For most of the last decade, energy maps of Central and Eastern Europe were drawn in straight lines running east to west, with Russian molecules flowing in and everyone else adjusting around them. That map is being redrawn right now, and it is being redrawn vertically. A new spine is taking shape along the western edge of the Black Sea, anchored by three countries: Greece at the bottom, Bulgaria in the middle, and Romania at the top. It is not arriving with a single ribbon-cutting moment. It is arriving the way real infrastructure usually does, one interconnector, one regulatory approval, and one pipeline weld at a time.
Here is why this three-country story matters for anyone watching CEE power, and why Romania keeps ending up at the center of it.
From a horizontal map to a vertical one
The clearest signal is the Vertical Gas Corridor. This is a north-south transmission network designed to carry liquefied natural gas from Greek terminals up through Bulgaria into Romania, and onward to Hungary, Slovakia, Moldova, and Ukraine. The concept reverses the old logic of the region. Instead of gas pushing south from the north, it now enters from the Aegean and travels upward.
The numbers behind it are becoming concrete. Once fully built, the corridor is designed to move up to roughly 10 billion cubic meters of gas a year, repurposing and expanding the existing Trans-Balkan pipeline that once carried Russian transit. Infrastructure under construction is set to increase transmission capacity from Greece to Bulgaria by more than 50 percent, and from Bulgaria to Romania by close to 100 percent. Two major Bulgarian segments are expected to come online by the end of 2026, and from the 2026 to 2027 gas year, operators plan to offer a wider menu of capacity products covering daily, monthly, quarterly, and annual bookings.
This is not a slide-deck ambition. The transmission system operators of Greece (DESFA), Bulgaria (Bulgartransgaz), Romania (Transgaz), Moldova (Vestmoldtransgaz), and Ukraine, together with the operator of the Greece-Bulgaria Interconnector (ICGB), have already secured regulatory approval for new cross-border capacity products known as Route 2 and Route 3. Route 2 moves LNG from the Alexandroupolis floating terminal northward, and Route 3 carries Azeri gas through the Greece-Bulgaria link. The plumbing and the paperwork are advancing together, which is usually the sign that something is real.
Power, not just gas
The phrase “energy corridor” can sound like it is only about pipelines. It is not. The electricity side of this three-country relationship is maturing just as quickly, and arguably matters more for the clean energy transition.
The three markets are already being stitched together through day-ahead market coupling, which lets electricity prices and cross-border flows be calculated simultaneously across the region. The results are visible in the data. In 2025, the Bulgaria-Romania border showed near-complete price convergence, with an average spread of only about 1.4 euros per megawatt hour during normal hours and net transfer capacity exceeding 1,500 megawatts in both directions. Bulgaria, Greece, and Romania now sit inside the same South-East Europe capacity calculation region, which is the technical backbone that lets a kilowatt generated in one country compete fairly in another.
Then there is the project that turns this corridor into something genuinely strategic: the Black Sea Submarine Cable. This is a high-voltage direct current link planned to run from Anaklia in Georgia to Constanta in Romania, stretching roughly 1,195 kilometers, most of it underwater, at 500 kilovolts and a capacity in the range of 1,000 to 1,500 megawatts. Its purpose is to carry renewable electricity, primarily wind and solar from Azerbaijan and Georgia, directly into the European grid through Romania.
The momentum here is recent and tangible. In December 2025 the project was added to the European Union’s list of Projects of Mutual Interest. In February 2026, Romania’s grid operator Transelectrica and Georgian State Electrosystem signed a fresh memorandum of understanding in Bucharest to advance the cable, which has already cleared feasibility studies and been folded into ENTSO-E network development planning. The broader Green Energy Corridor venture, which adds Hungary and Azerbaijan to the Romania-Georgia core, is targeting an operational date toward the end of the decade.
Why Romania keeps ending up at the top of the map
Try to tell this story without Romania and it falls apart. That is not national flattery, it is geography and project pipeline.
On gas, Romania is about to change category entirely. The Neptun Deep project in the Romanian Black Sea, developed by OMV Petrom and Romgaz with investment of around 4 billion euros, holds an estimated 100 billion cubic meters of recoverable gas and is built to produce roughly 8 billion cubic meters a year at plateau. Pipelaying in the Black Sea began in May 2026, with first gas targeted for 2027. That single project would nearly double Romania’s domestic output, which sat at roughly 9 billion cubic meters in 2025, and position the country as the largest gas producer in the European Union and a likely net exporter, with interest already coming from Germany, Moldova, and Slovakia.
On power, the case is just as strong. Romania already has around 3 gigawatts of onshore wind installed and is building a storage market with targets that reach toward 5 gigawatts. Its Black Sea offshore wind resource is enormous, with technical potential estimated at tens of gigawatts and a roadmap, produced with the European Commission and the World Bank, charting between 3 and 7 gigawatts installed by 2035. In the higher scenario, offshore wind alone could supply more than a third of Romania’s electricity. The ports of Constanta, Midia, and Mangalia are positioned to become manufacturing and supply hubs for the wider region, not just for domestic projects.
Add it up and Romania is the natural northern anchor of the corridor. It is the landing point for renewable power from the Caucasus, a coming gas exporter rather than importer, a deep interconnection partner for both Bulgaria and the wider continent, and a country with the offshore resource and port industry to host the heavy infrastructure the whole region needs. Greece provides the entry point for seaborne LNG and Mediterranean interconnection. Bulgaria provides the critical transit and a fast-growing storage market. Romania provides the production, the grid landing, and the renewable scale. Each leg is needed, but only one of them sits at the meeting point of all the flows.
What to watch next
A few markers will tell you whether this corridor is firming up on schedule. Watch for the two Bulgarian Vertical Corridor segments to enter service by the end of 2026. Watch the geotechnical surveys on the Black Sea Submarine Cable route, which are the next real step after feasibility. Watch Neptun Deep’s platform installation through 2026 ahead of first gas in 2027. And watch how quickly Romania’s offshore wind tenders move from legal framework into actual seabed concessions.
None of these are guaranteed, and timelines in large energy infrastructure tend to slip. But the direction is unusually clear. The east-west map is being replaced by a vertical one, and a region that used to be a passive transit zone is turning into a connected, multi-source market.
Momentum Energy’s View
The most useful way to read this story is to stop thinking about three separate national energy systems and start thinking about one regional market that happens to span three jurisdictions. The pipelines, the interconnectors, the market coupling, and the submarine cable are all doing the same thing: lowering the cost of moving an electron or a molecule across a border. When that cost falls, capital follows, and the projects that win are the ones positioned where the flows converge.
For developers, investors, and offtakers, the practical takeaway is that location strategy in CEE is shifting. Sites that once looked peripheral now sit on a backbone. We see Romania as the standout in this respect, not because of sentiment but because the fundamentals stack up: a gas position moving from deficit to surplus, the strongest offshore wind resource on the western Black Sea, the grid landing point for imported renewables, and a port base ready to industrialize. The smart move over the next 24 to 36 months is to plan as if the three-country corridor already exists, because the infrastructure decisions being signed today are building exactly that.
Momentum Energy will keep tracking the milestones that matter, from interconnector commissioning to offshore wind tenders, and translating them into what they mean for projects on the ground.
