NESO's Constraints Collaboration Project advances GB constraint-management reforms: DFS constraint capability live, Storage Behind Constraints consultation roadmap set, gas pre-gate CMM rejected, CMIS intertrip extensions tendering

NESO's 14 October 2026 CCP webinar confirmed that the Demand Flexibility Service (DFS) went live on 7 October 2026 with a new constraint-management and margin capability, absorbing the Local Constraint Market (LCM) at B6/B4; set out a three-stage indicative timeline (industry engagement end-Q3 2026, formal C9 consultation end-Q4 2026, report and review end-Q1 2027) for a Storage Behind Constraints options consultation with three charging-order options, industry favouring Option 3; concluded analysis of a short-term pre-gate Constraint Management Market (CMM) / expanded Schedule 7A trades for gas BMUs, finding a £1.27bn net consumer cost over 2025-2035 from wholesale price impacts, and recommended not progressing these options (Option 3: continue non-BMU/demand-side pre-gate work instead); and outlined the Extended Intertrip Scheme (CMIS) roadmap: EC5-Enduring (East Anglia OTS) enduring service go-live from Q4 2026 with forecast £170m savings (Dec26-Sep29), and B6 (Anglo-Scottish OTS, extended to B7a) and new B2-B5 (Highland OTS) tenders both due to launch October 2027.

This is a multi-workstream GB TSO programme under NESO's Reformed National Pricing (RNP) initiative aiming to materially cut consumer constraint-management costs before 2030 by combining demand-side flexibility market reform, storage dispatch/charging rules, and expanded automated intertrip network protection schemes. The rejection of the gas pre-gate CMM is a significant design decision ruling out a seemingly intuitive cost-reduction route due to adverse wholesale market liquidity/price effects, while the DFS go-live and CMIS tenders represent concrete, quantifiable implementation steps with material consumer savings (£150m+ realised on CMIS B6, £170m forecast on EC5) and new market access routes for demand-side flexibility and storage assets.

The CCP portfolio illustrates how GB is tackling constraint costs through parallel, interacting design tracks rather than a single reform: (1) short-term CMM design was tested against a gas-BMU pre-gate market and rejected after PLEXOS-based CBA modelling showed that removing CCGT volume from the wholesale stack to access cheaper within-day gas offers raises wholesale clearing prices by more than the balancing savings generated, with only ~10% of cleared volume coming from units that would not have cleared in the wholesale market anyway — a cautionary finding for any future NESO-side bilateral constraint procurement design that could affect wholesale liquidity; (2) Storage Behind Constraints introduces an explicit charging-order hierarchy for storage assets relative to other non-storage balancing actions, with the preferred option (allowing beneficial storage charging where it does not increase constraint costs) reflecting industry push-back against blanket de-prioritisation, indicating storage-specific dispatch rules are becoming a distinct design lever within constraint management; (3) the CMIS intertrip expansion (EC5 stability-trip upgrade, new B2-B5 OTS, B6/B7a extension) is a capital-intensive, tendered-asset approach to increasing real-time network headroom pre-fault, complementing market-based demand/storage measures and directly reducing pre-emptive curtailment volumes that would otherwise show up as constraint costs in the BM. Together these tracks show NESO sequencing quick, low-risk wins (DFS absorption of LCM, intertrip tenders) alongside more contentious and still-consultative reforms (storage charging order, non-BMU pre-gate markets) under a single RNP umbrella with a 2030 cost-reduction target.

NESO Reformed National Pricing (RNP) workstream; C9 consultation process for Storage Behind Constraints; CMIS tender/contract arrangements operated with Transmission Owners

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Primary sources