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SAF Sustainable Aviation Fuel

February 22, 2021
Harold Goodwin
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There are basically three kinds of SAF, it suits the airlines wanting to pursue business as usual to lump them together.
  • SAFw is made from waste, relies on large amounts of waste being available to make aviation fuel. It still puts greenhouse gases into the atmosphere.
  • SAFb is biofuels - these inevitably compete with agriculture, pasture or fish production. This strategy prioritises aviation fuel over food and protein
  • SAFe power-to-liquid fuels (PtL) use of synfuels derived from hydrogen and captured carbon emissions could become a scalable option. Such synfuels require water, renewable electricity to produce hydrogen, and CO2. Hydrogen can be used in fuel cells to produce electricity or combusted in engines
The problem is that the pursuit of SAFw and SAFb delays the transition to decarbonised aviation -without large government research grants or taxation on aviation fuel there is insufficient incentive to transition to decarbonised aviation

The problem is that the pursuit of SAFw and SAFb delays the transition to decarbonised aviation -without large government research grants or taxation on aviation fuel, there is insufficient incentive to transition to decarbonised aviation.  more

As Bloomberg reported on 10th November: “SAF is typically three to four times more expensive than kerosene, so airlines aren’t buying it in bulk. As a result, very little is being produced. If Delta Air Lines Inc. filled all its planes for one day, the carrier would soak up a year’s worth of U.S. SAF supply, said CEO Ed Bastian.”  Current production is estimated to be 0.1% of global jet fuel consumption.

The Blomberg report points out that SAF spews carbon dioxide and other pollutants into the atmosphere. “The reductions claimed by biofuels rely on a lot of complicated math and the idea that the materials being burned don’t come from extracting fossil fuels sequestered thousands of years.” In March, a working paper published by the International Council on Clean Transportation suggested that “fuel derived from municipal solid waste with high plastic content can produce as much as almost twice the amount of CO₂ as burning regular jet fuel.” Jozsef Varadi, Chief Executive Officer of low-budget carrier Wizz Air Holdings Plc. has suggested that money spent on SAF would be better invested in hydrogen and electric propulsion.

January 2021 The Fuelling Flight Project 

This group has pointed to "the risk of massive capital investments in things that increase emissions compared to fossil fuels and/or that become stranded assets" and called for "future proof sustainability requirements" higher than the ones in the European Commission's Renewable Energy Directive including "clear exclusions of unsustainable feedstocks and pathways such as biofuels from dedicated cropland and PFAD." [Palm Fatty Acid Distillate] The group has called for higher sustainability standards before SAF is prioritised and ramped up. They further suggest that "only EU-sourced feedstocks, electrofuels and other renewable fuels of non-biological origin" should be included. They assert that: "Competition for limited resources, particularly in relation to international transport, will not solve the global climate challenge."

"Meeting long-term decarbonization targets and deeper deployment rates will require the use of fuels with greater availability than bio-based wastes and residues. Electrofuels offer substantial long-term potential for supplying SAF, as there are fewer constraints to their production volumes. However, the high cost of supplying additional renewable electricity makes this one of the most expensive options for reducing aviation emissions. Despite initial high costs, policy support for electrofuels over the next decade can help to bring down the capital costs for electrolyzers and introduce the policy framework that would link transportation energy demand to new, additional renewable electricity from the power sector."

Climate change: Jet fuel from waste 'dramatically lowers' emissions more
Authors of a new study say the fuel cuts greenhouse gas emissions by 165% compared to fossil energy. This figure comes from the reduction in carbon emitted from aeroplanes plus the emissions that are avoided when food waste is diverted from landfill.

As WTM London’s Senior Exhibition Director Simon Press has said

“Aviation’s contribution to the climate crisis is a problem that needs a solution. It is not just the aviation sector’s problem – travel and tourism as a whole need to recognise the problem. We currently stand at an important crossroads in travel and tourism, where the direction we take will make an enormous difference to our destination.”

The Symposium can be viewed here. 
The white paper is available for download at Decarbonising aviation: The route to net zero for the travel and tourism industry, concludes with a call to action.
"The tourism sector calls on everyone with an interest in travel and tourism – governments, international organisations, airlines, aircraft manufacturers, airports, alternative fuel producers, academics and travellers themselves – to do their part. Without it, we may be forced into unsavoury choices on who is allowed to fly
Tourism is at an important crossroads and a choice on direction must now be made. Leaving the decision for only a few more years will make the solutions far more radical and undesirable. What can be done now to make decarbonising aviation a reality?

