That's why research is needed otherwise researching will take the research duration plus the delay imposed by people saying it won't be here anytime soon anyway.
> perfectly viable power sources like solar, wind, solar-thermal etc.
Until humanity has figured viable massively scalable long term power storage solutions we will always be at the mercy of natural phenomena (time of day, wind speed and direction etc). Additionally AFAIK "renewable power sources" don't have the necessary power density to make them viable as humanity's exclusive power source.