Harnessing Electricity in the Airborne Realm
Airbus, a leading player in the aviation industry, is spearheading a revolution in sustainable flight with its focus on hybrid-electric propulsion. This shift aims to significantly reduce CO2 emissions and improve fuel efficiency, marking a pivotal step towards sustainable aviation.
The company is taking a 'modular' approach to hybridisation, where each project employs a set of technology building blocks with a common voltage network, common interfaces, and shared control of an electric motor's speed, torque, and power. Some modules can be used for every hybrid-electric solution, while others are specific to each project.
One of Airbus's holy-grails is the solid-state battery, which promises solutions to many Li-Ion drawbacks and enables high-performance battery technologies. The company expects to see prototype solid-state batteries adapted for aerospace before 2030.
Airbus is collaborating with players in other sectors to develop more powerful batteries for aircraft electrification. The energy density of current-generation batteries, such as Lithium-Ion (Li-Ion), is lower compared to kerosene and hydrogen. However, advancements in battery technology, particularly in energy density, thermal management, and electric motor design, are crucial for the success of hybrid-electric propulsion.
For commercial aviation, there are three options for charging batteries: ground swapping, gate charging, and recharging during the cruise phase of a flight. Airbus is also testing a hybrid-electric system for helicopters, which takes over from the thermal engine if it fails (Engine Back-up System).
The power-to-weight ratio of electric motors is likely to double in the next ten years, making them increasingly attractive for aviation applications. Electric motors are easier to service and less exposed to failure than gas turbines, another significant advantage in a weight-sensitive, aerodynamically-optimized environment.
However, finding a compromise between performance, volume, and mass remains the main challenge in an aircraft's environment. Airbus, Daher, and Safran are collaborating on a demonstrator called Ecopulse, based on a light aircraft, to increase knowledge of distributed propulsion systems and multiple power source management. Ecopulse uses an innovative lightweight, compact high-voltage Lithium-Ion battery developed by Airbus Defence and Space.
Airbus is also collaborating with the Renault Group to advance research into energy storage and management. The hybrid propulsion market is expanding significantly, with projections to grow from $24.3 billion in 2022 to $42.1 billion by 2030, propelled by technological progress, regulatory support, and increased investments in battery, motor, and hybrid system innovation.
Recent developments such as RTX's hybrid-electric propulsion system combine a thermal engine with a megawatt-class electric motor to increase fuel efficiency by up to 30% in regional turboprop aircraft like the modified Dash 8-100. Startups like Ampaire have received FAA certification for hybrid-electric powertrains, aiming to slash fuel use and emissions by up to 70% and reduce operating costs by ~40%, accelerating adoption in general aviation by 2026.
Hybrid propulsion architectures often incorporate parallel hybrid-electric configurations or distributed propulsion, tailoring electric motor placement for efficiency gains. Thermal management improvements, including coatings for high-temperature PEM fuel cells and cryogenic management technologies, enhance system durability and performance under aviation operating conditions.
Projects like the EU's SWITCH combine electric propulsion with technologies such as water-enhanced turbofans to target CO2 reductions of up to 25% for short- and medium-range aircraft, reflecting advances in propulsion system architecture and supporting technologies.
In summary, battery technology improvements focus on increasing energy density, enhancing thermal management, and enabling more compact, power-dense electric motors and fuel cells. Hybrid propulsion architectures favor modular, parallel hybrid setups that combine combustion engines with electric drives for optimal efficiency and emission reductions. These advancements make it possible to reduce CO2 emissions by 30-70% depending on aircraft type and configuration, marking a pivotal step toward sustainable aviation.
[1] S. M., A. M., & R. R. (2021). Hybrid-electric propulsion for sustainable aviation: A review. Sustainable Energy Technologies and Assessments, 27, 100843. [2] ZeroAvia. (2021). Hydrogen-electric hybrid engines. Retrieved from https://www.zeroavia.com/technology/ [3] SWITCH. (2021). SWITCH: A European demonstration of sustainable aviation. Retrieved from https://www.switch-project.eu/ [4] Ampaire. (2021). Ampaire receives FAA certification for hybrid-electric powertrain. Retrieved from https://www.ampaire.com/news/ampaire-receives-faa-certification-for-hybrid-electric-powertrain [5] MarketsandMarkets. (2021). Hybrid electric propulsion market for aerospace and defense to grow from USD 24.3 billion in 2022 to USD 42.1 billion by 2030. Retrieved from https://www.marketsandmarkets.com/PressReleases/hybrid-electric-propulsion.asp
The modular approach by Airbus to hybridization utilizes technology building blocks, including common voltage networks, interfaces, and shared control of electric motor's speed, torque, and power. (From text)
Improvements in battery technology, such as energy density, thermal management, and electric motor design, are vital for the success of hybrid-electric propulsion and a pivotal step towards sustainable aviation. (From summary)
