Are eVTOLs really the green innovation that aviation needs

How the eVTOL industry overpromised on green

Image credit: Getty Images

Many companies that produce eVTOLs are saying that they can not only replace some air journeys with a greener alternative, but that their main competition is in fact cars. From a green standpoint, these claims don’t fully stand up to examination.

Last year, while moving through the hordes of people at the first Farnborough Air Show in four years, it quickly became clear that a certain genre of stand had stolen the show. Huge crowds gathered to sit in model cockpits or walk around the fuselages of retired prototypes. Their promises were radical – a greener way to fly and the potential for a zero-emission aviation industry. According to the marketing material at least, this had the potential to change everything.

Electric vertical take-off and landing aircraft, or eVTOLs, represent a substantial leap forward in the aviation industry’s path to net zero. Due to limitations in battery technology, electrifying aircraft is no easy feat. The energy density of lithium-ion batteries is around 50 times less than that of jet fuel and thus makes it extremely difficult to power an electric aircraft without adding excessive weight, which would in effect ground it.

The progress made so far is impressive, with some new batteries reaching energy densities around 20 times less than jet fuel and ranges of around 200 miles. After extensive testing, some companies, such as Vertical, are hoping to get certification in the next few years so that they can begin delivery and operation.

However, upon closer examination, some of the claims at Farnborough made little sense, especially talk of replacing car journeys between airports and even in the city itself. Their promises seemed not only outlandish and at times unfeasible, but also potentially damaging to the aim of net zero.

To understand some of these claims, it is important to take a look at the eVTOL industry itself. Firstly, due to the technical limits, every one of these aircraft falls into the small-aircraft category – with most only able to offer space for between two and four passengers. The aircraft themselves are currently not especially quick and their range is often small, almost universally falling below 200 miles.

AIR ONE City Approach

Image credit: AIR ONE

To make matters worse, performance comparisons, even with traditional propeller aircraft, appear to be somewhat unfavourable as these typically offer cruising speeds of 300 knots and ranges of over 1,500 miles (2,400km). Electric propulsion isn’t going to replace wide-body aircraft or even private jets any time soon. This, in effect, limits use cases to short-hop flights – great for greener transport between the Shetland Islands and mainland Scotland, for example, but less useful to the everyday passenger looking to their holiday in Provence.

When looking at performance alone, their competition appears to be helicopters, but this market has seen a 49 per cent decline between 2013 and 2019. However, for investors pumping hundreds of millions and even billions into these companies, the notion of investing into such a limited product, whose most obvious competition has seen a decline in sales, would make most baulk.

That is not to say that eVTOLs couldn’t compete with many light aircraft, but this market alone is possibly not big enough to support so many new entrants. Good innovation is seldom cheap, and if these companies wish to succeed they are largely at the mercy of institutional investors who want returns. With this in mind, it becomes imperative to offer investors the allure of not just an old market, but also a new one.

Much of the press literature coming from eVTOL companies seems to suggest that this new market will come in the form of air taxis. It is these operators who have so far purchased the greatest number of aircraft and will likely dominate the consumer market.

E&T has found that the market strategies of a range of eVTOL companies vary. Some discussed tackling urban congestion (read: replacing cars), while others seek to create new journeys entirely, with others a blend between replacing existing aviation and some other journeys.

Joby Aviation, a major player in the eVTOL industry which has received $1.7bn in funding to date, believes that ridesharing in the air is an invention that will shift the way people live and move. “By rethinking how air travel is delivered, we can open up new ways of moving around congested cities and under-served rural communities, helping to tackle congestion and climate change at the same time.”

The company also believes that it will have eVTOLs flying people across and between cities in an affordable, quiet and emissions-free way, with the firm’s overall vision to provide a service that is accessible to all. “Like any new technology, the service will start at a premium and become more affordable as it scales. But even to start with, the aircraft will be more affordable to operate than traditional aircraft.”

Meanwhile, Wisk, an autonomous eVTOL collaboration between Kittyhawk and Boeing, isn’t seeking to replace any existing form of transport, but rather create a new form of mobility. “Our goal is to operate an air taxi service that allows passengers to skip the traffic and get to their destination faster.”

“One of the unique benefits of eVTOL aircraft is that they do not require a runway and can land vertically on a traditional helicopter landing pad or retrofitted landing site,” says aircraft firm Archer Aviation. “This means these vehicles can fit into the fabric of cities without the need for long airport commutes.”

Graph air transport

Image credit: E&T

The California-based start-up, which signed a $1bn order with United Airlines in 2021, aims to operate its aircraft within cities to solve the challenges around congestion, sustainability, ground infrastructure and public safety. “Our vision is for eVTOLs to gradually integrate into existing systems and infrastructure, prioritising safety, efficiency and accessibility throughout.”

Archer Aviation also believes that, over time, its aircraft will augment existing transport networks in and around city centres and potentially replace helicopters as a safer, quieter and more cost-effective alternative.

While a large portion of the advanced air mobility industry is represented by eVTOL air taxis for commercial use, Israel-based manufacturer AIR is pioneering eVTOL aircraft for personal ownership. AIR’s inaugural vehicle, AIR ONE, offers individual consumers an “exciting alternative” to cars for everyday short-distance commutes.

