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Probabilistic Analysis of Emissions Data <br />To capture the range of uncertainty associated with the data reported by MCC, such as GVB production, <br />the number of GVBs in operation at any one time, and VAM emissions, probability distribution functions <br />were developed by using curve -fitting routines, using Crystal BaIIT`" to model these variables. Crystal <br />Ba IIT"" is an Excel spreadsheet add-in application used for predictive modeling, simulation, optimization <br />and reporting. The probability distribution functions resulting from the curve fitting are mathematical <br />descriptions of these variables that incorporate the full range of historical values and uncertainty related <br />to the available data sets. <br />The probability distribution functions generated in this fashion were then used to forecast probabilistic <br />outcomes by using the probability distribution functions to calculate parameters that indicate the <br />economic performance of the capture and use scenarios explored in this analysis. Forecasts presented in <br />this report are outputs of a Monte Carlo simulation conducted using Crystal BaIITI. A Monte Carlo <br />simulation is a re -iterative process that randomly samples the probability distributions so that every <br />possible value in the data set is used in combination with the other variables for calculating potential <br />outcomes. The resultant is also a mathematical model, or probability distribution that forecasts the <br />range of possible outcomes. <br />This re -iterative process allows for the full range of input values to be used in order to determine the <br />most likely outcome, or pyo value. The pyo value is the median value of the distribution, meaning that <br />there is a 50 percent probability that the value will be greater than the value presented, and a 50 <br />percent probability that the value will be less than the value presented. <br />Other probabilistic outcomes are calculated indicating the probability of that value occurring: <br />• The plo value is used to mean that there is a 10 percent probability that the value will be greater <br />than the value presented, and a 90 percent probability that the value will be less than the value <br />presented. <br />• The p90 value is used to mean that there is a 90 percent probability that the value will be greater <br />than the value presented, and a 10 percent probability that the value will be less than the value <br />presented. <br />Ventilation Air Methane Analysis <br />Presently, West Elk mine management reduces the amount of methane emitted into the mine's <br />workings using a combination of dilution and evacuation of the methane via the ventilation system by <br />using boreholes to drain areas of the mine where coal has been extracted. These areas are known as the <br />gob and they are largely closed off to the active portions of the mine. The low concentrations of <br />methane in the ventilation air indicate that the system is working to effectively keep the miners safe <br />from potential methane related accidents. This is the primary goal of methane management, but a <br />secondary goal should be to reduce the overall emissions of methane to the atmosphere and there is <br />potential to lower the amount of methane that is exhausted by the ventilation system. About two-thirds <br />of the methane liberated by mining is vented, therefore, it is important to understand the volume and <br />concentrations of the methane in the VAM. Our analysis shows that while it may not be possible to <br />achieve a positive economic outcome by using one of several commercially available options for <br />destruction of methane by oxidation, it is technically feasible to do so without endangering miners or <br />5 <br />