State-of-the-art assessment of cryogenic technologies for biogas upgrading: Energy, economic, and environmental perspectives

In this review, conventional biogas upgrading technologies, including physical absorption, chemical absorption, adsorption, and membrane technologies, are evaluated in terms of their production cost, energy consumption, and number of installed plants. Amongst these technologies, cryogenic technology is the most energy- and cost-intensive. Considering the advantages and disadvantages of upgrading technologies and transportation requirements, cryogenic technology can provide dual benefits if integrated with liquefaction, as both require low temperatures for operation. In recent years, various standalone or integrated studies have been conducted to analyze the performance of cryogenic processes based on energy consumption, economic benefits, and operational feasibility for a range of biogas compositions. These studies, which include technical, economic, and environmental analyses, are examined in this review paper. Based on these assessments, cryogenic distillation-based biogas upgrading was found to be economical in terms of energy consumption and product purity. Nevertheless, other emerging cryogenic technologies, such as controlled freeze zone and anti-sublimation, must be explored further from technical and economic perspectives. Furthermore, in this review, technical challenges are discussed and future directions for academic and industrial applications are suggested along with the practical implications of this study.