California Association of Sanitation Agencies
On May 13, 2010, US EPA published its final Tailoring Rule. The Tailoring Rule lays out Prevention of Significant Deterioration (PSD) and Title V Major Source permitting requirements for greenhouse gases (GHGs) under the Federal Clean Air Act. It is called the Tailoring Rule because it “tailors” the thresholds from the usual 100 or 250 tons/year thresholds used in the Clean Air Act for criteria pollutants to higher thresholds that are more implementable for GHGs.
Though the rule does not distinguish between anthropogenic emissions (e.g., GHGs from fossil fuel combustion) and biogenic emissions (e.g., GHGs from combustion of biomass fuels such as landfill or digester gas), on July 1, 2011, EPA issued the “Deferral Rule” deferring the permitting requirements for biogenic sources of carbon dioxide (CO2), including wastewater treatment plants and combustion of biogas, for a period of three years (through July 1, 2014). As part of the Deferral Rule, EPA established a panel of experts serving on a Scientific Advisory Board to study the issue of how best to address biogenic emissions under the Clean Air Act.
The Deferral Rule was a very positive development for the wastewater community and consistent with comments that CASA and the California Wastewater Climate Change Group (CWCCG) submitted in response to the original Tailoring Rule. Unfortunately, on July 12, 2013, the US Court of Appeals for the District of Columbia vacated the Deferral Rule on the grounds that EPA failed to adequately justify the need for it. The ruling calls into question whether EPA will now begin to regulate biogenic sources of CO2, or whether (and how) CO2 emissions from composting and anaerobic digestion activities are to be regulated going forward. Potential near-term impacts may include regulation of all sources of CO2 emissions from processes regulated under the EPA’s Mandatory Reporting Rule (MRR), and larger facilities may be in danger of triggering the PSD.
Fortunately, the court did not foreclose the possibility of a future exemption for biogenic sources. The court specifically noted that it “leaves for another day the question whether the agency has authority under the Clean Air Act to permanently exempt biogenic CO2 emission sources from the PSD permitting program.” It is possible that additional information regarding a potential permanent exemption will be forthcoming in early 2014.