EPA’s Environmental Appeals Board has rejected the Sierra Club’s attempt to require certain greenhouse gas (GHG) limits in a preconstruction permit for a new natural gas power plant, in one of the first EAB decisions to address this issue.  In re: La Paloma Energy Center, LLC, PSD Appeal No. 13-10 (EAB Mar. 14, 2014).  In La Paloma, EPA Region 6 issued a prevention of significant deterioration permit allowing construction of a natural gas-fired power plant in Texas.  In rejecting Sierra Club’s challenges, the Board indicated that it generally will defer to the permitting authority on technical issues relating to GHG limits, but that it reserves the authority to reject insufficiently explained determinations and expects permitting authorities to provide clear justifications for rejecting more stringent GHG limits proposed by those who comment on permits.

Notably, the Board suggested that in some cases it may be appropriate to require such power plants to include supplemental solar power generation as a Best Available Control Technology (BACT) to reduce GHG emissions, which could result in future natural gas plants being required to install supplemental solar power systems (or other alternative energy sources), even where the permit applicant did not suggest or envision the use of such systems.  Indeed, the Board suggested that it may well be improper for a permit applicant to “purposefully avoid[] use of solar hybrid technology in its proposed design to circumvent BACT analysis” of such technology.  If the use of such technology was required by a future BACT determination, it could be subject to challenges in court.

The Sierra Club raised two challenges to the permit, both of which the Board rejected.  First, the Sierra Club claimed that the Region erred in allowing the permittee to select between three different turbine models, each of which had a different limit on GHG emissions, and instead should have imposed the lowest GHG emission limit, based on the emissions that would be generated from the most efficient model.  The Board rejected this argument, finding that the BACT analysis required a comparison of “general types or categories of control technologies,” not a comparison between “specific equipment models.”  Moreover, the Board found that the difference in emission rates of the three proposed turbine models were “marginal,” and so the models could be treated as equivalent for BACT purposes.

In its second challenge, the Sierra Club argued that the Region should have required as BACT that the plant use a supplemental solar thermal system to reduce its GHG emissions.  The Board rejected this argument, finding that such a proposal would “redefine the source” because of site-specific constraints on the facility – namely, a lack of space for sufficient solar panels.   However, the Board criticized the region for not taking a sufficiently “hard look” at whether supplemental solar power would be viable, and made clear that an applicant’s decision not to propose supplemental solar power generation does not automatically mean that such a system is excluded from BACT analysis.  The Board made clear that permitting authorities should provide “a clear and full explanation of any decision to reject comments suggesting the use of a solar component at a proposed facility on the grounds that it would require redefinition of the source.”