RePoSe: Insights into flexible PtL production

The fluctuating availability of renewable energy poses new challenges for power-to-liquid (PtL) fuel production. In order to produce PtL fuels on an industrial scale, PtL plants will need to be able to respond flexibly to a volatile electricity supply. This presents technical, operational, and regulatory challenges for plant operation and industrial implementation.

Against this backdrop, the closing event of the RePoSe project, Real-time power supply for e-fuels: insights into the flexible production of PtL fuels, took place on 21 May 2026 at Provadis University of Applied Sciences in the Höchst Industrial Park. Project partners CENA Hessen, INERATEC, Fraunhofer LBF and Provadis University presented the results of several years of research and development work.

The event demonstrated that, while flexible PtL production is technically feasible, it requires adapted operational strategies, suitable regulatory frameworks, and an understanding of the effects of variable loads on processes and materials.

Download: Presentation slides in german

ERA ONE plant demonstrates flexible PtL production under real-world conditions

Sven Vilbois (INERATEC) presented data from INERATEC plants to demonstrate the feasibility of flexible PtL plant operation. The results show that this can be achieved through process, automation and operational optimisations, eliminating the need for costly and time-consuming modifications to the plant. Shorter start-up and shutdown times during the operation of the PtL synthesis plant also enable it to be better adapted to the real-world availability of renewable energy.

Hydrogen storage and electricity forecasts as the key to flexible operation

Dr Alexander Zschocke (CENA Hessen) assessed the technical feasibility of flexible plant operation from regulatory and economic perspectives. The focus was on sizing hydrogen storage facilities to compensate for production losses as efficiently as possible in the face of fluctuating electricity availability. It became clear that a balance must be struck between storage capacity, investment costs, and production losses. At the same time, improved forecasts of renewable energy availability offer additional optimisation potential.

A key challenge lies in implementing the temporal correlation between renewable electricity generation and PtL production, as set out in Delegated Act (EU) 2023/1184, in conditions of volatile electricity availability. In this context, the possibility of applying the temporal correlation exclusively to hydrogen production, rather than to the entire process, was discussed.

Load cycling affects material stress and plant reliability

Thomas Pfeiffer, Johannes Käsgen and Dr Steffen Schönborn (Fraunhofer LBF) presented their research on the impact of flexible operating modes on PtL plant reliability. Cyclic temperature changes caused by load cycling during actual plant operation can lead to losses in preload force and the loosening of bolted connections, amongst other things. Additional measurement and analysis methods also allowed stresses and material damage, such as cracks or corrosion, to be assessed. The study also investigated how potential sources of failure and failure probabilities for plant components can be quantified using probabilistic failure mode and effects analysis.

Sustainability assessment highlights the opportunities and challenges of PtL production

Professor Ralf Ehret (Provadis University of Applied Sciences) presented the results of a life cycle assessment (LCA) of the environmental impact of PtL production, based on cradle-to-gate and cradle-to-grave analyses. The sustainability of PtL fuels was found to depend on several factors, particularly the origin of the CO₂, the electricity mix used and the source of the hydrogen.

The analysis shows that using biogenic CO₂ is not without its drawbacks: while it may result in lower acidification potential for soils and water bodies, it can also contribute to higher eutrophication potential, thereby exacerbating the over-fertilisation of ecosystems.

This highlights the need for a nuanced environmental assessment of PtL fuels across the entire process chain and suggests that alternative carbon sources, such as direct air capture (DAC), could become more important in the future.

Flexible PtL production: between progress and challenges

The RePoSe project has shown that flexible PtL fuel production is possible under real-world conditions and can be implemented practically today. The RePoSe project has shown that flexible PtL fuel production is possible under real-world conditions and can be implemented practically today. With the ERA One pilot plant, which is set to produce up to 2,500 tonnes of e-fuels per year at the Höchst Industrial Park, Germany — and Hesse in particular — is taking important steps towards the industrial-scale production of PtL technologies.

During the closing event, it became clear that sustainable aviation fuels are essential for decarbonising air transport. In long-haul transport in particular, aviation will remain dependent on liquid hydrocarbons in the long term. The requirements of ReFuelEU Aviation are increasing the demand for alternative aviation fuels, as well as the importance of establishing industrial production capacities.

However, challenges remain: the fluctuating availability of renewable energy creates new demands for plant operations, materials, storage infrastructure, and regulatory frameworks. To be able to produce PtL fuels on an industrial scale in the long term, these issues must be addressed, and technological developments must be consistently driven forward and further refined.

The RePoSe project is being funded by the German Federal Ministry of Transport with around EUR 3.4 million as part of the overall Renewable Fuels Concept. The Hessian Ministry of Economics, Energy, Transport, Housing and Rural Areas (HMWVW) is contributing up to an additional EUR 1.25 million to the project.

Interested in the final report?

The final report for the RePoSe project will be published at a later date.

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