If SOEL technology is so promising, why isn’t it widely deployed yet?
Renewable hydrogen is expected to play an important role in the transition towards a low-carbon economy, particularly in sectors that are difficult to electrify directly. Among the different technologies available to produce renewable hydrogen, Solid Oxide Electrolysers (SOELs) have attracted growing attention due to their high efficiency and strong potential for industrial integration.
Like other electrolysis technologies, SOEL systems use electricity to split water into hydrogen and oxygen. However, unlike low-temperature electrolysers, they operate at temperatures between 600°C and 850°C and use a solid ceramic electrolyte to transport oxygen ions. Because part of the energy required for electrolysis is supplied as heat rather than electricity, SOEL systems can achieve very high efficiency levels and offer strong potential for integration with industrial heat sources.
These characteristics make SOEL technology particularly attractive for certain industrial applications requiring large volumes of renewable hydrogen, including steelmaking, chemicals manufacturing, oil refining and renewable fuel production. Those sectors also offer favourable conditions for SOEL deployment, such as the potential to use waste heat and, in some cases, the possibility of using hydrogen for different purposes (as a raw material, fuel or source of electricity).
So, if SOEL technology already offers significant advantages, why is it not yet widely deployed?
The main barrier to the wider deployment of SOEL technology is its cost. For any technology to move from demonstration to large-scale deployment, technical performance alone is not enough. Systems must be reliable, scalable and economically competitive. Manufacturers and industrial users need confidence that the technology can operate efficiently under real-world conditions while delivering attractive performance over its lifetime.
Improving SOEL technology requires advances in materials, stack components, system integration, operational flexibility and sustainability. All these technical barriers affect the operating costs (OPEX) and capital expenditure (CAPEX) of SOEL systems, which are major obstacles to their wider deployment. The holistic approach (tackling technical barriers at every scale) is at the core of DESIREE, which brings these different areas together to help address the barriers that currently limit the wider deployment of SOEL technology, with the aim of reducing costs and improving its economic competitiveness.
To support this transition, DESIREE will design, build and validate an advanced 40 kW multi-stack SOEL prototype integrating innovations at cell, stack and system level. The project will also generate technical and techno-economic data to assess how these innovations could contribute to reducing the Levelised Cost of Hydrogen (LCOH).
Durability remains a major challenge
SOEL systems operate under demanding conditions. High temperatures, thermal cycling and long operating periods can gradually affect materials and components, leading to performance losses over time.
Achieving stable operation over thousands of hours while maintaining high efficiency remains one of the most important challenges facing the technology. Otherwise, SOEL systems may need to be replaced after a few years, leading to a higher CAPEX.
DESIREE is developing advanced electrode materials enhanced with nanoscale approaches and new glass-ceramic sealing technologies to help address this challenge by improving thermal and chemical stability. Together, these innovations aim to improve system reliability and extend operational lifetime.
Performance depends on more than the stack
When discussing electrolysers, attention often focuses on the electrolysis stack itself. However, the performance of a hydrogen production system depends on much more than the stack alone. Thermal management, heat recovery, hydrogen compression, system architecture and component integration all influence efficiency, reliability and operating costs.
To address this challenge, DESIREE goes beyond individual components. The project is developing advanced heat exchanger solutions, a modular hot box architecture and integrated thermochemical hydrogen compression technologies designed to improve overall system performance and energy efficiency.
Renewable energy requires flexible operation
Future hydrogen production systems will increasingly be linked to renewable electricity sources such as solar and wind power. Unlike conventional industrial processes operating under stable conditions, renewable electricity generation can vary significantly over time. Operating costs (OPEX), as well as the cost of producing hydrogen over the system’s lifetime (expressed as LCOH), can be significantly affected by variations in electrolyser performance.
As a result, electrolysers must be capable of responding to changing operating conditions without compromising performance or accelerating degradation.
DESIREE is developing advanced dynamic control strategies, innovative power electronics and system-level optimisation aimed at improving operational flexibility and supporting integration with renewable-energy-based grids.
Sustainability and circularity cannot be overlooked
As hydrogen technologies continue to evolve, sustainability considerations extend beyond operational efficiency.
Several SOEL components contain valuable and critical raw materials, making resource management an increasingly important aspect of future technology deployment.
DESIREE therefore incorporates circularity principles into its approach. The project is developing recycling routes for critical raw materials such as nickel, cobalt, lanthanum and strontium and exploring ways to reintegrate recovered materials into new SOEL components, contributing to more sustainable value chains.
From technological promise to industrial reality
The potential of SOEL technology is well established. The challenge now is to translate that potential into systems capable of operating reliably, efficiently and competitively under real industrial conditions.
Through innovations in materials, sealing technologies, thermal management, hydrogen compression, system control and circularity, DESIREE seeks to help address some of the key barriers that continue to limit the commercial uptake of SOEL technology.
By validating these innovations in an integrated 40 kW multi-stack prototype, the project will help generate the knowledge and operational experience needed to support the next generation of high-temperature electrolysis systems.
Within DESIREE, Spain’s National Renewable Energy Centre (CENER), the Aragon Nanoscience and Materials Institute (INMA), Politecnico di Torino, Genvia, the Fraunhofer Institute for Silicate Research ISC, Bosal, EIFHYTEC, Commissariat à l’Énergie Atomique et aux Énergies Alternatives (CEA), VTT Technical Research Centre and Zabala Innovation are working together to advance Solid Oxide Electrolyser technologies and support the future deployment of renewable hydrogen across industrial applications.