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Aviation Carbon Footprint: Emissions Profile Insights

Article Overview

As the world grapples with the urgent need to drive down carbon and respond to climate change, no sector of the economy is immune from scrutiny—including the aviation industry. The sector, which is responsible for 2% of global anthropogenic greenhouse gas emissions, today finds itself at a crossroads. Global climate regulations are gaining momentum, and societal demand for sustainable travel is soaring to new heights. The aviation industry is under growing pressure to reduce emissions. To get there, companies in this sector must first understand where their greenhouse gases come from. 

In this blog post, we will do a deep dive into the emissions profile of the commercial aviation industry, covering scope 1 and 2 emissions, as well as some commonly overlooked scope 3 emission sources. We'll explore different ways of calculating emissions from Sustainable Aviation Fuel (SAF) — and how those calculations differ from the Greenhouse Gas (GHG) Protocol’s Corporate Standard. Finally, we'll investigate the emerging trends, regulatory pressures, and self-imposed incentives shaping the industry's approach to its substantial carbon footprint, drawing from an exclusive interview with our Climate Solutions Director, Jesse Nikkel.

What’s an Emissions Profile, and Why is it Important? 

An emissions profile serves as a starting point for robust carbon accounting.

An emissions profile provides a snapshot of the greenhouse gas emissions generated by an industry or organization. In the aviation sector, this profile includes not only scope 1 emissions, largely stemming from jet fuel combustion, but also scope 2 emissions from electricity at select buildings, and scope 3 emissions from activities farther up the supply chain — such as fuel extraction, refining, transportation, and emissions from purchased goods and services. We’ll get into the specific emissions profile of the industry later in this blog. 

What Does a Standard Emissions Profile Look Like in Aviation?

Jet fuel and a variety of scope 1,2, and 3 sources contribute to the sector’s profile.

One of the first steps in beginning your carbon accounting journey is asking the question: “What emissions sources do we need to track to accurately measure our carbon footprint in line with industry best practices?” An emissions profile is meant to be an initial guide to help you better understand the business activities that make up your carbon footprint and give you an idea of what financial and operational data will be required to complete your footprint. 

In the aviation sector, the breakdown of emissions between scopes can vary depending on factors such as the airline's operational efficiency, the type of aircraft used, the routes flown, and the airline's efforts to reduce emissions through measures like fleet modernization, fuel efficiency improvements, and investment in sustainable aviation fuels. 

Below, we outline common contributors to material emissions in this sector. In this context, ‘material’ refers to sources that likely account for at least 5% of total GHG emissions in scope 1, 2, or 3 categories. 

This emissions profile is based on Persefoni’s analysis of carbon benchmarking data from the CDP. It is intended to help you understand the business activities that may make up your carbon footprint, and to provide a roadmap for more comprehensive carbon accounting. 

aviation emissions profile

Scope 1 Emissions

For most airlines, scope 1 emissions tend to be the largest component of their carbon footprint. These are direct emissions from sources that are owned or controlled by the airline, such as emissions from aircraft engines during flight, ground support equipment, and vehicles owned by the airline. In aviation, the majority of scope 1 emissions originate from jet fuel, with 99% of these emissions being CO2. 

Airlines will typically be able to calculate their scope 1 emissions with relative ease due to existing fuel consumption data and the direct relation between that fuel consumption and emissions. As such, utilizing the fuel-based calculation method is common practice, and data sources required to calculate these emissions include the specific fuel type and amount. Examples of common owners of this data at an airline include flight operations, fuel procurement, and financial planning and analysis.

Scope 2 Emissions

Scope 2 emissions are indirect emissions resulting from the generation of purchased electricity, heat, or steam consumed by the airline. This primarily includes emissions from power plants that provide electricity to airports and other facilities used by airlines. Scope 2 emissions typically constitute a smaller portion of the overall carbon footprint for airlines.

scope 1 and 2 emissions airlines

Scope 3 Emissions

These are indirect emissions from sources not owned or directly controlled by the airline but are associated with its activities. Scope 3 emissions for airlines typically include emissions from the production of the fuel used for flights, emissions from passenger and cargo transportation to and from airports, emissions from the production of goods and services purchased by the airline, and employee commuting.

  • Fuel & Energy Related Activities not included in scope 1 or 2: The largest portion of scope 3 emissions arises from the upstream activities of fuel, including extraction, refining, and transportation. When calculating lifecycle emissions from jet fuel for a regulatory program like California’s Low Carbon Fuel Standard or CORSIA, these upstream emissions are typically less than zero, meaning that more carbon was removed or sequestered than was generated in the fuel’s production. The Greenhouse Gas Protocol’s current guidance for calculating these upstream emissions does not allow for these negative values, resulting in a discrepancy in the emissions profile of SAF when using different calculation methodologies.
  • Purchased Goods and Services: An often-overlooked category of scope 3 emissions, purchased goods and services can range from aircraft parts to onboard catering supplies and services. This category includes the extraction, production, and transportation of goods and services purchased or acquired by the airline. As a byproduct of an airline’s extensive supply chain, the emissions from purchased goods and services are material.
  • Business Travel: While not significant to the overall emissions profile, emissions from business travel activities like hotel stays for crews should also be accounted for.
  • Upstream Leased Spaces: Emissions associated with leased space at airport terminals are relevant to most commercial airlines.
scope 3 emissions airlines

In summary, while jet fuel dominates airlines' emissions profiles for scope 1, a substantial environmental impact arises from an airline’s supply chain. Comprehensive efforts to reduce the aviation industry's carbon footprint must extend beyond focusing solely on jet fuel consumption and encompass these other areas as well.

