Advanced MED solar desalination plants. Configurations, costs, future — seven years of experience at the Plataforma Solar de Almeria (Spain)

Among the several options to connect a seawater desalination system with a solar power plant the combination of a thermal desalination system such as a MED and a solar trough field as the heat source is one of the most promising. From 1988 until 1994, the Plataforma Solar de Almeria developed a unique experience in the desalination of sea water with solar energy. The system developed and still running, has a production capacity of 72 m 3/d. The project was carried out in two phases. During phase I of the project a solar desalination system composed of a 14-effect MED plant hooked up to a field of solar parabolic trough collectors was implemented and evaluated. This system showed a high reliability. Some potential improvements (i.e. coupling of a double-effect absorption heat pump and implementation of a steam ejector based vacuum system) were implemented and evaluated during phase II of the project and a cost analysis was performed. The cost analysis showed that implementation of an absorption heat pump considerably reduces costs: a total cost of about $2 per m 3 of distillate could be obtained for large plants. The technical feasibility of absorption heat pumps for seawater desalination processes was proven in this project. Due to cost reduction and further improvements of the equipment it seems to be likely that costs can be decreased in the near future. The next step towards cost reduction and market introduction of solar desalination systems will be the installation of a large scale demonstration plant under real operating conditions.