UW-Madison research informs upcoming EPA coal-combustion ruling

Nov. 9, 2010

by Renee Meiller

To some people, coal-combustion products such as fly ash and bottom ash are hazardous waste, fit only for sophisticated disposal. Others, particularly in the electric power industry, benefit from selling them as key additives in sustainable construction materials such as concrete.

Fueled in part by recent fly ash spills, it's a debate that has gone all the way to the U.S. Environmental Protection Agency, and the public comment period closes on Friday, Nov. 19.

If the EPA were to deem coal-combustion products hazardous waste, the decision would be a huge economic blow to the electric power industry, which relies heavily on coal-burning power plants for electricity, says Craig Benson, Wisconsin Distinguished Professor of civil and environmental engineering at the University of Wisconsin-Madison.

"If it's a hazardous waste, you go from making a little bit of money-a few hundred dollars a ton-on selling it to paying hundreds of dollars a ton to manage it," he says. "It changes the economics completely."

On July 22, Benson delivered testimony about his research of coal-combustion products to the U.S. House Small Business Subcommittee on Rural Development, Entrepreneurship and Trade.

"Research that I have conducted-and the research of others-has shown that coal-combustion products used in properly engineered applications generally do not release elements to the environment in amounts that exceed environmental standards," said Benson in his testimony.

At UW-Madison, Benson co-directs the Federal Highway Administration-funded Recycled Materials Resource Center, founded in 2007 with researchers at the University of New Hampshire. Center researchers test and evaluate recycled materials, and develop solid, science-based guidelines for those materials' use in transportation infrastructure construction and maintenance.

Working with the energy industry through EPRI, the Electric Power Research Institute, Benson and colleagues recently concluded a study that quantified the economic and environmental benefits of using coal-combustion products in beneficial construction applications, such as Portland cement.

"Our analysis showed that our annual energy offset from using these materials is equivalent to a city the size of Atlanta," he says. "We save a whole city worth of energy by using these materials in lieu of other conventional construction materials."

In 2007, for example, the United States produced nearly 72 million tons of fly ash, bottom ash and gypsum from flue gas desulphurization operations. More than half ended up in impoundments or landfills. However, the remaining 47 percent of these products were recycled in applications that range from concrete production, road base materials and asphalt filler to gypsum panel products, roofing granules, and materials for snow and ice control.

The researchers' study showed that recycling coal-combustion products in these applications yields a national cost savings of $5 billion to $10 billion annually, while the reduction in emissions is equivalent to removing 2 million vehicles from U.S. roadways.

The researchers' report, "Quantifying the benefits of using coal-combustion products in sustainable construction," will help the U.S. Congress make regulatory decisions, and the EPA to make policy decisions, about those products.

As background for the report, Benson, Civil and Environmental Engineering Professor Tuncer Edil and graduate student Jonathan O'Donnell also synthesized a decade's worth of environmental impacts data from instrumented test facilities in Wisconsin and Minnesota. "We find, for the most part, that there's really no measurable difference between the roadways we construct with coal-combustion products-or other byproducts-and conventional construction," he says.

Coal-combustion byproducts like fly ash and bottom ash are relatively benign, says Benson. "If you look at the criteria we use for hazardous waste, in terms of chemical composition, this stuff doesn't classify as hazardous waste," he says. "The risk associated with managing those products doesn't warrant them being designated as hazardous."

However, that's not to say there aren't guidelines for their appropriate use. Thanks to the Wisconsin Department of Natural Resources, Chapter NR 538 of Wisconsin's administrative code-which addresses beneficial uses of industrial byproducts-has become a national model. The regulations are practical and scientifically sound, says Benson. "It's thought of as the most forward-thinking rule-making on this anywhere in the United States," he says. "They're talking about using it as the basis for making federal rules."

Good policy is based on good science, and Recycled Materials Resource Center researchers are world leaders in research of materials for sustainable construction.

"As a university, we're helping our government make good policy decisions about how to manage these waste streams and do that in a way that it protects our environment and also doesn't impact our economy in a negative way," says Benson.