Windmill, combining reverse osmosis technology with traditional windmill capabilities, is tested for seawater desalination.

A traditional windmill that drives a pump: This is the simple concept behind the combination of windmill/reverse osmosis developed by the Delft University of Technology (TU Delft) in The Netherlands. In this case, it involves a high-pressure pump that pushes water through a membrane using approximately 60 bar. The reverse osmosis membrane produces fresh water from seawater directly. The windmill is suited for use, for instance, by small villages in isolated, dry coastal areas.

The combination of windmills and desalination installations already is commercially available. These windmills produce electricity from wind power; the electricity is stored and subsequently used to drive the high-pressure pump for the reverse osmosis installation. The storage of electricity in particular is very expensive. Energy also is lost during conversion.

In the TU Delft installation, the high-pressure pump is driven directly by wind power. Water storage can be used to overcome calm periods. The chosen windmill normally is used for irrigation purposes. These windmills turn relatively slowly, and also are designed to be very robust. On the basis of the windmill’s capacity at varying wind speeds, it is estimated that it will produce 1,320 gallons to more than 2,640 gallons of fresh water per day: enough drinking water for a small village of 500 inhabitants. A water reservoir will have to ensure that enough water is available for a calm period lasting up to five days. Three safeguards – in the event of the installation running dry, a low number of revolutions or a high number of revolutions – also are performed mechanically so that no electricity is needed.

The first prototype has been built, and already is working at a location near Delft. This prototype is to be dismantled and transported to Curaçao in early March, where the concept will be tested on seawater.