I think it depends on what our goals are. If we are just trying to replace current electricity capacity with renewables, the I think solar/wind/etc. + batteries

I think it depends on what our goals are. If we are just trying to replace current electricity capacity with renewables, the I think solar/wind/etc. + batteries are fine and can be done relatively quickly (though keep in mind new coal plants are still being built!). If our goal is to completely replace all fossil fuels, then I think it will take a lot longer (I think like 100 years) and requires serious investment in battery production such as described in Tesla Master Plan Part 3. However if the goal is all of the above, but also start removing CO2 from the air, I think only something like a fusion breakthrough will make it work. We will need to generate like and order of magnitude more energy to do this. Also we have to realize that while renewables are growing, so are fossil fuels! See https://ourworldindata.org/grapher/electricity-prod-source-stacked https://ourworldindata.org/grapher/electricity-prod-source-s... our total energy usage is increasing, so in order to replace all fossil fuels, you have to not only take up the new demand, you have to eat into the existing, almost like a double exponential! (not sure if the right term)