Below are the answers to some frequently asked questions about alternative fuels and energy recovery in cement kilns.
Why is Alternative Fuel Used in Cement Kilns?
Cement is the active ingredient in concrete, the most widely used construction material in the world. Cement is produced in huge rotary kilns by heating a mixture of minerals to over 2600 degrees F. This is a very energy intensive process and cement manufacturers have developed technology that allows them to use energy-rich secondary materials created by other industrial processes to replace non-renewable fossil fuels. These alternative fuels can be produced from: paint solvents, discarded paints and coatings, inks and ink solvents, various resins and organic sludges, petroleum refining by-products, scrap tires and many other materials.
Why are Some of These Alternative Fuel Sources Regulated as Hazardous Waste?
Many of the secondary materials that can be used in alternative fuels are labeled "hazardous" mainly because they are flammable. Others receive this designation because their improper handling and disposal could adversely affect the environment. A key point to understand is that the alternative fuels used by cement kilns that are regulated as "hazardous" cannot legally be land-disposed without prior treatment. For the vast majority of these types of wastes, EPA has designated thermal treatment such as energy recovery in cement kilns as the Best Demonstrated Available Technology (BDAT) for treating them safely.
Is Energy Recovery Safe?
Energy recovery from alternative fuels is a safe process. Each step of the recycling process that produces and uses these fuels is regulated by USEPA and subject to strict standards that govern both air emissions and management practices such as transportation, handling, and storage under the authority of the Resource Conservation and Recovery Act and the Clean Air Act.
What are the Benefits of Energy Recovery?
The benefits of energy recovery are significant. When cement kilns use alternative fuels derived from secondary materials, substances that would otherwise be regarded as waste are removed from the environment and handled and used in a safe and responsible manner. In addition, the amount of fossil fuel needed to produce cement is reduced, thereby conserving non-renewable energy resources and reducing emissions of greenhouse gases.
Does Using Alternative Fuel Affect the Cement?
No. The use of alternative fuel in cement kilns has no adverse effect on the quality of the cement. USEPA officially considered this question of cement product quality in 1995 and concluded that "It is not substantiated that burning [waste-derived fuel] increases risks posed to end users of cement."