PCI and PMI List

14.2 CROATIA AND SLOVENIA SMART GAS GRID PROJECT (PCI Project Proposal - Priority Thematic Area Smart gas grids) Brussels, 1.12.2025., C(2025) 8144 final
 

Together with the neighbouring gas transmission system operator in Slovenia, Plinacro prepared a cost-benefit analysis and applied a Croatia-Slovenia smart gas grid project to the PCI list in the group Smart gas grids, in compliance with the provisions of the TEN-E Regulation (EU/2022/869).

The project is aimed at the planning and reconstruction of gas nodes and safety and measuring equipment for the reception and mixing of decarbonized gases (hydrogen and biomethane) in the gas transmission system. This includes the development of a 'smart gas network' including advanced digital systems and components, control systems, sensor technologies, gas flow and quality management devices to enable the interactive and intelligent monitoring, measurement, quality control and management of the reception and transmission of decarbonised gases. The project also envisages the implementation of a system that will monitor, measure and reduce methane emissions to reduce the carbon footprint of gas transmission systems of both countries. 
 

More precisely, the project foresees the reconstruction or procurement of hydrogen-ready chromatographs (30 in Croatia and eight in Slovenia), enabling the receipt and control of a hydrogen content in the natural gas flow at gas nodes and at interconnection points. Advanced control digital systems and components, control systems, sensor technologies, gas flow and quality management devices will enable automatic demand forecasting, flow direction management and integration and undisturbed operation of as many hydrogen production facilities as possible. The development of an integrated SCADA system will enable simulations of operations and automatic control of natural, mixed and biomethane gas flows. 

Beyond chromatographs and SCADA, project assets include notably electrohydraulic actuators, Plexor systems, drones, associated software and data spaces, cameras and laser detectors, the reconstruction of main gas nodes in Croatia and Slovenia, compressor stations and associated physical digital assets. For both countries, a comprehensive hydrogen readiness study and hydrogen certification will be carried out for gas pipelines and facilities that are expected to transport gas mixtures with hydrogen concentrations greater than 10%. Adjustment of main interconnection points will be carried out to enable undisturbed cross-border transmission of methane with blended hydrogen, while in the advanced phase biomethane and hydrogen are to be transported. Interconnection points HR-SI Rogatec, HR-HU Dravaszerdahely and interconnection points SI-AT Morfeld/Ceršak and SI-IT Gorizia/Šempeter are to be reconstructed. 

Once this first phase of the project allowing for adding hydrogen and decarbonized gases into the methane flow is implemented, a system can be managed in which hydrogen and mixture of natural gas, hydrogen and biomethane will pass through parallel gas pipelines, until the complete transition to parallel biomethane and hydrogen transmission systems. 
 

Expected benefits 
 

The project is expected to increase the share of decarbonised gases in the transmission system and reduce methane emissions and other GHG and non-GHG gas emissions. The project will enable hydrogen blending, and management and control of gas systems with biomethane as well as smooth cross-border exchanges. 

The project is to create prerequisites for adding up to 10% of hydrogen produced from renewable energy sources, which will reduce the carbon footprint of both countries’ gas transmission systems. The project will enable the development and connection of smaller hydrogen production facilities to the gas transmission system in the transitional period, accelerating the creation of market preconditions and sufficient production capacity that will enable the repurposing of the existing gas pipelines into hydrogen pipelines as well as the production and use of hydrogen in its pure form and its transmission in the dedicated hydrogen system. 

Blending of hydrogen is also to be done in such a way as to have minimal effects on the operation of natural gas infrastructure, end-user applications and the interoperability of cross-border systems. The project should help optimizing the flow and level of hydrogen blending into the transmission system and maintaining gas quality at interconnection points.

 

Cross-border dimension 
 

The project will enable the advanced technical and informational connection of two gas transmission systems with the aim of optimizing the flow of gases to ensure unimpeded access of hydrogen and other decarbonised gases to the transmission system. The exchange of technological management data will enable the management of systems at the nodes; in the first phase of the project, mixing hydrogen and decarbonized gases into the methane stream, while in the advanced phase it will enable the management of parallel hydrogen and biomethane pipelines. 

The project will enable the cross-border transmission of gas with an increased hydrogen content and the development of the cross-border hydrogen market and other decarbonized gases. An integrated advanced intelligent monitoring and control system is expected to enable gas flow management in a way that fully implements the provisions of Article 21 of Regulation 2024/1789, both at the interconnection point between Croatia and Slovenia and between other interconnection points with neighbouring countries. Overall, the project is expected to facilitate smooth cross-border exchanges in compliance with Directive (EU) 2024/1788 and Regulation (EU) 2024/1789. 

The project is presented as an integral part or significantly helping implementation of the following EU TYNDP projects: for Croatia: RET-N-1155 Gas system retrofitting for 100% H2 future capability, OTH-N-778 Gas transmission methane emission reduction project, H2T-N-619 H2 interconnection Croatia/Slovenia, H2T-N-1274 H2 backbone Croatia - North, H2T-N-1307 H2 backbone Croatia - South, H2T-N-1255 H2 repurposing interconnection HR-HU, H2T-A-68 H2 Ionian-Adriatic Pipeline Plinacro Ltd, H2T-A-302 Interconnection Croatia-Bosnia and Herzegovina (South), and for Slovenia: HYD-N-442 SLOP2G, OTH-N-1201 Reduction of transmission system methane emission, HYD-N-1237 Croatia-Slovenia-Austria H2 corridor and HYD-N-1356 Italy-Slovenia-Hungary H2 corridor. 
 

Timeline 
 

The project is expected to start in 2026 with the procurement and installation of new hydrogen enabled chromatographs and methane emissions control and monitoring, and reduction equipment. The replacement of old with new hydrogen enabled chromatographs will be carried out in the 2025-2028 period. Methane emissions control and monitoring equipment will be procured in 2026, while replacement of natural gas driven actuators with electrohydraulic actuators will be carried out in the 2026-2028 period. In the period 2026-2028 a comprehensive hydrogen readiness study will be carried out, where a detailed analysis of all gas pipelines and equipment planned to transport more than 10% of hydrogen will be conducted, and hydrogen recertification will be performed for them. In the period 2026-2028 a study, design and permitting phase for reconstruction of gas nodes and other advanced digital systems and components, control systems, sensor technologies, gas flow and quality management devices (compressors, gas flow control sets) will commence. In the period 2027-2028 an advanced integrated control and monitoring system (Integrated SCADA system) will be developed and tested, and gradually integrated into control elements (nodes and compressors during the Construction phase). 

The construction phase will start in 2030 and finish in 2034. The first volumes of hydrogen are expected to enter the gas network in the 2026-2028 period when chromatographs are replaced, while the whole smart gas grid project will be fully operational in 2035.