Measuring Carbon Emissions in the Aviation Industry

Selecting a method can be complex and nuanced.

Airlines can employ different methodologies for calculating emissions. For example, the Greenhouse Gas (GHG) Protocol is typically utilized as the basis for the calculation of an airline’s total emissions footprint. Argonne National Laboratory’s Greenhouse Gases, Regulated Emissions, and Energy Use in Technologies (GREET) model is commonly used by fuel producers to determine their lifecycle fuel emissions for California's Low Carbon Fuel Standard.

 Another method is the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA). The CORSIA Default Lifecycle Emission Values for CORSIA Eligible Fuels are emission intensities calculated in the same manner as GREET, but with more generalizations baked in (whereas the results from GREET are specific to each producer and feedstock). 

For SAF emissions, airlines can use the results from the fuel producer's calculation (generated in part using GREET), or they can use the CORSIA default values. Because of the generalizations integrated into the CORSIA default values, the emissions intensities between these default values and a fuel producer’s carbon intensity as calculated for the Low Carbon Fuel Standard can differ. It’s also important to note that the adoption of SAF is currently pretty minimal; it’s expensive and limited in supply, but with the SAF incentives from the Inflation Reduction Act (IRA), it’s positioned to become more economically viable.

According to the GHG Protocol, CO2 emissions from the combustion of SAF are not included within scope 1, since they are biogenic emissions. However, methane and nitrous oxide emissions from an airline’s use of SAF must still be included within scope 1. This reporting nuance offers benefits in terms of lower scope 1 emissions but underscores the need for comprehensive understanding and tracking of the entire emissions profile. 

Key Trends in Aviation: Insights from our Director of Climate Solutions

Like most industries these days, the aviation sector is facing a pivot as sustainability emerges as a core value of consumers and other stakeholders. To get a read on the key trends affecting the industry, we talked to Jesse Nikkel, Director and Head of Climate Solutions at Persefoni. He shared the following insights about what leaders in the space can expect:

1. SAF Adoption is Promising and Complex

  • Diverse Calculation Methods and a Variety of Feedstocks: Sustainable Aviation Fuel is recognized as an essential element for reducing emissions within the aviation sector, potentially lowering lifecycle greenhouse gas emissions compared to conventional jet fuels. However, accurately measuring these emissions reductions is complex due to diverse calculation methods and various feedstocks involved in SAF production.
  • Adoption Challenges and Compatibility: Widespread SAF adoption faces hindrances such as blending requirements with traditional fuels and the current scarcity of the product on the market. 

2. Disclosure Regulations and Scope 3 Reporting Create Hurdles

  • Scope of Emissions in Aviation: The majority of greenhouse gas emissions in commercial aviation stem from scope 1 emissions, primarily from jet fuel combustion. Reporting these emissions holistically necessitates considering scope 3 emissions, which have been historically reported inconsistently and without encompassing all significant emission sources.
  • Transition to Regulatory Reporting: Airlines are experiencing a shift from voluntary to mandatory regulatory reporting of scope 3 emissions. This transition demands a thorough assessment of emissions across the entire value chain, including supply chains, leased airport facilities, and electricity used by electric Ground Support Equipment (GSE).

3. Future Technologies Present Challenges and Opportunities

  • Advantage of SAF Over New Technologies: SAF's ability to serve as a drop-in replacement for conventional jet fuel in existing aircraft presents a substantial advantage over newer technologies like electric and hydrogen planes, which would require entirely new aircraft and infrastructure. This makes SAF a more immediately feasible solution for emission reduction in aviation.
  • Progress in Emerging Technologies: Major aircraft manufacturers are focusing on making their fleets compatible with 100% SAF in the future. Additionally, innovative approaches like power-to-liquid technologies are emerging, though they face challenges aligning with current greenhouse gas protocol accounting due to their non-biological origin.

Charting Pathways to a Sustainable Aviation Future

The aviation sector is essential for our connected world. Yet it persists as a significant contributor to global carbon emissions. In looking at the industry’s emissions profile, it's evident that the complexities and scale of the challenges require a multi-pronged strategy. From advancing fuel-efficient technologies to embracing sustainable aviation fuels and reimagining air travel operations — reshaping this sector for a more sustainable future is within reach. To unlock these solutions, airlines first need transparent emissions reporting and rigorous data management. With reliable information and strong collaboration with partners and stakeholders, the aviation industry will be well on its way to greener horizons.

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