As I'm sure you know, the electric Pipistrel Taurus G4 won the CAFE Foundations Green Challenge prize for the most efficient aircraft in the world. The 4-place aircraft managed to fly to the equivalent of 400mpg/person! That's obviously less gas/person than any aircraft has ever done before (and it relegated the former high scorer Boeing's 787 Dreamliner to the back row). But what's even more impressive is that it's less than any hybrid or electric car has ever managed as well! The G4 flew almost 200 miles and still had to have an equivalent of a "reserve" charge left when they landed. It averaged about 100mph.
Even with batteries so low in capacity as they are, it shows that you can still achieve almost usable performance. Today. What will happen when batteries double, quadruple?
BTW, I just recently learned a new fact - who is the biggest single user of electricity? Oil refineries. They need tremendous heat to be able to crack and refine crude oil. Apparently, just putting the electricity they use back into the grid would cover any electric vehicle recharging programs. So the efficiency if this gets factored in, is even less for fossil fuel engines. Maybe below 20%, even. So if the energy density of 12Kwh/kg for gas only in real life is closer to 2.4kwh/kg, then today's batteries with 0.5kwh/kg are not so far off. Even with a doubling of capacity (1kwh/kg), it will start to be a real contender due to the low weight of electric propulsion systems. The bell is tolling for fossil fuels...
But the most exciting fact for me personally, is that in the near future we'll start to see technology that's accessible and cheap enough for multiple developers to use. This means that the future might hold a true revolution in personal transport. It also means that there's a potential to reverse the decline in GA and the decline in pilots. It might just be that in 50 years time, the cheapest way to get from London to Paris might be in your own electric aircraft that you tow to your garage and charge there. Isn't this exciting?