Analysis by the International Council on Clean Transportation (ICCT) shows there are sufficient sources of sustainable feedstock to support the production of 3.4 million tonnes (Mt) of advanced sustainable aviation fuels (SAF) annually in the EU by 2030, around 5.5% of projected EU jet fuel demand. Waste oils is the most technically mature SAF pathway at present and could produce up to 2% of the share although this resource is highly constrained and largely consumed by the road sector. Moving beyond 2% of SAF deployment will require targeted support by the EU for more conversion pathways such as lignocellulosic biofuels and electrofuels, which come with more challenging economics and uncertain production timelines, says ICCT. Current volumes of SAF are below 0.1% of EU annual jet fuel consumption. The European aviation industry’s recent Destination 2050 roadmap estimates SAF deployment of 3 Mt in 2030, rising to 32 Mt – equal to 83% of total jet kerosene consumption – in 2050 if given strong political support.
Ahead of the forthcoming launch by the European Commission’s ReFuel EU Aviation policy initiative, the study by ICCT evaluates the resource base that could support SAF production in the EU from 2025 to 2035, focusing only on the potential volumes available from sustainably available feedstocks. It also takes into account sustainable harvesting limits, existing other uses of feedstock materials and SAF conversion yields.
Deploying SAF requires overcoming even greater economic and technological constraints than deploying alternative fuels to the road sector, cautions the study. The vast majority of biofuels up till now have come from first-generation, food-based production, although the EU is transitioning away from these fuels. By targeting the deployment of advanced SAFs from non-food feedstocks early on, the developing SAF industry can avoid the controversies around food-based biofuels, it argues, although there will be limiting factors around economic viability, feedstock supply and pace of technology advances.
Waste oils, including used cooking oil, animal fats and other fatty acids, offer the cheapest and easiest means for producing SAF with current technology. In 2018, hydrogenated esters and fatty acids (HEFA), which can be blended up to 50% by volume with petroleum-based kerosene, were the most common alternative drop-in jet fuels with about 360,000 tonnes of capacity in the EU. Their advantage is that infrastructure is already in place to support large production volumes and are likely to be the cheapest source of SAF in the near term. Production costs are around twice the cost of fossil-based jet fuel production, while other conversion processes may be as much as eight times higher.
Lignocellulosic feedstocks from agricultural and forestry residues and from municipal and industrial waste are more technically challenging to convert than waste oils due to their physical properties. However, these feedstocks are more abundant than waste fats and, when converted into SAF, generally have higher GHG savings than food-based SAF pathways. Feedstock conversion pathways include gasification with Fischer-Tropsch synthesis or by upgrading ethanol or isobutanol into drop-in fuel quality or alcohol-to-jet fuels. The delays in building compatible biorefineries have so far slowed down the commercialisation of lignocellulosic biofuel pathways.
ICCT estimates 76.5 Mt of feedstocks from agricultural residues, 5.1 Mt from forestry residues and 21.2 Mt of municipal and industrial waste will be available for biofuel production in 2030.
Cover crops, which are grown during the winter and harvested in the spring before sowing of principal crops, could also provide additional feedstock for SAF production, though their future contribution is uncertain. Cover cropping is relatively uncommon in Europe so in theory there is the possibility to expand the practice without substantial negative environmental or market impacts. Potential cover crops could include oilseeds such as rapeseed and carinata. ICCT estimates cover crops could provide an additional 7.15 Mt of lignocellulosic feedstocks for SAF production in 2030.
The study also looks at non-biological pathways for producing SAF such as electrofuels (e-fuels), also called power-to-liquid (PtL) fuels. This is a potentially low-carbon yet resource-intensive pathway involving splitting water into hydrogen and oxygen via electrolysis, with the hydrogen then synthesised in a reactor with carbon dioxide to produce liquid or gaseous hydrocarbons or alcohols. To ensure these fuels are both sustainable and low-carbon, renewable electricity used in SAF production should not be diverted from other uses.
The amount of PtL that could be theoretically available for SAF is very large, says the study, but the potential is unlikely to be met in the timeframe, given the high cost and time required to commercialise an emerging industry. For the most economical scenario, using grid-connected wind electricity and industrial CO2, it would require policy support of €2 per litre, which, according to the study, is very high compared to current alternative fuel subsidies and other forms of European policy support. However, at that incentive level and if SAF is a high political priority, then PtL aviation fuels could conceivably be provided in the 2030 timeframe in quantities estimated at 0.006 Mt in 2025 to 0.15 Mt by 2030 and 0.23 Mt by 2035.
Achieving higher production quantities would be possible, says ICCT, with greater policy support, such as a sub-mandate for e-fuels, and especially with more time for industry commercialisation and when the price of renewable electricity declines.
The final source of feedstocks examined by the study that could play a part in 2030 EU SAF production is industrial flue gases, which are captured, fermented and upgraded into SAF, a process developed by LanzaTech for steel mills. The process produces an ethanol intermediate which is then converted to a synthetic hydrocarbon. Assuming steel production remains near 2018 levels, the study estimates industrial flue gases would yield 3.3 Mt of ethanol for further upgrading to transport fuels, contributing an additional 0.76 Mt of alcohol-to-jet SAF in 2030.
Estimated 2030 SAF production and contribution to overall EU jet fuel demand by feedstock (source: ICCT)
ICCT’s central estimate of EU jet fuel demand, based on a 4.5% growth rate in conjunction with a 2.0% annual fuel efficiency improvement and without accounting for the Covid-19 pandemic, is 55.5 Mt in 2025, 62.8 Mt in 2030 and 71.1 Mt in 2035. Although there is a sufficient resource base to theoretically support peak production of 12.2 Mt of SAF a year, it says with deployment and feedstock constraints in place there is a maximum potential for 3.4 Mt, or 5.5% of 2030 jet fuel demand. Without any targeted support for more challenging pathways, the actual SAF potential could be closer to 1.9%, primarily drawn from easier-to-convert HEFA fuels.
“Expanding SAF beyond today’s production levels will require substantial financial incentives to overcome the economic and technical barriers that have thus far kept production low,” concludes the study. “Absent strong policy support and long-term commitments to advanced fuels, it will be difficult to do more than divert waste oils from other sectors. High blending targets in the absence of complementary policies may instead open the door to higher use of food-based biofuels in aviation.
“Even with strong policies in place, the limited availability of the best-performing feedstocks suggests that SAF production alone cannot achieve the EU aviation sector’s long-term GHG reduction obligations.”
Photo: Air BP