Electric vehicles have become a mainstream option for e-mobility on our roads, and electric aircraft are showing promising early progress.
While hybrids and electric vehicles are firmly on the road as even the best e-mobility option for many consumers, electric planes are mostly still in the hangar, at least where large kerosene-fuelled jets are concerned. The real progress thus far has been in small planes, holding a pilot and maybe an extra passenger.
Why? The limitations at the moment are precisely around energy, and energy density. Battery packs can’t provide the same amount of energy as jet fuel, which packs far more energy per kilogram. Even the best battery technology still has just six per cent of the energy density as jet fuel – and modern batteries remain cripplingly heavy, as well.
In aviation, this is an issue. Weight is the foremost concern of every decision that is made for plane manufacturers and airlines, where every kilogram is stripped out for better fuel efficiency, and lower emissions. (One 2004 study estimated that the obesity epidemic in the US through the 1990s forced domestic carriers to burn an additional billion kilograms of jet fuel – another reason to eat healthily!)
Still, the use of electric-turbines is up to 20 to 30 percent more efficient over conventional kerosene powered turbofan engines. There’s also a reduction of up to 30 per cent of fuel requirements, and there are no local emissions. Electricity is ten times cheaper than jet fuel and can be sourced from renewables wherever possible, although this shouldn’t be considered excessively green. Maintenance costs should also be significantly reduced.
That implies a useful lifecycle improvement over conventional craft, despite the current limitations.
Of course, not all aviation is done on a jumbo-jet. But even if larger-scale transportation is at least a decade away, much smaller electric aircraft may be able to shake-up traffic flows, replacing helicopters, and some vehicles.
Hybrids and pure-electric planes – right now
One pure-electric example from Munich in Germany is the Lilium Jet, which can take-off and land vertically.
The video shows encouraging signs, but has been carefully edited to remove the noise of the aircraft, which is likely to be significant although hopefully less than helicopters or small planes. In addition, the Jet is shown without passengers, another 150-200kg of crucial cargo that needs to be catered for.
More conventional pure-electric aircraft, without vertical landing or takeoff, are already available from Pipistrel, who are taking orders for multiple electric aircraft, including the Alpha Electro aircraft. This plane has a flying time of one hour, and has a very short takeoff distance, with a co-developed Siemens motor, and can be recharged in as little as 45 minutes.
In 2015, Airbus crossed the Channel with the E-Fan, the world’s first twin-engine electric plane, taking 37 minutes to jet 74kms from Lydd, England to Calais, France.
(In fact, Pipistrel were attempting the same challenge three days earlier before Siemens pulled support, citing issues flying their engine over water. Many suspect that their sponsorship of the E-Fan flight played a larger role!)
Boeing have their own engineers busy, working on both concept electric and hybrid planes, including the SUGAR Volt concept which combines battery power and fuel to power flight, as per hybrid cars such as the Toyota Prius.
Autonomous flight is another area of interest with e-mobility, with the emergence of small planes considered a type of drone that may be able to quickly transport people around in a ride-sharing capacity.
It will no doubt be some years before you can boast about crossing your busy city in just a few minutes, but e-mobility will have an extra dimension in time to come.