EPA Accepts Industry Methods for Calculating Warming Potential of Fluorinated Gases

The Environmental Protection Agency has made a preliminary decision to accept industry methods for calculating the global warming potential of seven fluorinated greenhouse gases, approval that will help manufacturers of the gases comply with the agency's broader greenhouse gas reporting rule, according to a Feb. 3 Federal Register notice (77 Fed. Reg. 5514).

The methodologies, originally submitted for EPA's consideration by DuPont and Honeywell International, would be used by industry in calculating and then reporting greenhouse gas emissions as required under the agency's mandatory greenhouse gas reporting rule. The reporting methodologies would apply to five facilities categorized as fluorinated gas production facilities under Subpart L (Fluorinated Gas Production) of EPA's mandatory greenhouse gas reporting rule.

Those facilities are Honeywell International's Buffalo (N.Y.) Research Laboratory and four DuPont plants in Fayetteville, N.C.; Deepwater, N.J.; Washington Works, W.Va.; and Eldorado, Ark.

Honeywell submitted methodologies to EPA for calculating the global warming potential of two types of fluorinated greenhouse gases, HFC-1234ze and HFC-1234yf, according to the EPA notice. DuPont submitted its own methodologies for six others: hexafluoropropylene (HFP); perfluoromethyl vinyl ether (PMVE); tetrafluoroethylene (TFE); 3,3,3-trifluoropropene (TFP); vinyl fluoride (VF); and vinylidine fluoride (VF2). Generally, the global warming potential of fluorinated greenhouse gases is several times that of carbon dioxide.

Stack Testing Threshold

EPA's decision is important to those facilities because an agreed-upon measure of the global warming potential of each compound is needed to determine whether their emissions trigger a requirement for “stack testing”--actual physical monitoring to calculate emissions from vents. If the emissions released by “continuous process vents” in each operation fall below the equivalent of 10,000 metric tons of carbon dioxide a year, facilities can opt to use less costly engineering calculations rather than stack testing.

In general, EPA tentatively concluded that the methodologies submitted by the companies would most likely overestimate and not underestimate the global warming potential of seven of the eight compounds. The agency thus gave preliminary approval to industry-supplied methodologies for all but one: HFC-1234yf.

EPA said Honeywell's methodology for calculating the global warming potential of HFC-1234yf suggested the total quantity of the compound emitted in its manufacturing process would fall short of the EPA threshold that triggers requirements that it report such emissions.

“Because the calculated emissions did not meet the threshold criterion, EPA is not evaluating the provisional GWP for HFC-1234yf in this action,” the notice said. EPA will reconsider the issue in future updates of tables that list the global warming potential for each greenhouse gas, it said.

EPA is requesting comments by Feb. 21 on the preliminary decision on the seven compounds as well as on certain data underpinning its decision. Comments should be submitted to the federal eRulemaking portal at http://www.regulations.gov and should reference Docket OAR-2009-0927.

By Dean Scott