IMPORTANT!: Please note, that the following graph has a nonlinear axis - each line grows in order of magnitude. Think about it, then it will for sure hit you !!! It is mildly depressing that he published this graph in 2015, at the time when science was supposed to be settled.
"The transition from wood ("traditional biofuels") to fossil fuels—first coal, then oil and natural gas—took more than a century. Today, fossil energy is dominant, with wind and solar making up a mere sliver of the mix. The pace of past energy transitions suggests that a full-scale shift to renewables will be slow."
"Humanity has typically adopted energy sources that have greater "power density," packing more punch per gram and requiring less land to produce. Renewables (green), however, are lower in density than fossil fuels (brown). That means a move to renewables could vastly increase the world's energy production footprint, barring a vast expansion of nuclear power."
"One troubling implication of that density reversal, Smil notes, is that in a future powered by renewable energy, society might have to devote 100 or even 1000 times more land area to energy production than today. That shift, he says, could have enormous negative impacts on agriculture, biodiversity, and environmental quality."
Meanwhile, despite years of promotion and hope, wind and solar account for just about 1% of the world's primary energy mix. In part, he notes, that's because some of the key technologies needed to deploy renewable energy on a massive scale—such as higher-capacity batteries and more efficient solar cells—have seen only slow improvements. The bottom line, he says, is that the world could take many decades to wean itself from fossil fuels.