ACER Opinion 06-2025 on ENTSOG's Summer Supply Outlook 2025

PUBLIC

OPINION No 06/2025 OF THE EUROPEAN UNION AGENCY FOR THE COOPERATION OF ENERGY REGULATORS of 4 July 2025 on ENTSOG’s Summer Supply Outlook 2025

THE EUROPEAN UNION AGENCY FOR THE COOPERATION OF ENERGY REGULATORS, Having regard to Regulation (EU) 2019/942 of the European Parliament and of the Council of 5 June 2019 establishing a European Union Agency for the Cooperation of Energy Regulators Regulation (‘ACER’), and, in particular, Article 4(3)(b) thereof, Having regard to Regulation (EU) 2024/1789 of the European Parliament and of the Council of 13 June 2024 on the internal markets for renewable gas, natural gas and hydrogen, and, in particular, Articles 26(3) and 27(2) thereof, Having regard to the outcome of the consultation with the ACER’s Gas Working Group, Having regard to the favourable opinion of the Board of Regulators of 26 June 2025, delivered pursuant to Article 22(5) of Regulation (EU) 2019/942, Whereas:

EXECUTIVE SUMMARY

(1) ACER welcomes the timely publication of the Summer Supply Outlook 2025 (the Outlook) by the European Network of Transmission System Operators for Gas (ENTSOG). The Outlook evaluates the possible development in gas supply and the ability of the European gas system infrastructure to meet demand and handle storage injections during this summer and the coming winter. The expected gas demand and supply projections are modelled under a reference scenario, which is complemented with various gas system stress sensitivities, i.e. a cold winter and disruptions in Russian gas supply. The Outlook concludes that the current European gas infrastructure is adequate for reaching the storage filling targets and for supplying gas demand one year ahead.

Phasing out Russian gas imports

(2) ENTSOG examines the EU dependency on Russian gas supply. In all Outlook’s scenarios gas imports via the TurkStream pipeline are minimised. Additionally, two Russian gas supply disruption sensitivity scenarios are modelled: (i) TurkStream disruption and (ii) reduction of the liquified natural gas (LNG) supply (20% down from the historical supply). The latter impedes reaching the 90% gas storage filling before the winter season. (3) The recent Communication of the European Commission proposes a coordinated and gradual phase-out of Russian gas imports by prohibiting new gas supply contracts and stopping existing spot contracts by the end of 2025, as well as stopping all remaining gas imports by the end of 2027. In the future outlooks, ACER encourages ENTSOG to include a stepwise phase-out of Russian gas supply, while focussing on LNG imports dynamics, considering the globally expanding market , and securing additional supply to phase out from Russian gas.

Gas demand

(4) The reference gas demand in the Outlook, as estimated by Transmission System Operators (TSOs), is about 10% higher than the historical demand outturn in the last three years. ACER recommends reviewing the TSOs’ demand estimates by comparing them with the historical demand development, political and economic trends, and third-party projections.

Market drivers

(5) ACER further invites exploring the gas price effect on gas supply and storage filling, as it may change the regular supply pattern. Such assessment would indicate market driven gas off-take and feed-in patterns offering additional insights into the use of the gas infrastructure.

1. INTRODUCTION

(6) On 10 April 2025, the European Network of Transmission System Operators for Gas (ENTSOG) published its Summer Supply Outlook 2025 (the Outlook) with Winter 2025/26 Overview pursuant to Article 26(3)(g) of Regulation (EU) 2024/1789. (7) Pursuant to Article 4(3)(b) of Regulation (EU) 2019/942, ACER may provide an Opinion to ENTSOG on, inter alia, relevant documents referred to in Article 26(3) of Regulation (EU) 2024/1789, as submitted by ENTSOG to ACER pursuant to Article 27(2) of Regulation (EU) 2024/1789.

2. SUMMARY OF THE ENTSOG’S SUMMER SUPPLY OUTLOOK

(8) ENTSOG’s Outlook presents EU-wide simulations of the European gas infrastructure readiness in the coming year (summer 2025 and winter 2025/26) to cope with various gas demand and supply scenarios. (9) In total, eighteen (18) scenarios were modelled in the Outlook. Figure 1 shows the possible combinations of three gas demand scenarios, TurkStream supply disruption scenario and three liquified natural gas (LNG) supply scenarios. The Reference scenario combines the yellow blocks in Figure 1. Any other combination of blocks constitutes sensitivity scenarios that test the readiness of gas infrastructure and gas storage filling with respect to the targets.

