video Episode 2.2

Clean Fuel: Jet Fuel

Aviation is responsible for 2.5% of global greenhouse gas emissions, though this figure is expected to grow as developing parts of the world become wealthier and increase demand for air travel.

Experts have looked to sustainable aviation fuel (SAF) to decrease emissions as it can be used with existing jet engines and decrease CO2 emissions by 60-80% – moving toward 100% – and potentially become a negative emissions technology.

* Note: as of October 2021, the International Air Transport Association voted to strengthen the airline industry’s climate goals and set a net-zero carbon emissions by 2050 target.

Running Time: 10 mins

Date: 08.03.2021

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Steve Csonka
CAAFI Executive Director


Steve Csonka

CAAFI Executive Director

Steve Csonka is the Executive Director of the Commercial Aviation Alternative Fuels Initiative (CAAFI) which serves as a liaison between the clean energy and aviation industries. Steve is a commercial aviation professional with 35+ years of broad airline and fuels experience, and a strong technical background in commercial aircraft/engine life-cycle, from design through operations.

Hosted By:

Ozak Esu
Climate Now Host


Ozak Esu

Climate Now Host

Dr. Ozak Esu is a Chartered Engineer and a STEM Education Ambassador, working within Construction and the Built Environment industry. Inspired by her lived experience of energy poverty growing up in Nigeria, she chose to pursue a career in Electronics and Electrical Engineering, receiving her bachelor’s degree from Loughborough University, UK. She graduated with a first-class and was awarded a scholarship to advance to her PhD. in wind energy. By participating in Climate Now, Ozak is keen to contribute her knowledge of technologies, her experience of the challenges faced, and to be a voice for regions often underrepresented, in the conversations about climate change and a sustainable energy future.

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Video Episode 2.2 Transcript

As airlines face pressure to reduce their carbon footprint, many firms are looking to Sustainable Aviation Fuel, abbreviated as SAF and pronounced “saff”, as a way to cut CO2 emissions without replacing existing jet engines.


Using conventional aviation fuel, a roundtrip flight from New York to Los Angeles generates 2 metric tons of carbon dioxide on a typical airline [1]. That’s the same as driving a passenger car more than 5,000 miles [2]. Jetting from Denver to Paris generates 5 metric tons of CO2. While Miami to Shanghai puts out nearly 10 tons of carbon dioxide. This chart shows how much carbon dioxide and other greenhouse gases are generated by air travel as compared to other forms of transportation on a passenger per kilometer basis [3].


In this video, we’ll take a look at how SAF is produced and some of the obstacles for companies hoping to capitalize on the demand for green jet fuel. The path to commercialization takes several years, and it’s only now arriving for a handful of SAF producers. The demand will likely grow as policymakers in Europe and the US consider new requirements for the use of sustainable aviation fuels.


Although carbon emissions from jet travel make up only 2.5% of global greenhouse gases, experts worry that as the demand for air travel grows in developing parts of the world, so too will that figure. In addition to carbon dioxide, jet engines also produce additional sulfur and nitrogen pollutants, water vapor and contrails [4]. These compounds amplify the overall contribution of jet travel to climate warming to an estimated 7-8% of global emissions [5]. According to projections from the International Civil Aviation Organization, carbon emissions from the aviation sector are projected to double by 2050 [6].


The United States is the biggest polluter, according to the International Council on Clean Transportation, but China is catching up quickly [7]. For context, the US’s 179 million metric tons is approximately 2% of total US emissions. For the EU and China the percentage is similar. But sustainable aviation fuel might allow commercial aircraft to keep flying while mitigating their overall environmental impact. Aviation industry studies show SAF can reduce CO2 emissions by 60 to 80% moving towards 100% and potentially become a negative emission technology through supply optimization, use of biofuels for transport, use of green hydrogen for the fuel processing, and carbon sequestration [8,10].

SAF is essentially a synthetic form of kerosene produced by refining various plant or animal feedstocks, waste oil from cooking, and solid waste. SAF is a drop-in fuel meaning it can be used without making modifications to existing jet engines [11]. Right now, SAF only accounts for somewhere between 4 to 10 million gallons of the 100 billion gallons burned each year by commercial aviation [12]. But that number is starting to grow. To better understand SAF, we spoke with Steve Csonka, the executive director of the Commercial Aviation Alternative Fuels Initiative (CAAFI) about how SAF is made and who is making it.


Steve Csonka:

So far, the aviation industry has approved seven different methodologies whereby a fuel can be produced from a renewable resource. At the end of the day, what we’re really after is being able to take the primary things that nature gives us and convert those into fuels. And those are lipids, sugars and starches, lignocellulose generally, and then these, I refer to them as circular economy by-product streams, things like industrial off gases, waste streams that come off of food processing facilities. And there’s a lot of waste streams actually, there are seven or eight different waste streams that we’re accounting for.


So who is producing SAF? There are now five producers worldwide producing sustainable aviation fuel. Those are World Energy in California, Neste in Finland, Gevo in Minnesota and Texas, TotalEnergies in France, Eni, and Air BP, and many others are well on their way. Fulcrum Bioenergy has just completed construction on a facility outside of Reno, Nevada that converts municipal solid waste to jet fuel, and they anticipate producing fuel by the end of 2021. And Red Rock is working on a facility in Southern Oregon using forestry residues. The SAF produced by these facilities currently costs about twice as much as petroleum-based jet fuels [20], but they also produce up to 80%, fewer emissions compared to conventional fossil fuels over the lifecycle of production [8].


When biomass is used to produce SAF, these plants have absorbed CO2 from the atmosphere during photosynthesis in relatively short time scales. The carbon that is emitted back into the atmosphere during jet engine combustion will be reabsorbed by plants in a closed loop. Ideally, by using plant-based fuel, no additional carbon would be injected into the atmosphere. Of course, some carbon emissions are created during the refinery process, as well as transporting the fuel from the refinery to the airport. It’s also important to avoid the use of feedstocks from non-sustainable sources, such as Palm Oil produced on farms that replaced tropical forests. But reports by the International Civil Aviation Organization find that sustainable aviation fuels produce up to 80%, fewer carbon emissions over the lifecycle of production than a comparable amount of conventional aviation fuel, which is refined from crude oil.

As more energy companies commit to making SAF, Csonka expects the cost to come down. SAF will go a long way in helping the airline industry’s promise to cut emissions to one half of 2005 levels by 2050 [21]. But the nascent SAF industry has to be financially sustainable as well as environmentally sustainable.


Steve Csonka:

If a producer comes and wants to talk to an airline about buying sustainable aviation fuel, one of the things that they’ll be requested to demonstrate is whether they have a plan for how they can continue to take price out of the renewable product and be moving it in the direction of the price point of a petroleum-based jet fuel.


Sustainable aviation fuel companies must prove that their product works in a jet engine, reduces emissions, and is cost effective over the long-term [22].

Policy makers in the US and Europe are looking at SAF as a part of a broader effort to cut carbon emissions. White house cabinet members met recently with airline executives to discuss the idea of tax breaks for using green fuels and support for new low carbon technologies [23]. US representatives Julia Brownley from California, Brad Schneider from Illinois, and Dan Kildee from Michigan introduced legislation that would require tax incentives to blend SAF into existing fuels [24]. Representative Brownley also introduced a bill going further and requiring the US military use at least 10% SAF in its air fleet by 2024 [25].


United Airlines says it will purchase 3.4 million gallons of SAF made from trash this year paid for by contributions from Nike, HP, Siemens, and a dozen other corporate clients [26]. Air India signed an agreement with a commercial SAF refinery in 2020 to use biofuel produced by sugarcane waste [27]. Lufthansa agreed to buy SAF made from animal waste in flights between its European hubs and San Francisco International Airport [28]. European Union leaders are expected to approve new rules that will require European airports to gradually increase their use of SAF from 2% in 2025 to 63% in 2050. Those rules would affect all aircraft, whether they are from European, Asian or US-based commercial carriers [29]. There are clear signs of progress in ramping up both production and use of sustainable aviation fuel. Even though many hurdles remain, advocates say the future looks bright for sustainable aviation.


For more information, and to listen to the full podcast with Steve Csonka, go to our website at climatenow.com. Thank you and goodbye.


