Page - 168 - in Clean Water Using Solar and Wind - Outside the Power Grid

168 Clean Water Using Solar and Wind: Outside the Power Grid eight hours of operation in the summer and six hours in the winter. Some of the system characteristics are: Solar panels Total capacity = 4.8 kWp 64 modules of 75 Wp each Battery storage 19 kWh Well pump Max altitude above the sea = 3 m Capacity = 1 kW Max flow rate = 2.5 m3/hour; pressure = 3 bar High-pressure pump for RO Capacity = 2.2 kW Max flow rate = 1.5 m3/hour; pressure = 60 bar Effluent salinity <500 mg/l The authors describe an interesting aspect of the operation to protect the membranes. When the plant is shut down at the end of every day there is a flushing process, using produced water, to keep the membranes clean. The membranes are submerged in low-salinity water, preventing deterioration due to their intermittent operation (see 10.1.3; Lienhard et al., 2016). Example 14.5: Solar Heating for Desalination, California In the California Central Valley, the Panoche Water District is using a solar thermal system for desalination (Lavelle, 2015). The solar energy is not used to produce electricity. Instead, parabolic trough mirrors turn the solar radiation directly into heat to distil salty water. Example 14.6: India India has a highly seasonal pattern of rainfall, with 50% of precipitation falling in just two weeks. The Central Water Commission estimates that the total annual rainfall in the country is 4,000 billion (4 ⋅ 1012) m3. The utilisable or internally renewable water resources are estimated to be 1,200 billion m3. The annual water demand is increasing: it was around 800 billion m3 in 2010 and is estimated to approach 1,500 billion m3 in 2050. This will not be sustainable, and many regions will face severe water shortage. Furthermore, the impact of climate change will lead to variation in rainfall patterns Downloaded from https://iwaponline.com/ebooks/book-pdf/520710/wio9781780409443.pdf by IWA Publishing user