It’s the end of the line for the proposed Killingly natural gas plant as far grid operator ISO-New England is concerned, at least for the immediate future. Two rulings in the last two weeks, one by the Federal Energy Regulatory Commission and the other by the U.S. District Court of Appeals in Washington D.C., paved the way for the ISO to complete its recent annual auction that determines future power sources for use by the New England grid. It’s unclear whether Killingly’s owners, NTE, have additional recourse to force the ISO to include the plant — and, if they do, whether they would use it. While the state and especially Lamont have been blunt about not wanting Killingly, under the current system there’s really no way for the state to stop it. If all the criteria for permits are met, the state has to issue them. In fact, Killingly has almost all its permits.