Croatian Minister of Economy Ante Susnjar in Rijeka, March 10, 2026. Photo: VladaRH/AnteSusnjar/X

Croatia on Tuesday put into operation its heavy residue processing plant at the Rijeka Oil Refinery, one of the most important energy projects in Croatia in the last decade, worth 700 million euros.

The key energy project comes into fruition as war continues in Iran, closing the Strait of Hormuz, affecting supply chains and oil markets.

“This is a major investment in Croatian industry and an even greater investment in the country’s energy security, in times of geopolitical instability and disruptions in the energy market. Strong and reliable infrastructure means greater security, more stable supply and a more resilient economy,” Economy Minister Ante Susnjar said at the refinery’s inauguration ceremony.

The refinery in Rijeka, a port city on the northern Adriatic, is owned by the Croatian oil company INA, in which Hungarian oil group MOL holds a controlling stake.

Minister Susnjar alluded to the slow pace of the refinery’s modernisation. “I am the eleventh Minister of Economy since the modernisation of the Rijeka refinery began,” he said, adding that “partners from MOL have obviously approached this project very carefully and not at all hastily.”

The central part of the modernisation is a so-called Delayed Coker Unit, DCU, which enables the processing of heavier crude oil residues and the production of larger quantities of higher-value fuels.

The new plant converts heavy refining residues into products such as diesel and gasoline, significantly increasing the efficiency of refining.

According to the company, modernisation could increase diesel production by around 400 thousand tons per year, or up to 30 per cent.

Once the project is fully launched, the refining capacity at the refinery is expected to increase from around three to four million tons of crude oil per year by 2027.

“Croatia is a reliable partner to its neighbours and allies, and our energy infrastructure – from LNG terminals to oil pipeline and refinery capacities – is part of the broader European security architecture,” the minister emphasised.