Turbulence Ahead: The Challenges of Electric Aviation

Through the fledgling eVTOL (Electric Vertical Take-off and Landing) aircraft industry, the electric aviation sector has gained significant attention in recent years, with promising new horizons of sustainability, affordability, and accessibility. Forecasts have suggested that by 2040, the industry could become $192 billion USD industry. This has fuelled substantial investments worldwide. Yet, the realisation of electric aviation’s full potential hinges on overcoming an array of significant technical, infrastructure, and supply chain hurdles.

At its core, the key to electric aviation lies in the advancement of battery technologies and electric motor evolution. Additionally, alternative energy solutions such as hydrogen fuel cells seek to complement batteries. While concerns loom over the scarcity of rare earth minerals, what is equally concerning is the apparent lack of basic arithmetic comprehension in the industry.

Simple Mathematics

To illustrate the challenges of electrifying of existing commercial aviation, consider the energy requirements of a Boeing 737, a workhorse of both civil and military aviation.

The Boeing 737-400 variant has an empty weight of around 35,040 kg. When fully loaded with 130 passengers, cargo, crew, and 20,000 litres of jet fuel, it reaches a maximum take-off weight (MTOW) of 65,500 kg. To match the energy provided by 20,000 litres of traditional jet fuel, an electric aircraft would need to store 694,000 Mega Joules (MJ) of energy– equivalent to powering over 65,000 average family homes for a day – within the same MTOW constraint. However, current lithium-ion battery technologies fall far short of this requirement:

  • Standard Lithium-Ion Batteries would require roughly 771,000 kg of batteries to power the aircraft, exceeding the 737’s MTOW by over 10 times.
  • Theoretical Limits of future Lithium-Ion Batteries still demand 365,000 kg of batteries, over 5 times the MTOW.
  • Lithium-Carbon Fluoride Batteries require 264,000 kg of batteries, which is 4 times the MTOW.
  • Lithium-Sulphur Batteries need 77,000 kg, but still exceed MTOW by 50%.

Even when considering the higher efficiency of electric motors, assuming a 2.2x efficiency gain, the most advanced lithium-sulphur batteries would still require 35,100 kg, leaving only 7,750 kg for energy storage after accounting for useful load. This implies an impractical battery-specific energy density of 41 MJ/kg, over eight times more than the best current battery technologies in laboratories.

This very basic calculation shows the chasm between existing battery technology and the energy storage demands of commercial aviation. This still doesn’t take the effective same landing weight being the same as take-off, which has many other factors, questions and considerations.

While optimism exists for future improvements in battery energy densities, charging rates, and lifecycles, a comprehensive rethinking of every aspect of the aircraft is necessary, electric motor innovation should be a pivotal starting point for advancements in aviation.

Ongoing innovations, advances, and investments in electric motor technology have transitioned them from secondary components to primary propulsion drivers in aircraft like the Boeing 787 Dreamliner. The 787 features an advanced electric architecture, utilising 1.5 MW of onboard power through superconducting motors to enhance efficiency and reduce weight.

Companies like Collins Aerospace are also making strides in developing high-power-density electric motors tailored for aviation. Collins has introduced a 500-kW motor for the Airlander airship and a 1 MW motor for a Dash 8 hybrid-electric test plane. Expertise in optimised electric propulsion will be crucial for addressing the energy gap highlighted by the Boeing 737 example.

The Multifaceted Challenges of Commercial Aviation Electrification

The disparity between jet fuel and batteries is just one challenge. High-voltage operation at altitude, wiring, power distribution, thermal management, flight control integration, and other essential systems for safe flight also present substantial hurdles, not to mention that aircraft require redundancy to mitigate propulsion failures, which further compounds the weight issue. Certifying these novel architectures poses difficulties, as aviation regulators worldwide grapple with framing new standards for electric aircraft categories.

On the ground, charging infrastructure for quick aircraft turnarounds represents another formidable obstacle. Charging stations face complexities regarding power delivery, cooling, battery life preservation, and resilience to weather conditions.

Airport remodelling is inevitable, with inter-agency coordination and public-private partnerships playing a pivotal role in this infrastructure expansion.

