Alternative Jet Fuel Maturation Tools

CAAFI® has carried out various activities to develop the documents on this page to aid in the development, demonstration, deployment, and commercialization of sustainable alternative jet fuel.

Path to Alternative Jet Fuel Readiness

The goal of the Commercial Aviation Alternative Fuels Initiative® (CAAFI®) is to facilitate the development and deployment of alternative jet fuels that offer equivalent levels of safety and performance and compare favorably on cost with petroleum based jet fuel, and that offer environmental improvement and security of energy supply for aviation. Over time, the leadership of CAAFI has found that many are not aware of the process by which the Fischer-Tropsch (FT) and hydroprocessed esters and fatty acids (HEFA) fuels were successfully developed and deployed.

The "Path to Alternative Jet Fuel Readiness" briefing document was developed by the CAAFI R&D Team to outline the process of fuel development, qualification and certification and the role of CAAFI in facilitating the process. It is intended for use by individuals and organizations interested in producing alternative fuels.

The "Path to Fuel Readiness" document provides information on how to become involved with the aviation community, the testing and environmental evaluations required to show the fuel's suitability for aviation use, and how to best facilitate ASTM International certification for a new fuel.

The "Path to Fuel Readiness" document also refers to several CAAFI communication tools designed to aid in the communication of both the necessary steps to be taken and the progress of alternative jet fuel projects:

  1. The Fuel Readiness Level (or FRL) provides guidance on fuel technical development and certification testing;
  2. The FRL Exit Criteria, a checklist detailing what is performed at each FRL level;
  3. The Feedstock Readiness Level (FSRL) Tool, developed in collaboration with the US Department of Agriculture. tracks development and availability of the raw materials (or feedstocks) required to make alternative jet fuels;
  4. The Guidance for Selling Alternative Fuels to Airlines provides to serve as a roadmap for potential producers and other supply-chain participants contemplating purchase agreements with airlines for non-petroleum-derived jet fuels.
  5. The Environmental Progression provides guidance on performance of necessary environmental analyses.

These documents are outlined and available below. For further information about any of these documents, please contact us at

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Fuel Readiness Level (FRL)

The leadership of CAAFI needed a way to classify and track progress on research, certification, and demonstration activities. A variety of scales were in use by CAAFI organizations including TRL (Technology Readiness Level) used by industry, NASA, and the Air Force and Manufacturing Readiness Level (MRL) used by the Air Force and others. Originally, an Airbus CAAFI representative developed a special TRL scale for fuel development, but it was a mixture of research achievements and production development. The CAAFI leadership team wanted a new fuel development scale that would allow for parallel fuel research activities and certification activities, as well as clearly showing how to transition activities between the CAAFI R&D, Certification, and Business & Economics teams. Also, CAAFI desired to show how these new Fuel Readiness Levels (FRL) mapped to the TRL and MRL scales also in use.

The leaders of the CAAFI Certification and R&D teams developed the FRL table contained in this document. It includes descriptions that are customized to fuel research and certification events and includes specific items of interest to CAAFI members, including required fuel quantities. Note that the fuel quantities listed are from CAAFI Certification guidelines, and the Air Force uses different fuel quantities in their military fuel certification process. Color coding used to show the transition points between the CAAFI R&D, Certification, and Business & Economics teams. The CAAFI teams operate with the realization that overlap will occur, with R&D leading FRL 1-5, Certification FRL 6-7, and Business & Economics FRL 8-9. Environment Team assessment requirements will also overlap with the FRL. Preliminary assignments of environmental touchpoints are reflected in steps 3 and 8.

The roadmaps and milestone databases developed and maintained by CAAFI use FRL to help organize and track the research and development milestones and the process of developing, certifying, and supplying alternative fuels to commercial aviation.

The FRL was endorsed at the United Nations' International Civil Aviation Organization (ICAO) Commercial Aviation Alternative Fuels (CAAF) meeting in Rio de Janeiro in November 2009. The outcomes of that meeting can be found here.

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FRL Exit Criteria

To facilitate the use of the FRL, a checklist of exit criteria (tasks that must be accomplished to move from one FRL level to the next) was developed by CAAFI in collaboration with the Air Force Research Laboratory.

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CAAFI® ASTM D4054 Users' Guide

Prospective alternative jet fuel producers continue to engage with the Commercial Aviation Alternative Fuels Initiative® (CAAFI®), ASTM International, and the Coordinating Research Council (CRC) regarding the qualification of new production pathways. ASTM D4054 was developed to provide these producers with guidance regarding testing and property targets necessary to evaluate a candidate alternative jet fuel. The ASTM D4054 data and proposed specification properties investigated through the four-tier approach are then used as the basis for continued engagement with ASTM. The certification process requires fuel producers to iterate through the defined checkpoints, and if the fuel successfully passes, this process may result in the development of a proposed annex for incorporation into ASTM D7566 as a drop-in synthetic jet fuel.

Therefore, it is important to get prospective producers engaged with the testing community as early as possible. CAAFI's intent of creating this D4054 User's Guide is to provide an index of facilities that have:

  • demonstrated the technical capabilities necessary to perform the aviation fuel property testing required by D4054, and;
  • expressed an interest in performing those tests in the future.

We hope this helps prospective fuel producers locate resources to support testing of their fuels for ASTM approval.

This document is not static, and as with other CAAFI guidance material, we will continue to add helpful resource information as the need is identified.

