Oliver Posdziech (Sunfire GmbH) about HTCoEl
Up to 25% higher conversion efficiency thanks to high-temperature SOEC electrolysis
CO2-WIN Connect: Mr Posdziech, together with 5 project partners, Sunfire carried out the HTCoEl project as part of the CO2-WIN funding measure, in which the further development of compact synthesis gas production through high-temperature co-electrolysis was driven forward. What distinguishes SOECs (solid oxide electrolyser cells) from more widely used electrolysis technologies such as polymer membrane or alkaline cells and what do you think are the key advantages and unique selling points?
Herr Posdziech: Sunfire's high-temperature SOEC electrolysis has two unique selling points: If steam from waste heat or a coupling process such as Fischer-Tropsch synthesis is available in an application, then it has a significantly higher conversion efficiency (up to 25 %) compared to other technologies. This means that considerably more hydrogen can be produced with the same electricity demand. On the other hand, SOEC can produce synthesis gas (H2/CO) directly from H2O and CO2 in the co-electrolysis mode.
CO2-WIN Connect: What makes your approach to produce synthesis gas through co-electrolysis so unique and what long-term strategic advantages do you expect from this technology?
Herr Posdziech: Green hydrogen makes an indispensable contribution to decarbonisation. However, it is also important to understand that many chemical products are based on the use of hydrocarbons that can be produced from synthesis gas. The direct production of synthesis gas in electrolysis can eliminate a laborious conversion step. Together with the higher efficiency, this means a significant advantage in terms of CAPEX and OPEX. One very interesting application is the production of synthetic fuels using Fischer-Tropsch synthesis. Here we are looking particularly at the aviation and shipping sectors, as these are very difficult to electrify.
CO2-WIN Connect: The technology is currently assigned to TRL 6. What were the key advances within the project and where is the greatest need for further development and research to reach the next TRL? For example, how can the longevity of the components be guaranteed or improved under the high temperatures?
Herr Posdziech: We have tested the co-electrolysis technology for the first time in a module of an industrially interesting size of 230 kW. This is a major milestone for us. We have developed critical components such as reformers and electric heaters and worked on materials technology issues relating to the use of synthesis gas.
Naturally, durability is still an issue for us. Customers expect a service life of 20 years or more, which we have to prove step by step in prototype projects. There are still several issues to be developed and verified when it comes to controlling the modules, particularly in a direct connection with synthesis processes. We have also decided to take another development step both in the stack and in the system peripherals to significantly reduce our costs.
CO2-WIN Connect: What other steps are necessary to achieve market readiness and mass production and in what time frame can this be expected? Is the structurally compact system periphery and the SOEC technology in principle modular and easily scalable?
Herr Posdziech: Sunfire is setting up a pilot production facility for stacks in parallel with development. This is scheduled to go into operation at the beginning of 2026. This will enable Sunfire to serve prototype projects to validate the technology in the order of up to 50 MW. We will then set up series production. We expect this to be available in 2027/2028. In a first step, we will focus on the lower-risk pure hydrogen production in customer projects before switching to synthesis gas after successful validation.
We are working on significantly increasing the size and power density of our modules further. We want to go from the present 230 kW to at least 10 MW, which will then be multiplied in customer applications. If you imagine a large-scale power-to-liquid plant, then it will have an output of more than 1 GW to be economically viable. It makes a big difference here whether you want to install and operate 100 or 5000 individual modules.
CO2-WIN Connect: How dynamic is the technology in terms of load utilisation? Does only continuous operation at full load make sense, or can short-term fluctuations in the supply of renewable electricity also be balanced out?
Herr Posdziech: The modules can transfer their load from idle mode (hot standby) to load mode and back within a few minutes. This provides a very high dynamic response, as individual units can simply be switched off if there are many parallel modules. The modules would only be switched off completely if no renewable energy is available for a longer period. Restarting then takes several hours. When coupled with synthesis processes, the dynamics will play a subordinate role, as the load change speed of the syntheses is the limiting factor.
CO2-WIN Connect: Which market for PtX products do you want to serve in the future, especially with your high-temperature co-electrolysers? And how reliable and favourable do you consider EU requirements for PtX products, e.g. PtL quotas for SAF and in the maritime sector, to be in promoting the success of your technology? Are there any (legal) obstacles and further framework conditions (e.g. support measures) that you would like to see?
Herr Posdziech: In co-electrolysis, we are focussing strongly on SAF and methanol. Methanol can be used as a fuel, for example for ships, and is also a starting product for many chemicals. Political support for the market ramp-up is extremely important for renewable fuels and chemicals. Initiatives such as the EU hydrogen bank are the right instrument to trigger an initial wave of demand by supporting business models and thus final investment decisions. However, the financial resources of these funding measures are far from sufficient. In addition, the funding instruments for expanding the hydrogen economy in Europe are also open to manufacturers outside the EU. The mistakes of photovoltaics should not be repeated here. As part of an intelligent industrial policy, financial support for the hydrogen market should therefore be consistently linked to European value creation. In practice, this means that the next tendering phases of the EU hydrogen bank must include non-price criteria that require quality, sustainability, and European production.
As part of the EU's Fit-for-55 programme, ReFuel EU Aviation and FuelEU Maritime contain interesting quota targets that must be ratified accordingly. Even if the targets of 1.2% synthetic SAF in 2030 initially seem unambitious, this would require electrolysis capacities of 2 GW. In subsequent years, the proportion of synthetic SAF that needs to be blended will continue to rise significantly.
CO2-WIN Connect: Can the future demand for PtX products within Germany and the EU be covered by these themselves, or do you expect that a large proportion of production will take place outside the EU, e.g. in regions where more renewable electricity will be available for these purposes? In other words, are you already analysing and monitoring export opportunities (outside the EU)?
Herr Posdziech: The significantly higher conversion efficiency makes the technology particularly suitable for applications with high electricity prices. Nevertheless, we also recognise that the potential for renewable energy within Germany is limited and that the electricity costs for competitive PtX products can be critical. The share of electricity in the final product costs is very high, especially for renewable fuel. Regions in the EU and worldwide will benefit here, where the large-scale expansion of low-cost renewable energies is viable. One advantage of renewable fuels over hydrogen is that they are very easy to transport and large-scale logistics such as tankers, harbours or pipelines already exist. At the moment, we as a company are still focussing on the European market, but we are nevertheless looking worldwide which countries are interesting and where project opportunities could open up.
CO2-WIN Connect: Mr Posdziech, thank you for your answers!
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