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Lowcarbon, longer duration energy storage (LDES) currently plays a relatively minor role on the UK energy system. However, as the electricity system decarbonises, the amount of LDES needed is likely to increase significantly to replace the storage traditionally provided by fossil fuels. The Government is currently supporting the demonstration and commercialisation of new LDES technologies. Examples include flow batteries, mechanical and thermal storage, and hydrogen.  

As the proportion of wind and solar generation on the electricity system grows, flexible types of generation (such as LDES), which can be scheduled to meet demand under low wind and dark conditions, will become increasingly important. Storage can also contribute to security of supply by meeting prolonged supply shortfalls, such as wind droughts, low annual wind speeds and power generator failures. In addition, LDES can provide a source of demand for the growing number of renewable plants, preventing costly constraints when the electricity networks are congested.    

Storage will need to be deployed throughout the UK, with certain technologies needing to be located in particular geographic areas that have suitable conditions, such as salt caverns and mountains. Many of these technologies are not well known to the public, with positive and negative perceptions of their safety starting to emerge. 

Current market arrangements do not adequately reward energy storage over longer timeframes, particularly over seasons and years. The Government are reviewing electricity market arrangements for the GB power system, which will impact the potential business cases of LDES assets. 

Key messages 

  • There is a range of different energy storage technologies in development, which includes flow batteries, mechanical devices (such as pumped hydro, liquid air and compressed air), thermal storage, and hydrogen. 
  • Longer duration storage can support a future energy system with high proportions of renewable energy by providing flexible energy supply and demand, and increasing the resilience of energy networks. 
  • Increasing amounts of energy storage will be needed, but to deploy the technologies at scale will likely require further innovation, demonstration, better business cases, investment and Government support. Deployment will also depend on ongoing developments in energy markets and a better understanding and communication of the risks. 
  • The Government will implement a policy on longer duration energy storage by 2024. 


POSTnotes are based on literature reviews and interviews with a range of stakeholders and are externally peer reviewed. POST would like to thank interviewees and peer reviewers for kindly giving up their time during the preparation of this briefing, including:  

  • Members of the POST board* 
  • Jessica Bays, UKERC* 
  • Keith Bell, University of Strathclyde* 
  • Owen Bellamy, Climate Change Committee  
  • Bruno Cárdenas, University of Nottingham 
  • Stephen Crosher, RheEnergise  
  • Nerys Davies, Scottish Affairs Committee 
  • Paul Davies, The Royal Society* 
  • Department for Business, Energy and Industrial Strategy 
  • Paul Dodds, University College London* 
  • Jeffrey Douglass, Invinity Energy Systems* 
  • Patrick Dupeyrat, EDF Energy 
  • Katriona Edlmann, University of Edinburgh* 
  • Lewis Elder, Statera Energy  
  • Andrew Finch, Northern Ireland Housing Executive* 
  • Olly Frankland, Electricity Storage Network Regen 
  • Seamus Garvey, University of Nottingham*  
  • Antony Green, National Grid Gas Transmission*   
  • Alex Hart, National Grid ESO*  
  • Cilla Hellgren, National Infrastructure Commission* 
  • Edward Hough, British Geological Survey* 
  • Rhodri Jervis, University College London 
  • Jinmi Macaulay, National Grid Gas Transmission*   
  • Alison Monaghan, British Geological Survey* 
  • Daniel Murrant, Energy Systems Catapult 
  • Marcus Newborough, ITM Power 
  • Rupert Pearce, Highview Power 
  • Gary Preece, Highview Power* 
  • Jonathan Radcliffe, University of Birmingham* 
  • Robert Raine, British Geological Survey* 
  • Rebecca Rosling, EDF Energy* 
  • Ben Shafran, Energy Systems Catapult* 
  • Michael Simpson, Cheesecake Energy 
  • Luke Sweeney, National Infrastructure Commission 
  • Tom Vernon, Statera Energy 
  • Yonna Vitanova, RenewableUK* 
  • Xinfang Wang, University of Birmingham* 

*denotes people and organisations who acted as external reviewers of the briefing.  

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