A key cost that is seldom estimated during evaluation of various technologies in seawater reverse osmosis (SWRO) projects is the cost of downtime, both planned and unplanned. This paper will prove that these downtime costs are significant to both the investors and the operators of the plant. Therefore, plant availability must be a primary factor to be considered in the design phase. Plant availability is even more critical in evaluating the energy recovery technologies as they can cripple production if they break down often and require high maintenance.

Energy recovery devices (ERD) cost less than 2% of initial capital costs but could cost twice that due to lost margin and capital costs. Due to large initial capital expenses, long project life, and criticality of water for end-users, every component should be designed for longevity and robustness along with highest performance. As many plant operators have to pay for liquidated damages when missing the minimum production requirements, it is imperative that the plant is designed for the highest availability possible.

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