_H2News: Dr. Julia Bauer, Spark e-Fuels was founded in 2021. What prompted the company’s founding?

Dr. Julia Bauer: The catalyst was less a single event than an observation about the industry as a whole: Until now, e-fuel plants have largely been developed according to the logic of the oil and gas industry—designed for an energy supply that is as steady as possible around the clock. This is only partially compatible with wind and solar power, which naturally fluctuate. At the same time, renewable electricity is by far one of the most important cost factors in the production of e-fuels. Anyone who wants to operate the synthesis process as continuously as possible must therefore compensate for these fluctuations elsewhere in the system.

Many plant designs rely on hydrogen storage or other buffering solutions for this purpose. These can account for a significant portion of the investment costs and further increase production costs. At that time, there was no process available that could directly handle fluctuations rather than completely buffering them out. It was precisely this gap that gave rise to the idea for Spark e-Fuels.

Dr. Arno Zimmermann at the public unveiling of the pilot plant on September 9. © Samira Joy Frauwallner / getpress

_H2News: What is your company's mission?

Bauer: We want to transform e-fuels from an expensive niche product into a competitive solution for sectors that are difficult to electrify directly. The need is particularly evident in aviation: Batteries are of very limited use for long-haul flights due to their weight, while hydrogen, because of its low volumetric energy density, would require significant changes to aircraft and infrastructure. Liquid, high-energy fuels will therefore continue to play an important role in the long term.

The figures show just how large the gap currently is: According to the International Air Transport Association (IATA), the umbrella organization for airlines, approximately 1.9 million metric tons of SAF were produced worldwide in 2025; production is expected to reach about 2.4 million metric tons in 2026, which is still less than one percent of global kerosene consumption. It is precisely this gap between demand and actual production that we want to narrow.

_H2News: You founded Spark e-Fuels together with former BCG* consultant Dr. Mathias Bösl and Dr. Arno Zimmermann, who has a background in techno-economics. How did this collaboration as a founding team come about?

*Boston Consulting Group*

Bauer: We knew each other from different professional backgrounds that eventually converged: research on e-fuel concepts at the Technical University of Berlin and the Massachusetts Institute of Technology (MIT), several years of experience with chemical processes and plant engineering in industry, as well as an economic perspective on the energy transition gained through strategic consulting. When we first discussed the topic together, it quickly became clear that these three perspectives complemented each other very well. This led to the decision not only to discuss the problem but to tackle it together.

_H2News: As you mentioned, the three of you—the founders—bring together backgrounds in chemistry, management consulting, and technoeconomics. How has this interdisciplinary approach influenced the development of your technology?

Bauer: We started with the market challenge, not the technology—and that guided the entire technical development process. Instead of first optimizing a reactor configuration in the lab and only then assessing whether it would be economically viable, we addressed technical and economic issues in parallel from the very beginning. Every decision was also evaluated in terms of its implications for investment and production costs, as well as the storage requirements of a future plant. This is a key reason why reducing hydrogen storage requirements through a flexible process was at the heart of our development from the very beginning—rather than being added later as a cost-optimization measure.

_H2News: Can you briefly explain the steps involved in your process, from CO₂ and hydrogen to the finished e-fuels?

Bauer: First, green hydrogen is produced from renewable electricity via electrolysis. CO₂, such as that from industrial exhaust streams or other point sources, is converted into carbon monoxide (CO) via the reverse water-gas shift reaction (RWGS). Combined with hydrogen, this produces synthesis gas, which is then converted into liquid hydrocarbons via the Fischer-Tropsch synthesis. The synthetic crude oil produced in this way can then be refined and further processed, for example, into sustainable jet fuel or naphtha-like feedstocks for the chemical industry.

Naphta. © Samira Joy Frauwallner / getpress

_H2News: How does your patented technology differ from conventional methods for producing e-fuels?

