Fuel of the Future: A Layman’s Glimpse at Sustainable Aviation Fuels

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Graphic by Maralmaa Munkh-Achit

Written by Juliet Jordan

Edited by Courtney Schneider

The Environmental Impact of Air Travel

Air travel is an essential means of transportation for many people. Flights are generally fast, convenient, and worth the investment for frequent flyers; however, as global C0₂ emissions continue to rise, a thorough look into the industry’s sustainability and environmental impact is warranted.

Fig.1: Global Carbon Emissions Diagram, Source: Our World in Data, Accessed on: 12/15/2021

Airlines impact the economy and have global transportation responsibilities.^{^[1]} Global air travel alone accounts for 2.5 percent of all C0₂ emissions (Figure 1);^{^[2]} an outsized share given this represents only one means of transportation. At this rate, the UN predicts that the aviation industry will expend 12% of the global carbon budget of 1.5 degrees Celsius by 2050. If the industry continues to rely on fossil fuels, this expenditure will increase to 27%.^{^[3]}

Air Travel and C0₂

The C02 and greenhouse gas emissions released by planes cause many adverse environmental effects. In the spirit of perspective-taking and fighting against the urge to catastrophize, there is a potential solution that may mitigate the most extreme of these effects: Sustainable biofuels.

Before discussing solutions, it is important to address that the current climate crisis is not the first time the Earth has warmed and catalyzed intense atmospheric responses, extinctions, and similar consequences.^{^[4]} The notable difference within the current warming period, however, is that a sizable percentage of the damage is now a result of human activity. Nevertheless, the Earth has historically run through natural warming and cooling cycles. This fact is not meant to argue that increased emissions are not devastating to the climate; they are. However, these emissions are also human-induced: The climate crisis can conceptually be mitigated, to some extent, by the same population that inflicted it.

It may be easy to villainize certain emissions-increasing actions, including airline travel. The aviation industry itself has come under great scrutiny for its negative effects on the climate. The industry does, however, face the difficult challenge of providing convenient transportation and expanding economic development and global trade while also holding sustainable incentives in mind.

Mitigating the Emissions Problem

Sustainable biofuels may prove helpful in mitigating the drastic negativities of air travel while still offering the benefits this mode of transportation boasts. While fossil fuels remain the most prominent source of power for the aviation industry—used primarily in the form of Jet A, Jet B, and AvGas—biofuel is progressively gaining traction as an emissions-reducing alternative fuel source or engine additive. Biofuels are the subject of an extensive and ever-evolving area of research and are categorized into multiple ‘generations’. First generation biofuel is made from feedstocks like ethanol and biodiesel (made from sugar and corn, respectively) and is used in transportation, heating, and power. However, it is characteristically unsustainable as it generates a chasmic shift in agricultural land use, water availability, and occasionally deforestation.^{^[5]}

Second generation biofuels are considered more sustainable due to their comparatively minimal reliance on feedstocks, water, and forests. They are also generally used in aircraft due to their ability to maintain high performance and safety specifications. Known as sustainable aviation fuels (SAFs), they represent the peak of sustainable progress among aviation fuels as they can actually replace jet fuel: SAFs and jet fuels have the same hydrocarbons, but those present in SAFs come from a sustainable source.^{^[6]} SAFs are produced from bio-excess and regenerative sources, including solid municipal waste–from organic clippings, clothing, paper products, packaging, and more–and cellulosic waste, or plant material (Figure 2).

Fig.2: Carbon Life Cycle Diagram, Source: International Air Transportation Association, Accessed on: 01/31/2022

Other SAF sources may include used cooking oil, excess animal feed material, algae, and less commonly, electric energy.^{^[7]} Given they are made from repurposed materials, SAFs have a minimal carbon footprint throughout their lifecycle and are often cited as a substantive answer to the aviation industry’s environmental problems. Despite outside critiques and criticism of the industry itself, a focus on sustainability is becoming more prevalent. As detailed by the Business Aviation Coalition for Sustainable Aviation Fuels, the aviation industry is perpetually pursuing efficiency while mitigating its emissions impact.^{^[8]}

SAFs can reduce the lifetime of the aviation industry’s greenhouse gas emissions by 80%.^{^[9]} A transition to SAFs may also be easier to implement than other sustainability methods because it is a ‘drop-in’ fuel—a sustainable fuel that can be used immediately and does not require modifications to engines or storage and fueling infrastructure.

