Technology roadmap of renewable natural gas: Identifying trends for research and development to improve biogas upgrading technology management

•Technology Roadmapping is a useful tool for biomethane strategic R&D management.•Biogas upgrading cost and energy & environmental efficiencies are critical factors.•Cryogenic and membranes with adsorption or absorption are promising options.•Optimisation of mature technologies rather than new ones prevails in the mid-term.•Biological upgrading, Power-to-Gas, and carbon capture are long-term trends. Upgrading biogas offers interchangeability with natural gas, plus the benefits of converting waste into energy to help address climate change. However, only 5% of the biogas produced worldwide is purified to biomethane and injected into the gas grid or used as a transport fuel. Using a Technology Roadmapping approach, this study aims to identify technology trends, key players, and critical factors to broader the production and application of biomethane. Data included 53 companies’ websites, 194 granted patents, 177 patents applied for, and 225 articles, correlating them to different timeframes. We classify the gathered information into taxonomies, which outlines the sector's global trends and gaps over time. Our findings have direct implications for guiding R&D management and strategic planning. Overall, we found that hybrid processes, mainly membranes combined with pressure swing adsorption and absorption with membrane contactor, and cryogenic separation are tendencies for short and medium-term development focus. Carbon Capture, Utilisation and Storage, and biological upgrading processes, especially microalgae-based, have had a great academic interest and are long-term trends, present in 32% and 20% of the articles, respectively. Biogas upgrading technologies are at a high maturity level with more prominent activity in optimisation and hybrid technologies. There is room for materials improvement and breakthroughs in second-generation technologies, such as biological methanation and Power-to-Gas, by converting carbon dioxide instead of its separation. Finally, to ensure biomethane sustainability and competitiveness, energy & environmental efficiencies and cost reduction are critical factors for R&D, which has prioritised gas purity, yield, and recovery.