Economic analysis of desalination techno

The economics of membrane distillation (MD) and common seawater desalination methods including multi-effect distillation (MED), multistage flash (MSF) and reverse osmosis (RO) are compared. MD has the lowest cost of the desalination technologies considered and is particularly well suited to the recovery of waste heat. We demonstrated that by concentrating RO brine to 361,000 mg/L total dissolved solids, an order of magnitude more saline than typical seawater, validating this potential. On a reference 30,000 m3/day plant, MD has similar economics with other thermal desalination techniques, but RO is more cost effective. With the inclusion of a carbon tax of $23 per tonne carbon in Australia, RO remained in the economically favorable process. However, when heat comes at a cost equivalent of 10% of the value of the steam headed for MD and MED, under a carbon tax regime, the cost of MD reduces to $0.67/m3 which is cheaper than RO and MED. The way to MD was to lower thermal cost. On how multi, highly electrically efficient installations can desalinate water from low temperature (<50 °C) heat sources at a cost of 505.7/m3 our advances may render it financially more competitive, particularly where it is available at low cost, while extended recovery of RO brine is also viable.