Bulgaria’s gas policy: stalled diversification amid persistent Russian influence

The Vertical Gas Corridor, designed to channel non-Russian gas to Romania, Moldova, and Ukraine, struggles to reduce Southeast Europe’s reliance on Russian-dominated TurkStream pipelines, writes Ilian Vassilev.

Ilian Vassilev is a former Bulgarian ambassador to Moscow, now a media publisher and commentator. His website Alternativata is a content partner of EUalive.

Despite its aim to diversify energy supplies through the Greece-Bulgaria Interconnector and the Alexandroupolis LNG terminal, progress on the Corridor’s second and third routes has faltered, raising doubts about Bulgaria’s commitment to energy independence. Ongoing delays warrant renewed scrutiny.

Stagnation in infrastructure development

Despite a high-profile launch of the Corridor’s first route and upgrades to the Sidirokastro-Kulata interconnection, progress has stalled. A critical 67 km pipeline between Rupcha and Vetrino, which could enable 13 billion cubic meters (bcm) of annual reverse flows through the Trans-Balkan Pipeline, remains unbuilt.

Instead, Bulgartransgaz’s CEO has prioritized minor expansions north of the Greek border. As a result, the Trans-Balkan system’s Kardam-Negru Voda 2 and 3 pipelines, with a combined capacity exceeding 13 bcm annually, report zero throughput, representing Southeast Europe’s largest unused transmission capacity, capable of meeting demand in Moldova, Romania, and Ukraine.

In contrast, the older Kardam-Negru Voda 1 pipeline, once a Gazprom conduit, now operates in reverse at near-full capacity, handling up to 15 million cubic meters (mcm) daily, up from 6 mcm. This surge highlights the urgent need to activate the idle pipelines, yet Bulgaria repeatedly delays decisions despite rising seasonal demand.

Sources of gas flows

Though the Vertical Corridor is technically operational, only Route 1 (Sidirokastro-Kulata) delivers modest northward exports of ~4 mcm/day, primarily Russian backhaul gas, insufficient to account for the ~15 mcm/day flowing to Romania. Entry flows into Bulgaria’s gas transmission system reveal:

Sidirokastro-Kulata (Greece): ~4 mcm/day, mostly Russian gas, with stable but limited growth.
IGB (Greece-Bulgaria Interconnector): ~2.5 mcm/day, fully absorbed by Bulgargaz’s Azeri contract.
Strandzha (Turkey): ~4.5 mcm/day, mainly under SOCAR and Botas contracts.
Strandzha 2 (TurkStream): ~50 mcm/day of Russian gas, with 26–28 mcm to Serbia and the rest split among Greece, Bulgaria, Hungary, and Romania.

The data is stark: increased flows to Romania rely almost entirely on Russian gas via TurkStream, not the Azeri or LNG supplies the Corridor aims to prioritize.

Causes of inaction

The official reason for delays is the unbuilt Rupcha-Vetrino pipeline, essential for linking the Trans-Balkan system to Routes 2 and 3. Yet, this segment was repurposed to serve TurkStream, which Bulgaria completed in just over a year to meet Moscow’s demands.

Meanwhile, no progress has been made on infrastructure supporting Ukraine.

Bulgartransgaz has instead focused on domestic projects, such as pipeline loops feeding power plants like TPP Bobov Dol, Toplofikatsia Pernik, and Maritsa basin sites, owned by a politically connected energy oligarch.

The Chiren gas storage expansion, crucial for balancing non-Russian imports, has been delayed since 2011. This pattern suggests a deliberate policy prioritizing Russian gas flows over diversification.

Geopolitical implications

Bulgaria’s inaction coincides with Russia’s intensified attacks on Ukraine’s energy infrastructure, targeting compressor stations to disrupt winter supplies. The Trans-Balkan’s unused capacity could bolster Ukraine’s energy security, but politically driven delays undermine the EU’s goal of phasing out Russian gas.

The Alexandroupolis LNG terminal’s “technical” outage further strengthens Moscow’s grip, limiting access to alternative supplies. These developments highlight how Russian influence continues to shape Bulgaria’s energy decisions, entrenching TurkStream’s dominance.

Promoted as a beacon of energy independence, the Vertical Gas Corridor currently channels more Russian gas than intended, with Bulgaria’s failure to activate the Trans-Balkan’s second and third pipelines reflecting a geopolitical choice. This inaction undermines Bulgaria’s energy security and weakens Europe’s ability to support Ukraine, allowing TurkStream to maintain its stranglehold on regional gas flows.

A longer original version of this article can be found here.

Caption: File photo. Turkish President Recep Tayyip Erdogan (2-R), Russian President Vladimir Putin (c) and Serbian President Aleksandar Vucic (R) and the then Prime Minister of Bulgaria Boyko Borissov (2-L) attend the opening ceremony of the Turkstream Project in Istanbul, Turkey, 8 January 2020. EPA/ALEXEY DRUZHININ / SPUTNIK / KREMLIN POOL