Use of Coal in Areas of Water Shortage
AUTHOR: Gordon Couch
DATE: December 2005
Water is one of the most basic necessities associated with human existence. It is needed to sustain agriculture and food production, as well as underpinning energy distribution in the form of electricity. The world's population is increasing, and the per capita use of water is also growing with changing and improving lifestyles. Together with changes in its distribution due to climatic variations, the consequence is that water is becoming scarcer, and its effective price/value higher.
Regulation and management vary greatly in different parts of the world. Large amounts of water are needed for power generation, mainly for cooling the exhaust steam from the turbine, although it is also needed for the steam used in the boiler and turbine; for some flue gas cleaning processes and for ash handling. Water is also used for coal preparation, while mining operations often give rise to substantial quantities of acid mine drainage which requires treatment. The world's major coal producers, including China, India, South Africa and the USA are all expected to be subject to increasing competition for the available water. The situation in each country is discussed - in the context of the projected growth in worldwide coal-fired power capacity from 1400 GWe to some 2300 GWe by 2030.
Recent developments have brought about a much better understanding of the role of the plant chemist or water engineer in connection with power plant operation. Water chemistry plays a key role in determining the cost of the necessary treatments. Technical advances with the membranes used for reverse osmosis have contributed to the availability of new options. The water managers job is to facilitate water recycle and the use of low grade waters, providing adequate and economic treatment to prevent deposition and corrosion in the equipment where it is used. Various approaches to reducing water use and to treating lower grade waters to facilitate reuse are discussed. Case studies are presented where minewaters are used for supplying power plants, and of sites which have been required to implement a zero discharge policy.