Source: Nature Sustainability
Abstract
Low-temperature CO2 electrolysis represents a potential enabling process in the production of renewable chemicals and fuels, notably carbon monoxide, formic acid, ethylene and ethanol. Because this technology has progressed rapidly in recent years, a systematic techno-economic assessment has become necessary to evaluate its feasibility as a CO2 utilization approach. Here this work provides a comprehensive techno-economic assessment of four major products and prioritizes the technological development with systematic guidelines to facilitate the market deployment of low-temperature CO2 electrolysis. First, we survey state-of-the-art electrolyser performance and parameterize figures of merit. The analysis shows that production costs of carbon monoxide and formic acid (C1 products) are approaching US$0.44 and 0.59 kg–1, respectively, competitive with conventional processes. In comparison, the production of ethylene and ethanol (C2 products) is not immediately feasible due to their substantially higher costs of US$2.50 and 2.06 kg–1, respectively. We then provide a detailed roadmap to making C2 product production economically viable: an improvement in energetic efficiency to ~50% and a reduction in electricity price to US$0.01 kWh–1. We also propose industrially relevant benchmarks: 5-year stability of electrolyser components and the single-pass conversion of 30 and 15% for C1 and C2 products, respectively. Finally we discuss the economic aspects of two potential strategies to address electrolyte neutralization utilizing either an anion exchange membrane or bipolar membrane.