• Tour operators and destinations must insist that airlines adopt e-fuel mixtures and accept the higher cost for tickets associated with e-fuel use;
• Governments and international bodies must legislate for e-fuel mixtures;
• Airlines to make greater use of drop-in e-fuels, at least for the short- to mid-term, and explore other sustainable fuel options such as hydrogen for the longer-term;
• Aircraft manufacturers must invest more in the development of zero-emission aircraft and speed up the pace of fleet replacement;
• Governments to withdraw support for the development of existing aircraft technology in favour of e-fuels and hydrogen fuel cells;
• International commitments to adopt carbon-friendly flight procedures, such as Single European Sky and avoiding parts of the atmosphere where contrails develop;
• More offsetting, using approved schemes, in the short term;
• Travellers must vote with their feet, forcing airlines to make the changes or switching to other modes of transport.

The Report can be downloaded here 

As the Economist cautioned back in November 2018
"A report by America’s National Academy of Sciences says that even the cheapest negative-emissions technologies such as biomass with carbon capture and storage are still too limited in scale to make a big dent in atmospheric CO2. A study by Britain’s Royal Society and Royal Academy of Engineering said a carbon price of $100 a tonne may be needed to make most negative-emissions projects feasible. The danger is that policymakers will delay curbing emissions now in the hope of being able to remove large amounts of greenhouse gases from the air in the future. In fact, both are needed on a massive scale."

When burned SAF produces the same amount of CO2 emissions as conventional jet fuel. SAF is preferred because its production process absorbs CO2, leading to a reduction in CO2 emissions of 70 to 100 per cent on a life-cycle basis.

SAF has the advantage of being a drop-in fuel, compatible with fuelling infrastructure and engines.

The technical feasibility of SAF from vegetable or waste oils is now proven, the product is certified, and some airlines use the fuel regularly as part of the mix ion the tanks. The feedstock, supply chain and the production and refining are costly. The biggest problem is the competition for land use - “food versus fuel”. Cathay Pacific and United Airlines have invested in producing fuel frim household waste and the fermentation of wood waste is a possibility. 


  • Used cooking oil and other non-palm waste oils from animals or plants.
  • Other sources including forestry waste (such as waste wood), energy crops (fast growing plants) and algae.

Biofuels Digest 

Solid waste from homes and businesses, such as packaging, paper, textiles, and food scraps that would otherwise go to landfill or incineration.
British Airways is working with Velocys to manufacture jet fuel from household and office waste at the Altalto facility in North East Lincolnshire.  IAG has commited to investing $400m in alternative sustainable fuel development over the next 20 years. The Altalto plant could produce enough fuel for more than 1,000 London to New York flights each year using SAF in an A350 aircraft, reducing greenhouse gas emissions by 70 per cent for every tonne of sustainable jet fuel that replaces a tonne of conventional fossil fuel
In 2019, less than 200,000 metric tonnes of SAF were produced globally – a tiny fraction of the 300 million tonnes of jet fuel used by commercial airlines. So, despite the potential fulfilment of aviation’s fuel needs using SAF by the end of this decade, the reality is that planned production capacity investments will only yield just one per cent of global jet fuel demand for 2030. Mandates are required to raise demand, as airlines are required to use SAF . Neville Hargreaves, VP Waste to Fuel, Velocys argues that  in the longer term, fossil-based aviation fuel will rise, “As the price of carbon goes up, and the cost of SAF comes down, the price(s) of jet fuel and SAF will equalise – but it’s a long process to reach that equalisation point.” source
19 January 2021 Shell has pulled out of the Altalto Velocys project. Shell announced plans earlier this month to take a 40% interest in the Varennes Carbon Recycling project, the first waste-to-low-carbon-fuels plant in Quebec, which will use Montreal-based cleantech company Enerkem’s proprietary technology. more

Synfuels: power-to-liquid fuels (PtL)
The use of synfuels derived from hydrogen and captured carbon emissions could become a scalable option. Such synfuels require water, renewable electricity to produce hydrogen, and CO2. The efficacy of synfuels to reduce greenhouse gas emissions requires that the Hydrogen is produced using green electricity and the CO2 needs to be extracted from the carbon cycle (taken from the air with direct air capture). McKinsey's analysis suggests that while current SAF costs are high in relation to kerosene cost, they will come down over time and could reach breakeven between 2030 and 2035, in an optimistic scenario. more

PtL uses renewable electricity, carbon dioxide captured from air and water to form a sustainable fuel that chemically resembles conventional jet fuel. Despite more R&D work being required and high implementation cost, PtL has advantages over other SAFs. It is “drop-in” capable, uses renewable feedstock and does not require as much land compared to other types of SAF.

