((a)) ** Permanent exemption due to lack of alternate fuel supply, site limitations, environmental requirements, or adequate capital**

((1)) After consideration of a petition (and comments thereon) for an exemption for a powerplant from the prohibitions of part A, the Secretary shall, by order, grant a permanent exemption under this subsection with respect to natural gas or petroleum, if he finds that the petitioner has demonstrated that despite diligent good faith efforts—

((A)) it is likely that an adequate and reliable supply of coal or other alternate fuel of the quality necessary to conform with design and operational requirements for use as a primary energy source (i) will not be available within the first 10 years of the useful life of the powerplant, or (ii) will not be available at a cost (taking into account associated facilities for the transportation and use of such fuel) which, based upon the best practicable estimates, does not substantially exceed the cost, as determined by rule by the Secretary, of the fuel that would be used as a primary energy source during the useful life of the powerplant involved;

((B)) one or more site limitations exist which would not permit the location or operation of such powerplant using coal or any other alternate fuel as a primary energy source;

((C)) the prohibitions of part A could not be satisfied without violating applicable environmental requirements; or

((D)) the required use of coal or any other alternate fuel would not allow the petitioner to obtain adequate capital for the financing of such powerplant.

((2)) The demonstration required to be made by a petitioner under paragraph (1) shall be made with respect to the site of such powerplant and reasonable alternative sites.

((b)) ** Permanent exemption due to certain State or local requirements** After consideration of a petition (and comments thereon) for an exemption for a powerplant from the prohibitions of part A, the Secretary may, by order, grant a permanent exemption under this subsection with respect to natural gas or petroleum, if he finds that the petitioner has demonstrated that—

((1)) with respect to the proposed site of the powerplant, the construction or operation of such a facility using coal or any other alternate fuel is infeasible because of a State or local requirement (other than a building code or a nuisance or zoning law);

((2)) there is no reasonable alternative site for such powerplant which meets the criteria set forth in subsection (a)(1)(A) through (D); and

((3)) the granting of the exemption would be in the public interest and would be consistent with the purposes of this chapter.

((c)) ** Permanent exemption for cogeneration** After consideration of a petition (and comments thereon) for an exemption from one or more of the prohibitions of part A for a cogeneration facility, the Secretary may, by order, grant a permanent exemption under this subsection with respect to natural gas or petroleum, if he—

((1)) finds that the petitioner has demonstrated that economic and other benefits of cogeneration are unobtainable unless petroleum or natural gas, or both, are used in such facility, and

((2)) includes in the final order a statement of the basis for such finding.

((d)) ** Permanent exemption for certain mixtures containing natural gas or petroleum** After consideration of a petition (and comments thereon) for an exemption for a powerplant from the prohibitions of part A, the Secretary shall, by order, grant a permanent exemption under this subsection with respect to natural gas or petroleum, if he finds that the petitioner has demonstrated that—

((1)) the powerplant uses, or proposes to use, a mixture of petroleum or natural gas and coal or another alternate fuel as a primary energy source; and

((2)) the amount of the petroleum or natural gas used in such mixture will not exceed the minimum percentage of the total Btu heat input of the primary energy sources of such powerplant needed to maintain reliability of operation of such powerplant consistent with maintaining a reasonable level of fuel efficiency, as determined in accordance with rules prescribed by the Secretary.

((e)) ** Permanent exemption for emergency purposes** After consideration of a petition (and comments thereon) for an exemption from one or more of the prohibitions of part A for a powerplant, the Secretary shall, by order, grant a permanent exemption under this subsection with respect to natural gas or petroleum, if he finds that the petitioner has demonstrated that such powerplant will be maintained and operated only for emergency purposes (as defined by rule by the Secretary).

((f)) ** Permanent exemption for powerplants necessary to maintain reliability of service** After consideration of a petition (and comments thereon) for an exemption for a powerplant from one or more of the prohibitions of part A, the Secretary may, by order, grant a permanent exemption under this subsection with respect to natural gas or petroleum if he finds that the petitioner has demonstrated that—

((1)) such exemption is necessary to prevent impairment of reliability of service, and

((2)) the petitioner, despite diligent good faith efforts, is not able to make the demonstration necessary to obtain an exemption under subsection (a) or (b) in the time required to prevent such impairment of service.