More coal combustion residue from power plants is being recycled for beneficial uses, such as construction material, but – due to the decline in coal-fired generation – less coal ash is being produced in the first place.
More than half of the coal ash produced in the United States in 2015 was recycled – for the first time breaking through a 50% utilization level that has long been a goal for beneficial use industry leaders, the American Coal Ash Association (ACAA) said Oct. 12.
“We are pleased to report that 52 percent of coal combustion products were beneficially used in 2015 – up from the previous year’s record of 48 percent,” said ACAA Executive Director Thomas Adams.
“It is gratifying to know that for the first time, we are using more of these valuable resources than we are throwing away,” Adams said. “With some help from markets and regulatory certainty, we look forward to continuing to grow these practices that conserve natural resources, make products that are more durable, and dramatically reduce the need for landfills,” Adams said in a news release.
According to ACAA’s just-released “Production and Use Survey,” 61.1 million tons of coal combustion products were beneficially used in 2015 out of 117.3 million tons that were produced.
The report was released at a news conference in Washington, D.C.
Although the rate of ash utilization increased from 48% to 52%, the total volume of material produced and utilized declined. Coal ash production volume declined 10% from 2014 levels as coal’s share of the electricity generation mix shrank in response to environmental regulations and competition from other energy sources.
Coal ash utilization volume declined 2 percent overall as usage trends shifted in several key applications:
Use of coal fly ash in concrete increased 20% to 15.7 million tons – up from 13.1 million tons in 2014. Fly ash improves concrete durability and significantly reduces greenhouse gas emissions associated with concrete production.
Use of fly ash and bottom ash in structural fills declined 54% and 19% respectively. The decline of 1.9 million tons of utilization may be related to regulatory uncertainty over a provision in the Environmental Protection Agency (EPA) Final Rule for coal ash disposal that requires evaluation of structural fill projects greater than 12,400 tons in volume. That provision is currently under legal challenge.
Utilization of a “non-ash” coal combustion product continued to increase. Synthetic gypsum is a byproduct of flue gas desulphurization units, or scrubbers, located at coal power plants. Use of synthetic gypsum in panel products (i.e. wallboard) increased to 12.3 million tons in 2015. Use in agricultural applications – in which the gypsum improves soil conditions and prevents harmful runoff of fertilizers – increased to 1.6 million tons.
Production of boiler slag declined 17% to 2.2 million tons as more power plants that produce this type of material were retired. Nearly 84% of boiler slag is utilized, mostly as blasting grit or roofing granules.
Cenospheres – a very valuable form of ash mainly harvested from wet disposal impoundments – saw utilization drop by 80% as impoundments began to close in response to EPA’s Final Rule for coal ash disposal.
“Although 2015’s results are a milestone worth celebrating, it’s important to remember that the United States is still disposing of millions of tons of coal combustion products that could be put to good use,” Adams said. “Additionally, the coal ash beneficial use industry is taking significant strides in developing strategies and technologies for reclaiming coal ash materials that were previously disposed.”
Adams referred to a 2015 ACAA-commissioned study by the American Road and Transportation Builders Association that found there will be ample supplies of coal combustion products for beneficial use in the future.
The American Coal Ash Association has conducted a survey quantifying the production and use of coal combustion products in the United States each year since 1966.
Data is compiled by directly surveying electric utilities and utilizing additional data produced by the Energy Information Administration. The survey’s results have been widely utilized by federal agencies including EPA and U.S. Geological Survey (USGS).