Yocova recently spoke to Dr. Helge Sachs, Senior Vice President at Sasol ecoFT, about the development of sustainable aviation fuels, what makes some energy sources more sustainable than others, the prospect of a carbon negative fuel and how he thinks things will develop in future.
Dr. Helge Sachs is Senior Vice President at Sasol ecoFT, part of the Sasol Group, which is a global chemicals and energy company based in Johannesburg, South Africa. Sasol sources, produces and markets products in 22 countries around the world. Sasol ecoFT is a world leader in the development and application of the Fischer-Tropsch (FT) technology and leverages this expertise to produce sustainable fuels and chemicals from green hydrogen and sustainable carbon sources.
Helge gives aviation journalist John Walton the lowdown on sustainable aviation fuels (SAFs), what ecoFT is doing and what the future might look like.
What is Sasol ecoFT and what do you do?
“Sasol ecoFT is part of the Sasol Group, which is headquartered in Johannesburg, South Africa and was founded more than 70 years ago. We started off early on using the Fischer-Tropsch (FT) technology to produce fuels from coal and then, through the years, from natural gas. Since 2021 we have moved towards producing renewable fuels and, more specifically, sustainable aviation fuels (SAFs), leveraging our more than 70 years’ experience to build, own, operate and maintain the biggest FT plants in the world.”
What is the Fischer-Tropsch process and how does it differ from other options?
“There are multiple pathways to get to sustainable aviation fuels, and the beauty of the FT technology is that it is agnostic to the feedstock. Biomass or municipal solid waste can be gasified to directly get to the carbon monoxide molecule. Alternatively, direct air capture can absorb the carbon dioxide from the air or industrial point sourced CO2 from industrial emitters like steel factories or cement plants, which are then catalytically reduced to carbon monoxide via a so-called reverse water gas shift reaction. The other part is obviously that you use renewable electricity to produce hydrogen through electrolysis that is then synthesised in the FT reactor to produce syngas. In a product workup unit to hydrocarbon chains are cracked to different fractions , be it sustainable aviation fuel, green diesel Naphta, LPG or other chemicals.
“We’re currently developing a next-generation catalyst that will enable Sasol to further increase the product yield of sustainable aviation fuel. which is mainly a fraction with hydrocarbon chains in the range of 10 to 16 carbon atoms per molecule The next generation catalyst will allow us to increase the yield of SAF to more than 80%.
What are sustainable aviation fuels and what makes them more sustainable across their lifecycle?
“Good question. SAFs, are renewable, low carbon alternatives to conventional jet fuels derived from crude oil. So, for SAFs, fossil feedstocks need to be avoided and they need to be designed such that carbon emissions and environmental impacts associated with the aviation industry are reduce. And then there are biofuels, advanced biofuels, renewable fuels of non-biological origin or recycled carbon fuels (RCF), which come from waste streams, solid waste streams and waste gases. There are also low carbon fuels and energy recycled carbon fuels with low energy contents. The EU renewable energy directive defines the specific properties of sustainable feedstocks and carbon and hydrogen content.
What makes some energy sources less sustainable than others?
“We can start with what makes SAFs truly sustainable. Hydro processed esters and fatty acids (HEFA) have big advantages since they are drop-in solutions. HEFA SAFs are produced from feedstocks such as vegetable oils, waste cooking oils and animal fats. For example, in some geographies, you need to manually collect and use cooking oil from one restaurant to another. Sourcing feedstocks in sufficiently large volumes becomes a challenge.
“In 2019, prior to COVID, more than 300 million tonnes of jet A1 fuel was consumed and this was almost 100% fossil based. If we are to replace that with SAFs in the decades to come to achieve net zero by 2050, we’ll theoretically have to produce around 300 million tonnes of sustainable aviation fuels in a growing aviation market. The HEFA pathway can only contribute up to 20 to 30 million tonnes, so that’s actually only around 10% of what’s needed.”
What are the various pathways to SAFs and what are some of the advantages and disadvantages of each?
“Well, we spoke already about the HEFA pathway, which has a lot of advantages as it uses existing refineries that have been revamped, so it can repurpose existing assets. Another pathway is based on the alcohol to jet process. This utilises feedstocks such as ethanol and butanol, all derived from biomass, which are also quite agnostic to different energy crops. The disadvantage here is the availability of cost-effective and sustainable alcohol feedstocks, which are limited. There is also the gasification FT pathway as well as the power to liquids (PTL) pathway, which can bring you up to 99% of carbon intensity reduction, so it’s very powerful.
“There are a multitude of different feedstocks. There’s sugar cane, molasses, corn, algae, cooking oils, plant or animal fats, and energy crops, agricultural residuals, which we can gasify, so there are a lot of options.”
What is carbon intensity driven by?
“Well, the idea with SAFs is to use carbon from feedstocks that have already absorbed carbon dioxide from the atmosphere, for example, biomass waste materials. So, when the fuel is burned in the engine the carbon is released again into the atmosphere. Basically, the carbon is recycled, and no additional carbon is released from fossil feedstocks.”
Is there any prospect of achieving a negative carbon fuel?
“Absolutely! The ‘silver bullet’ of the industry is very much seen as direct air capture, and ultimately how to get to carbon negative fuels by absorbing carbon molecules from the atmosphere and reducing the carbon intensity. The scalability and capital requirements of direct air capture are issues, though. The first plant is about to be built in Texas, US, costing more than US$ 1 billion, but this will ultimately absorb around a million tonnes of carbon dioxide annually.”
At what point do we withdraw from a pathway when a more sustainable alternative becomes preferable?
“That’s quite a difficult question to answer, because it’s actually a question around whether we are on the right path to achieving net zero, as an industry. Anything that is better than fossil crude oil jet fuel should be accepted by the market and incentivised, but there are differing regulations aimed at significant carbon intensity reduction.
“In terms of the carbon incentive schemes, it’s considered that there’s a carrot and stick approach, with the US dangling a carrot and the EU holding a stick. I think the US schemes are probably preferable as they offer tax harbours and incentives.”
Is there one approach you believe will work more advantageously overall?
“Crucially, the big question is what is going to enable the industry to get to net zero and what the most powerful levers are. Obviously, sustainable aviation fuels will contribute to a large extent because they are using existing infrastructures. You don’t need to replicate an existing infrastructure for instance with green hydrogen to fuel the next generation of aircraft. We might see some hydrogen planes here and there, but these will only be able to operate on short-haul flights. The beauty of leveraging existing infrastructure adds another aspect of sustainability, and that’s why I think SAFs make a lot of sense. Obviously, the next generation of aircraft need to be far more efficient, but there are other things the industry can do to become more efficient. In terms of Europe, initiatives like Single European Sky would make a lot of sense to harmonize air traffic management across a fragmented European airspace. For example, a direct from Frankfurt to Charles de Gaulle could easily save up to 15% of fuel.
“The biggest lever by far, however, will be SAFs with the main challenge to scale the ramp-up of the SAF market due to limitations in cheap renewables and sustainable carbon sources.”
Yocova on Air: Watch John Walton and Dr. Helge Sachs discuss these topics in person.
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Author: Yocova, with special thanks to John Walton
Published 10 August 2023
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