Decarbonise Travel

^{Air New Zealand “NZ0” - Flying zero-emissions from 2026}

What is decarbonisation?

Decarbonisation is the process of reducing and removing net greenhouse gas outputs by reducing the amount emitted, using zero or low-emission energy sources, increasing energy efficiency and by carbon sequestration.

Net zero refers to the difference between the amount of greenhouse gas produced in the atmosphere during a set period of time and the amount that is removed from the atmosphere.

🍃 We reach net zero when the two amounts are equal.

Emissions from Flying

Flying can be a highly controversial topic in climate debates. It accounts for around 2.5% of global CO₂ emissions, but 3.5% when we take non-CO₂ impacts on climate into consideration.

^{Our World in Data}

Why flying can be a controversial topic?

• The first is the disconnect between its role in our personal and collective carbon emissions. Air travel dominates a frequent traveller’s individual contribution to climate change. Yet aviation overall accounts for only 2.5% of global carbon dioxide (CO₂) emissions. This is because there are large inequalities in how much people fly – many do not, or cannot afford to, fly at all → best estimates put this figure at around 80% of the world population.

• The second is how aviation emissions are attributed to countries. CO₂ emissions from domestic flights are counted in a country’s emission accounts. International flights are not – instead, they are counted in their own category: ‘bunker fuels’. The fact that they do not count towards the emissions of any country means there are few incentives for countries to reduce them.

• It is also important to note that unlike the most common greenhouse gases – carbon dioxide, methane or nitrous oxide – non-CO₂ forcings from aviation are not included in the Paris Agreement. This means they could be easily overlooked – especially since international aviation is not counted within any country’s emissions inventories or targets.

The Future of Flying

While a flight today produces half the CO2 it did in 1990, the aviation industry needs to continue working on ways to reduce fuel use and emissions further.

In 2016, the International Civil Aviation Organization (ICAO) made the historic decision to adopt a global market-based measure for aviation emissions. This scheme, the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA), is the culmination of many years of work at ICAO, with the support of the industry.

As the name suggests, CORSIA is a global offsetting scheme, whereby airlines and other aircraft operators will offset any growth in CO2 emissions above 2020 levels. This means that aviation’s net CO2 emissions will be stabilised, while other emissions reduction measures, such as technology, sustainable aviation fuel, operations and infrastructure options, are pursued.

It is anticipated that CORSIA will mitigate around 2.5 billion tonnes of CO2 between 2021 and 2035, which is an annual average of 164 million tonnes of CO2.

🍃 CORSIA helps aviation towards its mid-term goal of carbon-neutral growth from 2020 onwards and is only one part of aviation’s climate plan.

IATA Fly Net Zero

IATA’s strategy towards net zero by 2050 requires a combination of maximum elimination of emissions at the source, offsetting and carbon capture technologies.

^{IATA - Achieving Net Zero in 2050}

New Technologies

Each new generation of aircraft has double-digit fuel efficiency improvements, up to 20% more fuel efficient than the previous one. This has led to today’s modern aircraft producing 80% less CO2 per seat than the first jets in the 1950s, though there is more work to do.

^{New Generation Aircrafts}

New technologies on the horizon have the potential to decrease greenhouse gas emissions from aviation significantly, and solutions being implemented today promise further savings. Even incremental savings offer significant benefits overall.

Fuel efficiency is critical to the future of the aviation industry, not just for environmental reasons but also for financial ones. Fuel makes up over 30% of airline operating costs.

To formalise and complement the market-driven improvement in fuel efficiency, the International Civil Aviation Organization (ICAO) agreed on a CO2 emissions standard in February 2016, which applies to all new aircraft designs from 2020 and newly-built existing models from 2023.

Zero-waste cups and cutlery: Instead of exchanging plastic products for biodegradable or recyclable ones, the future could be zero-waste or edible products. Air New Zealand trialled edible biscotti coffee cups while PriestmanGoode has designed aircraft trays made from coffee grounds, algae, banana leaf and coconut wood that it is proposing to airlines.

Sustainable Aviation Fuel

The development of alternative aviation fuels could be the key to sustainable air travel, contributing hugely to the industry's emissions-reduction strategy. Using alternative fuels could reduce CO2 emissions by up to 80% compared to fossil fuels.

What Is SAF?

Sustainable Aviation Fuels (SAF) - sometimes known as aviation biofuels or bio-jet fuels -are low-carbon fuel alternatives for the aviation industry. These non-petroleum-based drop-in aviation fuels are generally produced from bio-based feedstocks including waste, residues and end-of-life products, or fossil waste such as CO, waste plastics, and tyres.

🍃 Choosing airline partners that are committed to reducing their carbon footprints is one way to support sustainable travel. While not exhaustive, the following airlines have been recognised as pioneers or leaders in the adoption and promotion of SAF.

While only 1 in 10 flights booked may currently be eco-friendly, this is bound to increase as time goes on as airlines, as well as airports, commit toward more sustainable practices. Technology advances are also expected to increase which will see an increase in low-emission fleets and a decrease in single-use plastics from them.

Hydrogen & Battery-Electric Aircraft

As cars and buses move away from traditional fuels, aircraft may soon as well. Both electric and hydrogen-powered aircraft are feasible, but both have their challenges.

There would be a need for significant changes in airport infrastructure globally, this means it is likely to be some time before we see hydrogen-powered aircraft operating on a considerable scale. For manufacturers and airlines to commit to making it work, there would need to be a shift from the whole industry.

