Combined water and power production systems
Most large thermal desalination plants are combined with power production systems. This is usually due to the following:
Simultaneous increase of water & power requirements
Countries such as those of the Middle East are witnessing a fast growth in population which turn into increased demand in water and electricity. Building combined facilities to address both needs simultaneously make therefore much sense.
Valorisation of heat reject
Electrical power production systems have an efficiency ranging from 35 to 50%. This poor efficiency rate is the result of much heat - between half and two-third of the total heat generated - being rejected in the atmosphere in the form of low grade heat. Since thermal desalination systems can be driven by low grade heat, they can recover and give value to this rejected heat by producing fresh water downstream the power generation system. The overall energy cycle is optimised.
The combination of power and water production gives the best economical performance and is therefore widely used in the Middle East. Such projects known as Independent Water & Power Production (IWPP) projects are usually subject to large public tenders.