We present a detailed analysis of the supply potential and use of biomass in the context of a transition to a fully renewable global energy system by 2050. We investigate bioenergy potential within a framework of technological choices and sustainability criteria, including criteria on land use and food security, agricultural and processing inputs, complementary fellings, residues and waste. This makes our approach more comprehensive, more stringent in the applied sustainability criteria and more detailed on both the supply potential and the demand side use of biomass than that of most other studies. We find that the potential for sustainable bioenergy from residues and waste, complementary fellings, energy crops and algae oil in 2050 is 340 EJ a (1) of primary energy. This potential is then compared to the demand for biomass-based energy in the demand scenario related to this study, the Ecofys Energy Scenario [1]. This scenario, after applying energy efficiency and non-bioenergy renewable options, requires a significant contribution of bioenergy to meet the remaining energy demand; 185 EJ a (1) of the 340 EJ a (1) potential supply. For land use for energy crops, we find that a maximum of 2,500,000 km(2) is needed of a 6,730,000 km(2) sustainable potential. For greenhouse gas emissions from bioenergy, a 75%-85% reduction can be achieved compared to fossil references. We conclude that bioenergy can meet residual demand in the Ecofys Energy Scenario sustainably with low associated greenhouse gas emissions. It thus contributes to its achievement of a 95% renewable energy system globally by 2050. (C) 2012 Elsevier Ltd. All rights reserved.