Two Data Centre Figures for One Queue, and What Ofgem Leaves Unstated

What Ofgem published

On 29 July 2026 Ofgem opened a consultation titled Curate: Demand Connections Reform, proposing two measures aimed, in its own words, at "deterring speculative and non-viable projects and facilitating viable developments". The document's executive summary states the position it is responding to: "Between November 2024 and June 2025, contracted demand in the connection queue increased from 41 GW to 125 GW. Of this, around 73 GW are data centres. For a sense of scale, peak demand in Great Britain in 2025 was 45 GW."

Paragraph 2.6 breaks the movement down by network level. The 41 GW was 17 GW transmission and 24 GW distribution. The 125 GW was 97 GW transmission and 29 GW distribution, which sum to 126 GW against the stated total of 125 GW; the consultation does not explain the difference. The rise of 84 GW is this report's subtraction of Ofgem's two totals. Almost the whole increase landed on the transmission network.

From the National Energy System Operator's call for input, as summarised in March 2026, Ofgem says the remainder of the demand queue, outside data centres, is composed mainly of hydrogen electrolysers, industrial demand and transport. It also records that it is working with the National Energy System Operator and the network companies to collect this data regularly, which is a statement that the present understanding of the complete demand queue is incomplete.

The 73 GW and the 80 GW

Ofgem's press release of 29 July 2026 describes the same movement. It says demand connection applications "have surged from 41 gigawatts (GW) to 125GW, in under a year", and that the rise "is driven largely by data centre projects, accounting for at least 80GWs". Later it says data centres "currently account for a significant proportion of demand in the connections queue", with around 73GW referenced in the consultation.

The dated items in the evidence the consultation lists for its view of the current queue run from November 2025 to March 2026 (paragraph 2.3). The consultation does not say which of that evidence the 73 GW rests on, and neither it nor the press release reconciles the 73 GW with the 80 GW.

If both describe the data centre queue on one date, they are about 7 GW or more apart. If the 73 GW is the June 2025 data centre queue and the 80 GW is the data centre part of the 84 GW rise (125 GW less 41 GW), the November 2024 data centre queue would be 73 GW less 80 GW, which is about minus 7 GW or lower. Neither document says how the two fit together. One coincidence is plain arithmetic: the transmission part of the rise, 97 GW less 17 GW (paragraph 2.6), is also 80 GW. Neither document links it to the press release's figure.

The executive summary follows the rise from 41 GW to 125 GW with "Of this, around 73 GW are data centres" and does not say whether "this" is the queue, the 125 GW or the rise. Two law-firm briefings from August 2026, by Slaughter and May (10 August) and Addleshaw Goddard (12 August), each describe the 73 GW as the data centre part of the rise in the demand connection queue from 41 GW to 125 GW between November 2024 and June 2025. Addleshaw Goddard attributes the figures to the consultation; Slaughter and May links the consultation but does not say where its figures come from. Paragraph 2.7 puts the 73 GW against the total demand queue.

Corrected on 21 October 2026: retitled from "One Queue, Two Bases". The report called the 73 GW and the 80 GW shares of different bases (58 per cent of the 125 GW queue, 95 per cent of the 84 GW rise). The consultation and press release give no date for the 73 GW and no base for the 80 GW, so that claim, the calculated 52 GW remainder and the nested bar are withdrawn. The law-firm sentence now states what the briefings say. References are corrected (queue totals 2.6, the 9 GW 2.9). The 9 GW no longer carries a cause paragraph 2.9 does not give; the 99 per cent is now of the 73 GW queue data. Status is dated as at 23 August 2026. No Ofgem figure changed.

Australia's data centre forecasts show the contrast: one AEMO projection is published as almost 10 per cent of underlying demand and as 12 per cent of grid-supplied consumption, with the base named each time (see Two Denominators, One Data Centre Forecast). Anyone quoting a data centre figure for Britain's connection queue should name the document, the paragraph, the date and the base, or say that one of them is not stated.