Unfortunately, SAFs are expensive and can cost up to 8 times the price of regular aviation fuel.^{^[10]} Nonetheless, due to their ability to replace jet fuel and utilize existing petroleum infrastructure, SAFs’ economic viability remains one of the only main production challenges. If SAFs can be rapidly scaled up, this viability will improve, making them a more lucrative fuel source. To achieve this, we must first enact policy that supports the use of sustainable, eco-friendly, and cost-effective aviation fuel.

Policy in the Works

There are numerous policy options for SAF uptake, including those suggested by the Atlantic Council Global Energy System.^{^[11]} These include:

Attracting capital to expand SAF supply
Assisting SAF facility operation through targeted incentives and tax relief
Recognizing the environmental benefits of SAFs
Creating demand by further incorporating SAFs into existing renewable fuel source policies
Creating demand by further incorporating SAF into existing low-carbon fuel standard type regulations
Demonstrating government leadership through ongoing SAF purchases, research, demonstration activities, and a clear statement of policy direction

State legislation is also in process: California offers an example of legislation that can help catalyze the use of SAFs. The Sustainable Aviation Fuel Act, a bill introduced by Julia Brownley (D-California), has been referred to the Subcommittee on Aviation but has not yet been passed. It seeks to set national US aviation C0₂ reduction goals, offer grant funding for SAF development and research, and incentivize SAF utilization for tax credits.^{^[12]}

Similarly, President Biden’s 2021 ‘Build Back Better’ program includes a SAF tax credit incentive. This regulation was supported heavily by the National Business Aviation Association and offers a $1.25 credit for every gallon of SAF sold as part of a jet fuel/SAF mixture (Figure 3). The SAF must demonstrate a 50% reduction in greenhouse gas emissions impact during its entire fuel cycle (from growth, to transportation, to utilization). If the lifecycle demonstrates an even higher reduction in greenhouse gas emissions, this credit increases one cent per additional percentage point.^{^[13]}

Fig.2: Depiction of the blending process of SAF and Jet fuel, Source: National Renewable Energy Laboratory, Accessed on: 012/10/2021

Though there are benefits to utilizing SAFs, the challenge remains that this type of fuel is much more costly than traditionally used fossil fuels.^{^[14]} Therefore, legislation surrounding biofuel creation and usage is understandably sluggish. With this in mind, a key to incentivizing airlines’ use of biofuels such as SAFs is generating a conglomeration of support from various aviation outlets, suppliers, and industries in order to increase demand, generate a surplus of supply, and ultimately decrease the cost of sustainable fuels.

Conclusion

Borrowing from the Shakespearian adage, idealization should not come at the expense of making small steps toward a better state or environment. SAFs arguably hold the answer to the airline industry’s emission woes; however, they are not currently mainstream due to the extreme cost barriers and lack of scalability. Additional research is critical to lower the cost barriers, though industry experts should continue to pursue additional alternative energy sources. Advocating for SAF-centered policy will be key in ensuring that the aviation industry can gain the visibility and support needed to pursue the utilization of this carbon-friendly energy source.

The aviation industry recognizes its role within the climate crisis and is actively pursuing steps to mitigate the most serious effects of its current fossil fuel use. The task for public administrators, officials, and interest groups is to continually advocate for and support alternative energy sources within this industry and demand constant visibility of its roles, actions, and mitigation processes. While the aviation industry works to scale its SAF usage to 100%, the simultaneous pursuit of alternative energy sources, such as electricity, can help diversify its fuel and power options.

