Burning coal is one of the most environmentally destructive ways to generate energy. It releases more carbon dioxide per unit of electricity than any other major fuel source, pollutes air and water with toxic metals, and leaves behind massive volumes of hazardous waste. Coal still produces about 35% of the world’s electricity as of 2024, so its environmental footprint remains enormous even as cleaner alternatives grow.
Carbon Emissions and Climate Change
Coal is the single largest source of carbon dioxide among fossil fuels used for electricity. Burning coal to generate one kilowatt-hour of electricity releases about 2.3 pounds of CO2, roughly double what natural gas produces for the same amount of power. That carbon dioxide traps heat in the atmosphere for centuries, driving global temperature increases, sea level rise, and more extreme weather patterns.
The climate damage starts before coal even reaches the power plant. Coal mines release methane, a greenhouse gas that is 28 to 36 times more potent than carbon dioxide over a 100-year period. U.S. coal mines and abandoned mines accounted for about 8% of total American methane emissions in 2019. When you combine the CO2 from combustion with the methane from extraction, coal’s total climate impact is substantially worse than the smokestack numbers alone suggest.
Air Pollution and Acid Rain
Coal combustion releases sulfur dioxide and nitrogen oxides into the atmosphere. These gases react with water and oxygen to form sulfuric and nitric acids, which fall back to earth as acid rain. According to the EPA, burning fossil fuels for electricity accounts for two-thirds of sulfur dioxide and one-quarter of nitrogen oxides in the atmosphere. Acid rain damages forests, kills fish in lakes and streams, corrodes buildings, and degrades soil quality over large areas downwind from coal plants.
At ground level, nitrogen oxides from coal plants also react with sunlight to form ozone, a key ingredient in smog. Fine particulate matter from coal smoke penetrates deep into the lungs, contributing to asthma, heart disease, and premature death in communities near power plants. These effects hit hardest within a few dozen miles of the source but can travel hundreds of miles on wind currents.
Mercury and Heavy Metal Contamination
U.S. coal-burning power plants release roughly 50 tons of elemental mercury into the air each year. The mercury itself isn’t immediately dangerous in that form, but once it settles into lakes, rivers, and wetlands, bacteria convert it into methylmercury, a highly toxic compound. Methylmercury enters the food chain through tiny aquatic organisms and bioaccumulates, meaning each predator up the chain carries a higher concentration. By the time it reaches large fish like bass and pike, mercury levels can be high enough to pose serious health risks to people who eat them regularly, particularly pregnant women and young children.
Mercury is just one of many toxic metals coal plants release. Cadmium, chromium, lead, nickel, arsenic, and selenium all escape through smokestacks or concentrate in the solid waste left behind after combustion.
Coal Ash and Toxic Waste
After coal burns, it leaves behind ash. Fly ash, the fine particles captured by filters, contains volatile trace elements like arsenic, lead, cadmium, and selenium at concentrations 10 to 100 times higher than in the heavier bottom ash. Arsenic levels in fly ash samples range from trace amounts up to 135 micrograms per gram, while selenium can reach 123 micrograms per gram.
This ash is typically stored in massive surface impoundments or landfills, often unlined. When these containment sites leak or fail, the contaminated material seeps into groundwater or spills into rivers. The 2008 Kingston, Tennessee coal ash spill released over a billion gallons of toxic sludge into surrounding waterways, destroying homes and contaminating land for miles. Even when containment holds, rainwater filtering through coal ash ponds can carry arsenic and selenium into local water supplies over decades.
Water Consumption and Thermal Pollution
Coal plants are extraordinarily water-intensive. They withdraw an average of about 19,185 gallons of water per megawatt-hour of electricity produced, nearly seven times more than natural gas combined-cycle plants. Most of this water is used for cooling: converting steam back into water so it can be reheated. While much of the withdrawn water is returned to its source, it comes back warmer, typically raising the temperature of receiving waterways by about 3°C (roughly 5°F).
That temperature increase matters more than it sounds. Warmer water holds less dissolved oxygen, stressing fish and other aquatic life. Species that depend on cold, oxygen-rich water, like trout and certain invertebrates, can be pushed out of affected stretches of river entirely. Algae blooms also thrive in warmer water, further depleting oxygen and degrading water quality downstream.
Land Destruction From Mining
The environmental damage begins long before coal is burned. Surface mining, particularly mountaintop removal in Appalachia, has destroyed or severely damaged more than a million acres of forest and buried nearly 2,000 miles of streams over the past two decades. Entire ridgelines are blasted apart and the rubble is pushed into adjacent valleys, permanently burying headwater streams that feed larger rivers and provide habitat for salamanders, freshwater mussels, and dozens of other species found nowhere else.
Underground mining carries its own risks: land subsidence, contaminated drainage that turns streams orange with iron and acidic runoff, and the methane emissions discussed earlier. Abandoned mines continue leaching pollutants into waterways for decades or even centuries after operations cease.
Can Technology Fix Coal’s Problems?
Carbon capture and storage (CCS) is sometimes proposed as a way to keep burning coal while limiting climate damage. The technology aims to capture 90% of CO2 from a plant’s smokestack before it reaches the atmosphere, and in theory could reach 98 or 99% efficiency. In practice, CCS has only been implemented at two coal power plants worldwide, one of which shut down in 2020. The technology remains expensive, energy-intensive, and nowhere near the scale needed to offset coal’s emissions.
Even if carbon capture worked perfectly, it would address only CO2. It does nothing about mercury, sulfur dioxide, nitrogen oxides, coal ash, water consumption, or the ecological destruction from mining. Coal’s environmental toll is not a single problem with a single fix. It is a cascade of damage at every stage, from extraction through combustion to waste disposal, affecting air, water, land, and climate simultaneously.