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When coal is burned, the vast majority of TEs are typically collected in the ash by particulate control systems and isolated from the environment. On a mass basis, the major air pollutants emitted from coal combustion are sulfur dioxide (SO 2), nitrogen oxides (NO + NO 2 or NOx), and particulate matter (PM), all of which affect human health and the health of ecosystems. The Impacts of Trace Elements from Coal Combustion on the Environment and Human Health Knowledge of the impact of TEs released during coal use grew tremendously during the 20th century. Ĭoal contains elements, including trace elements (TEs), that affect human health and the health of ecosystems, if released to the environment in specific forms. The global share of heat and power generated from coal has held steady at about 40% over the last 40 years, although the share of electricity and heat produced from coal in OECD countries has continued to decrease to 25% in 2018 because of factors such as low-cost natural gas, decreases in the costs for wind and solar electricity generation, and government policies supportive of renewable energy. In 2017, 66.5% of coal worldwide was used for heating and electricity generation, while in the 37 member countries of the Organization for Economic Cooperation and Development (OECD), the proportion was higher at 82.3%. Ĭoal is primarily used for the generation of electricity and commercial heat, with important quantities also used for the production of chemicals, tars, steel, and activated carbons. However, there is the potential for significant reductions if more sustainable policies are adopted, particularly in the Asian countries which are forecast to drive the mid-century increase in consumption. With current stated policies, coal consumption world-wide is forecast to be flat for the next 10 years and then rising after 2030 through 2050. At the same time, coal consumption in Europe, North America, and the former Soviet republics decreased. Over the last 40 years, global coal usage has increased, especially since the beginning of the 21st century, when rising industrial activity in Asia doubled global coal consumption relative to the end of the 20th century. Key accomplishments in measurement, modeling and control of trace element emissions in coal-fired systems are highlighted.Ĭoal has powered the world’s industries for centuries, but at a cost: coal contains many elements that affect human health and the health of ecosystems. This review focuses on the behavior of trace elements in industrial coal combustion systems with an emphasis on what has been learned over the past century uniquely related to the use of coal in boilers for electricity and heat production. The sampling and measurement of trace elements, in the inlet coal, outlet flue gas, aqueous scrubber solutions, and ash matrices, represents a significant challenge.

These transformations can, in many cases, impact the fraction of these trace elements that are removed by various pollution control devices compared to the fraction released into the environment. The transformations of the trace elements present in coal burned during combustion can be categorized as thermal volatilizations from the coal in the furnace thermal decomposition of trace element compounds inside the coal encapsulation inside ash structures through high-temperature vitrification oxidation of the trace elements with the myriad species contained in flue gas through gas phase (homogeneous) reactions or catalytic (gas-solid) reactions adsorption and/or reactions with active sites on entrained fly ash particulates contained in the flue gas and absorption into solutions. The impact of many of these elements on the environment via air and water discharges from coal-fired plants has been studied with decades of research on their chemical transformations within combustion systems and on their fates upon reintroduction into the environment. Coal contains many of the elements of the Periodic Table, in percent-levels or in trace amounts (ppm, ppb). In the 21st century, coal use has declined in North America and Europe, but continues to increase in Asia. Coal fueled the Industrial Revolution and the global expansion of electrification in the 20 th century.