Comparison of Hydrogen-Based Power Plant Technologies with a Focus on District Heating in Germany

In Germany, district heating is predominantly based on combined heat and power plants (CHP). Conversion of gas turbines of existing plants to 100% hydrogen is currently under development. Outside Europe, there are fuel cell power plants in the megawatt range that operate with CHP. So far, this has mostly been considered with natural gas and subsequent reformation. In this paper, existing technologies are analyzed and then evaluated for the energy transition in Germany. In particular, the use of hydrogen in existing gas turbines is considered. In addition, a comparison to a theoretical fuel cell only power plant to the one with a gas turbine is performed. Subsequently, thermodynamic and electrical approaches are developed for the evaluated technologies and the hydrogen saving potential are analyzed. Overall, the savings potential of the gas turbine comes from the reduction in end temperatures, and a retrofit depends on the flexibility of the network. The fuel cell, on the other hand, gives more flexibility to the heating network, and the hydrogen savings potential depends on the cell.