A very large dew and rain ridge collector in the Kutch area (Gujarat, India)

The world’s largest dew and rain collecting system, comprised of ridge-and-trough modules, was constructed in March 2006 at Panandhro in the semi-arid area of Kutch (NW India). The main goals were (i) to collect dew on a scale that could be beneficial to the local population (ii) to determine the efficiency of this new module shape, (iii) to determine whether results obtained from small measurement condensers can be projected to large condensers, (iv) to apply a computational fluid dynamic simulation to improve the condenser set-up. Preliminary studies performed with four standard plane condensers of 1 m2 surface area, inclined 30° from horizontal, identified Panandhro as a promising site. The cumulated dew water during 192 days was 12.6 mm with a maximum of 0.556 mm/night. A large dew condenser (850 m2 net total surface) was designed with 10 ridge-and-trough modules. The ridges are trapezoidal, 33 m long, 0.5 m wide at the top, 2.2 m wide at the base and sloping 30° from horizontal. The depth of the troughs between the ridges is 0.5 m. A 2.5 cm thick polystyrene foam rests on the surface as insulation with a radiative foil on top (similar to that developed by OPUR, see ).