A research institution supported by Airbus and other companies.
PtL-based fuel production comprises three main steps:
1) Hydrogen generation from renewable electricity through electrolysis of water;
2) Provision of renewable CO2 and its conversion along with the produced hydrogen;
3) Synthesis of liquid hydrocarbons with subsequent upgrading and refining. PtL fuels can be produced using established industrial-scale processes.
However, full system integration of the individual process steps is subject to ongoing work and still requires further R&D efforts.
2016 background study on PtL fuels can be downloaded from the German Environment Agency website: Power-to-Liquids – Potentials and Perspectives for the Future Supply of Renewable Aviation Fuel

The SAF+ Consortium, based in Canada, signed a first sustainable aviation fuel (SAF) offtake agreement with an Canadian airline (Air Transat), an important step in the process towards full-scale production. SAF+ Consortium partners include CCG, Air Transat, Aéroports de Montréal, Parachem, École Polytechnique de Montréal, CIRAIG and Valorisation Carbone Québec Project. This is an important circular economy solution towards zero-emissions aviation.
The lifecycle emissions of the process show at least an 80% reduction in CO2 emissions. SAF+ will, in the near future, use CO2, emitted from existing industrial plants, as the main feedstock. This is an important step towards the production of the synthetic fuel with CO2 captured directly from large emitters, which would close the carbon-cycle in a circular economy.

Direct Air Capture
Direct Air Capture can be used to pump CO2 underground and store it permanently underground. It is also possible that captured CO2 can be used to create aviation fuel.

June 2o20 the International Energy Agency reviewed progress on DAC.
The CO2 can be permanently stored in deep geological formations or used in the production of fuels, chemicals, building materials and other products containing CO2. When CO2 is geologically stored, it is permanently removed from the atmosphere, resulting in negative emissions. There are currently 15 direct air capture plants operating worldwide, capturing more than 9 000 tCO2/year, with a 1 MtCO2/year capture plant in advanced development in the United States. In the SDS, direct air capture is scaled up to capture almost 10 MtCO2/year by 2030. This is within reach but will require several more large-scale demonstrations to refine the technology and reduce capture costs. more

Dec 10, 2020 United Airlines announced that they plan to be 100% green by reducing its greenhouse gas (GHG) emissions by 100% by 2050. They plan to advance towards carbon neutrality by committing to a multimillion-dollar investment in revolutionary atmospheric carbon capture technology known as Direct Air Capture. Scott Kirby, United's chief executive officer. said "These game-changing technologies will significantly reduce our emissions, and measurably reduce the speed of climate change – because buying carbon offsets alone is just not enough. Perhaps most importantly, we're not just doing it to meet our own sustainability goal; we're doing it to drive the positive change our entire industry requires so that every airline can eventually join us and do the same." Rather than simply taking a conventional approach to decarbonization by relying solely on the purchase of carbon offsets, United intends to make a multimillion-dollar investment in 1PointFive, Inc., a partnership between Oxy Low Carbon Ventures, a subsidiary of Occidental (NYSE:OXY), and Rusheen Capital Management. 1PointFive's mission is to curb the rise in global temperatures by physically removing carbon dioxide (CO2) from the air using Direct Air Capture technology licensed from Carbon Engineering. more

Battery Powered 

Heart Aerospace’s first electric airliner to be operational by 2026.  all-electric aircraft ES-19 will sport a range of 400km with 215 knots of top speed. The airliner is also claimed to be capable of operating from shorter runways that are just 750 meters long. The new electric drivetrain, coupled with the new battery technology, will be able to push the aircraft to achieve a reasonable range, claims the company. They claim "Electrification changes the equation for regional air travel. Electric aircraft are affordable to buy, operate and maintain. Simple, reliable electric motors reduce maintenance costs by 90% compared to turboprops, and intelligent electronic monitoring reduces inspection needs. Most importantly, fuel costs go down by 50-75%."

Israeli firm Eviation has developed  Alicewhich they say will carry nine passengers for up to 650 miles (1,040km) at 10,000ft (3,000m) at 276mph (440km/h). It is expected to enter service in 2022. It is powered by three rear-facing pusher-propellers, one in the tail and two counter-rotating props at the wingtips to counter the effects of drag. It also has a flat lower fuselage to aid lift. Eviation has already received its first orders. US regional airline Cape Air, which operates a fleet of 90 aircraft, has agreed to buy a "double-digit" number of the aircraft. source

In 2017 Airbus, Rolls-Royce and Siemens teamed up to develop a hybrid-electric engine plane technology as part of a push towards cleaner aviation. In the E-Fan X programme, they planned to put an electric engine with three jet engines on a BAe 146 aircraft. This was abandoned in 2020



A Guide to Sustainable Aviation Fuels

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