Self-supporting power plant-capturing evaporated water and save energy- A new source of water

Abstract

One of the major challenges of this century is the provision of water for a growing population and industry. The shortage in water resources in arid areas requires the availability of more efficient and cheaper water production processes. In some arid regions water is even more important than electricity. A large source of water is found in the form of evaporated water emitted from different industrial processes. If for example 20% of the evaporated water from the flue gas stream of a coal fired power plant would be captured, the plant would be self-supporting from a process water point of view. This is about 30 m3 of water per hour. The results of the proof of principle project (2001-2008) show that >40% recovery can be achieved. Also an overall energy efficiency improvement can be achieved for industrial plants that reheat their flue gases. Calculations show that this can be about 1% overall efficiency for a coal fired power plant utilizing flue gas reheating. With an installed capacity of more than 600 GWe in China, this energy saving results in a very large economic and fuel (coal) impact. This energy efficiency will most likely be the driving force to implement the technology in both water rich and water poor regions. For the capture of evaporated water no chemicals are used, there is no waste water formed and corrosion attack in stacks is mitigated. These results have led to the set up of a large international project named CapWa which aims to produce a membrane modular system suitable for industrial applications within 2-3 years. The produced demin water from this system should be competitive with existing demin water technologies. The starting point will be the water vapour selective composite membranes that are developed in the proof of principle project. The CapWa project started in 2010 and consists of 14 partners of which 9 from the EU, 3 from the African continent and 2 from the Middle East. © Tsinghua University Press, Beijing and Springer-Verlag Berlin Heidelberg 2012.