Bulgaria and Ukraine near Bulgargaz-Naftogaz gas transit deal

If a tanker of American LNG docks in Greece this autumn and that gas reaches Ukrainian storage by November, it will have crossed five national pipeline systems in a direction those pipes never carried gas before. That hypothetical is now closer to reality than at any point since Russia weaponised its pipeline leverage. But the gap between commercial interest and physical delivery remains wide open.

Bulgaria and Ukraine's state gas companies, Bulgargaz and Naftogaz, are reportedly near a bilateral deal. A Bulgarian MP confirmed the two sides were "close to signing a contract," while adding that "nothing has been signed" and no legally binding terms exist (SEGA, Fakti). No volumes, pricing, or duration are public.

The corridor exists on paper. Firms are now paying to use it.

The Vertical Gas Corridor is not a single new pipeline. It stitches together existing and upgraded systems across Greece, Bulgaria, Romania, Moldova and Ukraine into a single commercial route running south-to-north. Current capacity is about 5.03 bcm per year, with a first expansion targeting 9.41 bcm (Energy Industry Review, ZF).

In early July, the first long-term capacity auctions at Sidirokastro (the Greece-Bulgaria interconnection point) drew real buyers. Around 46% of available capacity was booked for gas years 2026/2027 through 2029/2030 (Energy World, OT). These are energy traders paying for future pipeline access, not governments issuing press releases.

But a booking is only a right to use a pipe. It does not mean anyone has purchased gas, instructed daily flow, or delivered a single molecule to Ukraine. Romania is still checking whether the tariff (the all-in cost of moving gas through the system) is cheap enough for traders to actually use the route. The quoted cost from Greece to Ukraine is 5.85 EUR/MWh after recent Romanian-section reductions (Euro2day, Parapolitika). Without a direct comparator to Poland or Slovakia's transit fees, it is unclear whether that price works commercially.

Bulgaria's expensive mistake becomes someone else's infrastructure

Bulgaria has the clearest financial reason to make this corridor succeed. Under a January 2023 contract, Bulgargaz committed to paying roughly EUR 500,000 per day for Turkish regasification capacity (the right to convert LNG back to pipeline gas in Turkey) that it barely used. By spring, arrears to Turkey's BOTAS had reached around EUR 360 million (BTA). Actual May deliveries ran at just 25 million cubic metres against contracted capacity of 154 million cubic metres per month (EADaily).

After President Radev's June meeting with Erdoğan, that contract was frozen for 15 months: Bulgaria pays only for capacity it actually uses while both sides renegotiate (BNR). Energy Minister Iva Petrova said the settlement would not burden Bulgarian citizens. That claim needs balance-sheet verification: if Bulgargaz absorbs the accumulated losses, taxpayers or future gas consumers may still pay through higher regulated tariffs or state capital injections.

If Ukraine-bound gas actually flows through the corridor, Bulgaria converts a stranded-cost liability into transit revenue. That turns a money-losing contract into a reason to push molecules south-to-north.

Ukraine needs gas before winter. Only one import route is working.

Ukraine's baseline target is 14.6 bcm in underground storage before the heating season. Reaching it requires an estimated EUR 3.2–3.8 billion in gas imports at current prices (DiXi Group). As of early July, storage held 12.04 bcm, with imports arriving only from Poland at 0.8–1.6 million cubic metres per day (UEEX). The EU has mobilised an EBRD guarantee worth EUR 500 million to help replenish reserves (European Commission).

A second import direction matters because a pipe can exist and still go unused if tariffs, contracts, or expected margins do not justify the effort. Poland's northern corridor saw its latest long-term capacity auction end without any reservations (TelegrafUA). The southern route is Ukraine's realistic alternative.

The verdict the numbers support

The corridor is commercially credible but operationally unproven. Firms are paying for future access. Bulgaria's BOTAS freeze creates the right financial incentive. Ukraine's storage gap creates buyer need. Greece gains an LNG-gateway role; Bulgaria gains a path out of a ruinous contract; Romania gains transit business.

But no signed supply contract, no metered south-to-north physical flow, and no end-to-end nominations have appeared in the public record. The proof arrives when Ukrainian storage data start rising from the south.