Energy storage allows variations in the production and use of energy to be managed efficiently, across timescales that align with supply and demand. Historically, stored energy has been in the form of primary fuel stocks of coal, natural gas, oil, biomass or uranium. A relatively small amount of energy has been stored after conversion to electricity using pumped hydro storage (PHS), and in thermal stores of water heated by natural gas or electricity. This reflects an energy system in which fossil fuels are held in large stores, electricity can be quickly dispatched by large centralised generators, natural gas pipes are ‘packed’, petroleum products kept at filling stations, and patterns of demand for power and heat are quite predictable.

In a world where energy use must change rapidly to mitigate climate change, and supplies increasingly come from variable and more local sources, there is a requirement to have a more responsive energy system that is reliable, resilient and low carbon. One option to achieve this is to increase levels of energy storage, recognising the multi-scalar and multi-vector characteristics of energy demands, and the socio-technical nature of the system. The scope of such energy storage covers a broad family of technologies with different cost and performance characteristics, from domestic-level batteries to underground reservoirs holding hot water.

Storage has a cost, but brings benefits – how these are calculated and where they fall, will help determine their eventual role. Just as technological innovation and policy mechanisms have led to the deployment of low carbon generation, a combined approach will be needed to allow the full potential of energy storage to be exploited. Moreover, the increasing integration of heat, power and transport sectors and the energy vectors that link them, means that the institutional and regulatory environments will play a key role.

As a research and innovation ‘roadmap’ the purpose is not to prescribe a scale of deployment of energy storage, nor the specific measures that should be put in place; rather, we set out the challenges and the options as a guide, highlighting some important features. Future iterations will draw on research and analysis as results emerge.

This report is structured as follows: