Part 4/12:
The critical driver of electric flight is battery energy density. Musk has long argued that once batteries reach around 400 watt-hours per kilogram (Wh/kg), electric jets become a practical reality. Today, high-tech battery manufacturers like Emprius are nearing this threshold, delivering batteries capable of up to 450 Wh/kg. This is a significant leap from previous generations and suggests that the core energy requirements for electric flight are within reach.