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Case study

Cardiff East: a power station by another name?

Cardiff Council is considering application 26/00109/HYB for a 150 MW data centre on the Cardiff East Park and Ride site beside the A48 at Pentwyn. It would come with its own gas-fired energy centre, 40 diesel generators and a new bridge over the Rhymney. Comments close on 28 October 2026.

About this case study

Based on the documents on the Council’s planning register. It asks questions; it makes no allegation against any person or body. Where we draw our own inference, we say so.

Last checked against the register on 21 October 2026.

Points you may wish to consider

  • The Environmental Statement relies on a 2022 scoping opinion given for a shops, drive-thru and warehousing scheme. Even that opinion asked for major accidents and for noise to be assessed. Neither has been.[2][3][4]
  • The power station is described in at least four different ways in the application documents. The latest is seven gas turbines and a steam turbine, with controls to keep output under 49.9 MW. That is just below the 50 MW point at which the Welsh Ministers, not the Council, decide.[2][5][12]
  • The applicant’s own air quality report found a ‘significant’ effect from generator testing, and advised that in an emergency neighbours should be told to stay indoors with their windows shut. Later notes say the effect is not significant. The Environmental Statement itself has not been corrected.[2][8]
  • In a three-day power cut the applicant predicts nitrogen dioxide at up to five times the legal hourly limit near homes and schools. The only recorded outage on the local network lasted 80 hours, longer than the period modelled.[6]
  • There is no assessment of noise from the 40 diesel generators, and no assessment of fire or major accidents. Natural Resources Wales warned at the pre-application stage that it would object without details of fuel storage, battery fire risk and firewater.[7][11]
  • The water figures do not agree: the cooling is said to use less than a single household, yet an allowance of up to 300 cubic metres a day is sought. The cooling system has still not been chosen.[9]
  • None of the expert consultees’ responses has been published, only the applicant’s summaries of them.[1][8]
  • The latest round of consultation allows 14 days for neighbours and 21 days on the site notice, without a newspaper advertisement, for more than 400 pages of new technical material.[1][10]

Our inference: ‘installed generating capacity’ would ordinarily mean the plant installed, not the output a control system allows. Seven turbines of 8.18 MW and a steam turbine are well over 50 MW installed. Whether controls can keep the station below the threshold is a question for the Welsh Ministers.

What the public has not been shown

  • The responses of Shared Regulatory Services, Natural Resources Wales, Welsh Water, the Health Board, the Fire and Rescue Service and the drainage authority.[8]
  • The Welsh Ministers’ holding direction and the reasons for it.[14]
  • Any note of the meetings at which, the applicant says, the Council agreed that no new scoping opinion was needed and that major accidents could be left out.[2][4]
  • The final plant: the number and type of turbines, the make of generator, stack heights, fuel stores and batteries.[5]
  • How much water will be used, and where it comes from; how much waste heat will be produced, and where it goes.[9]
  • When the 150 MW grid connection will be available, and what happens if it is late.
  • The terms of the sale of the land. A 2021 report to the Council’s Cabinet says the land was marketed for a logistics centre, that the developer will build the new bridge and road link into Llanrumney instead of paying for the land, and that completion of the sale depends on planning permission. Do the terms allow a data centre and gas-fired energy centre instead? And, as the Council is both landowner and planning authority, how does it keep the two roles apart?[15]
  • Any assessment of fire risk, or of firewater containment.[8]

Batteries

The Design and Access Statement says the site will have ‘on-site battery storage’ and run as a ‘local microgrid’. It gives neither the size nor the type of battery, and the Environmental Statement does not assess the batteries at all. Batteries could let the diesel generators start less often, but they cannot replace the gas power station, and lithium batteries bring a risk of fire and polluted firewater on a site in a flood zone.

  • How big will the batteries be, what type, and where on the site?
  • Will the batteries be used first in a power cut, so that the diesel generators start only when they must?
  • Where is the assessment of fire, explosion and firewater?

Read our short guide: Batteries at Cardiff East: what they can and cannot do.

What you can do

  • Comment on the Council’s planning register by 28 October 2026, quoting 26/00109/HYB.
  • Ask the Council to require a single, corrected Environmental Statement and to consult on it for at least three months.
  • Ask the Welsh Ministers to call the application in.

Read: our representations to the Council

Representations on application 26/00109/HYB by Dennis Clarke and Max Wallis, covering the consultation history, scoping, screening, major accidents, compliance with the EIA Regulations, and the contradictions between the application documents.

Download the representations (PDF, 285 KB)

For the wider context, see the full paper ‘Beyond Planning Permission’ (PDF), especially the sections on planning, energy and Bro Tathan, and our guide to checking an environmental assessment.

