Really, solar is a no brainer. Why is it that no one has any brains?
Solar will be a no-brainer when we get cheap, durable, efficient batteries with which to store energy from when solar supplies it to when we need it: night, cloudy weather, winter.
Even then we will probably still need chemical fuels for aircraft, though there's no reason they can't be agricultural products.
And ROCKET FUEL!
Our skulls have to fit through our mothers' birth channels and therefore cannot get big enough for really good brains ?