Desalination
Desalination
Three technologies (biochar, biogas, biorefineries) can be stationary or mobile, opening new opportunities for dissemination and cooperative business models. Selected bio-based solutions include restorative and diverse crop production systems, integrated mobile biorefineries, adapted biochar and biogas processes to valorise a wide range of farming residues, the highly innovative clay-based micro-irrigation system “SLECI”, vegetation-enhanced solar desalination greenhouses and multifunctional constructed wetlands.
Solar desalination greenhouse for utilisation of saline and low-grade water: ALCN, IPT and NUST will develop evaporation greenhouses based on the principle of solar desalination stills. Saltwater is evaporated through open surfaces, and the evaporation increased by cultivating halophytic (salt-tolerant) plants in the desalination (evaporation) greenhouse. Either a standalone unit produces freshwater for open fields, or an existing conventional greenhouse is retrofitted with a desalination compartment (DIVAGRI ‘retrofit kit’).
DIVAGRI tests passive surface cooling mechanisms to condensate the evaporated water, e.g. low-quality water (e.g. saline groundwater) or seawater, roof cooling mechanisms such as materials, greening of roofs (xerophytes) and shaded/underground area. Locally available waste components, e.g. car-coolers or metal sheets will be used. The combined cooling and humidification with the injection of CO2 derived from the biorefinery creates optimal growing conditions inside the greenhouse, which could reduce water losses from evapotranspiration by 90% and increase yields by 10-30%. DIVAGRI also investigates cost-efficiencies of the trade-offs between surface area and energy requirement, and design considerations related to local production/assembly and O&M (operation and maintenance).