Estimating the cost of desalination plants using a cost database

Adelaide is the capital city of South Australia, one of the driest states in the world. The city receives its potable water from a series of water catchments and the River Murray. Unfortunately, the current drought combined with other environmental factors is putting a strain on the River and its water quality is slowly degrading. A potential solution to Adelaide’s reliance on the River is desalination of various alternate water sources. The initial step in selecting the appropriate desalination technology is to perform and order of magnitude cost study. A simple technique for generating order of magnitude cost estimates is the development of a series of cost correlations based on a cost database. A cost database of 300+ desalination plants was collated. The cost database demonstrated that current large-scale desalination plants are capable of producing water in the range of $0.50–$2.00/m3, depending on plant size. Capital cost correlations as a function of plant capacity have been developed for large scale MSF, MED, SWRO and BWRO plants. Unit product cost (UPC) breakdowns were also developed for these technologies. Using the cost correlations and UPC breakdowns order of magnitude estimates were performed. For the case-study of metropolitan Adelaide, reverse osmosis (RO) is the cheapest technology for seawater desalination.

RO was found to be the cheapest technology for large scale sea water desalination. This is fol- Table 4 Summary of costs for different technologies for 4 different capacities Capacity (m3/d) SWRO BWRO MSF MED 10,000 50,000 275,000 500,000 10,000 50,000 275,000 500,000 10,000 50,000 275,000 500,000 10,000 50,000 275,000 500,000 lowed by MSF and MED. Using the correlations developed, the capital cost of a large scale RO plant is somewhere in the range of 500–1000 million dollars, depending on the size. Plants could potentially produce water in the range of $0.45– 0.55/m3. These cost correlations can be used for simple initial order of magnitude studies to help determine which technology is best suited to the situation at hand.