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SAF taking off
SAF taking o
e global use of sustainable aviation fuel (SAF) is rising but the sector still faces a series of challenges – notably higher production and feedstock costs compared to conventional jet fuels – before it takes o on a wider scale Gill Langham
The aviati on industry currently accounts for approximately 2-3% of humaninduced carbon dioxide emissions and 12% of emissions from transportati on, according to a report on the sector by the Internati onal Energy Agency (IEA Bioenergy).
In response, the sector has introduced measures to reduce emissions such as improving fuel effi ciency by 1.5%/year (between 2009-2020), achieving carbon neutrality by 2020 and targeti ng a 50% reducti on in emissions by 2050.
Meeti ng the aviati on sector’s climate targets will require signifi cant volumes of sustainable aviati on fuel (SAF), the IEA Bioenergy report says, but current producti on volumes are less than 150M litres/year, which is considerably less than 0.5% of total jet fuel demand.
Commenti ng on the sector, Louise Burke, vice president Global Aviati on and SAF for Argus Media, says SAF and carbon off sets are considered the “main tools” for the aviati on sector to use to meet its decarbonisati on goals.
“We know that SAF is here to stay as the aviati on industry is diffi cult to electrify and is unlikely to have other means of decarbonisati on. As SAF is a drop-in fuel and can use current logisti cal transport means – the maximum SAF blend is currently 50% – this also provides ease of logisti cs in the market.”
Rising demand
Global SAF demand is forecast to range between 2bn-6bn litres/year by 2026, according to forecasts made by the IEA last year, when the total was 0.1bn litres/ year.
Recent investments will see producti on grow to more than 1bn litres/year over the next few years. However, the vast majority of these biojet fuels will come from hydrotreated esters and fatt y acids (HEFA) feedstocks and technology, according to IEA Bioenergy’s report ‘Progress in Commercializati on of Biojet/Sustainable Aviati on Fuels (SAF): Technologies, potenti al and challenges’.
Although other pathways are being developed, signifi cant technological challenges sti ll need to be resolved and the aviati on sector remains largely dependent on liquid fuels – and will be for the foreseeable future – despite ongoing research on alternati ve technologies such as electric motors and the use of green hydrogen, according to the report.
“Unfortunately, these… low-carbonintensity alternati ve opti ons are unlikely to be ready for commercial, large-scale and sector-wide deployment in the near term plus an additi onal hurdle is the long lifespan of aircraft ,” the IEA Energy report says. “Biojet fuels represent the single greatest opportunity for airlines to achieve signifi cant, long-term carbon reducti ons and they will be essenti al if the sector is to achieve a 50% emission reducti on by 2050.”
Current pathways
At the ti me of the IEA Energy report, seven pathways and two co-processing pathways had been certi fi ed under internati onal standards organisati on ASTM. However, only the HEFA pathway – also known as hydrotreated
vegetable oil (HVO) biofuels – is currently contributing significant volumes, according to the report (see Table 1, right).
Biojet fuel produced using this process is known as HEFA-SPK (synthetic paraffinic kerosene) and this term is used within the ASTM D7566 standard.
More than 5bn litres/year of HEFA, as renewable diesel, are produced worldwide and significant expansion of multiple facilities is currently underway (see Figure 1, right).
The commercialisation of other pathways is ongoing but HEFA technology is expected to supply the bulk of bio-jet over the next five to 10 years until other technologies become fully commercialised, according to the report.
HEFA challenges
Although any type of lipid can be used to produce HEFA, generally referred to as fats, oils and greases (FOGs), there are price differences.
Apart from cost considerations, an equally important element is the “sustainability” and the overall carbon intensity of making the feedstock, according to the report, with the use of vegetable oil in the sector competing with food production demands. The source of oil will also impact a fuel life cycle assessment, which has a direct impact on the carbon intensity of the final fuel.
Opportunities for technical improvements to the fully commercial HEFA pathway are limited, according to the report, but there is “considerable scope” to reduce the cost and carbon intensity of the feedstocks – as demonstrated by the increasing use of used cooking oil (UCO).
However, although several waste feedstocks have been used to date, they are a finite resource, the report says.
“Consequently, existing and evolving oilseed crops will be needed to increase feedstock availability. However, there will be ongoing concerns about the sustainability and cost of feedstocks.”
Other technologies
Large-scale, pioneer facilities for a range of other technologies are under construction or planned and include gasification with Fischer-Tropsch, ethanolto-jet, isobutanol-to-jet and catalytic hydrothermolysis, the report says. In addition, multiple alternative technology pathways, currently in the ASTM approval pipeline, are expected to attain ASTM certification.
By 2030, multiple facilities are expected to produce substantial volumes of SAF annually, with about 8bn litres/year
Table 1: Current world annual production capacity of HEFA drop-in biofuels
Figure 1: World SAF production capacity (million tonnes/year)
forecast to be available by 2030, according to estimates by the International Civil Aviation Organization (ICAO), a specialised agency of the United Nations.
“It is hoped that multiple facilities using various technologies/processes will routinely produce bio-jet as, in the longer-term, significant expansion of HEFA volumes will likely be constrained by the availability of low cost, waste lipid/ oleochemical feedstocks,” the IEA Energy report says.
“In order to achieve the significant volumes needed to meet the sector’s targets, aggressive commercialisation and scale-up of all biojet fuel technologies will be required”.
Other challenges
As all biojet fuels used in commercial flights have to be certified to gain market access, the lengthy, arduous and expensive certification process represents a significant hurdle, according to the IEA Energy report.
“Currently, all alternative fuels can only be used in a blend with fossil jet fuel, [but] some biojet fuel technology providers are trying to produce fully synthetic biojet fuels that could potentially be used without any blending with conventional jet fuel”.
