal power stations are located on the coast and abstract water from the sea, but there remains a significant demand for freshwater from hydro-electric power plants, which generate around 12 per cent of Scotland’s electricity.

Meeting existing demand for water already presents a challenge for the energy sector. The Environment Agency estimates that around 5 per cent of electricity generated in England and Wales is dependent on rivers where there is insufficient water for both the environment and abstraction, and far more power stations are subject to intermittent low flows. This raises the risk that generators may have to reduce output or, in extreme scenarios, shut down altogether.

Water companies manage these risks by curtailing water use in non-critical systems at times of low flow, such as implementing hosepipe bans in the summer or issuing drought permits that allow companies to take water from new sources. But in the future constraints on water are predicted to increase and this could put considerable pressure on existing management plans.

The Environment Agency estimates that by 2050, annual river flows could fall by up to 15 per cent, and this will be especially pronounced in late summer and early autumn, where flows could fall by as much as 80 per cent in some catchments. At the same time, demand for water from the electricity sector is predicted to rise.

Research from Newcastle University, looking at a range of future energy scenarios, concludes that by 2050 water abstraction for electricity generation could more than double. But whether this water comes from freshwater or seawater will depend on the type of power stations we build.

Nuclear power stations are largely built on the coast and use seawater, but if we strongly develop carbon capture and storage (CCS) with coal or gas, then it is likely that we will use far more freshwater. This could bring the energy industry into direct conflict with other water users.

In scenarios with high levels of CCS, freshwater consumption could exceed current levels by between 37 and 107 per cent, and the risks will be intensified if CCS facilities are clustered together, as has been suggested in government proposals.

Furthermore if we develop shale gas in any serious way, this could put added pressure on water resources. To meet 10 per cent of UK gas demand from shale gas over the next 20 years would require 1.2 to 1.6 million cubic metres of water per year, according to research carried out at the University of Manchester – it is a substantial amount.

On the other hand, increased rainfall in winter could provide extra capacity for Scottish hydro-electric power stations to provide peak and load-following response. However, with the rain comes the floods, and research suggests there could be a 79 per cent increase in the number of power stations at risk from flooding by 2050. We would all be wise not to underestimate the scale of the challenge facing the energy sector.

As part of the Climate Change Act 2008 the secretary of state has the power to ask organisations to report on the impacts of climate change to their business, along with proposals and policies for adapting to climate change.

The latest reports show that energy generators and network operators have already made significant progress towards making the system more robust, but building long-term resilience will take time and require a co-ordinated response from industry and government.

Competing demands for water from the public, industry and agriculture, as well as electricity generators, will bring the water and energy industries into direct conflict. Consequently we need to better understand the trade-offs between sectors, how the regulator will prioritise new water abstraction licences and what impact scarcity could have on the price of water.