ARERA finalizes updated BIO-PMG minimum guaranteed price formulas for biogas, bioliquid and biomass generators under DL 21/2026

With Deliberazione 404/2026/R/eel (3 Nov 2026), ARERA confirmed, following a post-hoc consultation, the urgent Deliberazione 174/2026/R/eel that implemented Article 5 of Decree-Law 21/2026 on minimum guaranteed prices (BIO-PMG) for electricity from biogas, sustainable bioliquids and solid biomass. The Authority replaced Annex A to Deliberazione 132/2024/R/eel and Annex A to Deliberazione 306/2024/R/eel with new Annexes A and B, effective from 1 July 2026, updating the fixed-operating-cost coverage formula to be parametrized to equivalent hours (only for plants for which GSE determines equivalent hours), clarifying that plants connected to a district-heating network count as thermally 'served facilities', relaxing the biomass/bioliquid 'filiera' certification requirement for 2026-2027, and requiring GSE to align the electricity volumes used for conventional revenues with those used for minimum guaranteed revenues (applied retroactively before 1 July 2026 for auxiliary-service configurations). ARERA rejected requests for a minimum floor on the equivalent-hours coefficient and for carrying over unused equivalent hours to later years, and deferred a broader revision of formulas and numeric parameters to a future proceeding after three years of data.

The decision determines the actual remuneration producers of biogas, sustainable bioliquids and solid biomass receive once their original incentive schemes expire, directly affecting the economics of these generation assets within a capped national spending envelope ('tendenziale di spesa'). By aligning conventional and guaranteed-revenue volumes and clarifying asset classification (served facility, filiera status), ARERA reduces interpretative disputes and settlement distortions flagged by operators and GSE, while leaving unresolved the structural issue—already flagged to Parliament—that low equivalent-hours allocations can produce very high per-MWh guaranteed prices for some bioliquid plants without increasing total system cost.

This is not a new market mechanism but a mid-course recalibration of an existing renewable support scheme operating alongside the wholesale market. The key design lever is the equivalent-hours parameter, set semi-annually by GSE against a legislated spending ceiling, which now explicitly feeds into the fixed-cost-coverage component of the guaranteed price formula; this creates an inverse relationship where capacity-constrained plants (especially bioliquids facing ~85-90% equivalent-hours reduction in H2 2026) see sharply elevated per-unit guaranteed prices even though aggregate system cost is unaffected, as ARERA itself flagged to Parliament. ARERA explicitly declined to soften this via a coefficient floor, preserving incentive compatibility with the standard-cost benchmarks from RSE studies. The alignment of conventional and guaranteed-revenue volumes is a technical but consequential fix: it removes an asymmetry that previously penalized plants drawing auxiliary-service electricity from the grid versus self-consuming plants, applied retroactively to avoid settlement distortions. The deferral of a fuller parameter review to a future consultation after three years of data signals this remains a live, iterative design track rather than a settled mechanism.

Article 5 of Decree-Law 20 February 2026, n. 21 (converted by Law 10 April 2026, n. 49), amending Article 24 of Legislative Decree 28/2011 and Article 5 of Decree-Law 181/2023; implemented via ARERA Deliberazione 174/2026/R/eel and finalized by Deliberazione 404/2026/R/eel, replacing Annexes to Deliberazioni 132/2024/R/eel and 306/2024/R/eel

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