There is a good article on electrically powered light aircraft under development in this month's Air & Space Magazine. The key element in their future seems to be batteries. Right now they can get only about 20 min of flight time. The article states that there are batteries under development that will allow significantly longer flights. This seems like the statements made about fusion power, great long life batteries always seem to be just around the corner. And yet my cellphone will only run off it's charger about 15 minutes.