4E analysis of a new multi-generation geothermal system based on Allam cycle for providing energy demand of a sample residential building

The increasing energy demand, the reduction of non-renewable resources, and the increase in environmental damage factors have drawn attention to energy supply through multi-generation systems. This study proposes a multi-generation system based on the Allam cycle, integrated with geothermal energy, with the aim of minimizing natural gas fuel consumption. This system includes the main sub-systems: an electrolyzer unit, a reverse osmosis unit, an organic Rankine cycle, a hydrogen engine, an absorption chiller, and a compression chiller. The proposed multi-generation system provides the hourly demands of freshwater, cooling, heating and electricity of a residential building located in the city of St. Petersburg (in Russia). For the purpose of feasibility, the system is studied from the thermodynamic, environmental, and economic points of view. The results of the thermodynamic analysis showed that the system has maximum energy and exergy efficiency of 29.759 and 25.879% respectively. The use of geothermal energy reduced CO₂ emissions to a maximum of 1895043 gr. Calculation of the NPV index for interest rates of 15 to 30% showed that this system will be profitable in the twelfth year at most.