It's not very efficient. The storage of electricity is expensive and energy is also lost during conversion. But Delft University of Technology (TU Delft) thinks the traditional windmill driving a pump directly can be more efficient and cheaper.
In the TU Delft installation, the high-pressure pump is driven directly by wind power. Water storage can be used to overcome calm periods. Plus, storing water is cheaper than storing electricity.
The high-pressure pump which pushes water through a membrane using approximately 60 bar. This reverse osmosis membrane produces fresh water from seawater directly. The windmill is suited for use by, for instance, small villages in isolated, dry coastal areas.
The chosen windmill is normally used for irrigation purposes. These windmills turn relatively slowly and are also very robust. On the basis of the windmill’s capacity at varying wind speeds, it is estimated that it will produce 5 to 10 m3 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) are also performed mechanically so that no electricity is needed.
The first prototype has been built and is already working at a location near the A13 motorway near Delft. This prototype is to be dismantled and transported to Curaçao the first week of March. There the concept will be tested on seawater.