Simultaneous Clean Water and Power Production from Seawater Using Osmosis: Process Simulation and Techno-economic Analysis

Abstract

In this work, process simulation and cost analysis of an osmotic-driven process for simultaneous clean water and power generation from seawater using the concept of solute-gradient method are developed, with the aim of determining its potential application at the industrial scale. The simulations were carried out by Aspen Plus® software, considering a plant size corresponding to 1 MW power generation, using ethanol–water as the draw solution. Different draw solution regeneration techniques are investigated with the aim of minimizing the thermal requirements while respecting the threshold purity of the extracted water. It is shown that, by optimizing the inlet draw solution flow rate and concentration, power densities of about 5 W/m2 can be obtained using hollow fine fiber membrane, with a projected cost of electricity around 152 €/MWh. Economic analysis, based on Saudi Arabia water cost, shows that the process profitability is strongly affected by the water selling price, which needs to be at least 1.7 €/m3 in order to have the cumulative cash position equal to zero at the end of the plant lifetime (25 years). Nevertheless, it is suggested that both water and power could be industrially produced in a profitable way (DPBP less than 5 years) with a drinking water selling price equal to 2 €/m3, which is about 30% higher than the current value yet a realistic one in the near future.