Balkan Gas Corridor Still Unfinished

Eleven gas-system operators, the companies that run national pipeline networks, signed a cooperation agreement in Thessaloniki on 4 September to extend the Vertical Gas Corridor towards the Western Balkans (Novini.bg, Powergame). For Malta, which imports energy rather than routing it, the corridor may sound distant. It is not. This is one of the ways the EU is trying to turn energy security from a Brussels slogan into pipes, terminals and booked capacity before Russian gas deadlines start to bite in 2027.

The corridor is not one single pipeline. It is a chain of national networks, cross-border links and LNG terminals tied together through bilateral agreements. Landlocked countries in south-eastern Europe want to use it to replace Russian gas. The problem is that the agreement signed in Thessaloniki widens a route that still exists partly as engineering plans and political intent.

The southern links work

At the southern end, the infrastructure is already there. Greece's Alexandroupolis terminal, a floating unit that turns shipped liquefied natural gas back into pipeline gas, has been operating since late 2024 with 5.5 bcm per year of capacity (Adevarul). The older Revithoussa terminal near Athens has booked almost all its unloading slots through 2040 (OT, Serbia Energy). Traders are not treating this as a short-term workaround.

The next test is Bulgaria. The IGB interconnector between Greece and Bulgaria has carried more than 39 million MWh since it began operating (ICGB). As we reported in July, traders booked 46% of available capacity at the Greek-Bulgarian border for several years ahead, which is a stronger signal than any ministerial photo call (To Brief).

Bulgaria is also where the corridor narrows. Bulgartransgaz completed duplicate pipe on a constrained section between Kulata and Kresna on 1 September, allowing more gas to move north. The larger upgrade, which would almost double capacity at the Romanian border to 9.4 bcm per year, still depends on construction scheduled through 2027–28 (Economic.bg, Jurnalul).

Further north, Moldova has begun selling time-limited rights for traders to move gas through its network towards Ukrainian storage. In March 2026, a record booking reserved 25,500 MWh per day on one route (Moldpres). The volumes are small, but they show that gas can move through the wider chain.

The Western Balkans branch is still mostly on paper

The Thessaloniki agreement brought North Macedonia's NOMAGAS and Serbia's Transportgas Srbija into the group. At a July meeting in Athens, the operators had already discussed available capacity, tariff rules and timelines at each border crossing, and set up a joint working group (Gastrade).

Greece and North Macedonia are building a 123 km interconnector from Nea Mesimvria to Negotino, financed by the EIB and EBRD (NOMAGAS). North of it, NOMAGAS has awarded a €29.4 million contract for its 22.4 km section of a link to Serbia, with completion targeted for Q4 2028 (Balkan Green Energy News). The Serbian section, about 144 km, has not yet been matched by the same level of public contracting detail.

Serbia shows the corridor's main contradiction. Srbijagas has reserved 300 million cubic metres per year at Alexandroupolis for ten years (Vreme). That is a real commercial commitment, but it covers only about a tenth of Serbia's annual consumption. Belgrade is still extending short-term supply arrangements with Gazprom (Enerdata). For now, the corridor gives Serbia leverage in negotiations, not a replacement supply system.

Who gains, who pays

The EU's Russian-gas phase-out regulation, adopted in January 2026, bans long-term Russian LNG contracts from January 2027 and sets a pipeline gas phase-out by late 2027 (European Commission, European Parliament). That legal timetable is what gives the corridor its political value.

Greece and Bulgaria gain hub status and transit fees. Romania gains as a transit country now, and later as a producer if its Neptun Deep offshore field starts pumping in 2027 as planned (OMV). North Macedonia shifts from being a dead-end market to a possible transit country. These are not marginal changes for smaller states. Malta knows that EU infrastructure rules can alter a country's economic position quickly, whether in energy, shipping, finance or digital services.

Hungary and Slovakia sit on the political edge of the project. Both still rely on Russian gas through TurkStream, the pipeline running from Russia through Turkey into south-eastern Europe. Slovakia's main transit operator moved only about 5.4 bcm in 2025, down from 17.8 bcm after Ukrainian transit stopped (Pravda.sk). Croatia's Krk LNG terminal offers another non-Russian route, with capacity due to double in late 2026 (HRT).

The caution is in the market data. When Ukraine auctioned two transit routes in December 2025, no company booked a single cubic metre (LIGA.net). Cooperation agreements, tariff discussions and political urgency do not move gas on their own. Thessaloniki made the Vertical Gas Corridor wider on paper. It has not yet made it physically complete, or commercially secure.