Storage is the lung of the gas system: it fills when demand is low and empties in winter. A business does not buy storage capacity and does not find it as an invoice item, but the filling level is one of the factors that move the wholesale prices to which contracts are linked. The European rules changed in 2025: anyone still reasoning on the "90% by 1 November" obligation is using an outdated reference.
The storage cycle
In Italy gas is stored in depleted fields, between 1,000 and 1,500 metres deep (Snam). Injection is concentrated between April and October, withdrawal between November and March; the storage thermal year runs from 1 April to 31 March. According to ARERA, the Italian energy regulator, storage supplies up to 30% of the gas consumed in winter.
The Italian system
ARERA indicates about 18 billion cubic metres of capacity for Italy, with 15 concessions and 13 active fields. Twelve sites belong to the Snam group: five in Lombardy, four in Emilia-Romagna, two in Abruzzo and one in Veneto. Three of these belonged to Edison Stoccaggio, acquired by Snam on 3 March 2025, renamed Stogit Adriatica and merged into Stogit from 1 January 2026. The only active site outside the group is Cornegliano Laudense (Ital Gas Storage), in operation since 2019, with about 1 billion cubic metres.
At the end of 2025 Snam reported for its own sites a total capacity of 18.1 billion cubic metres: 13.5 available for modulation, mining and balancing services and 4.6 of strategic reserve. The ARERA and Snam figures do not match to the decimal: they should be read as orders of magnitude.
What the capacity is for
- Modulation: this is commercial storage, which covers the difference between summer and winter. Capacity is allocated through auctions in which wholesalers and suppliers take part.
- Strategic reserve: 4.62 billion Smc, set by the Ministry of Environment and Energy Security (MASE). It is used only in an emergency, if commercial storage runs out.
- Mining storage and balancing: minor shares, reserved for domestic producers and for the operational balancing of the transmission network.
The European rules in force in 2026
Regulation (EU) 2025/1733, published on 10 September 2025, extended until 31 December 2027 the filling obligation introduced in 2022 and made it more flexible:
- the target remains 90%, but it can be reached at any time between 1 October and 1 December, no longer by 1 November; once reached, it does not have to be maintained until 1 December;
- the intermediate filling milestones are indicative, unless individual Member States decide otherwise;
- Member States may deviate from the target by up to 10 percentage points in difficult market conditions; the Commission may grant a further 5 points, for one season only, if those conditions persist.
Levels can be read on the AGSI platform of Gas Infrastructure Europe: on 8 October 2026 Italian storage was 88.4% full and European Union storage about 73% full. A year earlier, on 1 October 2025, the Union stood at 83% (European Commission).
Effect on prices
Full storage is not enough to keep prices low, but scarce storage amplifies every tension. ARERA documents this for the first quarter of 2026: the reaction of European prices to the tensions in the Persian Gulf occurred with storage levels seasonally low. In summer, moreover, purchases for refilling support prices: the flexibility introduced in 2025 was designed to reduce this pressure.
For a business: what to look at
- In the contract: storage does not appear. It does matter, however, for the moment a price is fixed: quotations for the winter months incorporate expectations of how much gas will be in store at the start of the season.
- On the invoice: there is no "storage" item. The cost of the strategic reserve is covered by a charge (CRVCS) applied to the volumes of gas transported and is therefore part of transport costs.
- The decisions it affects: when to close winter supplies and how much of the volume to leave indexed. Before fixing, it is worth looking at the filling level compared with previous years, together with PSV and TTF quotations.
- Typical mistakes: reading the Italian figure alone, when the price is formed on a European scale; comparing today's level with the old 1 November deadline; treating storage as a price forecast rather than as one of the indicators.
How to translate these signals into purchasing rules is a matter for price risk management and for our gas consulting for businesses.
To think through the timing of your gas purchases, IPGS ENERGY is available: Request a conversation.
Sources
- Snam — I siti di stoccaggio (accessed 10 October 2026)
- Snam — Risultati finanziari 2025 e Piano Strategico 2026-2030 (accessed 10 October 2026)
- ARERA — Relazione Annuale, Stato dei servizi 2025, volume 1 (accessed 10 October 2026)
- European Commission — Gas storage (accessed 10 October 2026)
- European Parliament — Gas storage: Parliament backs refill flexibility to bring down prices (accessed 10 October 2026)
- Gas Infrastructure Europe — AGSI, Aggregated Gas Storage Inventory (accessed 10 October 2026)
Informational content by IPGS ENERGY. Information is reviewed as of the stated update date and does not replace a contractual, tax or regulatory assessment specific to an individual business.
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