All about SAF Board Now

Sustainable Aviation Fuel Glossary A-Z

The terminology used in the SAF world can be baffling at times, especially for people who are just starting to learn about these fuels. New terms, acronyms and projects are created all the time, especially since the industry is still developing. In this glossary you can find the most up-to-date definitions of the terms we use within the SAF industry. If you’re just starting out in your research or conversations with us, we recommend you take a look at our SAF Bingo sheet and see how many words you can cross off! 


The Basics


SAF stands for Sustainable Aviation Fuel. SAF is a substitute for fossil kerosene produced from sustainable resources. In general, in its neat form, the use of SAF results in the reduction of lifecycle CO2 emissions compared to fossil kerosene. 



SAF is certified to the same standards as conventional fossil kerosene and needs to be approved according to ASTM International safety standards. Every new form of SAF is extensively tested and approved by the aviation-related ASTM community. The fuel can only be used following this approval.  



Currently, SAF is a drop-in fuel and must be blended with fossil kerosene to be used commercially. Once blended, SAF has the same characteristics and meets the same specifications as fossil jet fuel. SAF produced with the HEFA technology for instance (see below) can be used in an up to 50/50 blend with fossil kerosene. At the moment, tests to fly with 100% SAF are in progress. 


Biofuel is often a catch-all description, but not all biofuels are automatically sustainable, while SAF prioritizes sustainability. Biofuels can be made from unsustainable feedstocks that cause deforestation, such as unsustainably produced palm oil. This is why the term SAF is preferred. It highlights the possibilities for non-biobased fuels and the sustainability aspects that need to be considered when producing alternatives to fossil kerosene. 

Board Now 

Board Now (founded by SkyNRG) is a program helping corporates turn their business commitments into action by choosing to invest in and use Sustainable Aviation Fuel (SAF). In this way, we reduce Scope 3 emissions from business travel and/ or air cargo and support the development of an in-sector solution for sustainable flying. 

Book and claim system 

This means that the person/ company who paid for the SAF will receive the carbon reduction benefit, but not the physical SAF. In a ‘book & claim’ system, fuels are delivered to an airport near the production plant to minimize CO2 emissions and cost. SAF volumes are tracked and audited, and the organization that has absorbed the cost of SAF can claim the CO2 reduction of their allocated volume. 


Carbon offset 

A carbon offset is a reduction in emissions of CO2 or other greenhouse gases, for example through reforestation projects, made in order to compensate for emissions created elsewhere. 


The Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) is a carbon offset and carbon reduction scheme to lower CO2 emissions for international flights, to curb the aviation impact on climate change


Drop-in fuel 

SAF is a drop-in fuel, meaning it is a completely interchangeable substitute for fossil kerosene. This means it does not require adaptation of the engine, fuel system or the fuel distribution network. 


DSL stands for Direct Supply Line. A DSL is a SAF supply chain that consists of local feedstock, a commercial SAF production plant and long-term offtake contracts.  

DSL-01 is the first European dedicated SAF production plant. This production facility is a project of SkyNRG and will be located in Delfzijl, the Netherlands. 


The recast of the EU Renewable Energy Directive (RED) 

The EU Renewable Energy Directive II (EU RED II) establishes an overall policy for the production and promotion of energy from renewable sources in the EU. It requires the EU to fulfil at least 32% of its total energy needs with renewable energy by 2030. Of this 32% target, each Member State shall set an obligation on fuel suppliers to ensure that the share of renewable energy within the final consumption of energy in the transport sector is at least 14 % by 2030. In the RED II SAF is allowed to to be counted towards the 14% transport target.  



Feedstock refers to the raw material that is required for an industrial process. In the context of SAF, a feedstock is any (sustainable) biomass destined for conversion to alternative fuels. Examples can include industrial waste streams such as used cooking oils (UCOs). 

Fossil kerosene 

Fossil kerosene is kerosene made from fossil fuels, typically crude oil. This kerosene is traditionally used as jet fuel and has a significant impact on the environment due to the emissions of greenhouse gases, such as CO2, and other pollutants.  


Greenhouse gases 

Manmade emissions are causing an intensified heat trap through which the planet is warmed faster than normal. One of the main gases causing the greenhouse effect includes carbon dioxide (CO2). The use of SAF reduces the amount of CO2 emitted into the atmosphere, as the sustainable resources used to produce SAF recycle the CO2 previously emitted into the atmosphere. This results in a closed carbon cycle which doesn’t release as much additional carbon into the environment as the use of fossil kerosene does. 

Green premium / price premium 

The prominent challenge SAF faces is the “green premium” – the price difference between fossil kerosene and SAF. Because of this premium, airlines are limited in the volume of SAF they can buy. But there is a solution to this: organizations forming partnerships beyond the aviation industry to increase SAF uptake, sharing the green premium, and pushing the energy transition in this industry.  


Hydrotreated Esters and Fatty Acids (HEFA) 

HEFA is a conversion technology that refines vegetable oils, waste oils or fats into SAF through a process that uses (green) hydrogen (hydrogenation). This is currently the most commonly used pathway to create SAF. 


Life Cycle Assessment 

A Life Cycle Assessment (LCA) is an analysis of the impact an object or process has on its environment throughout its whole life, including its production and use. For example for SAF, this means emissions from transport, blending and processing, and use are among those included in the LCA. 



PFAD stands for Palm Fatty Acid Distillate. It is a processing residue resulting from physical refining of crude palm oil products. POME is an oily wastewater generated by palm oil processing mills and consists of various suspended components.  

At SkyNRG we do not regard either PFAD or POME as true waste and residues and therefore will not use them as feedstock for SAF production. 



The Roundtable on Sustainable Biomaterials (RSB) is a global, multi-stakeholder independent organisation that drives the development of a bio-based and circular economy on a global scale through sustainability solutions, certification, and collaborative partnerships. 

It provides tools and solutions that mitigate business risk and contribute to achieving the UN’s Sustainable Development Goals and has the world’s most trusted, peer-reviewed, global certification standard for sustainable biomaterials, biofuels and biomass production 


Scope emissions 

The Greenhouse Gas (GHG) emissions of a company are classified under three levels: Scope 1, 2 and 3 emissions. 

Scope 1 emissions 

Scope 1 emissions include all direct emissions from the activities of an organization. Examples could include company-owned facilities or vehicles. 

Scope 2 emissions 

Scope 2 emissions cover electricity purchased and used by the organization. 

Scope 3 emissions 

Scope 3 emissions cover all other indirect emissions from activities of the organization, occurring from sources they do not own or control. These can include business travel, transportation and distribution. SAF can be used to help corporates reduce their Scope 3 travel emissions through the Book & Claim method. 

Synthetic SAF 

Synthetic fuels – also called electrofuels, efuels or power-to-liquid (PtL) fuels – are produced from CO2, water and electricity. Synthetic fuel can reduce close to 100% CO2 across its lifecycle in comparison with fossil kerosene, but only if renewable electricity is used in the production process, and CO2 is captured from the air.