Note: Bit, bituminous coal; Subbit, subbituminous coal; ESP, electrostatic precipitator; PAC, powdered activated carbon; PFF, polishing fabric filter; SC, spray cooling; NA, not available. Source: [85].

Cost Estimates to Control Mercury Emissions

Cost estimates for mercury compliance are currently very approximate and vary from $5000 to $70,000 per pound of mercury removed, from 0.03 to 0.8i/kWh, and from $1.7 to $7 billion annually for the total national cost, depending on technical advances [78]. A breakdown of costs by various technology options is provided in Table 6-13 [85]. The costs of cleaning Eastern bituminous coals for mercury removal range from no additional cost (for coals already washed for sulfur removal) to a cost of $33,000 per pound of mercury removed [86]. The costs for cleaning Powder River Basin subbituminous coals are higher and approach $58,000 per pound of mercury removed [78]; however, mercury reductions from washing methods currently being applied are already built into the ICR mercury data for delivered coal; consequently, to realize a benefit from coal cleaning, higher levels of coal cleaning must be employed. Advanced cleaning methods can remove additional mercury, but they are generally not economical.

Potential Future Regulated Emissions

As discussed in Chapter 4, the increased CO2 concentration in the atmosphere from fossil fuel combustion is causing concerns for global warming. The capture and sequestration of CO2 from stationary combustion sources is considered an important option for the control of CO2 emissions. Currently, however, there are no cost-effective technologies for coal-fired power plants available. It is estimated that the costs for capture and separation of CO2 from flue gas comprises ~75% of the total costs of ocean or geologic sequestration. Consequently, DOE has a carbon sequestration program that is aggressively exploring technologies for CO2 capture, as well as the subsequent CO2 sequestration. The Carbon Sequestration Program, established in 1998, directly implements President Bush's Global Climate Change Initiative (announced on February 14, 2002), which has the goal of 18% reduction in greenhouse gas intensity of the United States by 2012 [87]. By 2018, the goal is to develop to the point of commercial deployment, systems for direct capture and sequestration of greenhouse gas and criteria pollutant emissions from fossil fuel conversion processes that result in near-zero emissions. This section contains a brief overview of the technologies being investigated for CO2 capture and sequestration in anticipation of future CO2 emissions legislation. The status and types of technologies under development are continually updated by the DOE on their Carbon Sequestration Program website (www.netl.doe.gov/coalpower/sequestration).

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