Solar desalination technology to supply water for agricultural applications

Agriculture represents nearly 70% of global water withdrawals and also contributes to considerable water pollution mainly caused by excess utilization of fertilizers, pesticides, and other pollutants. Urbanization and increased living standards along with contamination of water resources and climate change have all resulted in the current world’s water scarcity. Given such circumstances, seeking noncompeting water resources for agriculture has increasingly become a focus of global attention. In 2021, about 20% of total irrigated lands, contributing to one-third of global food production, are salt-affected while almost 4.4% of the world’s agricultural lands are annually degraded due to salt accumulation mainly because of irrigation with low-quality water. In many regions around the world, saltwater is the only available water resource for irrigation which can adversely affect crop growth and yield. To solve this problem, desalination can be considered as a solution to provide a steady alternative source for irrigation water, especially in arid and semiarid regions suffering severe freshwater shortages. The use of fossil fuel-based desalination plants operating to supply water for agriculture is no longer sustainable due to the depletion risk of fossil fuels and the emission of hazardous air pollutants. Solar energy is the most compatible renewable energy source that can be integrated with desalination plants especially in locations that enjoy high availability of solar radiation. In this chapter, the use of solar-powered desalination technologies to supply water for agricultural applications is presented with the highest focus on irrigation purposes, considering their technical, economic, and environmental aspects. Moreover, the relevant benefits and challenges associated with solar desalination technologies in agriculture are explored and commercial solar desalination projects implemented around the world are introduced and discussed.