Cheemeni Gas Power Plant – The Myth about Water Use

 

The go-ahead for the proposed 1100-1200 MW gas based power plant at Cheemeni in Kasaragod has brought a ray of light to Kerala’s rather dark power situation. The need for the development of a new power infrastructure in the state is obvious as the demand for power has consistently outstripped supply since 2010-11. Keralites have been living with power cuts and black outs at peak demand time in homes and factories. This has affected the quality of life as well as industrial development in the state.

 
The Myth on Water Use: But a rather unsavoury controversy is now being whipped up regarding the fact that the Cheemeni power station will be gas-fired. The opponents claim that gas power plants use much more water as compared to coal fired plants. The doomsday theorists claim that if the gas based plant goes through, Cheemeni would soon be transformed to a desert.
 
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There is far from the truth. There are several studies which prove that natural gas fired power plants are much more efficient, environmental friendly as well as economical as compared to coal based power plants.
 
The Fact about Water Use: There is little doubt that electricity generation involves the use of large amounts of water. Keeping a single 60-watt bulb switched on for 12 hours will use an astonishing 60 litres of water! This is because water plays a major role in keeping power plants running. Water is used to pump crude oil out of the ground, help remove pollutants from power plant exhausts, generate steam that turns turbines, flush away residue after fossil fuels are burned, and keep power plants cool. So how do we reduce the amount of water used to generate electricity?
 
The US-based Virginia Water Resources Group reports, “natural gas, the fuel of choice for most of the ultra-efficient electricity-generating turbines being built to meet the world’s growing energy demands, yields the most energy per unit volume of water consumed. Fewer than 38 litres of water are required to extract enough natural gas to generate 1000 kWh of electricity. By the time a coal-fired power plant has delivered that much energy, roughly 530 litres of water has been consumed.”
 
A similar result was reported after a study by the Texas Clean Energy Coalition. The study measured the three largest water needs in the power generation water cycle – energy production, plant cooling and emission control. Plant cooling required the largest volume of water and the study concluded that replacing coal-fired power plants with gas-fired power plants would save up to 60 percent water.
 
How Natural Gas Scores Over Coal: A paper published by Americans for Energy Leadership compared the lifecycle impacts of natural gas-fired and coal-fired electricity on fresh water in the United States. As mentioned, the largest amount of water is used for cooling and natural gas fired plants use less water for cooling. This is because unlike solid coal, natural gas can be directly burned in a turbine and gas turbines can be air-cooled thus reducing the consumption of water. Also natural gas power plants are generally more efficient than coal based power plants and therefore less heat is dissipated.
The paper also adds, “Coal-fired plants prove themselves dirtier on a number of other water related fronts. The emissions from coal-fired power plants are worse in terms of generating acid rain. Also, coal mining is often associated with dewatering, or pumping out all the groundwater near a mine to keep the operation dry. It can take years to restore the groundwater table near mines, as this disrupts hydrology.”
 
Natural gas based power plants are thus environmentally a much better option. Dangerous emissions are lower and the requirement of water is also much lower than that of coal based plants.