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

Pricing of electricity

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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