Design of PVT driven forward osmosis and membrane distillation pilot plant for co-production of water and electricity

Abstract

Desalination by photovoltaic thermal (PVT)-driven forward osmosis (FO) and membrane distillation (MD) stands out for its lower operational costs and reduced carbon emissions. However, the feasibility of a pilot-scale PVT-driven FO–MD system remains unexplored, which is crucial for industrialization. This study introduces a pilot PVT-FO–MD desalination system designed for simultaneous water and electricity production. The system aims to assess the feasibility of the process, evaluate its costs, and explore its potential for industrial applications. While PVT collectors have higher costs than standard PV panels, they offer improved electrical efficiency and additional thermal power generation, making them more efficient overall. The optimal design was tested using saline water with a concentration of 10 000 mg per liter and a NaCl draw solute with a concentration of 1 molarity. The system produces 172.1 kW h of thermal energy, 93.9 kW h of electrical energy, and 269 L of water daily. The FO water flux varies between 8.13 and 8.29 LMH, while the MD water flux fluctuates between 2.72 and 4.25 LMH throughout the year. Using average yearly weather data, the system produces 33 872 kW h of electrical energy, 65 846 kW h of thermal energy, and 106.84 m³ of water annually. Increasing the desalination unit size boosts average water production to 126.47 m³ annually. The project requires an initial capital investment of 212 741.38 USD. The return on investment is 11.84%, with a breakeven point at nine years. The net present value turns positive just before the end of the project's lifetime at a 10% interest rate. Although this type of system has not yet been commercialized, further studies are recommended to enhance its market competitiveness.