They assume that renewable energy will still only be 17% of the energy production in the USA by 2040. in 2018 we already have over 17% of the energy generation coming from renewable energy. That and Tesla cars are more efficient now (especially the model 3) that you can't say the CO2 burden is equal.

But in reality, the thing I care most about is getting to the point of near-infinite energy storage and then seeing how civilization can use that to build a more awesome future. 🙂