Feasibility of Integrating Solar Desalination with Greenhouse Systems in Semi-Arid Region of North-west India

A two-phase project is underway to develop greenhouse systems suitable for water scarce, semi-arid region of north-west India (Kutch). The first phase aimed at studying the effectiveness of natural ventilation and earth-tube-heat-exchanger for environmental control, in place of fan-pads commonly used. These measures were able to reduce the need for evaporative cooling significantly and offer scope for further improvement. The second phase, just started, aims at finding cost-effective means of desalinating brackish water for plant use. Arrays of simple basin type solar stills have been used in this region in the past to provide drinking water in villages. The area of stills needed to meet the greenhouse crop requirement works out to approximately half the cropping area. It would be cumbersome to integrate these with greenhouse structure. Besides, these were reported to be difficult to maintain. A new option - solar assisted low temperature thermal desalination - is therefore being pursued. An outline of the work in progress is presented. [W.P. No. 2008-07-02]