Anthropogenic carbon utilization and recycling into fuel using renewably sourced or nuclear energy and water is a potentially valuable strategy for replacing fossil fuels. The high-level elemental balance of the CO2-to-Fuel system involves oxygen rejection, with CO2 and H2O reduction dependent on crucial process steps that determine performance metrics such as energy efficiency, element utilization, economics, and carbon footprint. This study elaborates on carbon and oxygen recycling strategies for producing sustainable synthetic hydrocarbon fuels. It covers electrolysis routes, internal recycling pathways, and additional processes to increase synfuel yield. An element balance was derived for four process schemes with systematic recycling route variations, facilitating a comparison of elemental efficiencies: (1) carbon utilization (80.7–90.6 %), (2) hydrogen efficiency (4.8–30.8 %), and (3) oxygen gas rejection rate (56.8–63.1 %). A process flow diagram was proposed to discuss techno-economics through the existing route via the Fischer-Tropsch process. The energy intensity ranged from 118.5 to 177.4 GJ per tonne of synfuel, and the energy conversion efficiency varied from 0.24 to 0.36. We further evaluated the carbon intensity, considering the primary energy efficiency to show the different energy supply scenarios, including (i) 100 % fossil-based (506–1416 kgCO2eq/GJFuel), (ii) grid power with fossil fuel (246–687 kgCO2eq/GJFuel), (iii) hybridization of renewable sources (biomass and wind power) (42–78 kgCO2eq/GJFuel), and (iv) nuclear energy (7–18 kgCO2eq/GJFuel). This work considers the interplay between oxygen rejection, syngas conversion, and combustion, undertaking a novel analysis to bridge the high-level elemental analysis with detailed metrics calculations.

中文翻译：

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二氧化碳到可持续合成燃料生产中的碳和氧回收策略：回收路线、技术经济和碳强度


使用可再生能源或核能和水进行人为碳利用和回收成燃料是替代化石燃料的潜在有价值的策略。 CO2 至燃料系统的高级元素平衡涉及氧气排斥，CO2 和 H2O 的减少取决于决定性能指标（如能源效率、元素利用率、经济性和碳足迹）的关键工艺步骤。这项研究详细阐述了生产可持续合成烃燃料的碳和氧回收策略。它涵盖了电解路线、内部回收途径以及提高合成燃料产量的其他工艺。针对具有系统回收路线变化的四种工艺方案得出了元素平衡，以便于元素效率的比较：（1）碳利用率（80.7-90.6％），（2）氢效率（4.8-30.8％）和（3）氧气截留率（56.8–63.1%）。提出了一个工艺流程图，以通过费托工艺的现有路线讨论技术经济学。每吨合成燃料的能量强度为118.5至177.4吉焦，能量转换效率为0.24至0.36。我们进一步评估了碳强度，考虑了一次能源效率，以显示不同的能源供应情景，包括（i）100%化石能源（506–1416 kgCO2eq/GJFuel），（ii）化石燃料电网发电（246–687） kgCO2eq/GJFuel），（iii）可再生能源混合（生物质和风力发电）（42-78 kgCO2eq/GJFuel），以及（iv）核能（7-18 kgCO2eq/GJFuel）。这项工作考虑了氧气排斥、合成气转化和燃烧之间的相互作用，进行了一种新颖的分析，将高级元素分析与详细的指标计算联系起来。