Exploring the Viability of Hybrid Neo Engines and Their Potential to Lower Radiative Forcing

The aviation industry has long been under scrutiny for its significant contribution to greenhouse gas emissions and the ensuing radiative forcing, which exacerbates global warming. As the world seeks greener alternatives, the concept of hybrid engines, particularly for the new generation of engines like the Neo engines, has gained attention. This blog explores whether the development of hybrid Neo engines could be viable and how they might help reduce radiative forcing.

The Current State of Aviation and Environmental Impact

Aviation is responsible for approximately 2-3% of global CO2 emissions, but its impact on climate change is more pronounced due to other factors like water vapour, nitrogen oxides, and contrail formation. These factors collectively contribute to radiative forcing, which is the change in energy balance caused by greenhouse gases and aerosols in the atmosphere.

What Are Hybrid Engines?

Hybrid engines, much like those in the automotive industry, combine traditional fuel-based propulsion with electric power. In aviation, this typically means integrating electric motors with conventional jet engines to provide supplementary power during certain phases of flight, such as take-off and climb. The aim is to reduce fuel consumption, emissions, and noise.

The Viability of Hybrid Engines for the Neo

The Neo engines, part of the new generation of aircraft engines, are known for their improved efficiency and reduced environmental impact compared to older models. Retrofitting these engines with hybrid systems presents several challenges and opportunities:

  1. Technical Feasibility:
  • Weight and Space: Hybrid systems, including batteries and electric motors, add weight and require space. The design must ensure that the added weight does not negate the benefits of reduced fuel consumption.
  • Battery Technology: Current battery technology, such as lithium-ion, needs to improve in energy density to make hybrid aviation viable. Innovations like solid-state batteries could be a game-changer.
  • Integration with Existing Systems: The hybrid system must seamlessly integrate with existing aircraft systems without compromising safety and performance.
  1. Economic Considerations:
  • Cost of Retrofitting: The cost of retrofitting existing Neo engines with hybrid systems is substantial. Airlines will need to weigh this against potential savings in fuel and maintenance costs.
  • Operational Efficiency: Hybrid engines promise lower operational costs due to reduced fuel consumption. However, the economic viability depends on the balance between upfront costs and long-term savings.
  1. Regulatory and Certification Hurdles:
  • Safety Regulations: Hybrid engines will need to meet stringent safety standards and undergo rigorous testing before they can be certified for commercial use.
  • Environmental Regulations: As governments impose stricter emission regulations, hybrid engines could help airlines comply and potentially benefit from incentives.

Lowering Radiative Forcing

Radiative forcing from aviation is not solely due to CO2 emissions. It also involves other non-CO2 effects like contrails and NOx emissions. Hybrid engines could contribute to lowering radiative forcing in several ways:

  1. Reduced Fuel Burn: By supplementing conventional engines with electric power, hybrid systems can reduce overall fuel consumption, directly lowering CO2 emissions.
  2. Optimised Flight Operations: Electric power can enhance efficiency during critical phases like take-off and climb, where fuel burn is highest, thus reducing overall emissions.
  3. Lower NOx Emissions: Hybrid engines can potentially operate at more efficient combustion temperatures, reducing NOx emissions which are significant contributors to radiative forcing.
  4. Contrail Reduction: Some hybrid systems propose operating at altitudes or conditions that minimise contrail formation, thereby reducing their warming effect.


The transition to hybrid Neo engines presents a promising pathway towards more sustainable aviation. While the technical, economic, and regulatory challenges are non-trivial, the potential benefits in terms of reduced fuel consumption, lower emissions, and decreased radiative forcing are significant. Continued advancements in battery technology and hybrid propulsion systems, coupled with supportive policies, could pave the way for the broader adoption of hybrid engines in commercial aviation.

As the world grapples with the urgent need to address climate change, hybrid engines could play a crucial role in reducing the aviation industry’s environmental footprint. The journey towards hybrid aviation is complex, but the potential rewards make it a compelling endeavour for the future of sustainable air travel.