Optimization of the integrated power and desalination plant with algal cultivation system compromising the energy-water-environment nexus

Abstract This article examines the exhaust waste heat recovery potential of a microturbine (MT) for seawater desalination using an organic Rankine cycle (ORC). Waste heat from microturbine is exploited using organic Rankine cycle (ORC) and the power generated is delivered to the reverse osmosis (RO) plant. The brine of the reverse osmosis plant is sent to a membrane distillation (MD) plant for further treatment after preheating using the excess heat from the turbine. Also, biological capture of CO2 through cultivation of microalgae has been considered by using flue gases from the microturbine. Plant integration is performed on the basis of the energy-water-environment nexus concept. In this regard, a multi-objective optimization approach is implemented in this work considering economic and environmental points of views. The first objective function is to maximize the annual profit of the system. The second objective function is an environmental index which is defined as the CO2 emission per desalinated water production. Minimization of this index is considered as the second objective function. The results showed that the proposed integrated ORC-RO-MD-CO2 capture plant can considerably improve the system both economically and environmentally.