The Promise and Challenges of Alternative Energy Storage Solutions

Given the limitations of current battery technologies, alternative energy storage and conversion systems like hydrogen fuel cells are gaining traction for longer-range flights. Hydrogen, when stored as a cryogenic liquid, offers higher energy density when compared to jet fuel on a weight basis. Hydrogen fuel cells efficiently convert stored hydrogen into electric power for aircraft propulsion.

However, significant challenges surround liquid hydrogen as an aviation fuel, including its low density, requiring large, insulated tanks that add substantial weight. Scaling fuel cell technologies to meet the power demands of commercial aircraft, production costs, fuelling infrastructure, and maintenance over thousands of flight hours also pose questions.

Despite these challenges, companies like Airbus are exploring hybrid hydrogen-electric configurations, combining efficient hydrogen fuel cells for cruise segments with batteries for take-off and landing. If these challenges are surmountable, hydrogen may strike an ideal balance between energy density, efficiency, and sustainability.

The Rare Earth Element Supply Crisis

Rare-earth metals, including neodymium, dysprosium, and terbium, play crucial roles in high-performance permanent magnets. Used extensively in electric motors and generators, they enable the power densities essential for electric aviation.

Currently, the global rare-earth industry approaches a critical juncture. Demand for these elements is projected to surge over 200% by 2035, driven by the accelerating adoption of electric vehicles, however, planned mining capacity expansions are insufficient to meet these needs. China currently dominates over 80% of global rare-earth processing, enabling control over supply chains and pricing. This monopoly poses risks of supply instabilities or price hikes as demand rises. Developing new rare-earth mining and processing capacity outside China is crucial for electric aviation’s future.

Recycling technologies also play a pivotal role, as the West currently depends on China for 98% of its rare-earth magnets. which uses include critical components for electric cars, medical scanners, weaponry, and consumer electronics. This has initiated a race against time, spurring researchers, and entrepreneurs to explore alternative sources, minimise waste, and enhance recycling efforts.

Emulating China by developing domestic mining and processing capabilities is one solution, but it demands substantial investment and government intervention.

The Paradox of Progress

Ironically, Europe’s efforts to reduce dependence on Russian fossil fuels through electric vehicles and wind turbines have intensified reliance on Chinese rare-earth magnets, exchanging one dependency for another.

The term “rare-earth” is misleading, as these 17 elements are not scarce, but dispersed in the Earth’s crust, making extraction costly and challenging. China’s dominance results from strategic investments, while the rest of the world shuttered mines due to environmental concerns.

Rare-earth magnets are indispensable across various sectors, including electric vehicles, where each motor requires about 2 kilograms of these magnets. Wind turbines demand up to 400 kilograms per unit. These magnets also play crucial roles in modern weaponry, precision equipment deployed in conflict zones, and consumer electronics.

China’s Strategic Chokehold

The world received a wake-up call in 2010 when China halted rare-earth magnet exports to Japan during a maritime dispute, causing global prices to soar. Since then, tensions with Beijing have escalated, raising concerns that China could once again disrupt the supply chain. Moreover, global demand for these magnets is growing exponentially, driven by the expanding adoption of electric vehicles and wind turbines.

Environmental and regulatory concerns complicate mining initiatives, particularly in Europe, highlighting the delicate balance between resource extraction and environmental preservation. In recent years, the United States has reopened mines, reducing China’s dominance in mining, but not in processing and manufacturing.

Efforts are underway to discover alternative materials that can replace rare-earth magnets. Scientists are exploring novel alloys with similar efficiency without relying on rare-earth metals. These pursuits face challenges, primarily centerer around cost considerations.

Recycling presents an opportunity to augment rare-earth magnet supply, but currently, only 1% of magnets in cars are recycled. Increasing the recycling rate and identifying potential sources, such as household appliances, could help alleviate supply constraints. However, the rapid growth of the electric vehicle market outpaces recycling capabilities. Another avenue is 3D printing, which could eliminate waste and enhance magnet production efficiency. Though challenges remain, such as achieving magnetic strength comparable to traditional methods, early indications in 3D printing offer promising benefits.

Breaking Free of China’s Stranglehold on Critical Minerals

As the automotive and aviation industries transition towards electric propulsion and renewable energy, demand for critical minerals like lithium and cobalt skyrockets. China’s domination of global supply chains for these essential resources threatens progress towards electrification, national security, and clean energy goals.

