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Call for Evidence

Call for evidence

The House of Lords Science and Technology Committee is conducting an inquiry into long-duration energy storage as part of a net zero grid. The committee invites written contributions by Monday 11 September 2023.


The Government has set a target for a fully decarbonised electricity system by 2035 and Net Zero across the whole of the UK by 2050. This will require a large increase in variable renewable electricity generation from wind and solar and a substantial increase in electricity demand as the heat and transport sectors are electrified to remove dependence on fossil fuels. In order to balance supply and demand in this future energy system across different timescales, different types of energy storage technology will be needed. Short-duration energy storage to balance the grid, such as that provided by batteries, is important, but this inquiry will focus on longer-duration storage – in excess of 4 hours.

The UK is likely to need substantial investment in infrastructure that can store energy across days, weeks, months and years. Medium-duration energy storage could be defined as between 4 and 200 hours, while long-duration energy storage would store energy for over 200 hours. Both will be needed for a net zero electricity grid. As recent years have demonstrated, energy security is a crucial economic and societal issue and is now part of the remit of the new Department for Energy Security and Net Zero.

A range of technologies – such as hydrogen, compressed air, redox flow batteries, molten salts, pumped hydro or synthetic fuels – could be used to store energy in different forms, or for different durations. Deploying large-scale long-duration energy storage infrastructure will require significant investment and skilled engineering capacity, but the business case is uncertain at present given current market structures. Estimates for how much storage will be needed depend on a range of factors and assumptions around future electricity supply and demand. There may be non-financial challenges to building the infrastructure necessary to store and transport energy around the country.

The Committee’s inquiry will take evidence on these issues and seek to establish whether the Government has sufficient policies in place to support medium- and long-duration energy storage and whether it is on track to deliver this crucial component of a net zero energy system.



The Committee is seeking evidence on the following questions (there is no requirement to answer all questions in your submission):

1. How much medium- and long-duration energy storage will be needed to reach the Government’s goal of a fully decarbonised power grid by 2035 and net zero by 2050, and by when will it need to be ready?

  • Under what scenarios would the grid draw heavily on long-duration storage? How well are these scenarios understood?
  • What is the range of estimates for likely electricity demand in 2035?

 2How sensitive is the amount of storage needed to assumptions about the future balance of supply and demand on the grid?

  • What role could nuclear power, fossil fuel generation with carbon capture and storage, or other energy technologies, play in reducing the need for energy storage on a net zero grid?
  • What role could greater grid interconnectivity between Great Britain, Northern Ireland and other nations play in addressing the imbalance between supply and demand?
  • What role could demand-side management of electricity play in reducing the dependence on storage?
  • What impact will future climate change have on demand – for example, how much will the seasonal differences in power demand change with warmer winters and greater use of air conditioning? 

3. Which technologies can scale up to play a major role in storage?

  • Which timescales for storage are different technologies most suited to? Is there a preferred technology for medium-duration and long-duration storage?
  • What are the technology readiness levels for these energy storage technologies?
  • Is it possible to produce enough domestic green hydrogen to fulfil long-term energy storage demand needs?
  • Is there a distinct role for technologies that store heat instead of electricity?

4. What policy support is currently in place to support deployment of storage technologies? Is it sufficient to support deployment at scale?

  • How good is the economic case for long-duration energy storage? What policies and market structures need to be put in place to make the business case viable?
  • How will the grid need to change to support long-duration storage? Which stakeholders (e.g. energy companies, the Electricity System Operator, National Gas) should be planning for these changes?
  • What role does the Review of Electricity Market Arrangements need to play to support medium- and long-duration storage development?
  • Is the Government’s current reliance on market actors and technology competitions likely to deliver the storage needs on time?

5. How well developed is the UK industry across different storage technologies, such as hydrogen or redox flow batteries? How does the UK compare to global competitors in these industries?

  • Are there any storage technologies that have a significant export potential for the UK?
  • For which technologies does the UK have significant existing research or industrial capacity? Is the Government doing enough to support the industry to grow and drive exports and economic growth?

6. Beyond the cost of deploying long-duration energy storage, what major barriers exist to its successful scale up (e.g. the availability of a skilled workforce, the ability to construct the necessary infrastructure on time, or safety concerns around new technologies)?

  • Are there sufficient training schemes in place to ensure the UK has the workforce to deliver the energy storage the grid will need?
  • How long is it likely to take to develop the necessary infrastructure?

7. What steps should the Government take now to ensure this storage can come online later in the current decade?

  • Can the UK learn from other countries that have successful policies for supporting large-scale energy storage, or from pilot projects elsewhere?

ANNEX: Guidance for Submissions

This is a public call for written evidence to be submitted to the Committee. The deadline for submissions is 23:59 on Monday 11 September 2023.

Written submissions should be submitted online, as a Word document, using the written submission form available at This page also provides guidance on submitting evidence. If you have difficulty submitting online, please contact the Committee staff by email at or by telephoning 020 7219 5750.

Short, concise submissions are preferred. Scientific and technical content should be accessible to non-specialist readers. Responses should not be longer than six sides of A4 in size 12 font. There is no requirement to answer all the questions in your submission: you can answer only those that are most relevant to you. You may tell us about issues that we have not specifically asked about, but that are relevant to the topic of the inquiry.

All submissions made through the written submission form will be acknowledged automatically by email. Once you have received acknowledgement that the evidence has been accepted you will receive a further email, and at this point you may publicise or publish your evidence yourself. In doing so you must indicate that it was prepared for the Committee, and you should be aware that your publication or re-publication of your evidence may not be protected by parliamentary privilege.

Evidence which is accepted by the Committee may be published online at any stage; when it is so published it becomes subject to parliamentary copyright and is protected by parliamentary privilege. The Committee cannot accept any submissions that have not been prepared specifically in response to this call for evidence, or that have been published elsewhere.

Personal contact details will be removed from evidence before publication but will be retained by the Committee Office and used for specific purposes relating to the Committee’s work, for instance to seek additional information.

Persons who submit written evidence, and others, may be invited to give oral evidence. Oral evidence is usually given in public at Westminster and broadcast online; transcripts are produced and published online. Persons invited to give oral evidence will be notified separately of the procedure to be followed and the topics likely to be discussed.

Substantive communications to the Committee about the inquiry should be addressed through the Clerk of the Committee, whether or not they are intended to constitute formal evidence to the Committee.

This is a public call for evidence. Please bring it to the attention of other groups and individuals who may not have received a copy directly.

Diversity comes in many forms and hearing a range of different perspectives means that committees are better informed and can more effectively scrutinise public policy and legislation. Committees can undertake their role most effectively when they hear from a wide range of individuals, sectors or groups in society affected by a particular policy or piece of legislation. We encourage anyone with experience or expertise of an issue under investigation by a select committee to share their views with the committee, with the full knowledge that their views have value and are welcome. If you think someone you know would have an interest in contributing to the inquiry, please pass this on to them.

You may follow the progress of the inquiry at


This call for written evidence has now closed.

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