Coal-fired power plants: growing source of mercury emission in Pakistan

MERCURY IS attractively beautiful, but a toxic heavy metal that triggers brain damage; effects immune and reproductive system; exclusively harmful to developing fetuses; and cause heart problems. Less than one gram or 1/70th of one teaspoon of mercury deposited on a 25-acre lake can make the fish hazardous to eat. Sources of mercury are quite diverse, ranging from natural sources to anthropogenic activities like thermometers, electric bulbs, and switches to power plants, coal-fired power stations, metal smelters, gold mining and cement industry. It is also active in some cosmetics like facial creams and dental treatments like mercury amalgam filling. Globally, the main source of mercury emission considered to be coal-fired or coal power plants, queuing waste incinerators that burn mercury-containing products, and chlorine manufacturers. Certain industrial and hospital equipment such as thermometers and manometers, dental fillings along with the unrefined release of toxic waste, jewellery, skin-whitening creams, electric batteries, paints, cement plants and specific species of fish are also contributing in mercury emissions. The mercury emitted by burning coal is converted into a much more toxic substance (methyl-mercury), when it reaches the food chain through concentration and accumulation. In case of a coal-fired power plant, mercury is released into the air and falls to the ground with rain and snow, and then drain into watersheds, rivers, and lakes and remains into sediment. A typical uncontrolled coal plants emits approximately 170 pounds of mercury each year. In recent days, Pakistan is striving for enhancing the production of energy through coal-fired power plants. More and more coal power plants are setting up which will become the core reason of increase in mercury emission in the country. Fact is that, coal power plants plays significant role to generate a very large amount of cost effective energy through which we can overcome the energy crises of the country. But question is, at what cost? The total emission of mercury from coal combustion globally is 450-500 metric ton per year. If we compare Pakistan with its present and future expected power generation through coal or coal-fired power plants; we will find that presently (year 2017) Pakistan is producing 1,628 MW electricity through coal power plants which is planned to increase 5,810 MW by 2021. It is about 357 percent increase in power generation through coal power plants, which will certainly increase in mercury emission from these plants. This is alarming situation. In this regard, regular monitoring of cities’ atmospheric mercury emission is essential in which coal power plants are installed or going to be installed. Primitive monitoring plays good role to give an over view of before and after climate change. It is critical to investigate mercury emission specimens and measurements in coal power plants, mercury emission assessments and future trends, mercury speciation transformation during coal combustion, mercury control and mercury stability in byproducts. We need to conduct studies to research the characteristics for mercury emission from the coal-fired power plants, this will incorporate many aspects, such as the amount and kind of coal, the ways and means of combustion, the traditional pollutant-control devices, will influence the mercury emission for its special physio-chemical characteristics. We must develop a comprehensive study mechanism of mercury emission and its control. It is evident that Pakistan need to build more coal power plants to achieve cheaper electricity, but not on the cost of environment. Modern technologies can reduce mercury emissions by up to 90 percent. We should take measures that this increase in coal power plants will create no threat to climate change.

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