Beneficial use of power sector combustion byproducts exceeded material disposed in 2020

Combusting fuel for electricity generation creates solid byproducts, which have decreased in recent years as some fuels—especially coal, the source of nearly all of these byproducts—have been used less frequently in the United States. In 2020, for the first time since we began collecting these data in 2008, larger amounts of these byproducts were put to beneficial use rather than disposed of.

Combustion byproducts include fly ash (the lighter ash that rises in the boilers’ flue gases) and bottom ash (heavier ash that collects at the bottom of boilers) from boilers and gypsum from flue gas desulfurization (FGD) systems, which are used to control sulfur dioxide emissions. In 2020, each ton of coal consumed in the electric power sector produced about 0.17 tons of combustion byproducts. Combustion byproducts are either disposed of, used by the utility, sold to other businesses for beneficial use, or—less often—stored for later use or sale.

Between 2015 and 2020, total production of combustion byproducts fell by 36%, from 119 million tons to 76 million tons. This decrease coincided with a 41% reduction in coal consumption in the electric power sector during the same five-year period.

As total production of combustion byproducts has decreased, the disposition has shifted from relatively costly disposal to beneficial uses, such as manufacturing products, including concrete and wallboard. Fly ash and bottom ash are used in concrete and applied in structural fills, and FGD wastes are used to produce gypsum wallboard.

We also collect data on the operations and maintenance costs associated with collection, abatement, and disposal of combustion byproducts and revenues derived from their sales for beneficial use. Operation and maintenance costs decreased from $2.8 billion in 2015 to $2.0 billion in 2020. Collection and abatement costs accounted for 71% to 75% of total combustion byproducts’ operation and maintenance costs between 2015 and 2020.

Revenue from the sale of combustion byproducts for beneficial use partially offsets generators’ operation and maintenance costs. In 2020, total revenues were $382 million, $225 million of which was from the sale of fly ash or fly ash intermingled with bottom ash.

Principal contributor: Paul McArdle