Although there is lot of talk these days about electronic aircraft, technology required to develop a large electric transport aircraft remains more than elusive.
Actually, it is beyond imagination, says David Alexander, director at the aerospace standards-setting organisation SAE International.
The primary problem lies in battery technology: an electric-powered aircraft the size of a Boeing 747 would require 90MW at takeoff, the equivalent of 4.4 million laptop batteries, he says.
"No one yet has been able to predict with any certainty, based on technology today, that they would be able to find the right power-to-weight ratio for a fully electric large aircraft," Alexander says. "The only thing we have is a… trust in the ingenuity of aerospace engineers."
That is not to say fully electric large aircraft are impossible.
Indeed, technology can be unforeseen – just 10 years ago many people doubted the viability of electric cars, notes Alexander, whose group serves as a forum through which aerospace companies work together to advance technology.
Several companies recently announced plans to develop electric regional aircraft. JetBlue and Boeing are involved with a company called Zunum Aero to develop a 10- to 50-seat hybrid electric aircraft.
Aerospace companies are already converting some mechanical and hydraulic components to electric equivalents, says Alexander, noting that Bombardier's CSeries has electric brakes.
But such changes can reduce fuel usage by only 3%, he says.
An electric large transport is likely to look wholly different to today's jetliners. For example, the engines might be integrated into the aircraft itself, as with a flying-wing design, he adds.