What are the facts?
The transportation sector (i.e. road, air and marine transport) accounts for 16% of global emissions, with cars, SUVs and motorcycles contributing to 47% of those emissions, followed by garbage trucks, buses and 18-wheelers which account for 30%. Airplanes then account for 10%, while cargo and cruise ships contribute to 10% and others contribute for 3%.
Over the last decade, global air traffic has massively increased and since most flights are powered by fossil fuels, greenhouse gas emissions have been rising from this sector. In 2004, the carbon dioxide emitted from the commercial aviation industry itself was 627 million tonnes. This increased to 900 million tonnes in 2019.
When accounting for the entire emissions for the aviation sector globally, 915 million tonnes of CO2 were produced in 2019 which amounts at about 2.13% of the total 43 billion tonnes of CO2 emitted by all sources globally that year. Emissions from aviation have been increasing at a similar rate as total global carbon dioxide emissions and are still expected to show the same trend over the next few years. Emissions from domestic aviation are included under the United Nations Framework Convention on Climate Change (UNFCCC) which many countries have committed to. However, this framework does not include international aviation. The fact that countries do not account for international flights within their emissions means that these massive emissions can be overlooked by countries and governments will be less incentivized to take the necessary actions to reduce them. The demand for transportation will only continue to increase and current policies are not sufficient enough to fully decarbonize this sector, this is why it is critical that strict rapid measures are established while alternative low emission technologies continue to develop.
Can we operate flights with lower emissions?
Renewable biomass, municipal waste, used cooking oil and many bio-based feedstocks are all raw materials that can be used to make sustainable aviation fuel (SAF). This fuel has the potential to replace fossil-based jet fuels in planes but with lower carbon dioxide emissions. The way it is utilized currently is by blending it with conventional aviation fuels, and it is predicted that it can reduce emissions by 80% depending on factors such as raw materials used and production methods. The fact that there is a diversity in the raw materials that can be used to produce the fuel is another advantage, because this means that production will be possible in many countries whereas fossil fuels are only found in specific geographic locations.
The fuel was first tested in 2008, it has received approval to be used in 2011 and has powered 413,625 commercial flights since then. There are currently six airports that are regularly supplied with SAF and seven approved methods of producing SAF. The first commercial flight launched using 100% SAF was by United Airlines in December 2021 and in a more recent initiative, Emirates Airline will operate a flight using 100% SAF by the end of 2022. However, the use of SAF still remains low since it is not produced at a high capacity, this is due to high production costs leading to less investments. For instance, the usual fossil-based aviation fuel costs about €600/tonne in Europe whereas the bio-based aviation fuel can range between €950-€1015/tonne. There is also a high demand for bio-based fuels to be used in vehicles hence a high competition between using these fuels for vehicles and for aviation and this competition is expected to increase in the near future. In order for the use of SAF to expand, more research and support is required from energy companies and governments.
Electric fuels also have the potential to replace conventional jet fuel, but are still not widely used at a large scale. To put things into perspective, a typical Boeing 787 is able to accommodate 296 passengers, fly up to a maximum speed of 650mph and fly for almost 20 hours before needing to refuel. On the other hand, a fully electric airplane today is able to accommodate two passengers, fly up to a maximum speed of 210mph and fly up to three hours before needing to refuel. Electric planes cannot tackle this issue at a large scale yet due to the battery limitations and low energy density associated with such batteries and this will still require extensive research.
Where are we today?
These technologies may not be feasible at a greater scale in the near term but it is still critical that aviation meets decarbonization goals soon. While these emerging technologies continue to develop, initiatives such as carbon credits and offsets are being introduced by governments. These initiatives encourage compensation for CO2 being produced in one area by helping CO2 reduction in other areas such as investing in reforestation and renewable energy projects for example.
Such initiatives include The Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) strategy which was established by the International Civil Aviation Organization from 2021 until 2035, and it aims to mitigate 2.5 billion tonnes of carbon dioxide emissions during this timeframe. The CORSIA voluntary pilot phase began in 2021, and the voluntary first phase is to begin in 2024. The mandatory second phase will begin in 2027 with some exemptions and the scheme is expected to end in 2035. The offsetting programs utilized by this scheme aim to use offsetting as a way of stabilizing emissions, this method is temporary and will hopefully diminish on the long run once a breakthrough in the technological shift is achieved and alternative fuels will be used for aviation that have no or very low emissions.
