Release Date: November 5, 2004

PITTSBURGH, PA - The Department of Energy has announced four awards totaling $1.4 million for advanced research to aid the removal of mercury from existing fossil-fueled power plants. The four new projects support the President’s call for dramatic cuts in mercury emissions by providing an understanding of the mechanisms of mercury chemistry, and leading to novel approaches to measure and remove mercury from flue gas.

Coal contains only trace amounts of mercury, but when coal is consumed to produce power, gaseous species of mercury are formed and emitted into the atmosphere. These emissions are the largest human-created source of mercury emissions in the United States, and may contribute to a variety of health and environmental problems.

The complex nature of gas mixtures and process conditions in coal-fired power systems makes it difficult to develop predictable, effective, low-cost mercury control technologies. To remove the barriers to mercury control, awards were made in three areas: mercury measurement, removal in post-gasification cleanup processes, and chemistry and transport in post-combustion pollution-control processes.

The new projects will be managed for the Energy Department by the Office of Fossil Energy’s National Energy Technology Laboratory, which oversees the nation’s largest program in mercury control for existing coal-fired power plants.

The selected projects are described below:

• URS Group, Inc. (Austin, Texas) will conduct a bench-scale kinetic study of mercury reactions in wet flue gas desulfurization systems. The objective is to determine the mechanisms and kinetics of the aqueous reactions of mercury absorbed by these systems. A kinetic model to predict mercury reactions will be developed for a range of potential designs and operating conditions. The model can then be used to identify settings that maximize mercury capture, minimize mercury re-emissions, and help solidify mercury so that it leaves the system as a solid, rather than liquid, byproduct. The kinetic study and model should enhance understanding of the fate of oxidized mercury absorbed in wet flue gas desulfurization systems, and will help remove a barrier to a technology that can efficiently co-capture mercury. (Project duration: 2 years; Total award value: $342,408)
• Purdue University (West Lafayette, Ind.) will develop and apply new sensors for measuring the concentration of various mercury species in flue gas. Researchers will develop a new optical sensor to measure elemental and oxidized forms of mercury without extensive pretreatment. A novel and compact laser source will be designed to faciliate measurement. Approaches to eliminate or minimize interference from other gases will also be devised. Purdue will also investigate the use of laser-induced breakdown spectroscopy to measure total mercury in a system. Research will focus on the resolution of interferences and the accurate measurement of low levels (10 parts per billion) of mercury. The atomic mercury sensor can be applied to in situ measurements of elemental mercury in the actual coal-combustor exhaust stream. To assess the overall feasibility of using sensors as continuous emission monitors, Purdue will team with Texas A&M University to test the sensors using their bench-scale combustion facilities. (Project duration: 3 years; Total award value: $483,952)
• Gas Technology Institute (Des Plains, Ill.) will develop and evaluate nanoscale sorbents for mercury capture from the warm fuel-gas generated by coal-gasification systems. Investigators will conduct research aimed at understanding the chemistry of mercury, as it relates to sorption, on various metal-oxide materials. A fundamental understanding of these interactions will serve as a basis for developing a sorbent for mercury capture in coal-fired power generation systems under warm fuel-gas conditions (pressures near 300 psi and temperatures from 300 ^oF to 700 ^oF). Of primary interest is removing contaminants from the gas while it is under these conditions to maintain the high energy efficiencies of coal-gasification systems. In addition to mercury, other trace metals, such as arsenic, may also be captured, which would support development of a multi-pollutant control technology. (Project duration: 2 years; Total award value: $304,169)
• Arizona Board of Regents (Tucson, Ariz.) will study sorption mechanisms for mercury capture in warm post-gasification gas-cleanup systems. Researchers will conduct bench-scale experimental and computational tests to understand the interaction between certain trace metals, including mercury, and a novel sorbent derived from paper-recycling wastes. Experiments will not only investigate sorption at warm-gas cleanup conditions (300 ˚F to 700 ˚F), but will also extend this range to temperatures within the hot-gas cleanup range (above 1200 ˚F). The studies will center around understanding the mechanisms that govern the sorption of mercury and other metals, as well as the rate at which sorption occurs as a function of temperature, sorbent flow rate, metal and gas composition, and residence time. Computational methods will be directed toward predicting stable metal speciation on sorbent substrates. Quantum-mechanical and kinetic modeling will be used to correlate the experimental data, and to extrapolate it to high pressures (300–1,000 psi). The University of Arizona will team with Niksa Energy Associates for the derivation and evaluation of kinetic models of mercury speciation. (Project duration: 3 years; Total award value: $558,594)