Safe drinking water shortage in the world has necessitated research and development in the sea and brackish water desalination based on renewable energies. In the recent years, the interest in the use of reverse osmosis membrane desalination has increased due to the energy efficiency and versatility of this process relative to other water desalination technologies. When operating the reverse osmosis desalination unit it is imperative that system conditions are monitored and maintained at appropriate set points in order to produce the required amount of clean, portable water while preventing system damage.
Solar RO initially is most cost-competitive for small-scale systems where other technologies are less competitive. In RO filtration process salty water is pressurized to flow through a membrane, causing a separation of the saline solution from the solute. The energy required to pressurize the feed water is the major energy needed for the RO process. Reverse Osmosis is a scalable process, but the energy efficiency decreases on small-scale systems. Different control algorithms can be utilized to improve the efficiency and feasibility of PV-RO systems.
SOLAR RO system consists of power generation unit and desalination unit. Electricity needed by the system will be supplied by the Solar PV array, Since the RO unit needs a stable power supply, and batteries will be connected for supplying stable power. The energy produced by the PV is stored in battery Bank. The stored energy is used for powering the loads. RO desalination process consists of high pressure pump, membrane unit and pressure control valve at the brine side.
The solution is pressed by pump against the membrane, water molecules passes through the membrane reducing the concentration of the solute known as permeate and the rest of the water with high salt concentration is rejected as a waste known as brine. The valve at the brine side is used to control the amount of discharged brine and to control the system pressure.
LARGEST SOLAR RUN RO
Cairn India under a Memorandum of Understanding (MoU) with Public Health and Engineering Department (PHED) of Rajasthan is establishing clean water plants across Barmer District.
The first plant based on this pioneering initiative and India’s largest solar operated community based RO Plant, has been installed at Sewniwala in Baytu Tehsil. The solar plant will generate a power of 5KW and store the same in batteries, which can be used for 8-10 hours of plant operations. The water from this plant will be sold at 25 paise per litre to the local community. Barmer has abundant sunlight availability throughout the year. To maximize use of this renewable source of energy, Cairn India and Fontus Water will be operating some of the water purification plants using solar energy. This installation has put Sewniwala on world map and will help in improving various health issues of the local people by providing purified drinking water at their door step.
This is an innovative example of sustainable solutions in community development, where environmentally-friendly green solutions are being used to serve the poorest population with safe drinking water.