Earth Day 2021 Series Day 7: Flying Green

April 07, 2021

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by Gaulthier Blangez* (Advanced Biofuels USA) What are we talking about? Do you know that airlines' activities, from passenger transportation to freight are responsible for two to three percent of anthropic emissions yearly according to the latest Intergovernmental Panel on Climate Change (IPCC) report?

Indeed, flying comes at a cost. But while the number of planes over our heads was increasing, the industry started to think about how it could become sustainable to make people fly. Several paths are being explored, amongst them: lighten planes and onboard equipment, electrify taxi phases, optimize routes.

Another initiative considered by both companies and governments is the use of advanced biofuels. Nevertheless, because of the central position of fuels in this industry, the transition seems quite challenging. In this article we’ll depict briefly everything you need to know about this blooming revolution.

What is a sustainable aviation fuel?

A sustainable aviation fuel (or SAF) is a fuel that is produced sustainably with feedstocks other than crude oil. Nonetheless, all feedstocks aren’t comparable. To organize it and understand what is SAF we refer to generations and we count four of them:

The first generation is using feedstock compatible with human nutrition. We’re mainly talking about crops (corn/maize, soybean, sunflower and rapeseed). By extension all other crops using soil that could be dedicated to agronomic purposes are rated as first generation.

The second generation uses wastes and lignocellulosic biomass as primary feedstocks. Lignocellulosic biomass refers to most plants. In fact, the lignocellulose is composed of sugar that can be converted into biofuel. If we push the logic farther, agricultural wastes such as wheat straw or corn stover are lignocellulosics. Therefore agriculture can be a feedstock source for both the first and second generation for biofuels. In addition to that, are also industrial (used cooking oil, animal fat) and household wastes.

Third generation biofuels are made of algae that are lipid rich.

Fourth generation feedstocks are not really “bio” fuels since they are mainly composed of carbon dioxide and renewable hydrogen. Indeed, some technologies are able to capture CO2 out of thin air which, once mixed with hydrogen, can be converted into sustainable aviation fuels. Talking about that I invite you to follow our posts during this Earth Day event, later this month we’ll discuss such technologies.

From these four generations, only the three last ones are eligible for SAF production under current policies. In fact, in order to be sustainable, this type of fuel has to be available at a wide scale without creating conflicting usages.

On the benefits side, scientific studies claim that the use of SAF could reduce the carbon footprint from traditional jet fuel use at a minimum of 75% and could go up to 100% with the most advanced technologies. This percentage mainly varies due to the function of the feedstock used and the incorporation ratio allowed.

Did you just say incorporation ratio?

SAF is a “drop-in” fuel, which means that it can be delivered to planes without any engine or tank modification. This is due to the fact that SAF and traditional jet fuel (known as “Jet A1”) are chemically very similar.

To this date SAF may be used in a blend with petroleum aviation fuel. In fact, the ratio varies, for the SAF, in function of the chosen chemical technology, and therefore the feedstock used, from 5% in specific cases to 50% in the most common case.

100% SAF are expected later this decade and their technical certification by the American Society of Testing and Materials (ASTM) is already pending. This technical certification is a sine qua non condition to make a defined type of jet fuel commercially available.

Therefore, the higher the allowed ratio of the SAF, the higher the positive environmental impacts.

Where are we at?

Flying with SAF isn’t actually that new. The first commercial test happened in 2011. The company KLM used SAF at a 50/50 incorporation ratio to fill the tanks of a Boeing 747 connecting Amsterdam and Paris and carrying 171 passengers.

Unfortunately, we cannot say that SAF is commonly used. For 2017, the European Aviation Safety Agency estimated that the use of advanced biofuels represented only 0.004% of total jet fuel used worldwide.

If we can state that supply was at its early stage in 2017, the biggest roadblock for the market to develop is price. To date, SAF is two to five times more expensive than jet A1.

In a period of crisis such as the one we are going through; during which airlines have their planes grounded, an increase of operational costs isn’t welcome. That is the dilemma that aviation is facing today: finding a balance between economic survival and addressing the right answers when it comes to making their activity sustainable.

Such paradox highlights the critical importance of politics. Through incentive mechanisms that are represented by mandates and subventions, SAF could become a weapon of choice when it comes to decarbonizing aviation at a worldwide scale.

What can you do?

Spread the word about SAF and especially about the feedstocks it can be made of to end the common saying that SAF is only made of first generation crops.

When you book a flight, ask if the plane will be using SAF. If not, ask if there’s a way to contribute to development of SAF use by the airline company. Some airlines are providing options for customers, instead of buying offsets, they can pay into a fund that supports research, development and deployment of renewable aviation fuels. For example the Nordic countries’ Fly Green Fund [32] and KLM’s Corporate BioFuel Programme [33] or use Lufthansa’s calculator.

If planes are part of the fleet for freight or business, SkyNRG’s Board Now program provides an opportunity to reduce business air travel emissions and at the same time contribute to the development of a new production facility for sustainable aviation fuel. Board Now enables companies to contribute directly to the development of the sustainable aviation fuel (SAF) industry.

Find more Earth Day 2021 posts here.

Join us for Introduction to Renewable Fuels: What, How and Why? — April 28, 2021 — ONLINE

*Gaulthier Blangez has a Masters degree in Energy and Environment Economics from the French Institute of Petroleum and New Energies. He looks forward to a career managing sustainable aviation fuel (SAF) projects and is working on a white paper summarizing pathways to SAF for Advanced Biofuels USA.