(10) The Reference gas demand is estimated by the transmission system operators (TSOs). The “5-year average” and “5-year average -15%” scenarios model, respectively, higher and lower gas demand relative to the Reference. (11) ENTSOG applies supply stress scenarios to assess the EU’s dependence on Russian piped gas via TurkStream and on LNG imports. Russian piped gas supply is minimised and fully disrupted, while the availability of the LNG supply potential for Europe is modelled under a Reference, Low and High supply scenarios. The Reference LNG supply is based on historical data.

(12) ENTSOG’s main findings and conclusions are: a. A low gas storage level at the beginning of this summer season (34%) requires early storage filling and high LNG imports to facilitate reaching the 90% gas storage level before the start of the winter season. b. Gas infrastructure is adequate for reaching the storage filling targets and for supplying the gas demand through the summer and winter seasons. c. All sensitivity scenarios with Low LNG supply do not allow for reaching the storage filling target before the start of the winter season. Additionally, higher demand scenarios lead to lower storage levels.

3. ENTSOG’S APPROACH AND ACER’S ASSESSMENT

(13) ACER welcomes ENTSOG’s timely Outlook delivery and the continuous modelling updates that capture recent changes in infrastructure (mostly the new LNG terminals and cross-border capacities) and expand spatial coverage with the EU gas transit via Ukraine. (14) The following sections present ACER’s review of ENTSOG’s modelling assumptions – on demand, supply and storage – complemented with recommendations for future outlooks.

Demand

(15) The three gas demand scenarios modelled in the Outlook are shown in Figure 2: (i) reference demand based on the TSOs estimate, (ii) 5-year average (from 2017 to 2021/22), and (iii) 5-year average (from 2017 to 2021/22) reduced by 15%. Figure 2: Demand scenarios: EU-27 and other modelled countries

(16) The Reference scenario demand value is about 10% higher than the actual demand outturn in the last three years following the 2021 crisis (see Figure 3). Such reference value could be more appropriate as a cold winter sensitivity scenario. ACER notes that TSOs` assumptions behind the Reference demand estimates are not provided in the Outlook.

(17) The 5-year average represents the highest demand among the three demand scenarios, as it is based on the high gas demand period of 2017 - 2021/22. This approach does not account for the energy efficiency measures applied since 2021. Gas demand in 2023 and 2024 dropped 15-20% below the pre-crisis (2021) levels possibly reflecting an industrial shift and improved energy use efficiency according to recent findings from the ACER 2025 Monitoring Report of electricity and gas markets . The 5-year average demand scenario seems extreme, but it could be useful for testing the gas infrastructure. (18) The “5-year average -15%” demand scenario, which is based on the Council Regulation (EU) 2022/1369 on coordinated demand-reduction measures for gas, is close to the historical outturn in the last two years. In this Regulation, the voluntary 15% gas demand reduction target applied for summer 2023 & winter 2023/24 compared with the average annual demand from 2017 to 2021/22.

(19) ACER recommends reviewing the TSOs’ demand estimates by comparing them with the historical demand development, political and economic trends, and third-party projections.

Supply

(20) The maximum supply potential is based on the historical availability of the last 5 years. This potential is estimated per source and per season as the maximum of the 30-day rolling average supply. (21) Russian gas pipeline supply through TurkStream is minimised. The TurkStream connects Russia with Turkey and then onwards to Bulgaria. This supply is used as the last resort, i.e. when other supplies are exhausted. (22) Three LNG supply scenarios are modelled in the Outlook as shown in Figure 4: Reference, Low and High. The Reference LNG supply potential is based on historical data.

(23) The Low LNG supply potential is 20% lower than the Reference potential. This is due to the exclusion of the Russian LNG supply from Yamal. The High LNG potential is limited only by the LNG regasification capacity in Europe. Although the High LNG scenario exceeds the potential volume of contracted LNG supply , it is a good initiative by ENTSOG for the purpose of exploring maximum LNG supply needs required to meet gas demand under various sensitivity scenarios. (24) The Union’s domestic production is expected to decline following the historical trend. (25) ACER encourages adjusting the maximum LNG supply potential in the Reference LNG 3,8 supply scenario including the booked LNG capacities as the best forecast. (26) ACER also encourages to reflect the stepwise phase-out of Russian gas supplies in a sensitivity scenario.

