Two demonstration projects are presently under performance at the GKSS-research center in cooperation with AEG-TELEFUNKEN and DIGAASES, Mexico using wind and solar power for the energy supply of reverse osmosis desalination units. The main objective of these projects are the operation of two prototype plants to demonstrate the reliability and the low maintenance requirements for these plants, when they are located in remote areas with insufficient infrastructure. The engineering design, the site conditions and the provided operation mode of two RO-desalination plants with the GKSS plate module system supplied by a 6 kW wind energy converter and a 2,5 kW solar generator respectively are described below. © 1979.