Even with current advances in the development of mercury control technologies, there is no single best way to control mercury emissions that can be applied to all electrical distribution facilities in the United States . Based on available mercury control technologies, the cost of mercury removal is estimated to range between $11,000 and $150,000 per kg ($5,000 to $70,000 per pound)[17] and adds up to $0.005 per kWh to the cost energetic. of mercury emissions from coal-fired boiler exhaust gases is a much more challenging problem due to the low concentrations of mercury in utility boiler exhaust gases (typically 0.01 versus 100+ ppm) and the chemical speciation of mercury in different physical forms. Understanding the physical and chemical distribution of mercury in the system is essential for the development and implementation of control systems. There are numerous control technologies currently available that coal-fired power plants use to reduce mercury emissions into the atmosphere. The effectiveness of these technologies for mercury removal varies depending on the characteristics of the coal and the configuration of the power plant. In general, two approaches can be adapted to reduce mercury emissions from coal-fired boilers: pollution prevention and post-combustion pollution control. . Pollution prevention, in some cases, involves commercially available technologies, which do not require capital investments. Many of the conventional post-combustion control technologies used in coal-fired power plants to control SO2 and PM have the added benefit of reducing Hg emissions. A combination of some of these control devices can achieve high mercury control (greater than 95%). Coal cleaning can reduce the mercury content of coal fired... middle of paper... candidate shown to oxidize >95% of elemental mercury in pilot-scale tests.[21] The iron oxides, Fe2O3 and Fe3O4 in fly ash, have been shown to promote mercury oxidation.[23, 24] While fly ash appears to promote mercury oxidation, studies have shown that only a small amount of the active surface area (1 to 3%) ) plays a role in the process.[25, 26] Fe2O3 has also been used as an effective catalyst in small-scale systems.[27, 28] Two investment components, Al2O3 and TiO2, oxidize a portion of elemental mercury.[29, 30] Other metal catalysts that have been shown to promote mercury oxidation include iridium[31], MnO2 [28], and CuO.[28] Photochemical oxidation of mercury by ultraviolet irradiation, particularly promising in the presence of TiO2, is another emerging technology being studied for use in coal-fired power plants.[32-35]