(a) With the exceptions set forth in this subpart, the Administrator approves Maine's plan, as identified in § 52.1020, for the attainment and maintenance of the national standards under section 110 of the Clean Air Act.

(b)(1) Insofar as the Prevention of Significant Deterioration (PSD) provisions found in this subpart apply to stationary sources of greenhouse gas (GHGs) emissions, the Administrator approves that application only to the extent that GHGs are “subject to regulation”, as provided in this paragraph (b), and the Administrator takes no action on that application to the extent that GHGs are not “subject to regulation.”

(2) Beginning January 2, 2011, the pollutant GHGs is subject to regulation if:

(i) The stationary source is a new major stationary source for a regulated NSR pollutant that is not GHGs, and also will emit or will have the potential to emit 75,000 tpy CO2e or more; or

(ii) The stationary source is an existing major stationary source for a regulated NSR pollutant that is not GHGs, and also will have an emissions increase of a regulated NSR pollutant, and an emissions increase of 75,000 tpy CO2e or more; and,

(3) Beginning July 1, 2011, in addition to the provisions in paragraph (b)(2) of this section, the pollutant GHGs shall also be subject to regulation:

(i) At a new stationary source that will emit or have the potential to emit 100,000 tpy CO2e; or

(ii) At an existing stationary source that emits or has the potential to emit 100,000 tpy CO2e, when such stationary source undertakes a physical change or change in the method of operation that will result in an emissions increase of 75,000 tpy CO2e or more.

(4) For purposes of this paragraph (b)—

(i) The term greenhouse gas shall mean the air pollutant defined in 40 CFR 86.1818-12(a) as the aggregate group of six greenhouse gases: Carbon dioxide, nitrous oxide, methane, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride.

(ii) The term tpy CO2 equivalent emissions (CO2e) shall represent an amount of GHGs emitted, and shall be computed as follows:

(A) Multiplying the mass amount of emissions (tpy), for each of the six greenhouse gases in the pollutant GHGs, by the gas's associated global warming potential published at Table A-1 to subpart A of 40 CFR part 98—Global Warming Potentials.

(B) Sum the resultant value from paragraph (b)(4)(ii)(A) of this section for each gas to compute a tpy CO2e.

(iii) the term emissions increase shall mean that both a significant emissions increase (as calculated using the procedures in 06-096 1. of Chapter 100 of Maine's Bureau of Air Quality Control regulations) and a significant net emissions increase (as defined in 06-096, paragraphs 89 and 144 A of Chapter 100 of Maine's Bureau of Air Quality Control regulations) occur. For the pollutant GHGs, an emissions increase shall be based on tpy CO2e, and shall be calculated assuming the pollutant GHGs is a regulated NSR pollutant, and “significant” is defined as 75,000 tpy CO2e instead of applying the value in 06-096, paragraphs 143 and 144 D of Chapter 100 of Maine's Bureau of Air Quality Control regulations.