NESO will not yet release the data behind Ofgem's 73 GW data-centre queue
Victoria Shinder2 min readBritain's system operator has declined, for now, to hand over the project-level data behind one of the most quoted numbers in the connections debate. Ofgem's July consultation on demand connection reform says data centres make up about 73 GW of the demand queue, spread across around 315 projects ranging from 1 MW to 1,500 MW of contracted capacity. A requester asked NESO for the underlying list - capacity, connection point, local authority, queue status, application date and whether each project was among the 315 - with developer names removed.
NESO's answer, dated 22 September, refuses the request under Regulation 12(4)(c) of the Environmental Information Regulations, which applies when a request is too general or open to more than one reading. The letter sets out three things the requester might have meant: the project list behind Ofgem's paragraph 2.7; the datasets NESO supplied to Ofgem, which the consultation describes as coming from a voluntary call for input in November 2025, a mandatory information request notice to transmission-connected demand projects issued on 13 March 2026, and distribution-queue data aggregated through the Energy Networks Association; or everything NESO holds on data-centre projects in the pipeline. It points to an earlier disclosure, FOI-26-165, and suggests asking Ofgem directly, since the regulator is also covered by information law.
The letter also signals the likely outcome of a clarified request. NESO notes that it does engage Regulation 12(5)(e), the exception for confidential commercial information, when asked about individual energy projects of any kind.
What it means
The 73 GW figure is doing a great deal of work. It is the headline behind Ofgem's proposal to treat data centres differently in the queue, and it is routinely set against a national winter peak that is far smaller. Yet the only people who can test how much of it is real - how much is duplicated across sites, speculative, or already lapsing - are the operator and the regulator who produced it. The consultation itself lists a comparison against Companies House records among its methods, which suggests Ofgem had doubts about some applicants too.
For developers and local authorities the practical point is that the project-level picture is unlikely to be published. Aggregate totals by region or nation are the realistic ask, and the letter's own wording shows how to frame one: name the exact dataset, name the paragraph of the consultation, and ask for totals rather than rows. Until then, any analysis of where data-centre demand will land in Britain rests on a number nobody outside two organisations can reproduce.