Bulgaria advances Vertical Gas Corridor toward 2026 completion

he Vertical Gas Corridor, a pivotal infrastructure project aimed at enhancing energy diversification in Southeast and Central Europe, is on track for completion by October 1, 2026. Bulgaria's state-owned gas transmission operator, Bulgartransgaz, has reaffirmed its dedication to finishing its portion of the corridor, which will facilitate the flow of non-Russian natural gas from southern entry points to northern markets. This development is part of a broader regional strategy to diminish reliance on Russian supplies amid ongoing geopolitical tensions and Europe's push toward energy independence.

Accelerated construction progress

Construction activities on Bulgaria's segments of the Vertical Gas Corridor have surged ahead of schedule, demonstrating significant advancements in key areas. The 48-kilometer Kulata-Kresna pipeline, located near the border with Greece, has seen 80% of its pipes welded and positioned in trenches. Nearly 40 kilometers of terrain have been cleared, with 15 kilometers of welded pipes installed and 3 kilometers already buried. This segment is crucial for linking Greek liquefied natural gas (LNG) terminals to Bulgaria's network, enabling increased southward-to-northward gas flows.

Further north, work on the Rupcha-Vetrino loop, which will boost transmission capacity between Bulgaria and Romania, commenced in late August 2025. Bulgarian Energy Minister Zhecho Stankov has indicated that the initial 48-kilometer phase of this loop is targeted for completion by the second quarter of 2026, with the full system expected to be operational by year's end. The project currently employs over 450 workers and involves intricate engineering feats, such as traversing three rivers, the Hemus motorway, and sections of the Balkan Mountains.

In a notable milestone, a second shipment of pipeline segments arrived at the port of Burgas in July 2025, further propelling Bulgaria's contributions to the corridor. This delivery supports the expansion of the existing networks, allowing for the transmission of additional natural gas volumes from south to north. Overall, the Bulgarian sections represent a €300 million investment, with Bulgartransgaz securing financing through partnerships like a BGN 200 million loan from United Bulgarian Bank to fund infrastructure reinforcements.

Regional collaboration and strategic importance

The Vertical Gas Corridor initiative unites gas transmission operators from seven countries: Greece, Bulgaria, Romania, Hungary, Slovakia, Ukraine, and Moldova. Launched to create an alternative transportation route for natural gas, the corridor extends from Greece northward, branching into Moldova and Ukraine while connecting to Hungary and Slovakia. This north-south axis aims to integrate national gas networks from the Aegean Sea to the Baltic, enhancing energy security across the region.

The project's first phase will increase transmission capacity from Greece to Bulgaria by 50%, reaching up to 3.6 billion cubic meters annually, complete with reverse flow capabilities for flexible supply management. The subsequent phase is set to double the capacity to Romania, potentially handling 10 billion cubic meters per year. This expansion is vital for channeling LNG from diverse sources, including terminals in Greece and Turkey, to Central and Eastern European markets.

Beyond technical enhancements, the corridor fosters regional solidarity, particularly supporting Ukraine and Moldova amid their energy vulnerabilities. It aligns with Europe's broader goals, such as the anticipated complete ban on Russian natural gas by 2027, and positions the participating nations to achieve long-term energy independence. Recent developments include the introduction of a "super-integrated" tariff system in 2025 by Greece, Bulgaria, Romania, and Moldova, which has halved transit costs for certain routes, making the corridor more economically viable.

US partnership bolsters LNG integration

US involvement has been instrumental in advancing the Vertical Gas Corridor, with a focus on integrating American LNG into Europe's energy mix. During the 9th Southeast Europe Energy Forum in Thessaloniki, Bulgartransgaz CEO Vladimir Malinov engaged in bilateral discussions with US officials, highlighting Washington's strategic interest. Arleen Fetizan, the US Department of Energy's attaché for Central and Eastern Europe, stressed the reliance on Bulgartransgaz to amplify the role of US LNG in the region, aligning with European policies to phase out Russian gas.

Additionally, Malinov met with Josh Hook, Chargé d'Affaires at the US Embassy in Greece, to explore incorporating American technologies and financing into corridor projects. Both parties agreed that this collaboration could attract interest from the Trump administration and serve as a model for eliminating Russian gas dependencies in Europe. Since 2022, Europe has imported approximately 206 billion cubic meters of US LNG, underscoring its growing significance as a reliable alternative.

The corridor is poised to help Central and Southeast Europe address a projected 30 billion cubic meter gas supply gap, with increased US LNG imports playing a central role. This transatlantic partnership not only diversifies sources but also strengthens geopolitical ties, ensuring stable energy flows to vulnerable areas like Ukraine.

Challenges amid ongoing developments

Despite robust progress, the Vertical Gas Corridor faces commercial hurdles. Recent capacity auctions have seen limited interest due to elevated transportation tariffs, especially from Romanian and Moldovan operators. Currently, only about 2.9 million cubic meters per day of non-Russian LNG transits through the corridor, starkly contrasting with over 60 million cubic meters of Russian gas flowing daily via Bulgaria.

Technical and regulatory challenges persist, including entrenched commercial interests and the need for coordinated investments across borders. For instance, Romania's role has occasionally delayed aspects of the project, though recent advancements indicate overcoming these obstacles. Looking ahead, the corridor's success hinges on attracting buyers through competitive pricing and demonstrating its capacity to handle gas from varied suppliers like the US, Azerbaijan, and Egypt.

Projections for Bulgaria's natural gas consumption suggest it could nearly double by 2034, further emphasizing the corridor's necessity. With an estimated total cost of €400 million for related developments, ongoing financing and construction efforts are critical to meeting the 2026 deadline.

Broader implications for energy security

The Vertical Gas Corridor stands as a cornerstone for Europe's energy transition, enabling the redirection of LNG from southern terminals to northern consumers. By facilitating supplies from reliable non-Russian sources, it mitigates risks associated with supply disruptions and promotes sustainable energy practices. As construction accelerates and partnerships deepen, the project promises to transform the region's energy landscape, ensuring security and independence for decades.

Key benefits include: