Aviation is responsible for 2% of the world’s carbon dioxide emissions; it is a highly polluting means of transportation. Dramatic action needs to be taken to make the industry more environmentally friendly and sustainable. Electric powered planes may be the answer, but are we likely to see them this century?
Norway certainly seems to think so; they have ambitious plans to cut their carbon emissions by ensuring all short-haul flights leaving their airports are powered by electricity by 2040. Electrifying aviation could limit climate change by reducing the industry’s contribution to greenhouse gas emissions and the release of nitrogen oxides and particulates.
Electric flight is a hot topic in aircraft engineering; as of May 2019, there are around 170 electric aircraft programs in development. Many manned electric planes are in the experimental stages – powered by electric motors driving thrust-generating propellers or lift-generating rotors.
Electricity can be supplied in various means, and although some success has been seen with solar cells, for example, Solar Impulse 2 which circumnavigated the Earth using solar power in 2015-16, the general consensus is that batteries are the way forward.
However, the flight is a difficult challenge – an aircraft carrying dozens of passengers and their luggage requires a lot of energy to get off the ground and stay in the air. A key limitation for aircraft is the energy density of fuel; space and weight are at a premium so you need to pack as much energy in as small a space as possible.
Jet fuel has a high energy density, and modern planes are light and use their fuel economically. Batteries, on the other hand, can hold a lot of power but are much bigger. Swapping jet fuel for batteries and their electronic systems adds weight and therefore limits the flight range.
So, the challenge is to build batteries powerful and cheap enough for planes to fly on clean electricity. It is doubtful this will be realized until the middle of the 21st century, so it’s likely that the first generation of large-scale electric planes will use hybrid technology to ensure energy needs are met.
Demonstrating the Technology
Small-scale electric flight has already been demonstrated in Norway. In July 2018, transport minister Ketil Solvik-Olsen joined Dag Falk-Petersen, the head of the country’s airport company Avinor, on a flight in an Alpha Electro G2, a two-man electric plane built by Pipistrel.
However, there are no airliner-sized electric-powered aircraft being built; manufacturers such as Boeing, Zunum Aero and Pipistrel are developing much smaller electric aircraft, with the latter suggesting that training aircraft, where the emphasis is on short flights, are likely to make up the bulk of the electric plane market.
Norway wants manufacturers to build electric planes for 20 to 30 passengers by 2025. Pipistrel has plans for a 19-seater passenger aircraft that is likely to be powered by a hybrid fuel cell to begin with, while Zunum Aero has plans for a 12-seater short-haul airliner by 2022 and a 50-seater with a range of 1,000 miles by 2027.
The impact of such projects will be felt outside the immediate area; planes leaving Norway will be landing in other countries, who will need charging stations, and may then adopt the technology themselves.
Other benefits might include shorter runways and smaller airports, less noise pollution – meaning earlier and later flights might be possible – and lower running cost. This in turn might could lead to cheaper tickets, a powerful driver via consumers for change.
The potential of electric and hybrid-electric is clear, however, it is likely to be limited to short haul flights, where battery technology will not be a limiting factor. Furthermore, electric flights will radically change the design of such aircraft and aviation in general, while having the added benefit of shrinking the environmental footprint of air travel.