When Pigs Fly: How Is Biofuel Changing Sustainability In Aviation?
- Sahil Sehgal
- Aug 17
- 4 min read
What Is Sustainable Aviation Fuel (SAF)
Sustainable Aviation Fuels (SAFs), in simple terms, are aviation fuels derived from feedstocks like animal waste, plant oils, and agricultural waste. They are a more environmentally friendly fuel source (in comparison to kerosene and other types of conventional jet fuels) and are being developed to increase sustainability in the aviation industry.
Currently, the most commonly used jet fuel is kerosene-based, otherwise known as Aviation Turbine Fuel (ATFs). It is mainly used due to its high energy density in comparison to other types of fuel. ATFs generally have an energy density of 43-46 MJ/kg, a relatively higher amount than biodiesel, which has an average energy density of 33-35 MJ/kg. A higher energy density is preferable to sustain the long energy-intensive journeys that airplanes make.
Additionally, alternative energy sources like hydrogen are less preferable, as despite a similarly high energy density, the storage and infrastructure challenges that hydrogen fuels pose, due to its low mass per unit volume, make it an inefficient source of energy for airplanes.
However, ATFs have a higher carbon composition of about 86-87% leading to a relatively high carbon output in terms of carbon dioxide, a greenhouse gas. It is estimated that 1 gram of ATF can produce about 3.15 grams of carbon dioxide. As such, SAFs are seen to be the sustainable successor to ATFs in the future, as SAFs generally have a 60-80% lower carbon dioxide output of about 0.6-1.2g of carbon dioxide per gram of SAF used.
Despite having a similar carbon composition, the lower carbon dioxide output can be attributed to several reasons. As most SAFs are obtained from agriculture, the process of their growth offsets some of the carbon released during their use through photosynthesis. This is what is known as a closed carbon cycle, as the carbon dioxide absorbed during growth counteracts the carbon dioxide used during their use as an aviation fuel, resulting in a much lower net release of carbon dioxide.
Additionally, the growth of foodstocks to convert into SAFs lacks the energy-intensive and greenhouse gas-emitting processes of extracting and refining the fossil fuels that are needed in the use of ATFs.
Current Developments In SAFs
One pioneering company in SAFs is Neste, a Finnish firm that is currently leading in SAF production from residue raw materials such as cooking oil and animal fat waste. With refineries in Finland, Singapore, and the Netherlands, they have a current production capacity of 5.5 million tonnes of SAFs per year, which they seek to increase to 6.8 million tonnes by 2027 as the market for SAFs continues to grow.
Neste primarily uses the Hydroprocessed Esters and Fatty Acids (HEFA) process to produce SAFs, utilizing raw materials not intended for food use to avoid competition with agriculture, including waste and residual oils. These feedstocks undergo hydrotreatment in large reactors that deoxygenate (remove oxygen molecules) the feedstock, converting it into paraffinic hydrocarbons that share a similar structure to ATFs. The final SAFs are then mixed with traditional ATFs in jet fuel.
Recently, in a press release on 11 June 2025, Neste announced a collaboration with Chevron Lummus Global (CLG), a leading technology provider for the production of renewable and conventional transportation fuels, to jointly develop new technologies to convert lignocellulosic biomass into higher-quality SAFs. Lignocellulosic biomass refers to non-food plant biomass, which consists of lignin, cellulose, and hemicellulose, which are the structural components of plant cell walls.
Vast amounts of this waste are produced in the forestry and agricultural industries during harvesting and forestry industry processes that are massively underutilised as a raw material that could be used in the production of SAFs. As such, Neste wishes to utilise the extensive track record that CLG has when it comes to developing and licensing market-defining refining strategies to create new processes to extract the potential of Lignocellulosic biomass for SAFs. This is but one of many innovations that companies are doing in the aviation industry to increase the use of SAFs to meet sustainability goals in this industry.
Profitability Of SAFs
However, the adoption of SAFs is mired by several challenges, the most notable of which is its unprofitability. The price of SAFs, at $3.50 to $8.00 per gallon, is significantly higher than the price of ATFs, which is at $2.00 to $3.00 per gallon. This causes airlines to have to pay an additional fee per passenger mile when SAFs are used, making the use of ATFs more preferable to improve profit margins.
The high cost of SAFs can mainly be attributed to the low economies of scale in the SAF industry as compared to ATFs. This is due to the much lower quantity output in the market of SAFs, at tens of millions of barrels per annum, compared to the quantity output in the market for ATFs, which is millions of barrels daily. This, in addition to the higher costs of production of SAFs, causes a higher fixed price per barrel produced and a higher overall cost of production
The lower output is because the production of SAFs is more niche and in its early stages compared to the output of ATFs. SAFs tend to be produced in smaller and more specialised plants, which are located near to feedstock sources or airports, in comparison to ATFs, which are made in large-scale refineries globally. The high cost of production of SAFs can also be attributed to the fact that a significant amount of research and development is still required in this industry to improve the efficiency of SAF production.
As such, the use of SAFs in their current stages can only take place, provided countries subsidise their use to increase their cost-competitiveness in comparison to ATFs—policies like the Advanced Technology Vehicle Manufacturing (ATVM) Loan Program support SAF-related infrastructure and research. Similarly, the EU Horizon program funds research to reduce the costs of SAFs and to improve technologies. These programs are necessary to enable SAFs to develop in the future, increase their cost-effectiveness, and effectively replace ATFs, thereby achieving sustainability goals in the aviation industry.
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