Serbia’s gas security depends on whether alternative supplies can reach the country at a commercially sustainable price and in sufficient volumes during a regional shortage. The issue is tied to the Vertical Gas Corridor, which is built around pipelines, interconnectors, compressor stations, LNG terminals and capacity products. The corridor is designed to move gas northwards from Greece through Bulgaria and Romania towards Moldova, Ukraine and Central Europe.
Infrastructure expansion, new tariff arrangements and capacity auctions are intended to turn the corridor into a functioning commercial route. Serbia is positioned adjacent to the system rather than fully embedded in its main northbound axis. Its direct connection with Bulgaria provides access to the Bulgarian network and, through it, to Azerbaijani gas from the Southern Gas Corridor and LNG delivered through Greek terminals.
Most Serbian imports still rely on gas entering Bulgaria from Turkey via the TurkStream and Balkan Stream system. The Serbia–Bulgaria interconnector runs between Niš and Dimitrovgrad and continues onward to the Bulgarian network. It provides approximately 1.8 bcm per year of capacity towards Serbia.
Interconnectors and LNG supply base feeding northbound corridors
The Serbia–Bulgaria link created an alternative to the dominant Balkan Stream route. It also enabled Serbia to contract initial volumes of Azerbaijani gas. The interconnector’s strategic value increases when Greek LNG terminals and the Greece–Bulgaria Interconnector have available capacity.
The Greek supply base includes the Revithoussa LNG terminal, the Alexandroupolis floating LNG facility, the Trans Adriatic Pipeline, and domestic transmission infrastructure operated by DESFA. The Greece–Bulgaria Interconnector, or IGB, has initial capacity of approximately 3 bcm per year, expandable to 5 bcm. Bulgaria is also upgrading the south-to-north route to increase deliveries towards Romania and markets further north.
The corridor’s market test centres on delivered costs for LNG moving from Greece to Serbia. Gas transported from a Greek LNG terminal involves multiple commercial stages, including LNG procurement, shipping, regasification, Greek transmission, interconnection capacity, Bulgarian entry-exit charges and Serbian network costs. The cumulative effect of these charges can make diversified gas significantly more expensive than pipeline volumes delivered under established long-term arrangements.
This tariff stacking constrained use of the Vertical Corridor in previous years. Operators from Greece, Bulgaria, Romania, Moldova and Ukraine agreed on a revised commercial approach aimed at improving competitiveness. The planned structure introduces daily, monthly, quarterly and annual capacity products for the 2026–2027 gas year, with implementation scheduled from October 2026.
Capacity bookings show demand while utilisation depends on cargo availability
Infrastructure demand has started to appear in capacity bookings reported by Bulgartransgaz. For the 2025–2026 gas year, Bulgartransgaz reported bookings of approximately 99,398 MWh per day at the Kardam–Negru Vodă exit towards Romania. This represented more than 70% of offered capacity of slightly above 140,000 MWh per day.
The previous annual booking was approximately 44,710 MWh per day, indicating that market interest more than doubled. The increase reflects demand from Ukraine and Moldova as well as expectations that LNG and Caspian gas will play a larger role in Central and Southeast Europe. Shippers can book capacity as a strategic option even if physical flows depend on commodity spreads, Ukrainian demand, storage economics and LNG cargo availability.
ENTSOG’s Summer Supply Outlook 2026 highlights how tight conditions can affect storage outcomes across Europe. EU gas storage stood at only 28%, equivalent to approximately 314 TWh or 29 bcm, on 1 April 2026. Reaching a 90% storage level by the end of the injection season would require roughly 943 TWh, or 86 bcm, of LNG alongside continued pipeline supplies and intensive use of European gas infrastructure .
Serbia’s starting storage position versus regional replacement needs
Serbia entered the season with comparatively stronger storage levels. The country had approximately 2.0 TWh stored against working gas volume of around 4.1 TWh, corresponding to a filling level of 48.8%. Bulgaria was at 34.2%
Bulgaria stood at 34.2%, Romania at 23.9%, Hungary at 32.5% and Croatia at only 14.8%. Serbia’s percentage advantage should not be overstated because its absolute storage volume remains small relative to annual demand and potential winter consumption . Banatski Dvor provides essential seasonal flexibility, but dependable import capacity remains needed during prolonged cold weather, industrial demand recovery or disruption to its primary supply route.
The scale of replacement requirements is also central to regional exposure during shortages. ENTSOG calculates that a complete interruption of remaining Russian pipeline flows would require an additional 66 TWh, or roughly 6 bcm, of LNG during summer 2026 . Landlocked Central and Southeast European markets would be more exposed than coastal countries because replacement gas must pass through several networks before reaching final consumers.
Tight LNG conditions shape storage outcomes for landlocked markets
An optimal-LNG scenario indicates that the European network can technically support high storage levels. Under a tight-LNG scenario, storage would reach only around 76% by the end of September . Combining limited LNG availability with loss of Russian pipeline supply reduces the modelled level to approximately 70%.
The infrastructure can transport gas in these scenarios only if sufficient cargoes are procured and commercial incentives support continuous storage injections . For Serbia specifically, this distinction separates route diversification from supply diversification. A new interconnector creates an option to receive non-Russian gas but does not secure commodity availability, reserve regasification capacity, book transit rights or guarantee final delivered prices.
A layered portfolio links pipelines, Caspian volumes and contracted LNG
A robust Serbian gas portfolio would require multiple layers rather than reliance on one supply source. Long-term pipeline supply can provide a baseload component while Azerbaijani gas adds source diversity through the Southern Gas Corridor . Greek LNG can serve as contracted diversification and a flexible marginal source.
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