Electric and hybrid cars have been on the market for several years now and, albeit with some slowness, they are becoming more and more present on the roads all over the world, making a fundamental contribution to reducing CO2 emissions. But if electric power is now considered an efficient alternative to traditional fuel for cars, the same cannot be said for another means of transport used daily by millions of people and very polluting: the plane.
Duncan Walker, professor of applied aerodynamics at the University of Loughborough, in the United Kingdom, told on The Conversation website about how in recent years studies have increased to introduce electric power also on airplanes, but that for the moment the the hypothesis of electric planes flying long distances seems distant. Walker writes that airplanes contribute only 2 to 3 percent of global CO2 emissions – a small fraction of the 30 to 35 percent produced by the transport sector as a whole – but that over the next twenty years it is expected that the number of passengers on air flights will double, and it will become necessary to find alternative sources of power to fuel.
The biggest problem, according to Walker, is the low range of electric batteries compared to fuel, due to the lower energy density that can be stored: fuel contains 30 times more energy per kg than the most advanced lithium-ion batteries. Walker gives the example of the Airbus A380, one of the largest airliners in the world, which can carry up to 600 passengers and cover 15,000 km in a row.
According to Walker's calculations, the same plane, if powered by electric batteries, could travel just over 1,000 km, and even if it made room for other batteries by replacing all the passengers and the plane's cargo, it could still travel less. of 2,000 km. Another problem, Walker points out, is that a fuel-powered plane becomes lighter during travel – and therefore consumes progressively less – while an electric plane keeps its weight unchanged, and this affects range.
Nonetheless, studies on possible solutions have been going on for years, even by the large aeronautical companies. British low-cost airline EasyJet, for example, announced in 2017 that it had begun development of an electric aircraft capable of carrying 180 passengers together with the company Wright Electric, and estimates that it would be able to put it on the market by 2027. In March 2018 Instead, the Israeli company Eviation presented the prototype of an airplane equipped with three electric motors produced by the Australian MagniX, capable of covering short distances (about 1,000 km) and carrying a maximum of 9 passengers. The first flight of this prototype, called Alice, is scheduled for 2022.
While fully electric airplanes at the moment remain a distant hypothesis and in an embryonic phase, the possibility of a middle ground is closer, as is already the case with cars. In fact, Airbus, Rolls-Royce and Siemens are collaborating to create a hybrid aircraft that can carry about 100 passengers and is ready for flight around 2030. In the tests conducted so far, a BAe 146 aircraft has been used, in which one of the four propellers is powered by an electric motor.
Other alternatives are the use of more performing electric batteries such as lithium-oxygen batteries, currently under study, and a radical change in the way aircraft are built. One idea, Walker writes, is to build planes that are composed of a single piece, in which the fuselage and wings are welded, a shape that would allow many small electrically powered thrusters to be distributed throughout the plane's body. At the moment, however, neither Boeing nor Airbus, the two largest aircraft manufacturers in the world, seem willing to go down this path, given all the technological difficulties it would entail.
