An introduction to everything you need to know about sustainability in aviation.
The quick facts
1 billion mtCO2 were emitted by aviation in a single year for the first time in 2018. Approximately 50% of all aviation emissions were emitted in the last 20 years, despite improving fuel efficiency.
By 2050, aircraft emissions could triple.
Aviation represents 2% of global CO2 emissions, but the true impact is closer to 5% when considering all emissions and non-CO2 impacts.
In light of a growing aviation sector, and a corresponding growing footprint, the aviation industry has come together to identify certain sustainability goals for 2050 as well as introduce regulatory mechanisms to self-push towards emissions reductions. There are several concepts in aviation sustainability to understand as well as compliance requirements to be aware of.
Carbon Offsetting (Carbon Neutral Programs)
A growing number of companies are pursuing carbon neutral programs. This entails measuring the carbon footprint of a flight, aircraft, or fleet and purchasing verified carbon credits in an amount that offsets the total carbon emitted. Each carbon credit represents independently-verified reductions or avoidances of one metric tonne of carbon dioxide (“mtCO2”). Typically, credits are generated from projects like forestry, renewable energy, or new efficiencies; all of which must meet the following criteria: permanent, additional, verified, quantifiable and real.
Comprehensive Offsetting
Comprehensive offsetting looks at the non-CO2 impact from aircraft on the climate and converts that impact to a CO2-equivalent amount that can be offset with traditional carbon credits. This impact is largely from the emission of NOx and the creation of contrails which contributes to cirrus-cloudiness. These impacts collectively make up 2/3 of the entire impact of aviation, with only 1/3 being from CO2 impacts. Using radiative forcing indexes, the climate impact of these other emissions and impacts is converted to CO2-equivalent amounts and offset.
Sustainable Aviation Fuel
Sustainable Aviation Fuel (SAF) has actually been around for several years, but has just recently seen an exponential rise in production and interest. SAF is certified under the same standard as fossil jet fuel but comes from more sustainable sources. There are many available feedstocks, each with different emissions reductions, benefits, availability, and pricing, but the largest are waste cooking oil and solid municipal waste. Sustainable fuel is produced as “neat SAF” (undiluted) and then mixed with jet fuel from fossil, usually in a 30-70 blend, but as much as 50-50. Under this mixed form, it is certified with the same safety and performance characteristics as fossil jet fuel (sometimes with slightly better performance) and is a “drop-in solution” meaning no modifications are necessary to any storage, fueling, engines, fuel systems, etc. to use it.
It is, however, only available in limited supply and at a few airports around the world. As such the industry has introduced a “book and claim” system that allows one person to fuel and use SAF, while another person claims the emissions reduction benefit. This reduces the transport cost, preserves emissions savings, and helps scale up SAF more quickly. A book and claim system works very similar to a renewable energy credit (REC): where a person can claim the benefit from the REC as joules of energy from renewable sources entered the electric grid somewhere, even if the particular joules of energy they use didn’t come from that renewable source.
Whole Aircraft Sustainability
More than 90% of the impact from an aircraft comes from the fuel it consumes and this is why so much of the focus is put on fuel consumption and its impacts. However, there are other impacts and areas to consider when thinking about complete sustainability. Achieving whole aircraft sustainability requires considering the impacts from on-board waste from snacks and catering, the availability of reusable dishware versus one-use plastics, and even the materials used for the aircraft interior. Every aspect of the plane and from a single trip can be examined to ensure broader sustainability.
CORSIA, EU ETS & Other Compliance
In addition to many voluntary pushes for sustainability in aviation, there are some new regulatory requirements from the industry (ICAO) and several nationalities. Typically, these requirements only apply to large operators or manufacturers, but they may induce reporting or compliance requirements, particularly for companies with a high level of international travel. CORSIA is an ICAO initiative to achieve carbon neutral growth in international aviation, while EU ETS limits emissions for international travel between EU member states using tradeable emission allowances. There are growing regulatory requirements and new schemes on the horizon as well that may expand these reporting requirements.