10 CFR 503.14: Fuels search.

Prior to submitting a petition for a permanent exemption for lack of alternate fuel supply, site limitations, inadequate capital, or state or local requirements, a petitioner must examine the use of conventional solid coal as a primary energy source at the site under consideration, and at reasonable alternative sites. Where a petitioner believes that its use of such coal would be infeasible, however, and where OFE and the petitioner can reach accord, it may evaluate use of a different alternate fuel in lieu of solid coal. A petitioner of these exemptions must demonstrate for any fuel examined that he would qualify for an exemption.