Biogas production is rising in the context of fossil fuel decline and the future circular economy, yet raw biogas requires purification steps before use. Here, we review biogas upgrading using physical, chemical and biological methods such as water scrubbing, physical absorption, pressure swing adsorption, cryogenic separation, membrane separation, chemical scrubbing, chemoautotrophic methods, photosynthetic upgrading and desorption. We also discuss their techno-economic feasibility. We found that physical and chemical upgrading technologies are near-optimal, but still require high energy and resources. Biological methods are less explored despite their promising potential. High-pressure water scrubbing is more economic for small-sized plants, whereas potassium carbonate scrubbing provides the maximum net value for large-sized plants.

在化石燃料下降和未来循环经济的背景下，沼气产量正在上升，但原始沼气在使用前需要经过净化步骤。在这里，我们回顾了使用物理、化学和生物方法进行的沼气升级，例如水洗涤、物理吸收、变压吸附、低温分离、膜分离、化学洗涤、化学自养方法、光合作用升级和解吸。我们还讨论了它们的技术经济可行性。我们发现物理和化学升级技术接近最优，但仍然需要大量的能源和资源。生物方法尽管具有广阔的潜力，但很少被探索。高压水洗涤对小型工厂更经济，而碳酸钾洗涤为大型工厂提供最大净值。