South East Europe’s energy transition is often described as a renewable energy story. That description is accurate, but incomplete. The region is also a security-of-supply market, and in that context gas continues to play a structurally important role.
The core issue is flexibility. Solar and wind are expanding rapidly, but they are inherently variable and do not always generate power when demand is highest. Hydro provides valuable balancing capacity, but remains dependent on hydrological conditions. Coal still plays a significant role in parts of the Western Balkans, but it is increasingly constrained by economics and decarbonisation pressures. Batteries are scaling, but they primarily address short-duration flexibility. In this system, gas remains one of the few dispatchable tools capable of balancing variability and ensuring system reliability.
Romania’s Neptun Deep project is the most significant regional example. Developed by OMV Petrom and Romgaz on a 50/50 basis, the Black Sea project involves up to €4 billion in investment and is expected to begin production around 2027. Estimated output is approximately 8 billion cubic meters of natural gas per year, positioning it as a major domestic supply source.
The implications extend beyond Romania. New domestic gas production strengthens regional supply diversification, reduces dependence on more geopolitically exposed import routes, and enhances Romania’s potential role as a supplier within South East and Central Europe.
The Alexandroupolis LNG terminal in Greece represents another strategic pillar. The floating storage and regasification unit has a capacity of up to 5.5 bcm per year and is designed to supply not only Greece but also Bulgaria, Romania, Serbia, North Macedonia, Moldova, Ukraine, Hungary, and Slovakia.
This infrastructure is significant because it transforms Greece into a regional LNG entry point for the Balkans. Combined with interconnectors, reverse-flow capabilities, and the emerging Vertical Corridor concept, LNG infrastructure has the potential to fundamentally reshape gas flows across South East Europe.
From an investment perspective, this leads to an important conclusion: gas infrastructure should not be assessed solely as long-term fossil fuel exposure, but increasingly as part of a flexibility and security system.
However, this does not mean all gas assets are equally attractive. Traditional baseload gas generation exposed to volatile fuel prices and tightening carbon constraints carries increasing risk. In contrast, flexible gas assets, LNG infrastructure, storage capacity, and interconnectors can retain strategic and financial relevance where they enhance system reliability.
The most resilient gas-related investments in the region typically share several characteristics.
First, they enhance diversification. Infrastructure that expands access to multiple supply sources provides clear security-of-supply value.
Second, they enable coal displacement. In coal-dependent systems, gas can serve as a transitional fuel that reduces emissions when replacing older lignite capacity, particularly when combined with growing renewable generation.
Third, they provide system flexibility. Fast-ramping gas-fired generation can support evening demand peaks and compensate for solar variability.
Fourth, they offer regional optionality. Cross-border infrastructure and interconnected systems can capture value from price differentials and supply imbalances across markets.
At the same time, structural risks remain material. EU climate policy direction, carbon pricing, methane regulations, utilisation uncertainty, and competition from storage technologies all affect the long-term economics of gas assets. As a result, future-proof gas investments must be designed around flexibility rather than baseload dependency.
Financing markets increasingly distinguish between different types of gas exposure. Neptun Deep is viewed as strategic because it represents large-scale regional production with security implications. Alexandroupolis is strategic because it diversifies import routes and enhances resilience. Flexible gas-fired generation may still be financeable where it supports capacity adequacy and system stability, but speculative long-term demand growth is significantly harder to underwrite.
The interaction between gas and renewables is central to system design. As solar penetration increases, evening and seasonal flexibility becomes more important. Batteries can address short-duration imbalances, hydro can provide regional balancing where available, and demand response can reduce peak stress. However, during extended low-renewable periods, gas may still play a critical backup role.
This makes the energy transition in South East Europe less of a binary shift and more of a system optimisation challenge: ensuring reliability while steadily reducing emissions and coal dependence.
Gas is unlikely to dominate long-term growth trajectories, but within the current transition window it remains part of the operational flexibility mix.
For investors, the implication is clear. Exposure to gas should be selective. Assets dependent on long-term baseload utilisation face increasing risk, while those providing security value, flexibility, and transition-supporting functions may remain viable within the evolving energy system.
South East Europe will continue to expand renewables aggressively. But it will also require infrastructure that ensures the system works when renewable output is insufficient. In that sense, molecules and electrons will continue to coexist within the region’s energy architecture, at least through the medium-term transition phase.