Ultrapermeable Membranes for Batch Desalination: Maximum Desalination Energy Efficiency, and Cost Analysis

Reducing the energy consumption of membrane desalination is critical to reducing its cost of water and minimizing desalination’s CO2 emissions. Hybrids of reverse osmosis (RO) with ultrapermeable membranes promise to address the efficiency, rejection, and fouling issues. In a batch reverse osmosis (BRO) process, salinity is varied over time so that the applied pressure better matches osmotic pressure, increasing efficiency. In this paper, the impact of ultrapermeable membranes in BRO are modelled, and a cost analysis is performed. The results show energetic advantages for the BRO over the best continuous RO configurations. Batch RO systems offer significant cost savings, and saves more energy than the use of ultrapermeable membranes in continuous RO systems. The two combined, BRO and ultrapermeable membranes, has the potential for the most efficient desalination systems yet proposed. However, low membrane cost is needed for ultrapermeable membranes to be viable.