EOL/ACD Seminar: Improving coal fire emission inventories: A comparison study of two methods

Larry Radke

University of Washington

National Center for Atmospheric Research

  Airborne Research Consultants, LLC.

Besides physical hazards, uncontrolled coal fires also pose other direct hazards including the emission of pollutants, such as sulfur dioxide (SO2), hydrogen sulfide (H2S) carbon monoxide (CO), particulate matter (PM); air toxics releases such as arsenic (As), selenium (Se) and mercury (Hg); and greenhouse gas (GHG) emissions such as carbon dioxide (CO2), nitrous oxides (NOX) and methane (CH4). Few studies have concentrated on the immediate health impacts of coal fires or the contribution of coal fires to the global atmospheric CO2 burden.  Current estimates are poorly constrained by observations and highly uncertain.

  • Estimates of the amount of coal wasted by coal fires, range between 20 and 600 megatons per year (0.5-10% of global annual coal production).
  • Coal fires in China alone may emit as much CO2 annually as do all U.S. motor vehicles.
  • The Electric Power Research Institute (EPRI) estimates global coal fire Hg emissions to range from 0.2 to 780 (metric) tons per year with an average range of 26-78 tons per year or up to one-third of documented global anthropogenic Hg emissions. In comparison, the U.S. coal-fired power plants   emit ~44 tons of Hg annually.

 In a first attempt to reduce uncertainties, we applied a combination of independent airborne infrared (IR) and direct, surface-based, observational studies of the vented combustion products of active coal fires in the coal beds of the Powder River Basin (PRB) Wyoming, USA. Two separate case studies were explored in May, 2009: 1) Welch Ranch fire, and 2) Ankney fire (partial emissions). The PRB was selected to test 1) the use of the USGS flux chamber to estimate diffuse emissions for an entire fire, not just transects; in combination with vent emissions to get total CO2 emissions for a fire and 2) ARC’s airborne heat flux measurement, in combination with known coal energy density, to calculate the rate of coal combustion and thus total CO2 emissions for the same fire. 

Our two independent measures are in good agreement for the Welch Ranch coal fire, using the remote sensing thermal flux method we estimated a coal combustion rate of 2 – 4 metric tons per day (Mg d-1), corresponding to 4 – 9 Mg of CO2 d-1, and we found total (diffuse and vent) CO2 emission rates of 12 ± 4 Mg d-1 from ground observations. In addition, we observed that the vent emissions of CO, CH4 (kg d-1), H2S (g d-1), and Hg. While analysis and corrections continue, these results indicate that within known limitations, it is possible to reduce the uncertainty in calculating the global impact of coal fires by direct measurements and airborne remote sensing observations.

 

Friday February 18, 2011, 2:30 PM - 3:30PM

Refreshments 2:15 PM

NCAR-Foothills Laboratory

3450 Mitchell Lane

Bldg 2 Auditorium (Rm1022)

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Friday, February 4, 2011
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Friday, February 18, 2011