Using Coal to Generate Electricity
Of all of the methods for generating electricity, the one responsible for emitting the highest amount of pollutants into the air is the method employed by coal fired power stations. Still, coal fired power stations are used to generate about 41 percent of the electricity used globally. In the U.S., about 49 percent of electricity is generated by coal.
Coal took on this dominant position due to its flexibility, pricing and availability. Cheap coal is available for coal fired power stations to produce electricity at a cost that no other fuel can compete with. Moreover, power stations that are coal fired give out flexible power output; they can increase and decrease their electricity supply according to the demand.
Similar to oil, coal makeup depends on its mining source. It is organic in nature; it is a rock-like mineral that combines hydrogen, carbon, oxygen, sulphur and nitrogen. Coal’s ranking is dependent on its physical and chemical properties. Coals of low rank have low quantities of carbon and high quantities of oxygen and hydrogen; coals of high rank have high carbon content and low oxygen and hydrogen contents. Coals of low rank burn less efficiently than the high ranked types and give out more soot and ash. Hence, they are cheaper. Thus, most power stations that are coal fired are designed to use the lowest ranked coal in order to keep costs low.
The Union of Concerned Scientists presented the following figures of emissions from coal fired power stations in an average year:
carbon dioxide (C02) : 3.7 million ton
sulphur dioxide (S02) : 10,000 ton
particulate matters (PM) : 500 ton
nitrogen oxide (NOx) : 10,200 ton
carbon monoxide (CO) : 720 ton
volatile organic compounds (VOCs) : 220 ton
smaller bits of mercury, lead, arsenic, uranium and cadmium
Source: World Coal Institute
Besides air pollution, a typical coal fired power station can give out about 125,000 tons of ash as well as 193,000 tons of “sludge.” This is inclusive of toxic substances like mercury, arsenic, cadmium and chromium. In the U.S., three quarters of this waste is poured into unmonitored on-site landfills.
The United States’ power stations that are coal fired emit an average of 990g C02 /kWh (2.18 pounds C02 per kWh) carbon emissions.
Coal will never be a completely clean fuel, but because of the cost and ease of acquiring it, it will hold as a core fuel in the production of electricity for many countries for a long time to come. The World Coal Institute claims that we can continue to use coal for the next 130 years if the current consumption rate is maintained. Attempts to enforce clean emissions coming out of power stations that are coal fired are usually short term measures. Instead, new power stations that can replace coal are encouraged.