Compressed biogas production from agricultural residues in India: A techno-enviro-economic overview

Agricultural residue can produce about 20 million metric tonnes (MMT) of compressed biogas (CBG) in India. However, successful commercialization of CBG production from these residues requires addressing several technological, economic, and environmental challenges. This work first critically reviews the current status of the complete CBG production value chain, i.e., feedstock production and supply, pretreatment, anaerobic digestion, biogas purification, and compression and storage. Literature studies quantifying the environmental impacts and assessing the techno-economic performance of biogas/CBG production are reviewed. Additionally, various government schemes and policies aimed at fostering the CBG economy in India are discussed. Finally, challenges faced by the CBG industry along with potential recommendations are highlighted. The review found that India had approximately 234 MMT surplus agricultural residues majorly comprising rice straw (43.85 MMT), wheat straw (25.07 MMT), sugarcane bagasse (41.56 MMT), and cotton stalk (29.74 MMT). Further, pretreatment of these residues before anaerobic digestion could increase the biogas yield by 33–317 %. For many CBG production processes, electricity was the major contributor to the global warming potential (GWP) and cleaner power grids could lower the impacts. Furthermore, 80 % of the capital cost was attributed to machinery and equipment, 10 % to land acquisition and 6 % to infrastructure creation, whereas the operational cost was majorly dominated by the feedstock cost (26 %). Finally, the review found that government support in the form of subsidies, waivers, and guaranteed markets could ease off the investor burdens and make the project economically viable.