Based on current exponential growth curves, we get 100% of current electricity demand (even after allowing for capacity factor) just from just PV some time around 2032, and 100% of all current primary energy demand 3.5 years after that. And that's without counting any contribution from wind, geothermal, tidal, etc.
Practically this means some combination of the exponential turning sigmoid or energy use going up; but even so, CO2 from energy is no longer something I'm worried about. All the other CO2 sources (steel, aluminium, concrete), all the other non-renewable resources (phosphate), all the other environmental problems (biodiversity loss)? Those are still things to be solved (solutions are known for many and possibly all, but now they must be proven economically). CO2 though, especially from energy, that problem I think we're going to resolve.
Supplying world primary energy demand from PV, if the historical experience curve continues, could drove the cost of PV energy to less than $0.01/kWh, perhaps much less.
Practically this means some combination of the exponential turning sigmoid or energy use going up; but even so, CO2 from energy is no longer something I'm worried about. All the other CO2 sources (steel, aluminium, concrete), all the other non-renewable resources (phosphate), all the other environmental problems (biodiversity loss)? Those are still things to be solved (solutions are known for many and possibly all, but now they must be proven economically). CO2 though, especially from energy, that problem I think we're going to resolve.