Industry Insights with Susan Van Dyk - Feedstock availability, sustainability, and development
Susan Van Dyk
Biofuels and Sustainable Aviation Fuels Expert
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SVD Consulting
In this interview Susan Van Dyk, an expert in the field of Sustainable Aviation Fuels (SAF) and biofuels and the trainer for our SAF Feedstock Course: Availability, Supply Chain & Sustainability, shares her insight on the differences in global feedstock availability and exciting new feedstocks currently being researched.
To start, could you please tell us a bit about yourself and your experience
I am passionate about knowledge and driven to understand how things work. So, I would say I am a born scientist. I started off with a career in labour law and only decided to change direction to study science in my 30s. But I have never looked back.
I completed a PhD in the cellulosic ethanol area, specifically on enzyme synergy during lignocellulose hydrolysis. This was the start of my involvement in biofuels. In 2013, I moved from South Africa to Vancouver, Canada, for a postdoctoral position with Professor Jack Saddler, where I worked as Coordinator of IEA Bioenergy Task 39. My work expanded into drop-in biofuels, SAF, and coprocessing at existing petroleum refineries. I worked as project manager on multiple projects, including studies funded by Boeing to explore SAF production from forest residues in British Columbia, and the potential for using pyrolysis/HTL to produce SAF. I got all these opportunities by working with Professor Saddler, and I am very grateful to him.
So I have been working on SAF since 2014. Many of the projects that I worked on included every aspect of SAF, so I obtained experience in technology evaluation, policy, ASTM certification, sustainability, feedstocks, and every other part of the supply chain.
How do the availability and sustainability of different feedstocks vary globally, and what factors influence that?
Feedstock availability varies based on aspects such as population density, e.g. UCO and MSW, while geography and climate determine the availability of other types of feedstocks, such as vegetable oils and agricultural or forest residues. We must determine availability based on the proposed location for a SAF facility, as most feedstocks should ideally be sourced within a limited radius. Feedstocks such as agricultural residues have a low energy density and are only economical when collected and transported within about 100 km of the SAF facility.
CORSIA sustainability standards apply globally to international aviation, so this would not vary across the world. However, on a country basis, sustainability standards may not even be included as part of biofuel policy. For example, ethanol and biodiesel blending mandates across the world are not generally linked to sustainability at all. Most countries set volumetric mandates without requiring carbon intensity measurement.
What are some of the challenges in sourcing feedstocks in different regions, and how does that impact sustainability and cost effectiveness of the fuel?
Feedstock cost is a critical factor in the viability of a SAF facility. For HEFA production, feedstock cost can be about 80% of the production cost. However, the economics of all technologies is sensitive to feedstock cost. For low energy density feedstocks such as agricultural residues, the transportation distance will play a role in feedstock cost. The moisture content and logistics will
play a big role in feedstock such as forest residues. If you transport wet feedstocks, you are essentially transporting water as well. Where you collect residues within the forest at a logging site, size reduction at the site will also impact feedstock cost as this will maximise the volume of feedstock per truckload.
As the carbon intensity of SAF will be determined on a life cycle basis, the feedstock logistics can play a role as the transport will be factored in. Transporting feedstocks over long distances will reduce the carbon intensity of the SAF. Even the mode of transport will impact the carbon intensity, and shipping has a lower carbon intensity than transport by truck.
What do you see as the most promising feedstocks being researched, and what makes them viable?
The volumes of SAF required to meet the climate targets of the aviation sector will be very challenging. As a result, I believe that we will need every possible sustainable feedstock that can be converted into SAF. We can’t afford to pick winners.
I think non-food oilseed crops are very promising for expanding feedstock availability for HEFA and should be aggressively pursued. The main issue here is that we need to establish commercial-scale cultivation. As HEFA is a fully commercial technology, this makes the most sense to me. Oils are relatively simple to upgrade compared to feedstocks such as agricultural residues, where the technology is not even available on a commercial scale.
Feedstocks such as agricultural and forest residues are available in very large quantities and are a prime target for SAF production. However, these feedstocks are very complex, and the technologies have not been demonstrated at a commercial scale. Within this category, I would say the most promising residues are the ones that are produced at a central location, e.g. sawdust at a sawmill or bagasse at a sugar mill. These feedstocks are promising because they are already size-reduced and do not have to be transported from distant locations.
Do you see challenges in the global different LCA modelling methods, and is there scope for moving towards a more aligned method?
There are many different models that are used around the world, and now we have the CORSIA LCA methodology that is applicable to international aviation.
The differences between these models can result in significant differences in the calculated carbon intensity of the fuel product. There are different assumptions used in these models which will impact the results, but what I think should be emphasised is that the biggest differences in carbon intensity will come from the underlying data in the models. For example, the source of electricity used at a SAF facility will have a large impact on the carbon intensity of the SAF produced. LCA models in a specific country or region that have accurate data on the specific electricity sources and their carbon intensity will give a better result than another model, even where the same assumptions are used. Other types of underlying data that could have a substantial impact would be, for example, farming practices and fertiliser application. From the data perspective, a one-size-fits-all approach cannot give accurate information on the carbon intensity.
The CORSIA model has several shortcomings. For one thing, it does not include carbon capture and storage as a factor in reducing the carbon intensity of the fuel. But I think that the CORSIA model will (hopefully) be improved over time to more accurately reflect the real climate impact of fuels. This is not about manipulating the model but rather about measuring everything along the life cycle of the SAF production.
If you would you like to know more about SAF feedstock availability, sustainability, and development, you can register for the course taking place from 16 to 17 July via the link in the yellow box below.
It will be led by Susan van Dyk and will provide an excellent grounding in understanding the types of feedstocks that can be used, as well as their characteristics and challenges for use in SAF production.
It will also discuss some of the key challenges when comparing one SAF pathway over another, including feedstock availability, sustainability principles and criteria and understanding the maturity and readiness of their supply chains.