Higher production and feedstock costs for biojet fuels also remain a major obstacle for wider use, the report says.
“In 2022, SAF prices continue to price at least three times higher than those for conventional petroleum jet fuel,” Argus Media’s Burke says.
Argus assessed SAF at US$3,530.57/ tonne on 12 August compared to the conventional jet fuel price of US$1,114.50/tonne.
In addition, feedstock dynamics affect overall value of SAF values, Burke says, with European SAF pricing affected by underlying supply/demand fundamentals of HVO and UCO prices.
“For all of the biojet processes, the minimum selling price… is significantly u
u higher than that of fossil-derived jet fuel. Thus, policy will play a very important role in trying to bridge this price gap,” the IEA Bioenergy report says.
Global developments
The increasing commercial use of biojet fuels is reflected in its expanding use at numerous airports worldwide by multiple airlines, according to the IEA Energy report.
At the time of the report, seven airports were regularly distributing biojet fuel blends and about 300,000 commercial flights had used these blends.
SAF providers have also been forming supply deals with individual airline companies.
For example, Finnish renewable fuels producer Neste – one of the leading players in the renewable fuels and SAF sectors – has entered supply agreements with major airlines, including IAG, Lufthansa Group (including SWISS), Delta Air Lines and Southwest Airlines, cargo carriers such as DHL and low-cost airlines such as easyJet.
The company, which expects to increase its SAF production to 1.5M tonnes/year (around 1.875bn litres) by the end of 2023, also expanded its partnership with ITOCHU earlier this year to increase the availability of SAF in Japan. “It is likely that the increased availability of commercial volumes will see an increase in the establishment of regular downstream supply at multiple locations,” the IEA Energy report says.
In China, for example, the country’s largest oil refiner China Petroleum & Chemical Corporation (Sinopec) produced its first batch of SAF from UCO at its facility in the east of the country, Reuters reported on 28 June, paving the way for industrial-scale SAF production.
Other initiatives
Government initiatives look set to boost SAF production and usage, the report says.
In July, the European Union (EU) approved plans requiring suppliers to blend a minimum of 2% of SAF into their jet fuel from 2025, rising to 37% in 2040 and 85% by 2050.
Transport members of the European Parliament (MEPs) said the plan should include a gradual switch to alternatives to conventional fuel such as synthetic fuel and UCO.
The transport MEPs also proposed the creation of a Sustainable Aviation Fund from 2023 to 2050 to accelerate the decarbonisation of the aviation sector and support investment in SAFs, innovative
aircraft propulsion technologies, or research for new engines, the 27 June statement from the European Parliament said.
In the USA, the White House has vowed to lower aviation emissions by 20% by 2030, with a goal of boosting SAF production to 11.4bn litres/year (3bn gallons/year) by 2030, and to meet 100% of aviation fuel demand of about 132bn litres/year (35bn gallons/year) by 2050, according to a Reuters report on 10 August.
The US government’s landmark Inflation Reduction Act passed in August includes a dedicated tax credit for SAF, which is also expected to boost the sector.
The SAF tax credit of US$1.25/gallon, which could rise to US$1.75/gallon depending on the fuel’s greenhouse gas reduction level, will remain in place until 2024 and transition to Clean Fuel Production Credit (CFPC) payments from 2025.
“It will definitely incentivise renewable diesel producers to move over to SAF in North America as both new plants and the expansion of existing plants for renewable diesel will also produce SAF,” Argus Media’s Burke says.
Alternative feedstocks
As feedstock is generally a significant component of the cost of production (up to 80% of the cost of HEFA), the use of low-cost feedstocks will play a role in reducing SAF costs, according to the IEA Energy report.
Alternative technology pathways offer opportunities for producing SAF with low carbon intensity at a competitive price, the report says, by using low-cost, waste feedstocks such as municipal solid waste, sewage sludge, food processing waste, waste gases and forest and agricultural residues.
Other feedstocks, such as Brassica carinata, Camelina sativa, pennycress, pongamia and jatropha, are also under development as more sustainable options that do not compete with food, the report says, but these options are only available in small quantities.
In Japan, the New Energy and Industrial Technology Development Organization (NEDO) has been working with engineering company IHI Corporation on the development of SAF using algae as a feedstock. NEDO also worked on a project to develop technology to make SAF using waste wood as a raw material in partnership with Mitsubishi Power, JERA, Toyo Engineering Corporation and the Japan Aerospace Exploration Agency (JAXA).
Both technologies, when combined with conventional fossil fuel (JET A-1), have been certified under ASTM D7566 and SAF produced by both pathways has been used to fuel flights from Tokyo International Airport.
The company said it now plans to continue SAF research and development with the aim of starting large-scale production.
Looking ahead
The aviation sector’s emission reduction target of 50% is likely to require more than 100bn litres/year of SAF by 2050, according to a ‘Reaching Zero with Renewables: Biojet Fuels’ report by the International Renewable Energy Agency (IRENA).
Although future SAF production volumes is expected to increase significantly – based on the expansion of existing facilities and investment in the specific infrastructure required to make HEFA-SPK derived biojet fuel – challenges remain, the IEA Energy report says.
“Although it is likely that ongoing improvements and optimisation of processes will continue to reduce costs and facilitate biojet fuel production and use, meeting the sector’s decarbonisation targets will be challenging.” Accessing low-cost feedstocks will play a role in reducing SAF costs, the IEA Energy report concludes, but costs – and the future growth of the sector – will be closely linked to policies that incentivise their production and use.
“When we look at announced SAF capacity globally, we see growth from 1M tonnes/year to approximately 18M tonnes/year by 2028,” Argus Media’s Burke says.
“However, this will represent only 5% of global conventional jet fuel demand and clearly more incentives are required to move this number higher.” ● Gill Langham is the assistant editor of OFI
