What is Green Aviation and Is It Possible?

The transport sector accounts for 20% of the planet’s CO2 emissions, making it the second largest emitter of carbon worldwide. As a sub-sector of transport, aviation is lagging behind when it comes to sustainable solutions to combat climate change. The main reason is that in the last few years, the easiest way to reduce carbon emissions in aviation is by encouraging people to fly less, which is not particularly beneficial for airlines.

However, more and more solutions are being drawn up to make aviation a more sustainable industry and to align with the ambitious climate goals of Fly Net Zero. The initiative sets out to achieve net zero carbon emissions by 2050. From sustainable fuels and electric aircraft to carbon offsetting and next-gen aerodynamics, the industry has lots of ideas to reduce its impact on the planet.

What is Green Aviation?

Green aviation refers to the coordinated activities and programmes designed to improve the environmental sustainability of the aviation sector and lessen its adverse effects on the environment. It includes a variety of tactics, tools, technologies, and procedures intended to reduce greenhouse gas emissions, use less fuel, and advance all-around environmental friendliness in the aviation industry. Green aviation seeks to strike a balance between the industry's continuous expansion and advancement and its commitment to reducing climate change and safeguarding the planet's ecosystems.

Why is Green Aviation Important?

Despite the aviation industry contributing to around only 2% of global CO2 emissions, it has a much larger impact on climate change than that. Flights also emit other greenhouse gases such as nitrogen oxide, water vapour, and aerosols, but it’s not just greenhouse gas emissions warming the planet. There are multiple factors at play - some of which are listed below:

• High-altitude effects - Pollutants and greenhouse gases are released by aircraft at high altitudes, where their effects may be more noticeable. For instance, nitrogen oxides emitted at cruising altitudes can result in the creation of "aviation-induced" ozone, a greenhouse gas that is responsible for global warming. It’s said that aviation emissions released at high altitudes have between two to four times the impact that comparable ground emissions do.
• Contrail formation - Contrails, the white streaks that sometimes form behind aeroplanes, are composed of ice crystals that condense around aircraft exhaust particles. Contrails can reflect sunlight back into space, contributing to a cooling effect on Earth's surface. However, they can also trap heat in the atmosphere, acting like thin cirrus clouds and contributing to a warming effect.
• Cirrus cloud formation - Cirrus clouds brought on by contrails can significantly affect the climate. These clouds can operate as a "blanket" to capture outgoing longwave radiation, preventing heat from escaping into space and causing warming. They form as a result of water vapour condensation around soot from the plane’s exhaust.
• Indirect effects - As well as its direct impact, flights can indirectly lead to other climate repercussions. For example, aviation's influence on high altitude water vapour and cloud formation can lead to a net warming effect. Black carbon particles emitted from aircraft engines can settle on snow and ice, reducing their reflectivity and accelerating melting.

How Can We Achieve Green Aviation?

Green aviation initiatives encompass a range of strategies and technologies aimed at minimising the environmental impact of air travel operations. Some of these efforts include:

Fuel Efficiency

Airlines and aircraft manufacturers have been fervently investing in research and development to design aeroplanes with increased fuel efficiency. Advances in materials science, aerodynamics, and propulsion systems lie at the heart of this endeavour.

Modern aircraft engines are more precisely made and employ cutting-edge technologies like high-bypass ratio turbofans to move the aircraft ahead while using little fuel. These engines eliminate energy losses and maximise combustion efficiency, which lowers emissions per flight. Aerodynamic innovations have also led to the development of sleeker aircraft forms with reduced drag for more comfortable flights and less fuel use.

Additionally, the use of lightweight composite materials like carbon fibre reinforced plastics helps to reduce the overall weight of the aircraft, which in turn lowers the amount of energy needed for take-off and flight.

Sustainable Aviation Fuels (SAFs)

Unlike traditional fossil-based jet fuels, alternative aviation fuels are intended to lower carbon emissions and reliance on non-renewable resources.

One of the most researched options is the use of biofuels, which are produced from organic materials like plant oils, algae, or used cooking oil. Compared to conventional jet fuels, these fuels have the benefit of being renewable and producing fewer greenhouse gases during combustion. They may be constructed with readily available infrastructure and with only minor engine and aircraft changes.

Another option is synthetic fuels, sometimes referred to as e-fuels or power-to-liquids (PtL) fuels, which are created by combining hydrogen and carbon dioxide with renewable energy sources to create a liquid fuel. As the carbon dioxide used in production is balanced by its absorption from the atmosphere, this novel technology offers the potential to produce aviation fuels that are almost carbon-neutral.

In 2023, Honeywell announced new technology which can convert hydrogen and carbon dioxide captured from industry into lower-carbon aviation fuel.

Hybrid and Electric Aircraft

In a hybrid mode, the aircraft employs multiple power sources simultaneously or alternatively while in flight. We can maximise total energy efficiency and cut fuel consumption by combining energy sources, such as jet fuel or sustainable aviation fuels, with electricity.

Direct emissions are eliminated at the point of use with electric aeroplanes, which are totally powered by electric motors. These aircraft could achieve zero emissions while in flight by using electricity from renewable resources. They are especially well suited for short-haul regional routes and urban air mobility since they provide a quieter and cleaner flying experience.

There are obstacles to the development of electric and hybrid aircraft, including restrictions on energy storage, weight, and infrastructure needs. The development of battery technology is essential for enabling longer-distance electric flight.

However, these aircraft could be essential in helping the aviation sector meet its objectives of cutting emissions and adopting greener practices, resulting in a more sustainable future for air travel, as technology capabilities advance and investment in sustainable aviation increases.

Operational Efficiency

This involves effective flight planning to identify optimised flight paths, better taxiing techniques, and reduced idle time on the ground. Advanced air traffic management systems also improve communication between planes and air traffic controllers, which minimises delays and wasteful fuel consumption. In addition to reducing the environmental impact of flights, these initiatives also enable airlines to save money, making operational efficiency a win-win strategy for the aviation sector's sustainability and financial viability.

Carbon Offsetting

Carbon offsetting is a tactic used in green aviation to counterbalance the carbon emissions created by flights, by investing in initiatives which remove carbon from the atmosphere. This strategy acknowledges that, despite the aviation sector's efforts to cut emissions, some amount of carbon output is likely to persist in the near future. Projects for carbon offsets often fall into one of two categories:

• Carbon removal - These initiatives concentrate on actively removing carbon dioxide from the atmosphere. Projects that use natural mechanisms to absorb carbon dioxide include afforestation (planting trees), reforestation (restoring forests), and soil carbon sequestration. In addition, technologies like direct air capture and carbon mineralisation seek to sequester carbon from the atmosphere and transform it into mineralised forms or geological formations.
• Emissions reduction - These initiatives try to either reduce or stop future emissions. Installations for renewable energy (solar, wind, and hydro) take the place of fossil fuel energy generation, reducing emissions. Strong greenhouse gases are not released when methane is captured from landfills, farms, and wastewater treatment plants.

Conclusion

In the dynamic world of aviation, green aviation shines as hope. From transformative biofuels to electric aircraft, the industry blends aspirations with eco-responsibility. Efficiency and offsetting show commitment to a greener footprint. As planes embrace innovation and sustainability, the skies promise a brighter future for the world that we live in.