  1. 00:33, 00:49 Atmosfair Emissions Calculator, https://www.atmosfair.de/en/offset/flight/
  2. 00:39 EPA Greenhouse Gas Equivalencies Calculator, https://www.epa.gov/energy/greenhouse-gas-equivalencies-calculator
  3. 00:55 Climate Change: Should you fly, drive, or take the train? (August 2019) https://www.bbc.com/news/science-environment-49349566 
  4. 1:50 The impact of air travel on our climate. Atmosfair (based on IPCC 2007), https://www.atmosfair.de/en/air_travel_and_climate/flugverkehr_und_klima/climate_impact_air_traffic/ 
  5. 2:02 “The contribution of global aviation to anthropogenic climate forcing for 2000 to 2018,” Lee, et.al. Atmospheric Environment, Vol. 244, No. 1, Jan 2021. https://doi.org/10.1016/j.atmosenv.2020.117834
  6. 2:14 Fleming, G. and I. Lépinay (2019) Environmental trends in Aviation to 2050. International Civil Aviation Association, https://www.icao.int/environmental-protection/Documents/EnvironmentalReports/2019/ENVReport2019_pg17-23.pdf
  7. 2:22 International Council on Clean Transportation, “CO2 emissions from commercial aviation: 2013, 2018, and 2019,” By Brandon Graver, Ph.D., Dan Rutherford, Ph.D., and Sola Zheng, Oct. 2020. https://theicct.org/sites/default/files/GACA-FS-EN-oct2020.pdf
  8. 2:54, 6:33 International Civil Aviation Association (2021) Carbon Offsetting and Reduction Scheme for International Aviation (Corsia) Default Life Cycle Emissions Values for CORSIA Eligible Fuels https://www.icao.int/environmental-protection/CORSIA/Documents/ICAO%20document%2006%20-%20Default%20Life%20Cycle%20Emissions%20-%20March%202021.pdf
  9. 2:53 Image from Neste, Sustainable Aviation Fuel – tanker truck at airport
  10. 3:08 personal correspondence with Steve Csonka (CAAFI)
  11. 3:20 Air BP, Sustainable Aviation Fuel, https://www.bp.com/en/global/air-bp/aviation-fuel/sustainable-aviation-fuel.html
  12. 3:36 4 million gallons in the US alone (https://www.epa.gov/fuels-registration-reporting-and-compliance-help/spreadsheet-rin-generation-and-renewable-fuel-0) and at least as much if not more out of Neste according to Steve Csonka (CAAFI)
  13. 4:37, 4:44 videos from Neste facility Laitos 2 FHD https://brandhub.neste.com/d/2ckGcVbrbCzJ/images-videos/show/eyJpZCI6IjQ1OTgifQ:neste:myZHA1sYASbo_RUo26rQZlHWiY1k9TKuVnkqVNUG1Uc
  14. 4:46 video from Gevo https://vimeo.com/451342390
  15. 4:49 TotalEnergies factory image from https://bioage.typepad.com/.a/6a00d8341c4fbe53ef026bdecae04b200c-800wi
  16. 4:50 Eni image from  https://www.eni.com/en_DE/business-activities.page
  17. 4:52 Air BP image from © Raimond Spekking / CC BY-SA 4.0 (via Wikimedia Commons) https://commons.wikimedia.org/wiki/File:Airport_tank_truck_of_air_bp_on_Cologne_Bonn_Airport-7282.jpg
  18. 4:57 videos from Fulcrum https://youtu.be/ZpLsIRuvyZM
  19. 5:12 videos from Red Rock https://www.redrockbio.com/lakeview-site/
  20. 5:22 van Hal, J.W. (2021) Cost Effective Sustainable Aviation Fuel. TNO. https://www.tno.nl/en/about-tno/news/2021/4/cost-effective-sustainable-aviation-fuel/
  21. 6:50 Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) ICAO Environment, https://www.icao.int/environmental-protection/CORSIA/Pages/default.aspx
  22. 7:32 Epstein, Curt (2020) ASTM Approves New Sustainable Jet Fuel Process. AIN Online, https://www.ainonline.com/aviation-news/business-aviation/2020-07-06/astm-approves-new-sustainable-jet-fuel-process#:~:text=ASTM%20International%2C%20the%20standards%20body,the%20aviation%20industry%20to%20seven.
  23. 7:41 Koenig, David (2021) Airline CEOs, Biden officials consider green-fuel breaks. Associated Press,  https://apnews.com/article/scott-kirby-climate-climate-change-airlines-pete-buttigieg-6bed112b680f66762efe9a6ebf476c31 
  24. 8:00 Press Release from the Office of Congressman Brad Schneider (May 2021) Schneider Introduces Bill to Decarbonize Aviation Fulfill Climate Commitments, https://schneider.house.gov/media/press-releases/schneider-introduces-bill-decarbonize-aviation-fulfill-climate-commitments 
  25. 8:18 Brownley, J. (April 2021) Sustainable aviation fuel takes flight. The Hill. https://thehill.com/blogs/congress-blog/energy-environment/548591-sustainable-aviation-fuel-takes-flight 
  26. 8:25 Ajmera, A. and T. Rucinski, (April 2021) United Airlines unveils plan to fund more sustainable jet fuel made from trash. Reuters Sustainable Business, https://www.reuters.com/business/sustainable-business/united-airlines-unveils-bid-fund-sustainable-aviation-fuel-use-2021-04-13/ 
  27. 8:35 Gevo, Praj to commercialize sustainable aviation fuel in India. Biomass Magazine, http://biomassmagazine.com/articles/17285/gevo-praj-to-commercialize-sustainable-aviation-fuel-in-india
  28. 8:44 ICAO SAF Initiatives, https://www.icao.int/environmental-protection/gfaaf/lists/saafa/view.aspx
  29. 8:55 Carroll, S. EU considers applying green jet fuel mandate to all departing flights. EURACTIV https://www.euractiv.com/section/aviation/news/eu-considers-applying-green-jet-fuel-mandate-to-all-departing-flights/

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