A novel cascade heat design for a geothermal energy-based combined power plant in integration with water electrolysis and ammonia synthesis processes: Comprehensive thermo-environ-economic analyses

Abstract

The present paper introduces an innovative integrated system for simultaneous cooling, heating, power, and ammonia production utilizing geothermal energy. The novel configuration incorporates a geothermal-based single-flash power plant, a modified Kalina cycle, an organic Rankine cycle, an electrochemical unit, and an ammonia synthesis process. The Kalian cycle has undergone modifications aimed at enhancing its production capacity, while the electrochemical unit provides hydrogen for the ammonia synthesis process. The research encompasses a thorough assessment of the proposed system's potential with regard to thermodynamic, environmental impact, and economic considerations. Additionally, a parametric assessment is conducted using the flash pressure of the geothermal fluid and the proportion of unreacted gases to the ammonia synthesis reactor in order to analyze the performance variables of the system. The proposed system demonstrates a power generation capacity of 15513.18 kW, a heating load of 24880 kW, a cooling load of 11540 kW, and an ammonia production capacity of 0.282 kg/s. Moreover, the process exhibits irreversibility with a total value of 16977 kW. Consequently, the energy and exergy efficiencies amount to 34.55% and 57.17%, correspondingly. Besides, geothermal energy offers environmental benefits, as its non-polluting nature results in reduced CO2 emissions in comparison to biomass, coal-based, and hybrid energy systems. Eventually, the economic analysis demonstrates that the total cost rate and sum unit cost of products are 825 $/h and 9.57 $/GJ, respectively.