2. Global Stats & Facts Availability of fresh water supply for agricultural, industrial and domestic uses is reaching critical demands. 1.1 billion people around the world have no access to clean drinking water. The World Health Organization reports that contaminated water contributes to 80% of all sickness and disease worldwide.
5. Distillation Multi-Stage-Flash Distillation: The leading method The traditional process used in these operations is vacuum distillation-essentially the boiling of water at less than atmospheric pressure and temperature. Lesser energy requirement
7. Reverse Osmosis Reverse osmosis (RO) is a filtration method that removes many types of large molecules and ions from solutions by applying pressure to the solution when it is on one side of a permeable membrane. The result is that the solute is retained on the pressurized side of the membrane and the pure solvent is allowed to pass to the other side. Overview: Uses electricity rather than heat Proven technology
11. For a typical community level solar powered RO plant:
12. Solar Desalination Direct SolarDesalination Still Humidification-Dehumidification HD Single-effect Multi-effect The process is based on the use of solar thermal energy to evaporate water, thus separating pure water from brine. Direct Solar Desalination: Indirect Solar Desalination
13. Direct Solar DesalinationSingle-effect Stills Water production < 6 liters/m2,day Examples: Basin stills Wick stills Greenhouse integrated stills
23. Operational parameters Water Depth: Higher distillate output was observed with lower water depth. Preheating of Water Coloring of Water: The effect of dye on water output was also studied. The output got increased by colouring the water.
24. Multiple-effect basin stills have two or more compartments. The condensing surface of the lower compartment is the floor of the upper compartment. The heat given off by the condensing vapor provides energy to vaporize the feed water above. Efficiency is therefore greater than for a single-basin still typically being 35% or more but the cost and complexity are correspondingly higher.
25. Direct Solar Desalination Humidification - DehumidificationWater production1 - 20 litres/m2,dayHD with open-air cycle
32. Solar Air Conditioning Air conditioning is the control of the indoor environment by controlling the thermal characteristics mainly heating and cooling the air supplied to the room. Solar air conditioning refers to the use of solar energy to power a cooling appliance. Days that have the greatest need for cooling are also the very same days that offer the maximum possible solar energy gain.
33. There are several basic types of solar cooling technologies Absorption Cooling Desiccant Cooling Vapor Compression Cooling Photovoltaic Solar Cooling Evaporative Cooling
34. Absorption Cooling The basic principle behind solar-thermal driven cooling is the thermo chemical process of absorption of a liquid or a gaseous substance into a liquid or a solid material. Solar cooling uses the solar collectors to provide thermal energy to drive thermally driven coolers. The usefulness of a given absorbent - refrigerant pair is determined by the temperature dependence of vaporization and absorption process.
36. Desiccant Cooling Desiccant cooling is a new and clean technology which can be used to cool the inside air of the buildings without using any harmful refrigerants. Desiccant cooling systems are basically open cycle systems using water as a refrigerant in direct contact with air. Desiccants like silica gel or zeolite draw moisture from the air and they are regenerated by using solar thermal energy.
39. In a vapor compression cooling , the solar thermal energy is used to operate a Rankine cycle heat engine The solar power also converted to electricity can be used to run the air conditioning systems. Evaporative cooling is to spray water into dry air where the temperature is reduced by evaporation water into the air.
41. Conclusions Integrating desalination units with renewable energy sources is important for addressing the issues related to adverse impacts of climate change. Also, for remote areas, where scarcity of power and water co-exist, the one and only solution to produce safe drinking water is to go in for renewable energy sources. With improvement in PV efficiencies and the subsidies available, cost of PV systems is expected to come down, making the solar PV based desalination systems more cost-effective.