Battery power has its limits, too, with significant advances in battery technology and the size needed for large aircraft. Hybrid aircraft can be developed in the interim, though, which should help with emissions reduction and research and development. What is more likely to arrive are hybrid-electric aircraft which produce less fuel burn than current aircraft.

^{Embraer’s Energia H2 Fuel Cell E30-H2FC variant}

Operations & Infrastructure

Operations

Efficiencies gained through operational improvements can make a big difference. At every step of an aircraft’s operations, there are opportunities to reduce fuel burn and consequently, emissions.

Airlines are saving fuel through more efficient procedures and weight reduction measures. These can range from ensuring the plane’s engines are clean to developing and using new arrivals procedures. Some airlines taxi to the runway using just one engine instead of two.

Infrastructure

Airports and ground facilities need to take responsibility to become more energy efficient by:

• Investing in offsetting schemes to become carbon neutral, most notably the ACI Airport Carbon Accreditation programme, and building 'green-certified' terminals.

• Reducing on-airport vehicle emissions by introducing automatic metro lines, or switching to vehicles with alternative fuels and low-emission technology.

• Providing electricity to aircraft at terminal gates using fixed electrical ground power rather than the aircraft's auxiliary power unit, and

• Installing solar and other alternative energy supplies for terminal buildings.

• Organic waste bins are expected to be added to airports alongside recycling and general waste bins. Sydney Airport trialled this in 2018 and saw a 20% reduction in landfill waste.

There is a significant impact on emissions from congestion at airports. When flights have to hold and circle before they land, or queue on taxiways before taking off, it is inconvenient to passengers and also adds to fuel use. These inefficiencies are continually assessed to determine whether operating restrictions on flights or new facilities like runways are needed.

🍃 One way the industry is working to reduce congestion and delay, and therefore fuel use, is through Airport Collaborative Decision Making (A-CDM).

^{Infrastructure}

The infrastructure area that makes the biggest impact on aircraft fuel efficiency is the Air Traffic Management (ATM) system. The route a plane takes, the height it flies, and the weather it flies through, all affect the amount of fuel it burns, and therefore the CO2 it emits. These factors are managed by air navigation service providers (ANSPs) who provide air traffic control services.

🍃 Changes in aircraft navigation can help cut flight time, CO₂ emissions and noise impact.

Conventional	RNAV	RNP
Limited design flexibility.	Increased airspace efficiency.	Optimised use of airspace.
Traditionally aircraft have been guided into airports through a series of ground-based navigation aids, almost literally flying from one to the next.	Performance-based navigation (PBN) uses “waypoints” to indicate approach paths. These are identified points on a map, coordinated with a mix of satellites and ground-based technology.	Required navigation performance (RNP), takes technology to its optimum by providing pilots with a precise box in which to guide the aircraft past geographic obstacles (like mountains) for a very accurate landing.

Train Over Plane

With air travel accounting for 2.5% of global CO2 emissions, several countries such as those in Europe (EU), are phasing out certain short-haul flight routes, in favour of greener alternatives like rail.

Train Over Plane zones present exciting opportunities for governments to decarbonise the transport sector and several EU countries are already taking steps in the right direction.

✈️ Short-haul flight is usually a flight lasting up to three (3) hours in duration.

Short-haul Flights Banned

Europe

Several EU countries including France and Austria are aiming to phase out short-haul flights that can be completed by train in a comparable time frame.

• France - effective December 2022, the European Commission approved the country’s move to ban flights between cities that are linked by a train journey of fewer than 2.5 hours. This change is part of France’s 2021 Climate Law to reduce the country's carbon emissions. 

• Spain - Spain might soon follow France’s move with their intentions stated to impose a similar ban on flights under 2.5 hours where a train or bus can supplement the route. An additional step that Spain is considering is the taxation of frequent flyer miles and taxing all flights based on their distance.

• Austria - Austrian Airlines was bailed out in 2020 due to losses from the COVID pandemic. The bailout stipulated that the airline had to eliminate domestic flights where alternative train journeys under three hours were available, affecting the carrier’s route between Vienna and Salzburg. It is estimated that 80 per cent of short-haul trips in Austria can be replaced by rail travel due to its vast rail network, OBB.

Japan

The first high-speed rail system began operations in Japan in 1964, and is known as the Shinkansen (新幹線), or “bullet train”.

Today, Japan has a network of nine high-speed rail lines serving 22 of its major cities, stretching across its three main islands, with three more lines in development. It is the busiest high-speed rail service in the world, carrying more than 420,000 passengers on a typical weekday. Its trains travel up to 320 km/h (200 mph), and the railway boasts that, in over 50 years of operation, there have been no passenger fatalities or injuries due to accidents.

^{JR Central & JR East}

The Shinkansen network consists of multiple lines, among which the Tokaido Shinkansen (Tokyo - Nagoya - Kyoto - Osaka) is the oldest and most popular. All lines, except the Akita and Yamagata Shinkansen, operate on tracks that are exclusively built for and used by Shinkansen trains. Most lines are served by multiple train categories, ranging from the fastest category that stops only at major stations to the slowest category that stops at every station.

The single biggest factor for not flying short-haul in Japan is usually convenience. If you are travelling from city centre to city centre, the Shinkansen is almost always going to beat flying. The stations are often centrally located at major hubs for all other local train lines. Furthermore, there is no hassle of having to deal with security and checking baggage at the airport.

^{Japan’s Shinkansen (Bullet Train) Network}

China