Techno-economic optimisation of multi-sector coupled energy systems: A 1 GW electrolyser case study in Esbjerg, Denmark

This study evaluates the techno-economic performance of a multi-sector energy system coupling Power-to-X, district heating, and district cooling. A 1 GW electrolyser was coupled to the existing district heating system in Esbjerg, Denmark, through heat-recovery and cooling pathways that allocate excess heat between district heating and district cooling while maintaining the required thermal conditions. A techno-economic mixed-integer linear programming model was developed to optimise hourly operations, integrating merit-order dispatch and mass-flow dynamics. Three system configurations were assessed: a fully coupled Power-to-X, district heating, and district cooling system; a Power-to-X and district cooling system without district heating integration; and a reference district heating system. The results show that coupling Power-to-X, district heating, and district cooling creates cross-sector synergies between industrial hydrogen production and local energy system operations. The fully coupled system increased district heating performance factor by 7%, reducing annual heating costs by 15%. District cooling operating costs were reduced by 23%. The electrolyser’s excess heat generates 58 million DKK/yr in heat revenue, while district-heating pre-cooling avoids 21 million DKK/yr in cooling costs. This two-fold benefit improves Power-to-X operation and leads to 191 million DKK/yr in additional hydrogen sales.