<p>This paper offers a comprehensive numerical investigation of carbon dioxide (CO₂) emissions from hydrogen production using various renewable feedstocks. With the increasing demand for hydrogen, its production is experiencing rapid development. However, environmental considerations are very important because of the pollution associated with the production process. This study specifically examines CO₂ emissions associated with hydrogen production. CO₂ emissions are a significant contributor to the greenhouse effect. This research focuses on renewable raw materials, such as landfill gas (LFG), animal waste (AW), food waste (FW), and wastewater sludge (WSW), for hydrogen production using SMR. This research uses GREET® to analyze and is supported by UniSim Design R460 to calculate the Steam Methane Reforming (SMR) system. The finding that WSW as a raw material produces the lowest CO₂ emissions, namely − 26.83&#xa0;kg CO₂/kg H₂, deserves special attention. Besides that, using LFG produces the highest CO2 emissions, reaching 3.92&#xa0;kg CO₂/kg H₂. Of course, not only CO₂ emissions are considered when considering the use of renewable feedstock for hydrogen production, but other emission factors, such as carbon monoxide (CO), nitrogen oxide (NO_x), and other relevant pollutants, are also considered in selecting renewable feedstock. </p> Graphical abstract <p></p>