Multiscale Assessment of Solid Oxide Electrolysis with a Combination of Modeling and Material Property Optimization
Authors: Stahl Moritz , Rutz Malte , Do Nga , Schlüter Nicolas , Eull Michael , Ekperechukwu Adaora , McCann Fraser , Steedman Andrew , MacDonald Lewis , Brightman Edward , Rae Callum , Bhagavathy Priya , Burt Graeme , Neagu Dragos , Schröder Daniel 
Published: December 2024

Hydrogen has emerged as a versatile energy carrier poised to play a pivotal role in the future energy landscape. Electrolysis, particularly when powered by renewable energy sources, stands out as a promising method for hydrogen production. However, the cost of hydrogen from renewables remains relatively high, hindering widespread adoption across key markets and industries. Overcoming this barrier requires establishing market mechanisms and policies that promote cheaper renewable electricity costs and technology penetration. Additionally, radical innovation across multidisciplinary aspects, including materials, design, scaling up, operation, and digitalization, is crucial to reducing capital expenditure (CAPEX) and accelerating the transition to widespread sustainable energy systems.

Our study addresses these challenges by providing a connected multiscale assessment of Solid Oxide Electrolysis (SOE) systems for hydrogen production. This assessment spans from the exploration of novel materials to the development of digital modeling tools for evaluating various scales, including the investigation on the material level, cell and stack assembly level, system integration, and grid performance. Given the significant duration it takes for a new product to transition from material development in the laboratory to the market, this approach of bridging the gap between scales, from fundamental material properties to system performance and grid integration holds great importance in understanding the interplay between these different scales and allows for rapid decision making along the design chain.

Figure 1a) provides a comprehensive overview of all the scales involved in an electrolysis system, encompassing material, cell/stack assembly, system integration with auxiliary components, and the connection to the electric grid. At the material scale, we focus on the transformative effects of enhancing ionic conductivity, a fundamental property influencing multiple scales of electrolysis technology. Values for ionic conductivity are derived from materials simulation of state-of-the-art solid oxide ion conductors, which are further improved by application of a conductivity-enhancement concept. For this approach, we extended a method for the synthesis of Yttria-stabilized zirconia and Strontium-magnesium-doped lanthanum gallium electrolytes incorporating internal nanoparticles ('endoparticles’). At the cell level, a comprehensive mathematical model allows access to cell voltage data at set current density. At the system level, we delve into electric-to-hydrogen conversion efficiency and CAPEX. Finally, at the grid scale, we explore the levelized cost of hydrogen (LCOH), and the potential energy and cost savings if materials with improved conductivity were implemented at a large scale to meet early hydrogen production targets.

The primary findings of our study are illustrated in a parallel axis plot shown in figure 1b). We found that increasing the ion conductivity of the electrolyte by 1-2 orders of magnitude results in a noticeable decrease in cell voltage, and therefore boosts the electric to hydrogen conversion efficiency. The CAPEX is projected to range, depending on several factors such as cell operating conditions (for instance, utilizing affordable steel supports at lower temperatures if the ionic conductivity allows), advancements in cell manufacturing, and scaling benefits. When we consider these factors along with the enhanced conductivity, the hydrogen production cost with this technology could significantly vary. However, the cost reduction linked to electrolyte conductivity enhancement is minor, contributing to less than a tenth of this range. Essentially, our findings suggest that major alterations at the material level have a marginal direct effect on the final hydrogen cost LCOH. Significant material improvements therefore play a more crucial role in reducing the CAPEX, as they could allow for the use of cheaper materials, which in turn could lower the cost of hydrogen significantly.

In conclusion, our study highlights the nuanced interplay between material properties and system performance in electrolysis technology, emphasizing the importance of multidisciplinary innovation and scaling up efforts to realize the ambitious hydrogen production targets. By bridging the gaps between different scales and leveraging advancements in materials and digital modeling, we can allow for quicker decision making and thus accelerate the transition towards a sustainable hydrogen economy.

Figure 1