Biomass as a sustainable renewable energy resource with numerous advantages in terms of storage, transportation, and conversion to gas and liquid that no other renewables can compete with bioenergy in these fields could be a proper power solution for Iran as a developing country with abundant fossil and renewable resources. Despite the lake of official statistics, a comprehensive review of biomass resource estimation of Iran has been conducted for the first time and 72 Mt animal manure, 61 Mt sewage and waste water, 19 Mt agricultural residue, 15 Mt municipal solid wastes, 4 Mt woody residues, and 1.3 Mt citrus residues are estimated. A novel biopower model structure is introduced using reference energy system modeling approach as a network representation of the technical activities to convert biomass to electricity. Therefore, 781 ML biodiesel, 5690 ML bioethanol and 20,500 MCM biogas could be extracted through the proposed structure. Thus, total biopower potential will be 63.7 TWh that is equal to 23.2% of total power generation in Iran (274.4 TWh). The sustainability assessment is conducted and the results show 79 Mt of carbon reduction, 9366 annual job creation and 0.01 USD/kWh cost reduction in order to 100% of bioenergy potential utilization, which are 79%, 22%, and 10% improve in social, environmental and economic indicators, respectively. © 2018 American Institute of Chemical Engineers Environ Prog, 38: 171–188, 2019