Proof-of-concept and economic feasibility evaluation of carbonic acid-based electrochemical system for simultaneous CO₂ utilization and hydrogen production

The rising urgency to decarbonize industrial operations has led to the development of a novel electrochemical platform known as the Carbonic Acid-Based Electricity Generation (CAEG) system, designed to convert captured carbon dioxide into hydrogen and value-added by-products under ambient conditions. Unlike conventional CO₂ electrolysis systems that require continuous external electrical energy input, the CAEG system operates through spontaneous galvanic reactions driven by carbonic acid, enabling simultaneous CO₂ utilization, electricity generation, hydrogen production, and mineral by-product recovery within a single platform. The system utilizes weak carbonic acid as the electrolyte and a sacrificial zinc anode to drive spontaneous electrochemical reactions without external power input. Three cell configurations were evaluated, and the optimal setup comprised an iridium oxide-coated titanium cathode, a potassium ion selective membrane (Flemion F8080K), and 1 M KOH anolyte. The optimized system achieved stable operation for 264 h with an average power density of 2.01 mW cm⁻², corresponding to a current density of 4.02 mA cm⁻², and a hydrogen Faradaic efficiency of 76.5%. Average product yields of 0.10 g day⁻¹ hydrogen, 9.06 g day⁻¹ KHCO₃, and 4.08 g day⁻¹ ZnO were obtained. Feed gas studies further revealed that the presence of trace nitric oxides significantly enhanced hydrogen production and electrical power generation, highlighting the influence of representative anthropogenic impurities on CAEG performance. A techno-economic analysis of a 10 kW modular CAEG system projected an annual revenue of USD 562,000 with a return on investment within six years, driven primarily by KHCO₃ and ZnO sales. The novelty of this work lies in the integration of CO₂ utilization, hydrogen production, electricity generation, and recovery of commercially valuable mineral products within a self-powered electrochemical system, combined with long-term operational validation, evaluation under simulated industrial gas compositions, and preliminary techno-economic assessment. These findings demonstrate the potential of the CAEG system as a self-powered platform for simultaneous electricity generation, hydrogen production, and CO₂ utilization, providing a promising pathway towards industrial decarbonization and circular carbon utilization.