Levelized cost of water assessment for small-scale desalination plant based on forward osmosis process

Availability and supply of fresh water is one of the most relevant challenges to be faced in the upcoming years. Efforts are being made worldwide to develop cost-effective and environmentally friendly technologies for the desalination of water. This work assesses the techno-economic performance of a forward osmosis desalination plant based on thermo-responsible polymers as a draw solute. Analysis of the plant performance for drinkable water production is carried out using a mathematical model for a small-scale application in Lipari (Sicily, Italy). Economic analysis was performed assuming that the thermal energy is provided by either a waste heat source or solar thermal collector, while electrical energy is supplied by either photovoltaic modules or from the grid. It was found that the lowest levelized cost of water of 2.68 euro/m3 was reached with a photovoltaic + waste heat configuration and with the highest transmembrane pressure (hence the minimum membrane surface area). This cost is higher than that achieved with a reverse osmosis desalination plant of similar capacity with electricity supplied by photovoltaic modules, equal to 1.65 euro/m3. As such forward osmosis technology must undergo sig-nificant improvements to become economically competitive.