Demystifying TRLs for Complex Technologies


With FP9 upcoming, beyond2020, the debate concerning how it should be established, framed and distributed between excellence, industry and societal challenges is on the mind of many stakeholders. To contribute to this debate, Leitat has proposed an overhaul of the way to understand the TRL scale towards a more practical approach based on the evolution of complex technologies: the Technology Readiness Pathway from basic units to applications in Society.

By Vincent Jamier, Benjamin Irvine and Christophe Aucher

Since the beginning of Horizon 2020 in 2014, the European Commission has adopted the Technology Readiness Level (TRL) scale as a measure of technology maturity to guide Research, Development & Innovation (RDI) in the EU’s Framework Programme for Research and Innovation (Figure 1). It is common place for H2020 call topics to provide a  reference TRL level to indicate which maturity of technologies are going to be funded under the call.  It is also often used to denote the difference between funding schemes and types of project, e.g. Research and Innovation Actions (RIA) or Innovation Actions (IA).

Figure 1. The TRL scale adapted to the KETs HLG three pillar-bridge model from EARTO.

As expressed in a position paper from the European Association of Research Technology Organisations (EARTO) in 2014,[1] the TRL scale performs a valuable function for funders in assessing the eligibility of innovation projects providing a measure of the maturity of the technologies involved. However, it has various limitations. One of which is the oversight of the inherent nature of setbacks in the process of technology maturity. Relatedly, the “single technology maturity approach” makes sense at lower TRL levels which focus on one technology or component but less so as these are integrated into complex products. The TRL scale was developed with a technical product development focus whilst conditions of manufacturability, commercialization and the readiness of organizations to implement innovations have only recently and unevenly been incorporated.[2] Finally, various organizations tend to adapt the definition of the TRL scale to their specific contexts and operational needs, e.g. planning and communication vs decision support for investments. This results in mismatches in the definition and interoperability of the scale arising from differing operational needs.

The TRL scale was first developed by NASA/DoD and adapted by the European Cooperation for Space Standardization (ECSS)[3] and the US Government Accountability Office (GAO). It was originally established as a tool to aid the monitoring of early technology initiatives to serve a larger mission and was applied to space system hardware and programmes. To fit it to technology development in general, various adapted readiness level (RL) scales and definitions have been elaborated from different point of views. The technology integration, system or manufacturing points of view have given rise to Integration Readiness Level (IRL), System Readiness Level (SRL) and Manufacturing Readiness Level (MRL).[4] Recently, Supply Chain Readiness Levels (SCRL) were developed aiming to solve the limitations of TRL and MRL.[5]  These various readiness scales make more sense for their specific use-cases – as the RL reference scale takes into consideration the particular industrial focus of the final adopter. Sector specific TRL definitions are also starting to be established in areas such as Biomedical,[6] Energy[7] and Software.[8] All these TRL concepts are valid and useful for the perspectives from which they arise nevertheless their multiplication may reduces the usefulness of TRL as a communication or decision support tool where definitions are not fixed. In order to be of use for innovation management it seems the TRL scale needs to be expanded and/or simplified.

From the perspective of the use TRL in EU Framework Programme projects (and many other publicly funded innovation projects) the simplification or extension of the TRL scale presents various advantages and disadvantages as noted by reflections from the Technology Readiness Level Report of the NEXOS project (FP7).[9]  Simplification by regrouping TRL1-2 as Technological concept (compiled as a written document), TRL3-4 as Proof of concept (done, first test in lab performed), TRL5-6 as prototype built (and tested in simulated environment), TRL7-8 as reliable prototype (tested in relevant environment) and TRL 9 as product (delivered on the market) is a useful approach for public communication and governmental bodies to clearly identify the overall technology maturity ( though it may overlook the complexities of actual technology development). Considering the second approach, the extension of the TRL scale, the NEXOS project tackled the apparent subjective (or perspective dependent) nature of describing the TRL of a technology by showing how the maturity level differs when using the technology at the component, sub-system or system level.

Based on this insight we propose here a general schema for the evolutions of technologies through readiness levels in the innovation process which better describes the process of innovation involving a complex technology. Rather than a singular ascent, there are necessary sideways downward movements passing from a basic unit (e.g. material, nanomaterial, bio-molecule, bio-organism) at one specific RL to its integration as integrated unit at a lower RL – as a result of the adaptation required for its integration. A similar movement occurs when passing from integrated unit to sub-system, then to operational system and finally to its application. We suggest this is a useful tool for planning, monitoring and reporting on technology evolution and in particular for complex technologies.

Evolution of a technology has to integrate the concept of Readiness Level (closely linked with its production scalability) at each step from the unit development to the final application (including, unit integration, sub-system and operational system) as described in Figure 2.