Sources for this page

  1. Cardiff Council planning register, application 26/00109/HYB (documents, comments and dates). https://www.cardiffidoxcloud.wales/publicaccess/applicationDetails.do?activeTab=documents&keyVal=T8YL3PECJ8T00
  2. Environmental Statement, Volume I Part 1 (Chapters 1 to 4), February 2026. https://www.cardiffidoxcloud.wales/publicaccess/files/E0E64E89C93D7E1CF72DFB53E1BABE76/pdf/26_00109_HYB-ENVIRONMENTAL_STATEMENT_VOL_I_PART_1-6351362.pdf
  3. Environmental Statement, Appendix 1.2: Cardiff Council scoping opinion of May 2022, for a commercial development. https://www.cardiffidoxcloud.wales/publicaccess/files/E1B6F9CD228263C83DE1DCE448710B9D/pdf/26_00109_HYB-ENVIRONMENTAL_STATEMENT_-_VOL_II_APPENDIX_1.2_-_CC_SCOPING_OPINION-6331552.pdf
  4. Environmental Statement, Appendix 1.1: Location of specified information. https://www.cardiffidoxcloud.wales/publicaccess/files/6FC37302C4A722595C52C0EA4DDCA52A/pdf/26_00109_HYB-ENVIRONMENTAL_STATEMENT_-_VOL_II_APPENDIX_1.1_-_LOCATION_OF_SPECIFIED_INFORMATIO-6331558.pdf
  5. Technical Note (Air Quality), combined reports, 6 October 2026. https://www.cardiffidoxcloud.wales/publicaccess/files/54C572792D4179F901419D580EE3D9FC/pdf/26_00109_HYB-TECHNICAL_NOTE__AIR_QUALITY__-_COMBINED_REPORTS-6465338.pdf
  6. Generator Air Quality Technical Note, 8 September 2026. https://www.cardiffidoxcloud.wales/publicaccess/files/B7CC056EABE58BCFADCDA56338EBA4DF/pdf/26_00109_HYB-GENERATOR_AIR_QUALITY_TECHNICAL_NOTE-6450738.pdf
  7. Environmental Statement, Appendix 3.3: Noise Impact Assessment. https://www.cardiffidoxcloud.wales/publicaccess/files/30A50E6E8CF3D97C0E2A9C01D9F0F8D4/pdf/26_00109_HYB-ENVIRONMENTAL_STATEMENT_-_VOL_II_APPENDIX_3.3_-_NOISE_IMPACT_ASSESSMENT-6331563.pdf
  8. Response to Consultee Comments, April 2026. https://www.cardiffidoxcloud.wales/publicaccess/files/6CDF63AE516EA1726F91C995AD42D4E6/pdf/26_00109_HYB-RESPONSE_TO_CONSULTEE_COMMENTS-6375566.pdf
  9. Water Usage Datasheet, published 6 October 2026. https://www.cardiffidoxcloud.wales/publicaccess/files/0B1B9164A37A106ADEC41E1D472E8976/pdf/26_00109_HYB-WATER_USAGE_DATASHEET-6465333.pdf
  10. Site notice of 7 October 2026 (comments by 28 October 2026). https://www.cardiffidoxcloud.wales/publicaccess/files/87FA8E27797D9DA8A29D9F62C3A13969/pdf/26_00109_HYB-DISCRETIONARY-6465335.pdf
  11. Pre-Application Consultation Report, January 2026, including Natural Resources Wales's pre-application response. https://www.cardiffidoxcloud.wales/publicaccess/files/0E5EE2C74B6C4FBA4147B30DA1F09450/pdf/26_00109_HYB-PRE_APPLICATION_CONSULTATION_REPORT-6336562.pdf
  12. Infrastructure (Wales) Act 2024, Part 1 (generating stations of 50 to 350 MW). https://www.legislation.gov.uk/asc/2024/3/part/1/data.htm
  13. Town and Country Planning (Environmental Impact Assessment) (Wales) Regulations 2017. https://www.legislation.gov.uk/wsi/2017/567/contents/made
  14. Nation.Cymru, 'Data centre plans put on hold as ministers intervene', 4 September 2026. https://nation.cymru/news/data-centre-plans-put-on-hold-as-ministers-intervene/
  15. Cardiff Council, Cabinet, 20 May 2021, agenda item 9, ‘Llanrumney Regeneration Scheme – Statutory Public Consultation and Land Disposal Update’, paragraphs 6, 7 and 24 to 27 (public reports pack, pages 359 to 363). https://cardiff.moderngov.co.uk/documents/g4316/Public%20reports%20pack%2020th-May-2021%2014.00%20Cabinet.pdf?T=10&LLL=0

Links to the Council’s register open PDF files directly; some browsers will download them. They are ordinary PDF documents, as is the Council’s Cabinet report.