Electric Aviation Takes Flight
Effective electrification could hold the keys to the future of air travel and air superiority.
Many feel our lives enriched by convenient and fast mobility. Our societies and economies have become dependent on the ability to get places quickly in planes, trains and automobiles, but easy mass access to air and road travel now appears at odds with the survival of the planet. We need a zero-emission solution if we are to continue enjoying its benefits, and electrification based on renewable energy appears to offer a way forward. Adoption of electric vehicles is accelerating while development of the internal combustion engine for private automobiles has all but stopped. But what are the prospects for electric aviation?
As in the automotive world, the electric aviation landscape is populated by established aircraft constructors looking to protect their position and high-tech startups seizing the opportunity to disrupt. In the second category, the aptly named Eviation accomplished a first demonstration flight of its Alice full-electric plane in September 2022. As a nine-seater commuter, Alice is a potentially serious commercial proposition – perhaps one of the first. The demo lasted eight minutes, flying at up to 3,500 feet, which compares well with the Wright Brothers’ 12-second flight at Kitty Hawk in 1903. We have come a long way since then.
But there are challenges. Swedish startup Heart Aviation has proposed the ES-19 regional airliner, which it says will have a range of up to 250 miles and fly at about 200 knots. But it will need to lift a 5-ton battery into the air as well as its passengers. To compare that with conventional technology, one US gallon of kerosene weighs about 3kg and a twin-turboprop plane may use around 100 gallons per hour, meaning a two-hour flight may need about 600kg of fuel. On the other hand, the ES-19’s electric motors are considerably less expensive than comparable conventional turboprop engines, and maintenance costs are vastly lower.
As always, we are engineering our way past these problems. Battery development is progressing at a fast pace, driven by universal global demand. Leveraging innovative materials and nanotechnologies will undoubtedly continue to increase the available energy storage per kilogram.
Hydrogen can offer an alternative solution to the weight issues that batteries face. Hydrogen is not only abundant, but it also has the highest energy per kilogram of any fuel. Among established aircraft companies, Airbus is developing hydrogen combustion turbines as well as hydrogen fuel-cell electric engines. A critical challenge, however, is storage. In its gaseous state, at ambient temperature and pressure, hydrogen has very low density. A huge volume of gas would be needed to provide power for a journey. Airbus is addressing this with plans to build its first liquid-hydrogen refueling facility by 2025, as part of a joint venture with ArianeSpace, in time to begin demonstrating its hydrogen-powered planes. Other storage options include ammonia (NH3), which can be liquefied using less extreme temperature and pressure. Challenges here include ammonia’s toxicity and its energy-intensive production methods.
One way or another, zero-emission aircraft are needed if consumer air travel is to have a future. However, electric planes will need to fly farther – and much faster – than at present to be a suitable replacement for military jets. When the sole objective is air superiority, the only option is to choose the technology that gives the upper hand. Clearly, sustainability and the environment are not key priorities for the military – although effective peacekeeping can arguably save wasteful destruction and the environmental burden associated with the rebuilding that comes afterwards.
Reliance on jet fighters may diminish, however, as the influx of new technologies like small and low-cost drones changes the nature of military engagements. These are driving creative new fighting techniques such as “swarming,” or using hundreds of drones to mount a coordinated attack. When weapons like these can be procured in large numbers at relatively low cost, a defense that is expensive to maintain will eventually lose. These include rapid-fire conventional weapons, which have been used effectively against incoming missiles at close-range. They consume vast quantities of ammunition, which also presents storage and transportation challenges.
New laser – or “directed energy” – weapons could be the answer. Some of you may recall the “Star Wars” plan from the Ronald Reagan era, although the power needed to destroy large targets rendered this unfeasible at the time. Today, an entirely achievable 300kW or so can quickly knock out small vehicles like drones. There is no need to store and feed ammunition, and the weapon can be operated at relatively low cost. Even bullets can be electrified, it seems.
The US Navy’s latest aircraft carrier, the USS Gerald R. Ford, is touted as a potential testbed for anti-drone lasers. It is not only large enough and important enough, but it also has twin nuclear reactors that generate several times more power than its predecessors and can handle the electrical demands from several lasers mounted on board. With further technical development, these weapons could become smaller and more efficient while also increasing their effectiveness – simply replicating the exponential improvement that our industry has delivered in numerous technologies from computing and communication to renewable energy.
Electrification looks set to become a critical support for our decarbonized and sustainable future. The sustainability of the trend, however, depends on workable supply chains, and these have become stretched and dispersed over the past few decades as expertise and manufacturing capacity has migrated across the world.
I have commented before about the difficulties of reshoring in relation to the PCB industry. Now, western governments are becoming concerned about technology security in general, from supplies of 5G communication infrastructure to manufacturing capabilities for advanced semiconductors. Re-establishing control will demand considerable financial investment as well as coordination with partners over an extended period. Action is needed if we are to continue setting the pace of electrification in the future.