Gas is most inefficient in what way? You think wind and solar are efficient? How many acres of land would you have to use to build a solar farm big enough to produce the same amount of power as a 1200 MW gas plant? Or how about wind farms, which just start dropping blades or burning up nacelles after about 8 years? Not to mention solar doesn't work at night and the wind doesn't always blow for the wind turbines, so even if producing the same amount of power, they aren't as reliable as a gas plant. Battery technology has to come a LONG way for those sources to be reliable, and that's very dependent upon China who aren't the most forthcoming with their testing and standards.
There's no perfect answer, but gas and nuclear are critical. I'm optimistic about modular nuclear down the road. The waste is a non-issue in the scheme of things. There is a place for renewables in the mix, but we would all be better off if more money was spent on R&D to make them actually competitive and cost efficient instead of just throwing more tax credits at production of poor technology. The whole industry is currently propped up by poor ESG logic, tax credits, Tax equity, hopes and dreams.