Protecting groundwater quality. Part 2. Utility solid waste: managing the by-products of coal combustion

The utility industry is continuing to explore new technical solutions to groundwater protection in the way it produces, uses, and disposes of waste from fossil-fuel power generation. Regulatory uncertainty has compounded the challenge. Although the vast majority of utility wastes are relatively benign, they are produced in large quantities - roughly 80 million t/yr. About 90% of this volume is fly and bottom ash and flue-gas desulfurization (FGD) sludge from coal-fired plants. The remaining 10% includes hundreds of low-volume wastes, including wash waters and spent solvents used to clean boilers and other equipment, cooling-tower sludge, coal pile runoff, ash from oil-fired plants, sludge from geothermal fields, and the like. Utilities also must manage wastes from technologies no longer in use, such as the coal tars from turn-of-the-century coal gasification plants. Even advanced coal combustion technologies now under development, such as integrated gasification-combined-cycle generation (IGCC) and fluidized-bed combustion (FBC), will produce some wastes. In fact, nearly all methods of electricity generation produce by-products. Consequently, waste handling and disposal are issues that will be with us as long as we use electric power.