Research conducted on biomass for Ulcos (“Ultra- Low CO2 Steelmaking” European Integrated Project) has progressively focused on charcoal supply from tropical eucalyptus plantations. The sustainability of such plantations is being investigated from the viewpoint of their carbon, water and nutrient budgets: they must all be neutral or positive. Field research is producing results at the tree or stand level in several sites of Congo and Brazil, while a spatial model is developed to identify the conditions of biomass neutrality at the scale of the forest ecosystem. The productivity of biomass has been analyzed through the description of practices along the Abstracts of technical articles various supply-schemes that competitively feed the steel industry in Brazil and the identification of bottlenecks for further expansion.