Nuclear Fission is not a plug and play solution either. Unlike other possible solutions like a breakthrough in mass energy storage, we know that fission could satisfy our needs. But it will still require some 30 years of investment to figure out the new breed of reactors and where to source the fuel from.
That's actually the intent of SMRs. Small-ish reactor (30~300MWe) assembly plants, then ship them wherever they're needed/desired, and either bury them or keep them mobile depending on the purpose. When the fuel load is expended (10~30 years, similar to nuclear subs and ships) you just replace the whole reactor assembly, pop a new one in, and send the old one for recycling and disposal.