“Recent changes in the FAA’s approach to this aircraft classifies eVTOLs under the new ‘powered lift’ category, which will require different certification standards compared to the airplane category,” says AIR EV’s CEO Rani Plaut. “eVTOLs will have their own separate and specific pilot training path, which is expected to both shorten and simplify the approval process and, ultimately, speed up eVTOLs’ feasibility for widespread use beginning in 2024.”

While there is some variation in the responses, there are significant worries from the get-go, even before addressing green issues. Discussion of ‘tackling congestion’ simply doesn’t add up. In a city such as London, there are around six million car journeys made every single day, of which around 1.4 million are passenger journeys. Even if thousands of eVTOLs operated throughout the city (which would likely more than double the number of flights around London and require new infrastructure), it is hard to see how this would reasonably make a significant dent on that figure.

Archer’s response is the only one to mention the replacement of existing aviation; it is this approach which arguably makes the most sense, but its position does not seem to appear at the forefront of Archer’s plans.

Freedom from congestion is likely to only meaningfully impact the passengers themselves. It is this which, given the initial premium market target, makes this seem like little more than the rebranding and proposed expansion of the much-maligned private flight – something which nations such as France are either already banning or are in talks to heavily restrict.

Furthermore, and perhaps of greater concern, Joby’s claim of ‘emissions-free’ transport displays a lack of nuance and adequate consideration when calculating carbon footprint. There are likely to be substantial emissions from both the production of batteries, materials used in construction and power generation itself, and neglecting upstream and downstream emissions in such a way would not meet EU ETS standards on emissions reporting.

Given offering the opportunity to fly green is the very principle that eVTOLs are built off, this requires further examination.

Creating new demand out of nothing, as suggested by Wisk, undermines the very principles of green innovation. If one creates novel journeys where previously none would have been undertaken, it will always be more emissive than inaction. Similarly, if one reduces emissions to 25 per cent of what they were previously, but then this activity is undertaken 10 times more frequently, emissions are in fact higher. It is this trap which can ruin the efficacy of green strategies.

Joby Aviation Aircraft

Image credit: Joby

Where are the green benefits?

There is also the question of whether replacing congested ground traffic with aircraft, especially in an increasingly electrified motor industry, would actually deliver any green benefits at all. A 2019 study led by students at the University of Michigan led to what initially seems to offer relatively favourable results. Three passengers in an eVTOL would emit 6 per cent less emissions than an electric car carrying 1.54 passengers over 100km and 52 per cent less than a petrol car. For shorter journeys, the figures are far less favourable as the energy expended in take-off and landing remains unchanged.

However, when delving deeper, these figures become more worrisome. Firstly, if assuming the same number of passengers, the eVTOL is a far worse performer than an electric vehicle and not much better than a petrol car. This is dependent on ridesharing working as it should do, which is hard to promise for a scheme that hasn’t been fully implemented. When compared to public transport, it is far worse. Secondly, and perhaps most crucially, the study does not consider lifecycle stages such as production. In electric cars, the contribution from production makes up around 46 per cent of the vehicle’s lifetime emissions, with much of this coming from battery production. In comparison, eVTOLs tend to have far larger batteries than comparable cars, with the AVA XC, for example, having two 124kWh batteries in comparison with the Tesla Model Y’s singular 82kWh.

Finally, and equally as significant, as heliports are not nearly as widespread as roads, it is highly likely that cars or some other form of transport would be needed to, at the very least, take passengers and perhaps even crew to launch-sites at each end, further adding to emissions.

In essence, it is still unclear whether there would be any real emissions benefits when comparing eVTOLs to cars and it is not impossible that in many cases they might be far worse.

While eVTOLs do likely hold an important place in the future of aviation, strategy and implementation are just as important as the engineering itself when it comes to successfully achieving aims. This is an example of a brilliant set of innovations which have been forced beyond their remit by the influence of investors and capital.

These aircraft will surely be brilliant; far greener, safer replacements when compared to very-short-haul light-aircraft/helicopter flights and air-ambulance services, but the notion that they are a viable green replacement for the car, especially when compared to other public transport innovation, does not stand up to much scrutiny.

The uncomfortable truth is that if green targets are going to be achieved, we need to shrink the markets for polluting activities rather than grow them. Aviation will, for the foreseeable future, always have a high energy demand relative to the number of people it carries and, even with the best technology we have, it will remain a relatively polluting method of transport. This is only set to get worse rather than better. While the aviation industry currently contributes around 2.4 per cent of global CO2 emissions, it is predicted that as other industries are able to clean up their act faster, this could reach around 22 per cent by 2050. Soaring demand for flights will be a big part of this, and expanding this demand won’t help.

While there is an argument that such innovation could lead to emissions reductions down the line, wide-body aircraft, which are the greatest polluters, are projected to arrive in electric versions at the very earliest by around 2040, with some predicting this to be far later.

In the meantime, growing the aviation industry, no matter how it is powered, could prove disastrous for people and the planet.

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