China has a near-monopoly control over critical mineral refining and processing, giving Beijing dangerous leverage over global battery and electric vehicle supply chains. Governments, particularly in the USA, strive to restore mineral supply chain resilience by responsibly developing domestic mining and processing capacity.

This requires significant updates to antiquated mining laws, enacting strong environmental, safety, and transparency standards to ensure responsible mining. Reforms should empower land managers to protect special places and involve local communities. Simultaneously, investment in rare earth recycling, researching substitutes, and promoting efficiency can reduce the need for new mining. Where mining occurs, it should create jobs across the supply chain.

The path to mineral independence from China is not without challenges, however innovation and determination, coupled with care and wisdom, could free the West from China’s mineral dominance. The time to restore mineral security is already overdue.

Navigating the Optimal Technology Pathways to Electric Aviation

The electrification of commercial aviation will require judicious navigation of multiple technology pathways, each with its advantages and challenges. The main one being that the Advanced Air Mobility (AAM) industry must take its head out of the sand. Incremental improvements in lithium-ion batteries will likely allow short-range regional electric flights using hybrid-electric propulsion, yet extending all-electric range affordably will demand innovations in battery technologies like lithium-sulphur or lithium-air, which are several years away.

There are many future projects that need to align to deliver what many have assured their investors. This requires continued fuel cell advancements, coupled with sustainable hydrogen production, which could enable long-haul electric flights. Hydrogen internal combustion engines (ICE) are also promising if challenges like combustor cooling are solved.

Further into the future, exotic technologies like high-temperature superconducting motors may hold potential, provided the cryogenic system penalty can be overcome or mitigated.

Predicting which technologies will prevail entails uncertainties, but as all innovators and engineers with experience know, a portfolio approach significantly maximizes the chances for success. Continued R&D investments combined with technology-agnostic infrastructure will provide flexibility. Prioritising environmentally responsible scaling is also key.

Electric aviation – while becoming a casualty of its own marketing hype with great deal of ‘head in the clouds’ ideas and hard ‘down to earth’ lessons – for many holds the potential to revolutionise sustainable air transportation, but it remains confronted by profound obstacles across technology, infrastructure, policy, and supply chains. Near-term constraints will likely limit all-electric propulsion to smaller aircraft and shorter regional ranges for at least the next decade, yet by building on the automotive sector’s momentum, aviation can achieve incremental progress, starting with hybrid-electric systems.

Electric Propulsion Motors, Generation and Hybrid

Electric motors, once relegated to secondary roles, have become the primary propulsion sources for electric aircraft, spanning from experimental regional turboprops to 150-seat narrow body jets.

To facilitate this transition, aviation-grade electric motors must achieve ground-breaking power densities within strict weight limits while maintaining uncompromising safety and reliability standards. These motors must also deliver peak efficiency across altitudes ranging from sea level to 40,000 feet. As aviation progresses toward electrification, electric motors face the challenge of matching or surpassing the performance of traditional turbofan engines in every aspect. Their designs must optimise the intricate balance between magnetic and electrical forces.

Where policy makers and Governments are not putting their focus or meaningful funding is to assist private companies in challenging the dominance of China. One such company exploiting the efficiencies of electric motor technologies and efficiency nuances is ePropelled – who also have a strict non-Chinese component policy – who have invested heavily in efficiencies and infrastructure in the USA, UK, and India. Also, YASA’s Evolito division promises future efficiencies and weight loss.

ePropelled is focused on absolute efficiency and is one of the only companies in existence conducting ongoing hanger tests of 10,000 – 20,000 hours, linked to sensors that deliver real-time data to understand general efficiencies over time and MTBF (Mean Time Between Failures) outcomes that aviation and military technologies depend on for preventative maintenance and obsolescence engineering prediction.

The consideration that a large industrial plant or business that is electric motor-dependent for its processes can see a 20-30% decrease in electricity consumption by using their motor technologies – efficiency becomes immediately apparent, laying a significant pathway towards the aviation industry. Likewise, this presents a significant advantage for electric vehicles, uncrewed assets, existing electric-diesel, and nuclear maritime assets that can always use greater efficiencies.

Further in the future, innovations across batteries, fuel cells, motors, and infrastructure may ultimately enable all-electric transcontinental carbon-neutral flights. Realizing aviation’s electrified future will hinge on the ingenuity of engineers, scientists, and innovators across both established and emerging companies worldwide. The industry hinges on winning through on incremental wins.