A queue is not a forecast

The reason the date and base matter is that neither figure describes demand that will arrive. A connection queue counts contracted offers, and Ofgem is consulting precisely because its analysis and stakeholder engagement suggest "a material volume of non-viable and speculative projects" (paragraph 2.17). The consultation puts the point in terms most forecasters would hedge: it argues that even if the proportion of non-viable and speculative applications in this sector were lower than in others, "which there is no evidence to suggest is the case", the impacts would still be considerable.

Two of Ofgem's own comparisons make the scale legible: peak demand, and the capital expenditure the data centre pipeline implies.

Neither comparison proves any individual project unviable. Together they establish the thing a queue figure cannot establish on its own: that the number is an upper bound on interest, not a projection of load. That distinction is what a fee is being designed to enforce.

Where the capacity sits

Table 1 of the consultation distributes the 73 GW across five size bands. Ofgem gives proportionality as its reason for a threshold (paragraph 5.4): smaller data centres would carry an administrative burden similar to larger ones, despite a relatively smaller impact on the wider energy system.

Project counts and total MW are Ofgem's, as are the capacity shares. The share-of-projects column is computed here from Ofgem's counts over its stated total of 315, and the five counts sum to 315 and the five MW figures to 72,978, so the table reconciles to the headline 73 GW.

Ofgem states that it arrived at its proposed 40 MW threshold by examining the statistical distribution of the 73 GW queue data, and that 99 per cent of the total capacity in that data sits in projects above 40 MW (paragraph 5.4). The forty hyper-scale projects carry 43.0 per cent of the capacity on 12.7 per cent of the count.

At least nine gigawatts changed technology

One paragraph of the consultation records a movement that is not visible in any total.

Between May 2024 and August 2025, on Ofgem's analysis, at least 9 GW of capacity already holding a transmission connection request modified that request from a battery technology to a data centre. Ofgem records that a number of stakeholders point to a financial incentive structure that makes battery and other technologies increasingly likely to convert at the next application window, also as a result of connections reform changes.

This matters beyond Britain because it is a measurement problem before it is a policy one. A queue position that was counted as storage is now counted as demand, through a modification to its connection request. Any series that reads a connection queue as a pipeline of storage is exposed to reclassification of this kind, and the reclassification is only visible where a regulator publishes it. Neither document links the 9 GW to the 73 GW or the 80 GW.

What is proposed, and when it is decided

Curate proposes two measures. The first is a data centre commitment fee for projects above 40 MW: a returnable financial commitment secured from the point a connection offer is accepted until energisation, proposed at between 2.5 and 7.5 per cent of average data centre capital expenditure, which Ofgem states as approximately £237,500 to £712,500 per MW of requested capacity. On Ofgem's worked example, a 100 MW project would secure between £23.8 million and £71.3 million at the point of accepting an offer. The commitment is returned if the project proceeds and forfeited if it terminates or fails to comply.

The second is a set of data centre queue management milestones, requiring developers to evidence progress, including financial capability, commercial maturity and procurement activity, to retain a queue position.

Responses were due by 16 September 2026. Ofgem states it will publish non-confidential responses alongside a decision on next steps. As at 23 August 2026, nothing here was settled policy. As at 21 October 2026 Ofgem's consultation page showed it closed and awaiting a decision.

Limits of this reading

• As at 23 August 2026 the consultation was open, and no decision, final fee value or confirmed threshold existed.
• Every published figure is Ofgem's own statement about a queue that changes continuously. The 41 GW and 125 GW readings are dated November 2024 and June 2025 and were already more than a year old when the consultation opened. The 73 GW has no stated date and the 80 GW no stated base.
• Ofgem states it is still working with the National Energy System Operator and network companies to improve its understanding of the complete demand queue, so the non-data-centre remainder is the least characterised part of these totals.
• Consultation responses have not been read and are not characterised here.
• Ofgem's November 2025 "Demand connections update" was not used. Its published PDF carries no extractable text layer, and no figure in this report is drawn from it.

What to watch

Three things resolve this. The first is whether Ofgem's decision states the date of the 73 GW and the base of the 80 GW, which the consultation and the press release do not. The second is the fee value set within the proposed range, since the range spans a factor of three and the deterrent effect is not linear in it. The third is the next published queue reading: the test of a measure designed to remove speculative applications is whether the queue falls, and by how much of the 73 GW.