Storage

(27) Gas storage levels at the beginning of the modelling horizon on 1 April 2025 were at 34% (35 bcm). It is about 20 percentage points lower than in the previous two years. This requires higher gas supply during the summer season to reach the storage target level of 90% (93 bcm) by 1 November 2025 (Regulation (EU) 2017/1938). Gas storage filling is supported via a mechanism of minimum intermediary targets (Regulation (EU) 2023/2633), which enables market flexibility for Member States to fulfil the filling target at their own pace. (28) ACER appreciates that, in the recent Outlooks, ENTSOG enhanced the gas storage assumptions by (i) modelling the country-specific strategic storage reserves and (ii) modelling the LNG tanks at regasification terminals for additional short-term storage flexibility.

Market drivers

(29) ENTSOG recognises the importance of demand side response in reducing pressure on LNG imports and meeting the gas storage filling targets. However, ENTSOG does not model price sensitivity of gas demand, rather it estimates the required demand side response capacity to keep gas storage levels above the minimum (11%) under various demand-supply sensitivity scenarios.

(30) The LNG supply potential is a fixed modelling input set under the Reference, Low and High scenarios. In the Outlook, the LNG supply does not react to changes in gas demand. Yet, higher demand may eventually attract cargos at higher prices . (31) While gas prices are currently not factored into modelling, the current summer-winter price spreads signal possible challenges for the market-based storage filling.

(32) ACER recommends further exploring modelling price-sensitive gas demand (demand side response). Considering price dynamics may reveal flow patterns that are relevant to test infrastructure adequacy. (33) ACER welcomes the Low LNG supply potential scenario and invites ENTSOG to provide the underlying assumptions behind it. (34) ACER recommends considering the future gas wholesale prices (e.g. EEX futures ) and the expected summer-winter price spreads. Negative or close to zero summer-winter spreads discourage market-based gas storage injections during the summer season.

4. CONCLUSIONS

(35) ACER acknowledges ENTSOG’s gradual improvements in the modelling assumptions that underlie the seasonal outlooks and the more structural modelling updates. ACER welcomes the fact that in addition to the central Reference scenario, ENTSOG methodically examines gas infrastructure readiness and storage filling through various gas system stress sensitivities. The Outlook concludes that the European gas infrastructure is adequate for delivering gas supply to meet demand in the coming year. (36) ACER encourages ENTSOG to consider more closely the recent trends in both – gas and electricity – sectors, especially the globally growing LNG market , energy efficiency and electrification, policy developments related to more flexible storage targets , as well as progress towards the Russian gas supply phase-out proposed in the roadmap by the European Commission . (37) ACER further invites exploring the gas price effect on gas supply and storage filling in the Reference scenario, also accounting for the intermediary minimum filling targets. Different summer-winter price spreads compared with the previous years may change the regular supply pattern resulting in unique gas flows and gas infrastructure loading.

(38) ACER recommends reviewing the methodology that underlies the Outlooks, considering the experience gathered so far and ACER’s recommendations in its opinions, including the cross-sectoral considerations with the electricity sector, where gas demand is decreasing. Gas consumption in electricity production fell for the second straight year in 2024, continuing a sharp decline since 2022 as renewables expanded their share . (39) ACER encourages ENTSOG to consider streamlining its gas scenario outlooks, possibly by reducing their number and focusing on the most policy-relevant ones to provide more actionable recommendations. HAS ADOPTED THIS OPINION: 1. ACER finds that ENTSOG’s Summer Supply Outlook 2025 is broadly consistent with the objectives listed in 4(3)(b) of Regulation (EU) 2019/942 and Regulation (EU) No 2024/1789. 2. ACER encourages ENTSOG addressing the recommendations from sections 3.1 Demand, 3.2 Supply, 3.4 Market drivers and 4 CONCLUSIONS in the upcoming outlooks. This Opinion is addressed to ENTSOG.

Done at Ljubljana, on 4 July 2025

- SIGNED -

For the Agency The Director C. ZINGLERSEN