It is understood that by the end of the century the use of fossil fuels will be substantially reduced either because we have largely exhausted them or because we regulated their use to a minimum.
What's next is unclear because at the present time, other than nuclear energy, nothing comes close to the energy density and portability of fossil fuels.
However, disruptive technologies are in the horizon that may change the way we make power. One such technology that recently crossed my radar screen is solar paint developed at the University of Notre Dame in Indiana.
Called “Sun-Believable,” the paint is still a ways from being commercially available. But its development could ultimately lead to a new generation of inexpensive power generation.
Once able to be produced at a reasonable cost this paint would combine well with neighborhood large battery storage for 24 hour power supply.