JAO Publishes Day-Ahead Explicit Auction Rules for GB-Belgian Nemo Link Interconnector (Effective 1 September 2026)

JAO published Appendix 3 of the Nemo Link Access Rules v5 — the 'Rules for Daily Capacity Allocation on the GB-Belgian Border' — establishing the complete explicit day-ahead auction framework for the 1000MW Nemo Link interconnector between Herdersbrug (Belgium) and Richborough (England). The rules cover Participation Agreement onboarding, collateral requirements (Bank Guarantee and cash deposit), Credit Limit verification, a single daily Auction Specification published no later than 09:00 CE(S)T D-1 with a Bidding Period closing at 09:30 CE(S)T D-1, Marginal Price-based settlement, contestation of provisional results, fallback procedures, curtailment protocols, and invoicing. The rules entered into force on 1 September 2026.

This rulebook governs how Cross Zonal Capacity on the GB-Belgian interconnector is explicitly allocated on a day-ahead basis, directly shaping price convergence, arbitrage opportunities, and access conditions between the GB and Belgian (CWE/CACM) markets. As Nemo Link is a key GB-Continental interconnection, the design of collateral, credit limit, and auction mechanics affects which participants can access capacity, how efficiently capacity is priced, and how curtailment risk (operational security or force majeure) is allocated between TSOs and market participants.

The design retains a single explicit day-ahead auction (as opposed to implicit/flow-based coupling), settled via uniform Marginal Price, which is a simpler but potentially less efficient allocation method than implicit auctions used on most other EU-GB or internal EU borders. The collateral framework (Bank Guarantee minimum credit ratings of BBB+/Baa1, four-Working-Day validity buffers, Credit Limit continuously recalculated) imposes meaningful entry costs that could constrain smaller participants' access to the border capacity. The Pre-Bidding mechanism (bids accepted before Offered Capacity and Credit Limit checks are finalized) is a notable procedural nuance that could affect bid strategy. The rules explicitly preserve national regulatory oversight (Ofgem, CREG) and remain subject to amendment upon EU/GB legislative change, indicating this is a durable but adaptable rulebook rather than a one-off allocation.

FCA Regulation; CACM Regulation (EU) 2015/1222; Regulation (EU) 2019/943; Regulation (EC) 543/2013; Directive 2019/944; Nemo Link Access Rules v5, Appendix 3

—

Primary sources