Coal Combustion Residuals (CCR) Basics
On this page:
- What is CCR?
- What do power plants do with CCR?
- How much CCR is there?
- Why is CCR reused?
- Why does EPA regulate CCR?
What is CCR?
Coal combustion residuals, also referred to as CCRs, are produced primarily from the burning of coal in coal-fired power plants. CCR includes a number of by-products produced from burning coal, including:
- Fly ash, a very fine, powdery material composed mostly of silica made from the burning of finely ground coal in a boiler.
- Bottom ash, a coarse angular ash particle that is too large to be carried up into the smokestacks so it forms in the bottom of the coal furnace.
- Boiler slag, molten bottom ash from slag tap and cyclone type furnaces that turns into pellets that have a smooth glassy appearance after it is cooled with water.
- Flue gas desulfurization material, a material leftover from the process of reducing sulfur dioxide emissions from a coal-fired boiler that can be a wet sludge consisting of calcium sulfite or calcium sulfate or a dry powdered material that is a mixture of sulfites and sulfates.
Other types of by-products are:
- Fluidized bed combustion ash.
- Cenospheres.
- Scrubber residues.
What do power plants do with CCR?
CCR is disposed of or used in different ways depending on:
- The type of by-product.
- The processes at the plant.
- The regulations the power plant has to follow.
Some power plants may dispose of it in surface impoundments or in landfills. Others may discharge it into a nearby waterway under the plant's water discharge permit.
CCR may also be recycled into products like concrete or wallboard.
How much CCR is there?
CCR is one of the largest types of industrial waste generated in the United States. According to the American Coal Ash Association's Coal Combustion Product Production & Use Survey Report, nearly 130 million tons of coal ash was generated in 2014.
Why is CCR reused?
Reusing CCR can create many environmental, economic, and product benefits including:
- Environmental benefits such as reduced greenhouse gas emissions, reduced need for disposing in landfills, and reduced use of other materials.
- Economic benefits such as reduced costs associated with CCR disposal, increased revenue from the sale of CCR, and savings from using CCR in place of other, more costly materials.
- Product benefits such as improved strength, durability, and workability of materials.
For more information, visit the CCR reuse webpage.
Why does EPA regulate CCR?
CCR contains contaminants like mercury, cadmium and arsenic. Without proper management, these contaminants can pollute waterways, ground water, drinking water, and the air.
The need for federal action to help ensure protective CCR disposal was highlighted by large spills near Kingston, TN and Eden, NC which caused widespread environmental and economic damage to nearby waterways and properties.
To address the risks from improper disposal and discharge of CCR, EPA has established national rules for CCR disposal and is strengthening existing controls on water discharges. For more information, visit the following webpages.