Science and Technology Committee
Long-duration energy storage: get on with it

1st Report of Session 2023-24 - published 13 March 2024 - HL Paper 68


Executive Summary

Chapter 1: Introduction

Chapter 2: The need for long-duration energy storage

The benefits of long-duration energy storage

Box 1: Units of energy and power, and scale of existing energy storage in the UK

Box 2: Energy storage technologies

Figure 1: Technology Readiness Levels Source: Technology Readiness Levels, as adapted by the CloudWATCH2

Scale and nature of the need for long-duration energy storage

Figure 2: Change in annual electricity generation under the Committee on Climate Change/AFRY’s central scenario for a fully decarbonised grid.

Box 3: Estimates for the scale of need and costs for long-duration energy storage

Urgency and pace of delivery

Chapter 3: Policy for long-duration energy storage

The economics of long-duration energy storage, support mechanisms and strategic reserves

Box 4: Economics and subsidy mechanisms for long-duration energy storage

Figure 3: Level of stored hydrogen across 37 years (Royal Society modelling)

The role of hydrogen

No-regrets investments for hydrogen

Repurposing gas storage for hydrogen

Box 5: Green, blue and grey hydrogen

Demand and use cases for hydrogen

Figure 4: Daily average hydrogen demand over a year in 2035 (CCC modelling)

Availability of electrolysers for green hydrogen


Medium-duration energy storage technologies

Pumped-storage hydropower

Compressed-air energy storage

Longer-duration battery chemistries

Incentivising the right mix of technologies for the grid

Chapter 4: Long-duration energy storage in context

Planning and regulatory systems

Connecting projects to the grid

Obtaining planning permission for energy storage

Skills for net zero

Minimising the need for long-duration energy storage

Demand flexibility


Thermal storage

The roles of different actors in the energy system

Transmission networks and the Strategic Spatial Energy Plan

Summary of conclusions and recommendations

Appendix 1: List of Members and declarations of interest

Appendix 2: List of witnesses

Appendix 3: Glossary

Evidence is published online at and available for inspection at the Parliamentary Archives (020 7219 3074).

Q in footnotes refers to a question in oral evidence.

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