Bibliography

ATAG, Climate Action Takes Flight, Beginner’s Guide to Sustainable Aviation, ATAG, November 3, 2017, https://aviationbenefits.org/media/166152/beginners-guide-to-saf_web.pdf.

Fred Ghatala, “Sustainable aviation fuel policy in the United States: A pragmatic way forward”, Atlantic Council-Global Energy Forum, April 30, 2020, https://www.atlanticcouncil.org/in-depth-research-reports/report/sustainable-aviation-fuel-policy-united-states/.

Hannah Ritchie, “Climate change and flying: what share of global CO2 emissions come from aviation?” Our World in Data, October 22,2020, https://ourworldindata.org/co2-emissions-from-aviation#:~:text=2.5%25%20of%20CO2%20emissions.

IATA. “SAF – Sustainability Considerations. Sustainable Aviation Fuels”, International Air Transportation Association, 2020 https://www.iata.org/contentassets/d13875e9ed784f75bac90f000760e998/saf-and-sustainability.pdf.

ICAO et al. “Aviation Benefit Report”, Industry High Level Group, 2019, https://www.icao.int/sustainability/Documents/AVIATION-BENEFITS-2019-web.pdf

Kelsey Reichmann, “Sustainable Aviation Fuel Aren’t Sustainable-Not Yet At Least”, Aviation Today, August 5, 2021, https://www.aviationtoday.com/2021/08/05/sustainable-aviation-fuels-arent-sustainable-not-yet-least/

Michael Goldstein, “Sustainable Jet Fuel Costs 8X Regular Fuel; Can Oil Giants Scale Up Production By 2025 To Cut Carbon”, Forbes, September 23, 2021, https://www.forbes.com/sites/michaelgoldstein/2021/09/23/can-oil-industry-giants-like-shell-provide-sustainable-jet-fuel-by-2025/?sh=8af00ee3e00d

Michon Scott, Rebecca Lindsey, “What’s the hottest Earth’s ever been?”, NOAA Climate.gov, June 18, 2020, https://www.climate.gov/news-features/climate-qa/whats-hottest-earths-ever-been.

NBAA, “NBAA-Backed SAF Blenders Tax Credit Advances in Build Back Better Act”, NBAA, November 19, 2021, https://nbaa.org/aircraft-operations/environment/nbaa-backed-saf-blenders-tax-credit-advances-in-build-back-better-act/

Rep. Julia Brownley, “H.R.8769 – 116th Congress (2019-2020): Sustainable Aviation Fuel Act”. Congress.gov, February 4, 202,https://www.congress.gov/bill/117th-congress/house-bill/741

Roz Pidcock, Sophie Yeo, “Analysis: Aviation could consume a quarter of 1.5C carbon budget by 2050”, Carbon Brief Clear on Climate, August 10, 2016 https://www.carbonbrief.org/aviation-consume-quarter-carbon-budget.

Sustainable Aviation Fuel Initiative, “Fueling the Future – Sustainable Aviation Fuel Guide”, The Business Aviation Coalition for Sustainable Fuel. https://www.futureofsustainablefuel.com/guide

Graphic Citations:

Hannah Ritchie, “Climate change and flying: what share of global CO2 emissions come from aviation?” Our World in Data, October 22,2020, https://ourworldindata.org/co2-emissions-from-aviation#:~:text=2.5%25%20of%20CO2%20emissions
IATA. “SAF – Sustainability Considerations. Sustainable Aviation Fuels”, International Air Transportation Association, 2020 https://www.iata.org/contentassets/d13875e9ed784f75bac90f000760e998/saf-and-sustainability.pdf.
Kristi Moriarty and Allison Kvien, U.S. Airport Infrastructure and Sustainable Aviation Fuel, National Renewable Energy Laboratory, February 2021, U.S. Airport Infrastructure and Sustainable Aviation Fuel (nrel.gov)