PATHWAYS OF TRACE-ELEMENTS IN POWER-PLANTS - INTERIM RESEARCH RESULTS AND IMPLICATIONS

EPRI's Plant Integrated Systems: Chemical Emissions Studies (PISCES) research program has been instituted to improve the understanding of chemical emissions from power plants. Key components of this program are to create an industry data base on trace chemical emissions, to define methods for measuring these substances, to establish the capabilities of existing and emerging environmental technologies for controlling these chemicals, if warranted, and to conduct field sampling campaigns at pilot and full-scale power plants to ascertain process trace chemical data absent from the literature. The ultimate aim of the current effort is to characterize industry emission profiles and produce information and tools for utilities to assess emission risks and evaluate alternative control options. Interim results from this research indicate microgram per cubic meter levels of emissions for many trace substances. In fact for mercury, the concentrations from coal-fired power plants can be much less. Particulate control devices such as ESPs and baghouses are capable of removing more than 90% of most non-volatile heavy metals from coal combustion flue gases. Further research continues to address mercury species behavior and its removal under varying flue gas conditions.