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Feedstock Readiness Level (FSRL) Tool

As a result of the implementation of the FRL, the CAAFI R&D team identified the need for a separate evaluation of feedstock readiness to complement the FRL. CAAFI therefore approached the US Department of Agriculture (USDA) to collaborate on the development of a Feedstock Readiness Level (FSRL), which was accomplished under a Memorandum of Agreement between USDA and the Federal Aviation Administration (FAA).

The Feedstock Readiness Level (FSRL) Tool is a companion to the CAAFI® Readiness Level (FRL) Tool. The FSRL Tool provides a means of tracking development and availability of the raw materials (or feedstocks) required to make alternative jet fuels. In detailing the steps necessary to establish feedstock production in the commercial sector, a complete supply chain systems context is implied. The FSRL Tool covers four components: (1) Production, (2) Market, (3) Policy - Program Support and Regulatory Compliance, and (4) Linkage to Conversion Processes. The FSRL Tool components parallel the FRL. This approach provides an integrated way to demonstrate the mutual requirements of feedstocks and conversion technologies.

As part of the Farm 2 Fly 2.0 Initiative, CAAFI is collecting evaluations of feedstock readiness levels for each region/feedstock/process combination with the goal of developing a publicly accessible repository of evaluations. The Feedstock Readiness Level Document (available below) is an Excel Workbook that contains: instructions for completing an evaluation, two evaluation checklists (one for crops and woody species and one for agriculture and forest residues), a summary report template for the feedstock evaluated, and an example checklist evaluation and summary report to show how to fill these out. CAAFI welcomes evaluation submissions from researchers and other stakeholders. Please contact with any questions about the document or to submit completed evaluations.

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Guidance for Selling Alternative Fuels to Airlines

CAAFI has published this document to serve as a roadmap for potential producers and other supply-chain participants contemplating purchase agreements with airlines for non-petroleum-derived jet fuels. It outlines key steps and criteria for potential producers to engage with airlines and highlights how and when CAAFI can help. The report was co-authored by CAAFI Business Team Leaders Dr. Bruno Miller and John Heimlich in close consultation with the heads of Airline for America (A4A) member airline fuel management departments.

To assist producers and investors, the paper constitutes a central source of answers to the following questions:

  • Why are airlines interested in commercial-scale alternative jet fuel production?
  • What are the airlines' requirements for contemplating the purchase of alternative jet fuel?
  • What are airlines willing to do to help commercialize alternative jet fuel?
  • What does a "term sheet" look like?
  • What is the best way to engage with airlines?
  • How can CAAFI help?

In addition, it includes a matrix of CAAFI readiness tools with recommended avenues for commercial engagement at various stages of development. The readiness tools are key communication protocols to help airlines, producers, and other stakeholders to explicitly understand one another's progress levels, by providing visibility and transparency into the current and projected state of aviation alternative fuel development.

CAAFI expects to augment this guidance in the future with appendices including additional lessons-learned and non-proprietary details from actual commercialization success examples as they occur.

Finally, CAAFI also provides a link to IATA’s “Aviation Fuel Supply Model Agreement” to serve as an additional resource for consideration of streamlining the process of purchasing and selling jet fuel. It can be found here.

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Environmental Sustainability Overview

The CAAFI Environment Team identified the need for a common understanding of environmental sustainability issues among the stakeholder community to facilitate understanding of environmental performance measures and engender confidence when entering off-take agreements for alternative jet fuels. While there are growing concerns regarding environmental and other risks associated with petroleum-based jet fuel, which might be addressed through the development and deployment of alternative jet fuels, the development of a new industry for alternative fuels also has its risks and challenges. Central among these are sustainability issues, and as one of the key drivers for adoption of alternative fuels is environmental benefit, the environmental sustainability challenges of alternative fuels have come under intense scrutiny. As the aviation community seeks to adapt to the changing energy landscape and facilitate the development and use of alternative jet fuels, the industry will need to ensure that the fuels into which it invests political and economic capital will provide the hoped-for benefits (environmental, economic, and otherwise). This document is intended to provide some common ground for discussing the environmental sustainability challenges associated with the development, deployment, and use of alternative jet fuels. This document is a working document, which will be subject to revision and updates over time as deemed appropriate by the CAAFI Environment Team.

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Environmental Progression

To facilitate evaluations of Fuel and Feedstock Readiness, the CAAFI Environment Team developed the Environmental Progression with input from a variety of organizations and stakeholders to provide guidance on when different environmental analyses might best be performed during the development of a new fuel production process. For example, aspects of environmental sustainability that are potentially difficult to mitigate or are irreversible (e.g., land use conversion and biodiversity impacts or invasive species introduction) need to be evaluated prior to facility establishment or feedstock introduction. Some of these (e.g., invasive species risks and/or impacts) also need to be evaluated both during scale up and during operations. Critical sustainability indicators such as GHG emissions may also be preliminarily evaluated prior to scale up (screening level GHG life cycle analysis (LCA)). Other evaluations may be done during scale up (e.g., study level GHG LCA). Other measures may not be possible until a commercial facility is in development (e.g., acquisition of permits) or established (e.g., compliance with permits, comprehensive GHG LCA). In many cases these evaluations should also be repeated over the course of development and/or process refinement, as the evaluation results may change substantially due to changes (including possible improvements) over time.

This tool parallels the Fuel and Feedstock Readiness Level tools and can be used in conjunction with them to better understand the developmental status of a fuel and/or feedstock. The CAAFI Environment Team intends to work with member organizations to produce case studies that describe the use of the Environmental Progression and other tools in order to identify gaps and enhance the tools' utility.

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