Global warming caused by increasing CO₂ atmospheric levels is calling for sustainable fuels. For instance, biomethane produced by biogas upgrading is a promising source of green energy. Technologies to upgrade biogas include chemical absorption, water scrubbing, physical absorption, adsorption, cryogenic separation and membrane separation. Historically, water scrubbing was preferred because of the simplicity of this operation. However, during the last decade, membrane separation stood out due to its promising economic viability with investment costs of 3500–7500 €/(m³/h) and operational costs of 7.5–12.5 €/(m³/h). Here we review biogas upgrading by membrane separation. We discuss gas permeation, membrane materials, membrane modules, process configurations and commercial biogas plants. Polymeric materials appear as most adequate for membranes aimed to upgrade biogas. Concerning membrane modules, hollow fibers are the cheapest (1.5–9 €/m²). Multistage configurations provide high methane recovery, of 99%, and purity, of 95–99%, compared to single-stage configurations.

由不断增加的CO ₂大气水平引起的全球变暖正在呼吁使用可持续的燃料。例如，通过沼气升级产生的沼气是绿色能源的有希望的来源。升级沼气的技术包括化学吸收，水洗，物理吸收，吸附，低温分离和膜分离。历史上，由于该操作的简单性，优选水洗。然而，在过去的十年中，膜分离技术因其经济上的可行性而脱颖而出，其投资成本为3500–7500€/（m ³ / h）和运营成本为7.5–12.5€/（m ³/H）。在这里，我们回顾了通过膜分离对沼气的提质。我们讨论了气体渗透，膜材料，膜组件，工艺配置和商业沼气厂。聚合物材料似乎最适合用于提高沼气的膜。关于膜组件，中空纤维是最便宜的（1.5–9€/ m ²）。与单级配置相比，多级配置可提供99％的高甲烷回收率和95–99％的纯度。