A new case for promoting wastewater reuse in Saudi Arabia: bringing energy into the water equation.

Saudi Arabia is the third-largest per capita water user worldwide and has addressed the disparity between its renewable water resources and domestic demand primarily through desalination and the abstraction of non-renewable groundwater. This study evaluates the potential costs of this approach in the industrial and municipal sectors, exploring economic, energy, and environmental costs (including CO2 emissions and possible coastal impacts). Although the energy intensity of desalination is a global concern, it is particularly urgent to rethink water supply options in Saudi Arabia because the entirety of its natural gas production is consumed domestically, primarily in petrochemical and desalination plants. This burgeoning demand is necessitating the development of more expensive high-sulfur gas resources that could make desalination even pricier. The evolving necessity to conserve non-renewable water and energy resources and mitigate GHG emissions in the region also requires policy makers to weigh in much more considerably the energy and environmental costs of desalination. This paper suggests that in Saudi Arabia, the implementation of increased water conservation and reuse across the oil and natural gas sectors could conserve up to 29% of total industrial water withdrawals at costs recovered over 0-30 years, depending on the specific improvement. This work also indicates that increasing wastewater treatment and reuse in six high-altitude inland cities could save a further $225 million (2009 dollars) and conserve 2% of Saudi Arabia's annual electricity consumption. By these estimates, some anticipated investments in desalination projects could be deferred by improving water efficiency in industry and prioritizing investment in sewage and water distribution networks that would ensure more effective water reclamation and reuse. Simultaneously, such initiatives would conserve non-renewable natural gas resources and could help prevent the lock-in of potentially unnecessary desalination infrastructure that is likely to become more energy and cost efficient in future.