From emissions to value: Techno-economic assessment of formic acid and green hydrogen production in porous solid electrolyte electrolyzers

Electrochemical CO2 reduction reaction (CO2RR) could produce various valuable chemicals from CO2 emissions. Among them, formic acid (HCOOH) is particularly promising, owing to its potential role in hydrogen economy. Emerging porous solid electrolyte (PSE)-based CO2RR systems achieve efficient electrosynthesis of HCOOH. This study elucidates – by exploring the cost impacts of key performance indicators and input metrics – what it would take to replace PSE-based CO2RR systems with carbon-intensive HCOOH production approaches. The analysis reveals that techno-economics shows high sensitivity to current density, full-cell voltage, Faradaic efficiency (FE), electrolyzer stack cost, electricity price, and catalyst/membrane/PSE and system lifespans, whereas moderate sensitivity to HCOOH electrosynthesis capacity, CO2 price, and water price. Feasible HCOOH electrosynthesis requires enhancements in current density (>400 mA/cm2), full-cell voltage (<3 V), and HCOOH FE (>85%). The analysis reveals the need for improved catalyst/membrane/PSE lifespan (>1 year), system lifespan (>15 years), and electrolyzer stack cost (<400 $/kW). The analysis also highlights the criticality of attractive and sustainable electricity prices (<6 c/kWh). The work concludes by underscoring research gaps and performance milestones, providing a technical roadmap to marketable and sustainable electrosynthesis of HCOOH.