Water Desalination: When and Where Will It Make Sense?

The earth is called "the blue planet". The reason is that about 71% of the earth surface is covered by water. Humans consist of about 60% water, some animals up to 70% and some plants even up to 95%. How can water shortage appear if 71% of the earth surface consists of water? The problem is that more than 97% of global water resources are "salty water" meaning that the salt content of the water is too high for drinking and also for irrigation. About 70% out of the remaining 3% of fresh water are stored in the ice of the polar caps. Another share is stored in deep ground water resources which are inaccessible. Finally only about 0.3% of global water resources are available from rivers, lakes or accessible ground water resources. The exponential growth of world population can be found mainly in the dry regions of the world (Africa, India) which leads to a shoot up of food demand causing an additional intensive stress on already short water resources. In many of those regions the groundwater level is dropping down by several meters every year leading to complete shortfalls or high salt intrusions making the water inconsumable. The fast growth of industrialization particular in some parts of Asia leads to a high pollution of rivers and the aquifer due to none sustainable use of the available resources. According to predictions for the year 2025 large parts of Africa and central Asia will be affected strongly by water shortage. It is expected that out of 7.2 billion people living 2025 in the world, 3 billion people (40%) will be strongly affected by water shortage. But even today the shortage of clean potable water is already a significant problem in several regions of the world and the reason for conflicts and war. An option to create new fresh water resources is the utilization of sea water by desalination, which can be considered as inexhaustible source. Particular in the Gulf region some countries do not have any natural fresh water resources but cover 100% of their demand by desalination of sea water. Also countries in southern Europe as Spain must supply part of their water by processing water from the sea. Today about 50mio m³ of fresh water are produced world wide by desalination daily and the number of new installed capacities is rising rapidly. The main draw back of desalination is the very high energy demand. The presentation will provide further information about the development of the desalination market. Different desalination technologies will be introduced and their technical boundaries will be explained. Furthermore some ideas and current trends regarding the employment of renewable energies for desalination will be discussed.