Exploring the implementation of CO₂ electrolysis for syngas production: scaling strategies and trade-offs

Co-electrolysis of H₂O and CO₂ at low and high temperatures remains in its early stages of development, but yet, has the potential to support the chemical industry transition towards net-zero greenhouse gas emissions. CO₂ (co-)electrolysis (CO₂E) involves distinct trade-offs; for instance, CO₂ origin, purity and availability, electrolysis scalability and (optimal) operating conditions and integration with intermittent renewable electricity sources. Synthesis gas, or syngas, is a mixture of H₂ and CO at different fractions. It can be used to generate power or as a versatile platform or chemical building block for various products. High-temperature co-electrolysis in a solid-oxide electrolyser (SOE) converts steam, CO₂, and electricity into syngas at high efficiency and is currently at TRL 5-6.

What if syngas is produced in electrolysers? What would be the plant configuration and size? The current work focuses on solid-oxide electrolysis to produce syngas at different H₂:CO fractions, for different applications. We use a mathematical model to understand the best implementation strategies when combining electrolysis, batteries, and renewable electricity generation for syngas production and a process model including CO₂ and water purification. Overall, the purpose of this work is to understand efficient implementation scales (matched with wind and/or solar power) and their impact on the electrolysis-based plant costs.