How United Airlines is Revamping the Skies with SAF

Is the sky the limit for sustainability, or can we make our stratospheric activities green and clean?

This is a question directed at the aviation industry, known for its considerable environmental footprint.

With the industry responsible for 3% of global greenhouse gas emissions a result of around 37.8 million yearly flights producing around 800Mt of CO₂, the need for sustainable solutions becomes unequivocal.

But is the carbon/convenience compromise something we should settle for?

According to Nili Gilbert, Vice Chairwoman of Carbon Direct and Lauren Riley, CSO and Managing Director of Global Environmental Affairs at United Airlines, the answer is a firm no.

Instead, they advocate for a robust investment in R&D for Sustainable Aviation Fuel (SAF).

Does SAF bring promise for the future of the aviation industry?

As Lauren articulates, SAF stands defined as "an alternative to conventional jet fuel derived from waste and renewable feedstock, meaning it has up to 85% less carbon on a lifecycle basis".

This marked reduction underscores why SAF has become such a sought-after solution for airlines aiming at achieving net zero targets.

Furthermore, it represents one of the few carbon mitigation strategies available to the aviation sector, accentuating the urgency for its development.

Lauren acknowledges the distinct challenges aviation faces, saying: “Whilst the 3% that aviation contributes to global emissions may not sound like a lot, what I anticipate happening is that number increasing as other industries decarbonise.

“We’re a ‘hard to evade’ industry, meaning we don’t yet have scalable solutions for flying.”

Scaling SAF: The challenges

Despite the promising potential of SAF, its actual production starkly under fulfils industry needs.

Nili points out a striking disparity: “If we look at the total production of sustainable aviation fuel last year relative to the amount of fuel that United alone uses annually, that the SAF share would be just 0.1% of your total usage".

To this, Lauren concedes the challenge, adding: "In a given year, United consumes about four and a quarter billion gallons of fuel.

“Last year worldwide, 150 million gallons of SAF were produced".

SAF feedstock and future directions

At the moment, used cooking oil and waste fats constitute the primary feedstock for SAF, but they can only meet about 6-8% of total fuel needs, indicating the necessity for alternative sources.

Lauren explores the potential of biomass and various agricultural products during their dialogue.

She says: "Whether that's municipal solid waste, corn sugarcane or other sources. We're able to collect a lot of that biomass and convert it through different technology pathways."

This could furnish a significant supply of feedstock necessary for expansive SAF production.

Beyond biomass, the promise of power-to-liquid technology also captures both Nili and Lauren’s enthusiasm.

"Power-to-liquid could create really what I see is a closed loop for aviation," Lauren says. "It pulls CO₂ out of the atmosphere. You convert that using a whole bunch of renewable power, green hydrogen and other stuff into a jet fuel that is lower carbon."

Moreover, immediate measures like 'lightweighting,' which involves reducing aircraft weight to decrease fuel consumption and thus emissions, and managing condensation trails (contrails) that trap heat in the earth’s atmosphere, could offer transitional environmental relief while SAF technology matures.

The role of policy and corporate partnerships

The advancement of SAF also hinges significantly on policy support and corporate cooperation.

Lauren praises the US Inflation Reduction Act's historic role in fostering sustainable aviation and emphasises the gravity of corporate partnerships, with many companies investing dedicatedly in meeting their climate commitments.

Nili adds that these partnerships could help achieve economies of scale, potentially bringing down costs for all consumers in the future.

"With those actors paying up today, the vision is that we'll achieve the economies of scale that are required to bring the cost down for others," she explains.

Despite the considerable obstacles, the future of sustainable aviation fuel appears promising.

Lauren succinctly sums up the industry's sentiment:

We have the solution set, we just don't have the economics that line up to make it the preferred channel, the preferred path forward.

"We need to shift that paradigm so it becomes the preferred path forward."

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