Towards sustainable seawater desalting in the Gulf area

Gulf countries experienced rapid growth in the last four decades from oil production and its price increase. Natural water resources are very limited to meet this growth, and as result, desalted seawater in Kuwait became the main source of potable water, about 93% in 2002. The electric power and desalted water, produced in co-generation power desalting plants (CPDP), consumptions are continuously increasing, almost doubled every 10 years, due to population and standard of living increases. This led to the consumption of huge amounts of fuel, draining the country main fuel (and income) resource, and negatively affecting the environment. One tenth of Kuwait's oil production was consumed by the CPDP in 2003. If the trend of almost doubling the consumption every 10 years prevails, the total oil production may not be sufficient to desalt seawater for people to drink, and to produce power to run space air conditioning units (a necessity for Kuwaiti harsh weather). It is essential therefore to look for energy efficient ways to produce power and desalted water so as to save the nation's income of these non-renewable fuel resources, to save the environment and indeed life itself in Kuwait, and this is the objective of this paper. It reviews the presently used desalting methods and their energy demand, and the correctness of fuel allocation formulas for CPDP, to determine the most efficient methods to apply and the less efficient ones to avoid. Fourteen desalting cases are analyzed by using the current practice, with and without combination with power generation plants (using steam or gas or combined gas/steam turbines cycles). The specific fuel energy consumed and the emitted CO2, SOx, and NOx per m3 desalted water were calculated for each case. The results show that operating thermally driven desalting systems by steam directly supplied from fuel-fired boilers is the most inefficient practice, and should be avoided. The use of the gas/steam turbine combined cycle, which is also the most efficient powergeneration cycle, to drive seawater reverse osmosis (SWRO) desalination plants is the most efficient combination. Also, all conservation measures in utilization of both water and power should be applied. Reclamation of waste water, at least for non-potable water needs must be promoted, because it consumes less energy and at cost much lower than those of desalting seawater.