UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WA SHINGTON, D.C. 20460 OFFICE OF AIR AND RADIATION June 10 , 2010 MEMORANDUM SUBJECT: Example Workbook Calculating the Error of the Mass - Balance Approach in

Estimating Fluorinated GHG Emission s from Fluorinated GHG Production FROM: Deborah Ottinger

Climate Change Division TO: The Record Under the proposed rule for Mandatory Reporting of Greenhouse Gases: Additional Sources of Fluorinated GHGs, facilities interested in pursuing the mass - ba lance approach to estimate their fluorinated GHG emissions from fluorinated GHG production would have to be able to demonstrate that their process measurements and calculation s passed an error test (75 FR 18652, April 12, 2010). Calculations for the test are included in the proposed rule. The workbook entitled “Example Mass Balance Error Calculation.xls” illustrates how the error calculation might work with one well - known production process. This workbook was developed as a "proof of concept," not an a ctual calculation tool. I f EPA finalizes the error test f

or the mass - balance approach, the Agency will provide a more user friendl y tool that will include instructions and background. Nevertheless, by working through the spreadsheets and referring to the corresponding equations in the proposed subpart L regulatory

text, one can see how the error test could be implemented. There are four spreadsheets in the workbook. The first two contain the calculations of interest for the two reactants (one spreadshee t per reactant). The third and fourth provi de background on the reaction and ensure that the masses will actually balance. A facility wouldn't need the third spreadsheet to calculate the error for an actual process because the relevant values would be me asured rather than calculated. To see how the first two spreadsheets work, spreadsheet users should refer to the equations in the proposed regulatory

text whose numbers appear in the heading of each group of columns. In general, the equations appear in the sheet in the order that a facility would solve them to calculate its emissions. Within each equation, the columns on the left side are the inputs, and the last column is the output. The values that are calculated using the mass - balance equations (and error propagation equations) appear in purple. (Since the spreadsheet is just a model, it also2

calculates some of the input values that appear in black, but they would be measured in an actual process.) The calculations proceed from left to right and down . T he outputs of some equations are used as the inputs for the next, both for the emissions calculation and for the error calculation. The values for the percentages of products and b y- products in various streams are h ypothetical. Users of the spread sheet can adjust these, but they should take care to ensure that they are accounting for all masses and flows (e.g., make sure the percentages of the by- product going to the various process streams don't add up to more than 100%). One important note: the spreadsheet uses the example of HCFC - 22 with HFC - 23 as the b yproduct because this is a widely known reaction . The workbook calculates both HCFC - 22 emissions (the product) and HFC - 23 emissions (the by- product). However, HCFC - 22 production is actuall y covered b y subpart O rather than subpart L, and onl y the HFC - 23 emissions, not the HCFC - 22 emissions, are covered by subpart O. Nevertheless, the basic math and logic should be the same for the processes covered b y subpart L.