Page - 74 - in Clean Water Using Solar and Wind - Outside the Power Grid

74 Clean Water Using Solar and Wind: Outside the Power Grid conventional systems in remote regions where the cost of energy transmission and distribution is higher than the cost of off-grid generation. Desalination based on renewable energy is mostly based on the RO process, followed by the thermal MSF process. In existing applications solar PV is the energy source for almost half of the installed capacity, followed by solar thermal and wind. The best combination of renewable energy source and desalination technology will depend on the geographical location, the salinity of the water, the available renewable energy source and plant size. Of course, the requirements to pump and to pre-treat the feedwater are other factors to consider. The cost for the solar cells is still the largest part of the cost, but batteries for electricity storage should also be considered (see Chapter 10). The batteries need maintenance. Any advances in storage capacity will have a profound impact on solar PV operations. On the other hand, the “fuel” is free, so the renewables will pay off with time, in contrast to diesel or grid electric power. Solar energy is the most readily applicable source of renewable energy to be integrated with desalination technology. It can produce the heat and electricity required by all desalination processes. Worldwide, various renewable energy sources are used for desalination, as illustrated in Figure 5.2. 43 27 20 10 0 10 20 30 40 50 Solar electrical energy Solar thermal energy Wind energy Other Figure 5.2 Renewable energy sources for desalination worldwide (in %). Data from Alkaisi et al. (2017). Solar PV powered reverse osmosis has been proven commercially viable with significant reduction in production cost. One example is from  Abu Dhabi. The levelised cost of large-scale desalination Downloaded from https://iwaponline.com/ebooks/book-pdf/520710/wio9781780409443.pdf by IWA Publishing user