Coal-combustion products
Coal is one of our country’s most plentiful and affordable energy sources. Coal-fired power plants supply about 50 percent of the electricity used by Progress Energy’s customers in the Carolinas and about 40 percent of the energy used by customers in Florida.
In the process of generating electricity, coal-fired plants also generate coal-combustion products. As part of our ongoing commitment to the environment, Progress Energy seeks to handle these products in the safest, most responsible manner possible, either through storage or beneficial use.
What are coal-combustion products (CCPs)?
Coal-combustion products are created by burning coal to generate electricity or through the use of emission-control technologies. CCPs include:
Coal ash: We produce approximately 2 million tons of coal ash each year. The electrostatic precipitators at our plants capture about 99.8 percent of the ash released from the boiler and in the exhaust gas.
Synthetic Gypsum: Wet scrubbers remove SO2 by passing the flue gas through a tower where a mixture of limestone and water is sprayed. When the SO2 in the flue gas reacts with the limestone, synthetic gypsum is produced.
Cenospheres: These are tiny, inert, hollow balls of sand‐like material. They are created inside a coal‐fired boiler when molten ash solidifies around a bubble of air to form a hollow sphere. The air bubble allows cenospheres to be so lightweight that the particles float on water and are typically collected by skimming the surface of an ash pond.
The new Raleigh Convention Center in Raleigh, N.C., is built with concrete manufactured with fly ash from a Progress Energy power plant. The company is actively pursuing similar projects that allow for the beneficial use of CCPs. Photo by Holly Jaques.
Beneficial use of CCPs CCPs are beneficially used in a number of products, including cement, concrete, structural fill, road bases, paint, bowling balls and wallboard. Using CCPs in these products is beneficial to both the environment and industry.
Reduced emissions. Using coal ash to make concrete replaces the need for other emission-causing products. For example, every ton of ash used in place of Portland cement eliminates approximately one ton of carbon dioxide emissions and 55 gallons of oil. Using ash this way prevents more than 13 million tons of carbon dioxide emissions annually in the United States, the equivalent of taking 2.1 million cars off the road, according to the EPA.
High-performance products. Building products made with CCPs have proved to be even more durable and cost-effective than products made with natural materials. Synthetic gypsum is used to manufacture nearly 30 percent of all wallboard in the United States. Fly ash is a vital component in high-strength concrete used in skyscrapers, major highways and bridges. For example, the new Raleigh Convention Center in Raleigh, N.C., was built with concrete that used coal ash from a Progress Energy coal plant.
Historically, we have beneficially reused more than 95 percent of the coal ash produced at the Crystal River Plant, located in Florida, in ready-mix concrete and the production of Portland Cement. In 2008, that number dropped to around 60 percent due to reduced demand for construction materials during the downturn in the economy. In the Carolinas, historically we have beneficially reused up to 30 percent of fly ash produced from our Roxboro Plant in ready-mix concrete. We are aggressively pursuing additional beneficial reuse opportunities for all of our coal plants.
Storage of CCPs
Progress Energy’s systems for capturing and storing CCPs are regulated, permitted and designed to protect the environment. They fall into two categories:
Dry: CCPs can be stored in dry, above-ground facilities. These lined storage areas are typically built in compartments. As these are completed, they are covered with topsoil and grass.
Wet: CCPs can also be stored in ash ponds, which are part of our plants’ wastewater treatment facilities. Progress Energy performs thorough and frequent inspections, including tests for water quality, structural integrity and environmental impact. An independent engineering firm inspects each of our ponds’ dams annually and conducts an in-depth assessment every five years. We share the results of these studies with the appropriate state agencies.
Progress Energy Carolinas has nine active wet storage facilities and one active dry storage facility. Progress Energy Florida has one active dry storage facility.
Future of CCPs
Progress Energy continuously seeks the best ways to store or use CCPs. The EPA’s goal is to beneficially use 50 percent of CCPs by 2011. Progress Energy and the CCP industry support this goal.
Used nuclear fuel
After uranium pellets have been used in our nuclear plants to make electricity, they are still radioactive and therefore must be safely stored and secured. We take this responsibility very seriously and have extensive safety and security measures in place. We use both wet storage (fuel is submerged under 23 feet of water in fortified concrete, steel-lined pools) and dry storage (fuel is secured in specially designed concrete canisters) for on-site storage of used fuel. The two methods are equally safe. To date, the U.S. Department of Energy has not fulfilled its commitment to open and operate a permanent used-fuel repository. Until a federal repository is operational for long-term storage, the fuel will be stored safely and securely at our facilities.
