The climate crisis has sped up the energy transition, which is nowadays a global problem. Achieving a more sustainable energy mix is a challenge from both technical and economic point of view. Hydrogen may represent a viable solution for the decarbonisation, but the real challenge is its integration into the energy systems. In this work, a real industrial case study is analysed: a semiconductor production plant that uses hydrogen as a gas carrier. The factory energy demand is covered by the on-site cogeneration plant that is fuelled with NG from the grid and generates heat and electricity. The system is made of three ICEs, two with a nominal power of 3.180 kW and one of 2.682 kW that burn 11,4 ktons of NG per year releasing 30,3 ktons of CO2.