AWWA ACE58250

AWWA ACE58250 Development of a Spreadsheet Tool for Brackish and Reclaimed Water Membrane Desalination Costs
Conference Proceeding by American Water Works Association, 06/15/2003

Kumar, Manish; Adham, Samer; Pearce, William H.

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This paper presents the methodologies used in the development of this unique cost modelthat is based on existing and/or planned membrane desalination plants. Data has beencollected from existing and planned treatment plants and normalized to prepare curves forcapital and operating costs. Three water sources have been considered for this projectincluding: reclaimed water, and brackish groundwater. The use of existing costsprovides a connection to reality with regard to costs as competitive bidding has causedthe market prices to be disconnected from theoretical prices in recent years. This modelincorporates special membrane cost curves for low pressure and high pressuremembranes to normalize membrane costs from different sources to provide specific costsbased on market data. In addition, the information gathered provides useful informationwith regard to the trend in historical market costs and development in productivity formembranes.The capital cost curves are based on widely used indices like the ENR -ConstructionCost Index, Marshall and Swift Equipment Cost Index and on specially developedmembrane indices which could be used to update the costs so that the model remainscurrent well into the future.Operating costs present a challenge for cost models because of volatile cost componentslike power costs and sometimes, chemical costs. As a part of normalization ofoperational cost data obtained from existing and planned treatment plants, a sliding scaleof costs based on user input was found appropriate. This sliding scale is based on userinputs for chemical costs and power costs and will generate new curves every time theseinputs are changed to provide "realtime" operational costs for the specific project, basedon capacity. Another feature of the model is that it uses a separate curve for power costsas power is the most volatile component of the total cost and does not scale up similar tothe other operational cost components. An option is being built into the model to usechemical cost indices instead of local costs for future use. Includes tables, figures, appendices.