On the water frontDesalinated water poses problem for agriculture

We have written about the convergence of two interests — in desalination of sea water and in nuclear power. Several countries have launched, or are planning to launch, large desalination projects powered by nuclear power. The most recent entrants are Libya and Egypt. It is not by accident that the dry desert countries of the Middle East and North Africa would be interested in desalination as a solution for their increasingly severe water shortages. Take Saudi Arabia: The Kingdom is now the world’s largest producer of desalinated water. The country’s twenty-seven desalination plants provide drinking water to major urban and industrial centers through a network of water pipes running for more than 2,300 miles. Desalination meets 70 percent of the Kingdom’s drinking water requirement. The state-run Saline Water Conversion Corporation (SWCC) has its work cut out for it: The Saudi Central Department of Statistics says that the Kingdom’s population will exceed 29 million by 2010 and rise to 36.4 million ten years later. Taking a baseline consumption of 300 litres per person per day, the resulting demand for water will increase to over 3,000 million m³/year by 2010 and nearly 4,000 million m³/year by 2020. The interest in using nuclear power to power desalination plants is the result of growing concerns about global warming: Desalination plants are exceedingly power hungry, and unless an alternative is found for fossil fuels now used to power them, there will be an inevitable collision between the cause of desalination and the cause of cleaner environment.

This collision had better be avoided. Nearly half of humanity is suffering insufficient access to potable water, and water scarcity for agriculture is regarded as a global crisis. Many point to the desalination of seawater as a feasible solution. Indeed, between 1994 and 2004 world desalination capacity increased from 17.3 to 35.6 million m³/day, and currently seawater desalination provides 1 percent of the world’s drinking water. Four researchers write in the recent issue of Science that desalinized water is increasingly considered a source of water for agriculture as well. With 69 percent of the global water supply going to irrigation, present freshwater resources may soon be insufficient to meet the growing demand for food. A recent report concludes that, although the costs of desalination remain prohibitively expensive for full use by irrigated agriculture, for high-value cash crops like greenhouse vegetables and flowers, its use may be economically feasible. In a few