The President may specify in any order issued under this section the periods of time during which such order will be in effect and the quantity (or rate of use) of natural gas that may be burned by an electric powerplant or major fuel-burning installation during such period, including the burning of natural gas by an electric powerplant to meet peak load requirements. No such order may continue in effect after the termination or expiration of such natural gas supply emergency.
The President shall exempt from any order issued under this section the burning of natural gas for the necessary processes of ignition, startup, testing, and flame stabilization by an electric powerplant or major fuel-burning installation.
The President shall exempt any electric powerplant or major fuel-burning installation in whole or in part, from any order issued under this section for such period and to such extent as the President determines necessary to alleviate any imminent and substantial endangerment to the health of persons within the meaning of section 7603 of title 42.
In applying the provisions of this section in the case of natural gas subject to a prohibition order issued under this section, the term “petroleum products” (as defined in subsection (h)(2) of this section) shall be substituted for the term “heavy petroleum fuel oil” (as defined in section 717y(e)(7) of this title) if the person subject to any order under this section demonstrates to the Commission that the acquisition and use of heavy petroleum fuel oil is not technically or economically feasible.