Bauer: Our technological approach begins with the RWGS stage. Conventional RWGS designs are often operated at high temperatures—in some cases well above 850 degrees Celsius—and are typically designed for operation that is as steady as possible. Fluctuations in the hydrogen supply can adversely affect conversion, temperature control, and process efficiency.

In contrast, our process operates at temperatures below 750 degrees Celsius, achieves CO yields of well over 90 percent with very low byproduct formation, and is intrinsically load-flexible. As a result, the RWGS process can be operated over a wide load range without significantly compromising CO yield or process stability. This significantly reduces the need for large hydrogen buffers to decouple electrolysis and synthesis. At the same time, the high CO yield and low byproduct formation reduce the need for downstream purification and recycling, thereby simplifying the overall process chain and improving process efficiency.

_H2News: You mention load-flexible technology. How do you enable this load flexibility?

Bauer: Hydrogen electrolyzers are already capable of responding to fluctuations in renewable energy thanks to their relatively good load flexibility. The problem so far has been synthesizing hydrogen and_{CO₂ into} e-fuels. The key is that our patented process does not have to process hydrogen and CO₂ simultaneously. Instead, the reaction steps occur one after the other. This allows the process to adapt much more effectively to a fluctuating hydrogen supply and requires less intermediate storage capacity. At the same time, the high CO yield ensures that less material needs to be recirculated. This simplifies the plant and also makes the entire process chain more flexible. With our pilot plant, we have already demonstrated this dynamic mode of operation integrated into the overall process chain—an important step toward industrial application.

_H2News: Your technology operates at lower temperatures and with reduced recycling flows. What are the resulting benefits in terms of efficiency and costs?

Bauer: Lower operating temperatures reduce energy consumption and can simultaneously lower the demands placed on materials and plant engineering. Thanks to the high CO yield, less unprocessed gas needs to be treated, compressed, and recycled. However, an even greater opportunity lies in hydrogen storage: Large storage facilities can account for a significant portion of the investment costs in e-fuel plants. Thanks to the flexibility of our process, the required storage capacity can be reduced by up to 90 percent in the scenarios we examined. Overall, our calculations show a potential for reducing production costs by around 40 percent compared to a conventional process designed for largely continuous operation.

_H2News: Beyond aviation: In what other industries or applications do you see potential for your technology?

Bauer: We also see great potential in the chemical industry. There, carbon is needed not only as an energy source but, above all, as a raw material—for example, for products that are currently naphtha-based. This is precisely where CO₂-based hydrocarbons can play an important role in the long term. At the same time, many chemical production facilities are designed for operating conditions that are as constant as possible, so flexible processes are becoming increasingly relevant there as well. Our initial focus is on aviation because the demand for sustainable liquid fuels is particularly high there and few technical alternatives are available. In the long term, however, our technology can also be applied to the chemical industry.

_H2News: You're currently working on a new generation of your RWGS technology—what exactly is it supposed to improve?

Bauer: In the laboratory and in the pilot plant, we have demonstrated that the process works in principle, even under real-world load cycles. However, when scaling up to a significantly larger scale, flow behavior, pressure conditions, and material requirements change—effects that only truly become apparent at this scale. The new generation of reactors is the answer to this challenge: It is designed to transfer the combination of load flexibility and high yield achieved at the pilot scale in such a way that it functions stably and economically even at plant sizes closer to industrial scale.

_H2News: You’ve been part of the Schwedt Startup Challenge since June. The goal of the challenge is to carry out pilot projects on sustainable materials at the site. What do you hope to gain from the program?

Bauer: As a traditional refining site, Schwedt is itself in the midst of industrial restructuring. This aligns with our approach of building wherever possible in locations where energy and industrial infrastructure already exists, and of collaborating with local partners. Above all, we hope the program will foster concrete dialogue with regional industry and academic partners—for example, regarding CO₂ sources and site-specific issues—and thereby provide key insights for moving from concept to a real-world development environment. Additionally, the exchange with the other participating startups in the fields of sustainable materials and the process industry is valuable, because many of them face similar challenges to ours when scaling up new chemical processes.

