When coal is burned to produce electricity, it generates several by-products. One of these by-products is coal combustion residuals (CCR), generically referred to as “coal ash.” Coal ash is mainly made up of rocks, minerals and other non-combustible, natural materials mixed in with the coal when it is mined from the earth. Our two coal combustion facilities (Four Corners Power Plant in Farmington, NM, and Cholla Power Plant near Joseph City, AZ) consume about 6 million tons of coal a year, yielding approximately 1.2 million tons of coal combustion residuals annually. Much of this material can be recycled and reused in manufacturing commercial products. Each coal-fueled plant is unique in the amount and type of ash produced and how it is reused or disposed.
We manage the reuse of coal ash to help reduce our environmental footprint while adding to our bottom line. To keep our coal ash from being landfilled, we sell much of our coal ash to concrete manufacturers, who use it as an essential component for cement in the production of their products. This reduces the amount of cement that otherwise would need to be produced, significantly reducing energy consumption and contributing to a decrease in greenhouse gas emissions.
Collectively, between Four Corners and Cholla, we generated 1,231,912 tons of coal ash in 2019 and sold 718,420 tons, representing 58% of the total amount produced. The amount of coal ash sold correlates to a reduction in carbon emissions of 431,052 tons in 2019, the equivalent to removing more than 84,000 cars from the road for a year. Because of its remote location, the market for selling coal ash is limited for the Four Corners Power Plant, and therefore Four Corners sells a lower percentage of its coal ash than the Cholla Power Plant.
It should be noted that we will cease combustion of coal at the Cholla facility by mid-2025 and have immediate plans to reduce the overall number of regulated coal ash impoundments at our Cholla and Four Corners facilities starting in 2019 as described below. In the interim, we are committed to reusing coal ash residuals beneficially to the extent practical and to reducing our overall coal ash management footprint.
We have installed monitoring wells around our coal ash impoundments and continue to monitor groundwater quality in accordance with the CCR rule finalized by EPA in 2015. Additionally, we are undertaking engineering projects at Cholla and Four Corners designed to minimize the impacts associated with CCR management. Combined, these engineering projects will reduce the total number of CCR operating units from 10 to 5. In addition to closing operating units, we have other capital projects scheduled or in progress at Cholla and Four Corners focused on minimizing CCR impacts to the environment.
Coal Ash Reuse Data Table