Feedstuck? Resolving Short- and Long-Term Feedstock Issues in SAF Production via Hydroprocessing

Sustainable aviation fuel (SAF) is considered one of the essential ways to decarbonize the aviation industry. SAF produced via hydroprocessing can be generated from various renewable feedstocks, including vegetable oils, waste oils and fats, and solid biogenic waste. However, feedstock supply is a critical challenge for the production of SAF via hydroprocessing due to limited availability, competition from other industries and uses (food, road transport, marine fuel, petrochemicals), technological maturity in some pathways and the wait on regulatory approvals, writes Milica Folic, Product Line Director for Renewable and conventional hydroprocessing technology at Topsoe.

HEFA and Beyond HEFA

Producing SAF from waste oils is the most technically mature SAF conversion pathway, referred to as hydroprocessed esters and fatty acids, or more commonly as HEFA. But waste oils are highly resource-constrained and are already largely consumed by the road transport sector. This limitation poses a significant challenge to the production of SAF from waste oils as the demand for SAF continues to increase.

Similarly, vegetable oils are commonly used to produce renewable diesel and food products, which limits their availability for SAF production. This has led to concerns about the impact of increased demand for SAF on the food industry and land use. Moreover, there are regulatory constraints on the use of these feedstocks, especially first-generation renewable feedstocks, in some regions of the world, such as the EU.

The Third Generation Coming Through

To address the feedstock availability challenge, research and development are focused on finding new and advanced feedstocks that can be derived from solid biomass waste, rotational crops, or recycled carbon. However, these third-generation feedstocks require different processes for conversion, which pose some technical and regulatory challenges. While the technologies for these conversion processes are maturing, strict aviation regulations mean some processes still need ASTM approval.

Solid waste, third generation feedstocks are a much more abundant resource than first and second generation and will remain so for years. It is estimated that annual worldwide municipal solid waste, a source of biomass material, will reach approximately 3.4 billion tonnes by 2050, in part due to rapid urbanization and rising global populations. Although in its earlier stages of development, it is clear that maximizing utilization of solid waste feedstock will be key to decarbonizing aviation.

SAF Producers Should Consider Several Factors Related to Feedstock Availability

SAF producers need to be aware of the market position and its competitive drivers, which could affect the demand and supply of SAF feedstocks. With the increasing demand for SAFs, competition for feedstocks between various industries could lead to higher prices and scarcity. The processing stage also plays a crucial role, with some feedstocks suitable for certain SAF pathways and others not. Therefore, producers need to consider the feasibility of using a specific feedstock for a specific pathway, its cost-effectiveness, and the environmental impacts associated with its production.

Geographical position and proximity to sources also matter, as it could lead to easier collection logistics leading to steadier supplies. For instance, sourcing feedstocks from local suppliers could minimize transportation costs and ensure a steady supply of feedstocks. The sustainability of feedstock supply chains can also be improved through local sourcing.

The Physical Environment and the Regulatory Environment

Sustainable feedstock sourcing and collection is critical to meeting the growing demand for SAFs while minimizing the environmental impact of their production. SAF producers should seek to ensure that their feedstock suppliers adhere to sustainable production practices and standards, such as minimizing land-use change and protecting biodiversity. In addition, feedstock producers should ensure that they are not competing with food production or causing social issues, such as displacement of local communities.

The availability and cost of feedstocks are also influenced by government policies and regulations. Governments can incentivize feedstock sourcing and collection through tax credits or subsidies, while regulations can restrict the use of certain feedstocks or require sustainability certifications. SAF producers should monitor government policies and regulations related to feedstocks to ensure that they can maintain a reliable and sustainable feedstock supply.

Lastly, SAF producers should consider how easy it would be for them to switch to alternative feedstocks if a chosen feedstock becomes scarce. In case of a shortage of feedstocks, SAF producers should have alternative feedstocks that they can switch to, with minimal impact on the SAF production process.

The Topsoe Outlook

The cost of producing SAF from first and second-generation feedstocks is currently at a reasonable level. However, the processing of advanced feedstocks, such as third-generation waste feedstocks, requires additional steps due to their solid nature – they need to be liquified. As a result, prices are expected to rise initially due to this extra production complexity.

The EU and IRA, however, are providing incentives for new technologies to encourage the industry to develop solutions for new feedstocks. The aim is to reduce the cost barrier, and this is likely to have the expected impact.

While hydroprocessing technology is mature and straightforward for liquid-first and second-generation feedstocks, it is more complex for third-generation feedstocks. Nevertheless, the industry and Topsoe are optimistic about the potential of third-generation feedstocks to become gamechangers. Sooner is obviously better, and we anticipate that there will be a turning point between 2030 and 2035, when third-generation feedstock projects take off and dominate SAF production.

Read more about the fast-developing SAF landscape in the Voices from the Sky report.