Currently, global annual CO2 emissions from fossil fuel consumption are extremely high, surpassing tens of billions of tons, yet our capacity to capture and utilize CO2 remains below a small fraction of the amount generated. Microbial electrosynthesis (MES) systems, an integration of microbial metabolism with electrochemistry, have emerged as a highly efficient and promising bio-based carbon-capture-and-utilization technology over other conventional techniques. MES is a unique technology for lowering the atmospheric CO2 as well as CO2 in the biogas, and also simultaneously convert them to renewable bioenergy, such as biomethane. As such, MES techniques could be applied for biogas upgrading to generate high purity biomethane, which has the potential to meet natural gas standards. This article offers a detailed overview and assessment of the latest advancements in MES for biomethane production and biogas upgrading, in terms of selecting optimal methane production pathways and associated electron transfer processes, different electrode materials and types, inoculum sources and microbial communities, ion-exchange membrane, externally applied energy level, operating temperature and pH, mode of operation, CO2 delivery method, selection of inorganic carbon source and its concentration, start-up time, and system pressure. It also highlights the current MES challenges associated with upscaling, design and configuration, long-term stability, energy demand, techno-economics, achieving net negative carbon emission, and other operational issues. Moreover, we provide a summary of current and future opportunities to integrate MES with other unique biosystems, such as methanotrophic bioreactors, and incorporate quorum sensing, 3D printing, and machine learning to further develop MES as a better biomethane-producer and biogas upgrading technique.

中文翻译：

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用于 CO2 减排、生物甲烷生产和异地沼气提纯的微生物电合成技术


目前，全球每年因化石燃料消费而排放的 CO2 量非常高，超过数百亿吨，但我们捕获和利用 CO2 的能力仍然低于所产生量的一小部分。微生物电合成 （MES） 系统是微生物代谢与电化学的集成，已成为一种优于其他传统技术的高效且有前途的生物基碳捕获和利用技术。MES 是一种独特的技术，用于降低大气中的 CO2 和沼气中的 CO2，同时将它们转化为可再生的生物能源，例如生物甲烷。因此，MES 技术可用于沼气升级，以产生高纯度的生物甲烷，从而有可能满足天然气标准。本文详细概述了和评估用于生物甲烷生产和沼气升级的 MES 的最新进展，包括选择最佳甲烷生产途径和相关的电子转移过程、不同的电极材料和类型、接种来源和微生物群落、离子交换膜、外部施加的能量水平、工作温度和 pH 值、操作模式、 CO2 输送方法、无机碳源的选择及其浓度、启动时间和系统压力。它还强调了当前与扩大规模、设计和配置、长期稳定性、能源需求、技术经济学、实现净负碳排放和其他运营问题相关的 MES 挑战。 此外，我们还总结了当前和未来将 MES 与其他独特生物系统（如甲烷营养生物反应器）集成的机会，并结合群体感应、3D 打印和机器学习，以进一步将 MES 发展为更好的生物甲烷生产商和沼气升级技术。