IN Brief:
- Rule 2.4 requires government to consult annually on technologies capable of supporting security of supply but absent from existing Capacity Market classes.
- DESNZ is seeking evidence on commercial deployment, reliability, controllability, duration, and performance during peak electricity demand.
- The 2025 review included proposals around flexible computing and offshore hybrid assets, which remain relevant to the 2026 evidence call.
The Department for Energy Security and Net Zero has opened its 2026 review of emerging technologies that could contribute to electricity security but are not adequately represented by an existing Capacity Market generating technology class.
The annual exercise is required under Rule 2.4 of the Capacity Market Rules. It asks developers, aggregators, energy companies, academics, and other interested parties to identify technologies capable of supporting security of supply that may need to be recognised formally before they can participate appropriately in future auctions.
The question is not whether an individual product is new. A separate Generating Technology Class becomes relevant when a technology has operating characteristics sufficiently different from existing categories that applying an established classification would misrepresent its dependable contribution to the system.
DESNZ is therefore asking for evidence on deployment rather than marketing claims. Respondents are invited to describe whether a technology exists commercially, whether it has a viable business model, and how it could contribute at times of peak demand or wider system stress.
Reliability and availability are equally important. A resource capable of delivering a large instantaneous output but only for a few minutes provides a different adequacy service from one that can operate for several hours, while a controllable load has different limitations again.
The department is asking about the underlying fuel or energy source, whether output is fully controllable or dependent on an intermittent resource, and whether there are limits on how long the technology can operate continuously at full capacity during a peak period.
Those characteristics ultimately affect de-rating. Capacity Market participants are credited according to the dependable contribution they are expected to make rather than simply the number printed on an equipment nameplate.
Battery storage provides an obvious example. A battery can respond extremely quickly and may be capable of delivering its full rated power, but its duration depends on stored energy and state of charge. A thermal generator may start more slowly but operate for longer if fuel is available. Flexible demand depends on how much consumption can be reduced and how long the underlying activity can remain curtailed.
Grouping resources into generating technology classes allows those characteristics to be represented consistently enough for auction purposes. The classification is administrative, but its consequences are technical and financial because de-rating influences how many dependable megawatts a project can offer.
The 2026 review follows evidence submitted last year on several less conventional technologies. One proposal concerned Flexible Compute Capacity, where computing loads could be curtailed rapidly and repeatedly with little warm-up or cool-down time.
Supporters argued that some computing workloads could remain curtailed for hours or days and therefore behave differently from more conventional demand response. Government did not simply create a new class in response, leaving the concept subject to further evidence and assessment.
Offshore hybrid assets also featured in the 2025 process. These can combine functions associated with interconnection and offshore generation, producing operating characteristics that do not map neatly onto a conventional standalone generator or interconnector.
That illustrates why the annual review is necessary. Electricity technologies are developing more quickly than market taxonomies, particularly where digital control, storage, flexible demand, and multi-purpose network assets blur boundaries that were clearer when adequacy depended primarily on large generating stations.
Creating new categories too readily would bring its own problems. Every new class requires evidence robust enough to establish how the technology should be de-rated, and poorly supported assumptions could cause the Capacity Market to overstate the amount of dependable capacity available during stress.
The opposite approach carries a cost as well. Forcing an emerging technology into an unsuitable existing class can understate its contribution or prevent a credible resource from competing on reasonable terms.
The evidential threshold therefore needs to distinguish technical possibility from operational dependability. A laboratory demonstration that can respond rapidly does not by itself show that a commercial fleet will be available during a winter peak, while one successful installation provides limited statistical evidence on fleet-wide performance.
DESNZ says the review will continue with the National Energy System Operator and delivery partners. Responses are due by 23:59 on 4 October 2026, with the outcome scheduled for publication by 1 December in accordance with Rule 2.4.
That timetable makes the exercise a regular route through which emerging power technologies can move from demonstration into market recognition. The standard should remain demanding: a novel resource earns its place in the Capacity Market when its operating limits are understood well enough to convert innovation into a defensible quantity of dependable capacity.