Section 504.7 - Prohibition against excessive use of petroleum or natural gas in mixtures-electing powerplants(a) In the case of electing powerplants, if OFP finds that it is technically and financially feasible for a unit to use a mixture of petroleum or natural gas and an alternate fuel as its primary energy source, OFP may prohibit, by order, the use in that unit of petroleum or natural gas, or both, in amounts exceeding the minimum amount necessary to maintain reliability of operation consistent with maintaining reasonable fuel efficiency of the mixture.(b) In making the technical feasibility finding required by former section 301 (b) and (c) of the Act and paragraph (a) of this section, OFP may weigh "physical modification" or "derating of the unit," but these considerations, by themselves, will not control the technical feasibility finding. A technical feasibility finding might be made notwithstanding the need for substantial physical modification. The economic consequences of a substantial physical modification are taken into account in determining financial feasibility.47 FR 17045, Apr. 21, 1982, and 47 FR 50850, Nov. 10, 1982 Energy Supply and Environmental Coordination Act of 1974, Pub. L. 93-319 , as amended by Pub. L. 94-163 , Pub. L. 95-70 , and 15 U.S.C. 719 et seq.; Department of Energy Organization Act, Pub. L. 95-91 , 91 Stat. 565 (42 U.S.C. 7101 et seq.); Powerplant and Industrial Fuel Use Act of 1978, Pub. L. 95-620 , 92 Stat. 3269 (42 U.S.C. 8301 et seq.); Omnibus Budget Reconciliation Act of 1981 (Pub. L. 97-35 ) ; E.O. 12009, 42 FR 46267, Sept. 15, 1977