Lithium-ion batteries are widely used for energy storage in commercial products; however they require improvements to meet the energy needs of advancing technology devices. Graphene balls have been suggested as promising materials to enhance lithium-ion batteries.

 The applications of graphene are also surprising in the aeronautical field. There are so many thoughts I have on this that could make a 3000-word editorial on its own. However, Graphene is already being used to create lighter and greater impact-resistant aircraft chassis and helicopter structures. Thanks to the high electrical conductivity of graphene, it will also be possible to create de-icing systems integrated into the wings, although news of Graphene in AAM and electrification is not something we hear a great deal about.

Graphene balls can prevent aggregation and volume changes in battery electrode materials during charging and discharging. This improves battery cycle life, charging speed, and efficiency. Graphene balls have been studied in different configurations:

  • Decorated with electrochemically active nanoparticles like Fe3O4 to improve capacity as anode material.
  • Crumpled graphene balls to prevent dendrite formation and enable efficient Li-ion diffusion.
  • Encapsulating metal oxide nanoparticles like SiOx or Co3O4 to boost capacity and cycle life.

Recently, researchers at Samsung used silica / graphene balls in the anode and as a coating on the cathode. This improved energy density by 27.6%, enabled 12-minute full charging, and boosted capacity by 45%.

Graphene balls also show promise in enhancing lithium-ion battery performance in terms of capacity, charging speed, cycle life, and thermal stability. Continued research and development could enable graphene balls to help lithium-ion batteries meet the increasing energy demands of advancing technologies.

The electric aviation and AAM sector have formidable challenges ahead that cast doubt on the lofty promises of a near-term green aviation revolution. While the potential for sustainability, affordability, and accessibility is undeniable, realities and physics are what they are. Efforts to improve battery technologies, explore alternative energy solutions, and secure rare earth elements are undoubtedly crucial steps, however those within the AAM industry need to understand optimism isn’t a panacea.

The potential technological leaps and anticipated ground-breaking innovations may divert attention from the most pressing issue at hand: efficiency. In the eagerness to chase the dream of electric aviation, the key players must not lose sight of the immediate need to optimise and maximize the performance of existing technologies. Prioritising efficiency as a cornerstone of meaningful progress in the industry is imperative.

Incremental gains in efficiency can deliver significant tangible benefits today, reducing energy consumption, emissions, and operational costs. Efficiency improvements should not be overshadowed by hype.

Rather than placing our faith solely in yet-to-be-perfected technologies, and in certain areas yet-to-be-created, we should redirect our efforts toward making the most of what we have. This entails embracing energy-efficient designs, refining operational procedures, and enhancing existing propulsion systems.

Efficiency-first and a combined hybrid powertrain approach is the logical bridge across the chasm between the present and the future aspirations of electric aviation.

The electrification of air transport faces supply chain vulnerabilities, energy storage limitations, and within aviation regulatory complexities, and safety cases are real issues. On a funding level, its enemy is lurking in the in the haze of endless grandiose promises that is several instances simply defy technology capabilities.

Only by prioritising efficiency and looking at the existing technologies to progress a realistic evolution, can we hope to make meaningful strides towards a greener, more sustainable aviation industry.

Carl Cagliarini

Author

With over 25 years of experience, I have merged special operations with high-value commercial technology. In leadership roles across public and private sectors, I have navigated key milestones from early Wi-Fi adoption to spearheading laser communications programs and rescue and restructure of failing companies. My journey stands out through deep technical aviation and autonomy expertise, demystifying complex narratives with humility. Moreover, I have harnessed AI and machine learning, sharing my experiences as an early adopter.

Bridging defence and commercial realms, I underscore innovation’s impact on security and progress. Amidst challenges, unwavering action and teamwork are essential.

From state security to driving commercial innovation, I operate on universal principles. Collaborating with capable teams, I have rescued investments and orchestrated solutions for significant returns.

Looking ahead, my dedication focuses on driving defence and humanitarian innovation, nurturing collaboration and advancing progress. Over the next quarter-century, my mission is to reshape defence outcomes and more by nurturing a future rooted in humility, innovation, teamwork, impactful change, and unwavering action, including dismantling barriers that hinder innovation.

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