Figure 2. Leitat Technology Readiness Pathway Matrix.

Firstly, new materials must reach a degree of readiness that shows they can be feasibly produced at competitive cost. Once materials reach that degree of readiness – testing turns to integration into components (integrated unit). These new components are often likely to require (or substantially benefit from) being tested at more experimental demonstrators at lower readiness levels. This is a way of saying that components, devices, systems and applications are re-designed in light of the new materials and RL upgrading activities occur at every stage from basic unit to application.  This is a more accurate picture of how we actually observe the evolution of technology readiness in EU projects and we can use this insight to plan the evolution of the RL of each step while preparing and executing an EU (or any other publicly funded) project. Whilst, of course, each project will not necessarily be starting from basic unit but from the step and the RL implied by the topic and technology in question..

As an example (Figure 3), here is the methodology applied to a complex technology in Leitat’s on-going EU Project ALISE on a Lithium Sulphur battery for hybrid electrical vehicle (HEV) funded under the call H2020-NMP-GV-2014-NMP17.

Figure 3. ALISE Technology Readiness Pathway.

ALISE started in May 2015 with the exploration of new materials at RL3 prior to their up scaling at pilot level (RL7). Materials have been integrated in cell components, such as the electrolyte and cathode. To do so their integration has been adapted from RL3 before being produced step by step at pilot scale (RL7) in order to build the first generation of more than 100 cells (sub-system at RL5, 12.5Ah, 290 Wh/kg) in May 2017. In November 2017, the first lithium sulphur module for PHEV was built (82V, 2.15kW). It achieved roughly a 20% weight reduction compared to a comparable lithium ion module. This Lithium sulphur module built for the very first time is considered a laboratory demonstrator with a fully new electronic management adapted to this new electrochemistry (operational system at RL3). Tests are ongoing to assess the real behavior of the module with simulated real driving cycle tests proper to PHEV and BEV (operational system RL5). Towards the end of the project, in May 2019, ALISE partners aim to develop at least 2 more generations of pouch cells (>200 cells) and 1 enhanced lithium sulphur module including new advanced lithium sulphur cells with the associated electronic management control. The first generations of pouch cells will be demonstrated operational systems at RL5 while the last ones will only be validated at RL3. Moving to application (building the battery into an electric vehicle) would likely benefit from demonstration activities at a lower readiness level such as RL3-4 to explore implications and opportunities created by the new battery for vehicle design).

To conclude, the use of the TRL scale to communicate technology maturity between public funding bodies and applicants is a useful tool which takes into consideration the sector and context of each specific technology. However the step by step RL validation outlined here is critical in considering the preparation and implementation of a project. The maturity of one step has to be high enough to be able to past to the next step at a similar or most likely a lower RL.

In innovation management there is a temptation to say that the only way is up but this isn’t a very accurate description of the innovation process. Traversing is the sideways movement of climbers and skiers which makes their routes possible. Behind the apparent ascending progress of technologies to higher readiness levels is an inherent up-and-down zig-zagging as the technology moves across various levels of integration from basic units into operational units, sub-systems, operational systems and finally to applications.

This underscores the importance of pilot production lines and demonstrators and research on enabling and industrial technologies. Between basic research and new products are the necessary sideways movement of new technologies into components and subsystems on their path to readiness. This process is part of the unique knowledge area of Research and Technology Organisations and of the specific value of pilot lines and demonstrators to Public Research Programmes and Industry alike.


[1] The TRL Scale as a Research & Innovation Policy Tool EARTO Recommendations 30 April 2014 EARTO.

[2] E.g. Manufacturability has been incorporated in the Arpa-E adaptation of TRLs and commercialization assessments are now part funded activities in higher TRL H2020 projects.

[3] ISO 16290:2013: Space systems — Definition of the Technology Readiness Levels (TRLs) and their criteria of assessment.

[4] Technology Readiness Assessment Guidelines – Best Practices for Evaluating the Readiness of Technology for Use in Acquisition Programs and Projects, GAO-16-410G.

[5] A. Matopoulos et al.; From technology and manufacturing readiness levels to the need for supply chain readiness levels, 24th Conference of European Operations Management Association, 3-5 July 2017, Edinburgh, UK.

[6] US Army Medical Research and Materiel Command (MRMC), Biomedical TRLs.

[7] Technology Readiness Assessment Report 2011, DOE G 413.3-A, US Department of Energy.

[8] EIT Health, Technology Readiness Levels TRL.

[9] J.-F. Rolin et al.; D3.1 Technology Readiness Level Report NEXOS (FP7 – GA Nº·614102)