Many islands in the Caribbean depend on seawater as the only source for producing drinking water . As a result of a growing tourist industry, the need for desalination capacity is steadily growing. However, the cost of seawater desalination is high . Optimizing and planning of seawater desalination capacity can reduce total costs for drinking water . Studies have been conducted for Aruba, Bonaire and Curacao . Co-generation systems for the combined production of electricity and water are in use on these islands . It is shown that the optimum size of evaporation (MSF, MED or VC) desalination units can be calculated in relation to the maximum required production capacity and storage capacity . Once the optimum combination of unit size and storage capacity is known, planning of extensions in production capacity can be calculated based on the forecast of water demand, available storage capacity and maintenance or breakdown periods .
There is no optimum unit size for reverse osmosis (RO), the alternative desalination process . Because of its modular concept, extension with RO can be planned in any desired capacity . R O is shown to be a more economical system compared to evaporation desalination . Future extensions by RO therefore will further reduce costs for seawater desalination . The lowtemperature MED process is shown to be economic in comparison with both MSF and RO in case of high energy costs and/or long expected lifetimes and a low rate of interest .