Techno-economic assessment of electro-synthetic fuel based on solid oxide electrolysis cell coupled with Fischer–Tropsch strategy
Yunyi Zhang, Ang Li, Yuxuan Fei, Chen Zhang, Lei Zhu, Zhen Huang
Abstract
Electro-synthetic fuel is proposed as an approach to achieve net-zero carbon emissions for heavy-duty internal combustion engines and meet carbon neutrality targets. This method is based on high temperature co-electrolysis using a solid oxide electrolysis cell (SOEC) coupled with Fisher-Tropsch (FT) synthesis due to its high efficiency and carbon recycling capacity. To access the techno-economic viability of this pathway and identify the key elements impacting the cost of electro-synthetic fuels, a comprehensive techno-economic model is constructed. This model aims to offer cost cutting guidance and includes SOEC, FT, and techno-economic sub-models, with SOEC and FT validated using literature data. The cost breakdown and sensitivity analysis indicate that heating costs, electricity prices, and stack lifetime are critical factors in reducing the cost of electro-synthetic fuel. Three alternative system layouts that fully utilize thermal and chemical energy are proposed to address the significant heating expense issue. Among these, the optimal system design lowers costs by approximately 5.3 %. Furthermore, this work introduces the contradiction between high performance, high stability, and low-cost accounting for the SOEC lifetime, which is bounded by operating current density. When considering the degradation and replacement of SOEC stacks, the long-term profitability of operating SOEC at a current density of 500 mA/cm 2 is superior to that of 850 mA/cm 2 . Despite the most effective layout being currently unprofitable, it is anticipated that in the future, carbon trade, renewable electricity and technological advancements will drive the cost of electro-synthetic fuel to become competitive with that of diesel. • A techno-economic model based on SOEC coupled with FT process is developed. • SOEC degradation effects on product cost is considered in TEA model. • Layouts with energy recycling are proposed with best case to reduce cost by 5.3 %. • Electro-synthetic fuel will be competitive as green electricity costs decrease.