_H2News: You have completed the development and planning of your demonstration plant in collaboration with the industrial services provider Bilfinger SE. What insights did you gain from this process?

Bauer: Based on our process simulations and conceptual studies, Bilfinger took on the engineering of the main components: reactors, pumps, tanks, heat exchangers, and piping. This led to the development of a basic design, including a timeline and cost estimate. A key finding concerns the design of the RWGS stage and its impact on the plant’s overall economic efficiency: In particular, when scaling up to an industrial scale, we have learned that parameters such as pressure and temperature can have a decisive influence on the capital and operating costs of the RWGS stage as well as the overall process. Changes to these operating conditions affect equipment sizes, materials, heat integration, and thus the total cost of the plant.

Another key finding concerns reactor design: At the plant scale, multiple reactors connected in parallel are needed, which alternate between the individual reaction steps, whereas a single reactor suffices in the laboratory. These reliable figures now form the basis for funding applications and the upcoming investment decision regarding the demonstration plant.

Visit to the pilot plant with Stefan Schnorr, State Secretary at the Federal Ministry of Transportation. © Samira Joy Frauwallner / getpress

_H2News: What major challenges still need to be overcome on the path to market readiness?

Bauer: The transition from a pilot plant to a demonstration plant and on to the first commercial plant takes several years and requires significant capital. This applies to the entire industry, not just to us. In the aviation sector, there’s the added challenge that strict safety and certification standards must be met before a fuel can even be used. And ultimately, the cost gap compared to fossil kerosene remains—a gap we must continue to narrow through scaling up and selecting suitable locations, namely sites with affordable electricity, a reliable CO₂ source, and short distances to transportation infrastructure such as pipelines, grids, or ports.

_H2News: Global demand for sustainable aviation fuel (SAF) is expected to rise to 340 million metric tons per year by 2050. What role can Spark e-Fuels play in this?

Bauer: Estimates vary widely depending on the study: Some project around 340 million metric tons by 2050, while an analysis by the auditing firm EY Corporate Solutions GmbH & Co. KG from March 2025 forecasts up to 600 million metric tons and 5,000 to 7,000 new production facilities worldwide. Whichever figure ultimately proves accurate, it does little to change the fundamental situation: Currently, only a fraction of what is needed is being produced. We do not build our own large-scale plants; instead, we license our technology to project developers and EPC* partners. Our contribution is to reduce the costs of CO₂ conversion to such an extent that more of these projects become economically viable in the first place, thereby helping to ramp up e-fuel production.

* Engineering, Procurement, Construction (German: Detailed planning and supervision, procurement, execution of construction and installation work)

_H2News: In your opinion, what does it take to achieve climate-neutral aviation?

Bauer: Above all, we need to move quickly, because the development cycles for new fuel production facilities are long, while the European Union has established binding SAF quotas—including a separate sub-quota for synthetic e-kerosene—through the ReFuelEU Aviation Regulation, which will increase gradually in the coming years. Bio-SAF and e-SAF will need to complement each other because they are based on different feedstocks: biomass is limited by region and season, while CO₂ and renewable energy are generally more widely available. And we need locations with affordable electricity and a secure supply of CO₂. Southern Europe, for example, as well as wind-rich regions such as northern Germany, the United Kingdom, or Scandinavia, are suitable candidates.

_H2News: Where do you see Spark e-Fuels in ten years?

Bauer: As a technology provider and licensor whose process is currently being operated in several commercial plants by partners, initially in Southern and Northern Europe and eventually on a global scale. Following the demonstration plant on a hundred-metric-ton scale, we plan to build our first commercial plant on a thousand-metric-ton scale by 2030. To that end, we are already in discussions with project developers in several countries. In ten years, our technology should no longer be the bottleneck, but rather one of several building blocks that can significantly narrow the gap between SAF demand and actual production.

_H2News: Dr. Bauer, thank you very much for the interview!