UK-Culham: Engineering design services.

Scope

Scope: Large Scale Battery Energy Storage Systems

Description:

The following summary is not intended as a complete or definitive specification of the requirement. A purpose of this engagement is to seek information from the market to help refine our understanding and aid the development of a future specification.

STEP is currently in its Concept Design phase, which is expected to be completed in 2026.
The electrical infrastructure of STEP will resemble that of large conventional thermal power stations; however, its design presents unique challenges:

Fusion power stations like STEP have exceptionally large parasitic (auxiliary/house) loads required to initiate and sustain fusion reactions—significantly higher than those in conventional power plants.

These parasitic loads must be supplied by external sources during plant start-up, before the power generation cycle begins producing electricity.

The highly dynamic nature of these loads could make compliance with grid code requirements challenging.

For more information, please refer to: Staying positive: producing net power | Philosophical Transactions of the Royal Society A | The Royal Society

UKIFS is seeking experts to support the technology selection of a central energy storage system (CESS) that is part of the STEP Electrical infrastructure. Due to the power dynamics of operating the STEP power plant and operating parameters set by the National Energy System Operator (NESO), an energy storage system is required to provide a mechanism to ensure that we remain within the NESO operating parameters.

Rather than a continuous output, STEP will operate on a pulsed basis. The power dynamics of the fusion pulses are typically different to a conventional power plant, and a CESS has been identified as a critical system to the design as it provides a mechanism to compensate for the changing load dynamics throughout the pulse. This will ensure STEP remains within the NESO defined operating parameters at the point of grid connection. Current assumptions are to exploit existing Battery Energy Storage Systems (BESS) to fulfil the energy storage needs.

We are interested in all battery chemistries used in large-scale energy storage systems, including Lithium Iron Phosphate (LFP), Sodium-Sulfur (NaS), Lithium Titanate (LTO), Vanadium Redox Flow Batteries (VRFB), Nickel Manganese-Cobalt (MNC), Solid State Batteries or others.

Due to knowledge gaps in BESS behaviour and limitations, the decision of using a BESS system for the CESS cannot be fully justified. This PME is looking to address this.

The proposed technical and operational characteristics of the BESS are:

2 operational cycles per day

Pulse length will be over 1 hour (continuous)

Power range larger than 300MW

Energy capacity 100-300MWh

Response in the millisecond range

Similar charge and discharge rates.

Fast response time during power swings (full charge to discharge)

High round trip efficiency: 80%

In conjunction the BESS will be required to be operated and maintained for the 20-year life of the STEP machine.
For more information about this opportunity, please visit the Delta eSourcing portal at:
https://ukifs.delta-esourcing.com/tenders/UK-UK-Culham:-Engineering-design-services./44277P4UUB

To respond to this opportunity, please click here:
https://ukifs.delta-esourcing.com/respond/44277P4UUB

Total value (estimated):

GBP 0 including VAT

Contract dates (estimated)

01/04/2029 to 31/03/2033

CPV Classifications:

71320000 - Engineering design services.
71323100 - Electrical power systems design services.
71323200 - Plant engineering design services.

Delivery regions:

UK UNITED KINGDOM

Engagement

Engagement deadline
23/03/2026
The engagement has not yet been carried out.Engagement process description:
A purpose of this engagement is to seek information from the market to help refine our understanding and aid the development of a future specification. UKIFS is seeking experts to support the technology selection of a central energy storage system (CESS) that is part of the STEP Electrical infrastructure.

To participate in this exercise, please complete and submit Appendix 1: Questionnaire and return any documents via the Delta portal. We are conscious of your time (and grateful to you for taking the time to complete the questionnaire), therefore we suggest you limit your responses to a maximum of 5 pages. If there are any areas you would like to expand on, please add a note to the relevant section for future discussion.

If you experience any difficulties with the portal, please contact the portal helpdesk helpdesk@delta-esourcing.com cc operationalprocurement.step@ukifs.uk

Information obtained from responses to Appendix 1: Questionnaire will help UKIFS understand current market capabilities and may shape the scope, direction, and design of the future procurement activities.

If you have any questions about this Preliminary Market Engagement, please contact UKIFS through the Delta portal. We are keen to engage with suppliers to assist with the questionnaire if needed, to ensure quality responses enabling us to shape the future requirement and procurement.

Following the submission and review of questionnaires, UKIFS intends to run an online conference call meeting/seminar/Q&A. The closing date for the pre-market engagement is Monday 23rd March 2026, 1 pm.

Contracting authority

United Kingdom Industrial Fusion Solutions, PCRM-7973-DCBL
Culham Science Centre, Abingdon, Culham, OX14 3DB, United Kingdom
Email: operationalprocurement.step@ukifs.uk
Contact: Operational Procurement
Address of the buyer profile: https://www.gov.uk/government/organisations/uk-industrial-fusion-solutions

Organisation type: BODY_PUBLIC
Devolved regulations that apply: None