It is predicted that 10 billion journeys will be completed by air between 2021 and 2050, making global air traffic responsible for 21.1 gigatons of CO2 emissions [1]. To reduce the carbon footprint of the aviation sector, the International Air Transport Association (IATA) has pledged to reach net zero by 2050. Achieving this goal will require a dynamic strategy alongside the adoption of new powertrain technologies and concepts.
Sustainable fuels provide a greener alternative to fossil-based fuels that can be ‘dropped in’ to current aircrafts with minimal adjustment required. However, combustion remains an inefficient process and so attention has turned towards hybrid and electric powerplants. As battery technology continues to push the boundaries of energy density, tech start-ups are now developing hybrid and electric eVTOLs, while traditional manufacturers look to electrify passenger aircraft for commercial routes. This has led to a boost in the electric aviation market from $8.5 billion in 2021 to a predicted $23.5 billion by 2031 [2].
The Aviation Challenge for Batteries: Energy Density
Similar to automotive, the biggest challenge facing aviation battery designers is energy density. The more energy a battery can store, the longer the range and the more versatile the aircraft can be. Increasing this energy density can be achieved through carefully selecting cell chemistries with the highest performance. These cells then need to be effectively integrated into a module with the necessary cooling and management systems to maintain the cells within their optimum operating conditions.
Minimising weight is another tactic to improving battery energy density. ‘Reducing the weight of the components within a battery essentially means that there is less mass that the battery has to power in the air,’ explains Siva Rajendran, BOLD’s Director of Sales. ‘This can significantly increase the range of the aircraft as well as the available payload for passengers and cargo. The typical energy density of a high-performing automotive pack is around 200Wh/kg, but we have already achieved aviation packs at 285Wh/kg.’
The Aviation Challenge for Batteries: Safety
Another obstacle for electrifying aviation is safety. Before a battery can receive certification to fly in an aircraft, it has to be proven to meet a comprehensive set of safety requirements. These standards have been designed by governing bodies such as the European Union Aviation Safety Agency (EASA), the UK’s Civil Aviation Authority (CAA) and the Federal Aviation Administration (FAA) in the United States to ensure an aircraft and its components are designed and manufactured for safety. Proving the airworthiness of a battery design requires rigorous testing programmes and considerable documentation.
‘Aviation has a completely different safety philosophy compared to the likes of automotive. Aviation is mission critical; if there is a failure, the pilot can’t just pull the aircraft over, so this has led to a large number of safety requirements and standards that aviation batteries must meet. The battery standards for automotive are primarily focussed on detecting a fault and encouraging a design that can withstand that failure for a certain amount of time. Whereas, for aviation the regulations force battery designs that not only detect and manage a failure but also contain that failure until the aircraft can land safely. For example, some of the safety tests require us to trigger thermal runaway in the entire system and prove that the battery remains structurally safe,’ continues Rajendran. ‘Any changes to the design have to be documented and re-tested which makes the certification process of a battery very documentation heavy. The only other industry that comes close to aviation in terms of documentation is healthcare.’
Transferring Technology from Formula 1 to Aviation
To achieve a lightweight battery design, thermoset composites such as carbon fibre prepreg are used for the battery enclosure. Understanding the characteristics of carbon fibre and then how to optimise these for a battery casing is a unique challenge, but a familiar one to BOLD as our team boast many years of motorsport experience.
‘Automotive ten years ago was at the forefront of what was possible with battery technology, but this has become a cost-based production exercise,’ highlights Rajendran. ‘The frontier has now shifted to aviation, along with motorsport and that’s one of the secret sauces that makes us experts in battery development. There are not many companies that have the advantage of understanding composites as well as how to design and build high-performance batteries whilst also having the resources to execute the design and manufacture at the speed of Formula 1.’
The Value of Facilities
At an early stage in our journey, we invested in manufacturing and testing facilities to establish a complete battery development solution for our customers. Our ability to design, manufacture and test in-house has become particularly important with the current state of the market.
‘Developing battery packs is extremely hard and expensive,’ says Rajendran. ‘This is compounded by the current market which is causing problems for non-automotive industries such as aviation. They are stuck because their product development cycles can be 10 to 20 years and currently, automotive is sucking up the majority of available battery technology and talent, continues Rajendran.
‘So, they either have to compromise the future development of their aircraft based on the technology that is available in the market now, or they can develop it themselves which drastically increases costs and can add another five to six years to their lead times. Whereas BOLD can design, test, develop and manufacture state-of-the-art battery modules that are exploiting the current capabilities of battery and composite technology with a team of battery experts.’
Levelling the Playing Field
With electric aviation an emerging industry, start-ups and other technology companies are joining traditional manufacturers in the race to solve net zero flight. We’re striving to be at the forefront of this change.
‘We don’t want to charge extortionate prices for our technology which alienates smaller companies,’ concludes Rajendran. ‘We want to make our technology affordable to the biggest aeroplane company as well as a one-person start-up with the next big idea. We want companies to come to us and buy the same product at the same cost, regardless of how many units they purchase,’ continues Rajendran.
‘Electrification is changing the face of the aerospace industry and we want to make sure that we are at the table. Whether a customer has an established project, or an initial concept, our engineers will work with them to develop a high-performance aviation module that meet their needs.’
References
[1] IATA, 2021. Net Zero carbon 2050 resolution Fact sheet [Online]
[2] IATA, 2021. Net zero 2050: new aircraft technology [Online]
Spread the word