Proposal and thermo-economic analysis of a novel multi-generation system producing heating, power and clean water under energetically self-sufficient operation

In this work, by using the energy released during the supercritical water oxidation process (SCWO) as the heat source, a cogeneration system producing heating, power and clean water is proposed. The system is modeled, and the performances under energetically self-sufficient operation are simulated. For the proposed system, parametric sensitivity analysis is first performed. Then the system is evaluated from exergy and economic aspects. The results show that under the given working condition, the proposed system can produce 1832.2 kW of heat and 245.2 kW of power simultaneously. The proposed system is a “heat dominant” system, for a larger part of the energy is utilized as heat, with the thermal efficiency reaching 85.9%. The exergy efficiency of the system reaches 40.1%. The total investment cost is 9053.0 k$. The equipment cost of turbines is 5703.5 k$, which accounts for 60% of the total investment cost. The electricity revenue of the system is 252.21 k$. The heat revenue is 867.94 k$. The clean water revenue is 31.73 k$. The obtained net annual income is 1124.78 k$. The dynamic payback period (DPP) is 12.31 years. While the simple payback period (SPP) is 9.03 years. This study may contribute to provide data support and theoretical basis for using the energy contained in organic wastewater.