Elon Musk has said that hundreds of gigafactories will be needed to replace ICE vehicles with EVs. I beg to differ and will propose a wild ass theory to prove that only 20 gigafactories or 1 Terrafactory will ever be needed for total world auto domination. Let's proceed. One gigafactory will have the capacity to produce 50 GWh of battery packs at 2017 energy density level. Let's assume that in the future consumers will only require 100 kWh average per vehicle. At current density this would give you about 300 miles range, but as energy density increases over time this range will grow owing to ever lighter battery packs improving miles per kWh. So put 20 of these gigafactories together and you get nameplate capacity of 1000 GWh in 2017. Behold the Terrafactory! But how could one Terrafactory be enough to dominate the auto world, you say? Isn't 1 TWh enough only for 10M cars each requiring 100 kWh? Indeed, that is the nameplate capacity in 2017. But let us consider that battery technology will continue to double energy density every 10 years. Moreover, the capacity of the Terrafactory is dictated by the volume and mass of the batteries, not the amount of energy they may hold. Therefore, as energy density doubles every 10 years, so does the TWh output of the Terrafactory. In 2017, 1 TWh. In 2027, 2 TWh. In 2037, 4 TWh. And so by 2050, the great and awesome Terrafactory is pumping out 10 TWh of battery pack, enough for 100M cars each to have 100 kWh and a range over 500 miles. This is total auto world conquest. Behold the Terrafactory!