Advanced Water Management Centre, The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia.
Advanced Water Management Centre, The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia.
Water Res. 2021 Jun 1;197:117120. doi: 10.1016/j.watres.2021.117120. Epub 2021 Apr 5.
As a clean and renewable energy, biogas is an important alternative to fossil fuels. However, the high carbon dioxide (CO) content in biogas limits its value as a fuel. 'Biogas upgrading' is an advanced process which removes CO from biogas, thereby converting biogas to biomethane, which has a higher commercial value. Microbial technologies offer a sustainable and cost-effective way to upgrade biogas, removing CO using hydrogen (H) as electron donor, generated by surplus electricity from renewable wind or solar energy. Hydrogenotrophic methanogens can be applied to convert CO with H to methane (CH), or alternatively, homoacetogens can convert both CO and H into value-added chemicals. Here, we comprehensively review the current state of biogas generation and utilization, and describe the advances in biological, H-dependent biogas upgrading technologies, with particular attention to key challenges associated with the processes, e.g., metabolic limitations, low H transfer rate, and finite CO conversion rate. We also highlight several new strategies for overcoming technical barriers to achieve efficient CO conversion, including process optimization to eliminate metabolic limitation, novel reactor designs to improve H transfer rate and utilization efficiency, and employing advanced genetic engineering tools to generate more efficient microorganisms. The insights offered in this review will promote further exploration into microbial, H-driven biogas upgrading, towards addressing the global energy crisis and climate change associated with use of fossil fuels.
沼气作为一种清洁可再生能源，是化石燃料的重要替代品。然而，沼气中高浓度的二氧化碳（CO）限制了其作为燃料的价值。“沼气升级”是一种先进的工艺，它可以从沼气中去除 CO，从而将沼气转化为具有更高商业价值的生物甲烷。微生物技术提供了一种可持续且具有成本效益的方法来升级沼气，利用可再生风能或太阳能产生的多余电力作为电子供体将 H 用于去除 CO。氢营养型产甲烷菌可用于将 CO 与 H 转化为甲烷（CH），或者同型乙酸菌可将 CO 和 H 转化为增值化学品。在这里，我们全面回顾了沼气的产生和利用现状，并描述了生物、H 依赖型沼气升级技术的进展，特别关注与这些过程相关的关键挑战，例如代谢限制、H 转移率低和有限的 CO 转化率。我们还强调了几种克服技术障碍以实现高效 CO 转化的新策略，包括优化工艺以消除代谢限制、设计新型反应器以提高 H 转移率和利用效率，以及采用先进的遗传工程工具来生成更高效的微生物。本综述提供的见解将促进对微生物、H 驱动的沼气升级的进一步探索，以应对与使用化石燃料相关的全球能源危机和气候变化。
