Sustainability is crucial for biofuels and bioenergy production in general. However, historically speaking, the biofuels industry has largely ignored sustainability criteria and consequently has been the source of considerable controversy. Despite a real expansion worldwide, biofuels development has still to face many barriers in the three pillars of sustainability. In the environmental domain, biofuels have to face accusations of deforestation, loss of biodiversity, carbon emission, water usage, etc. In the economic domain, they are accused to compete with other land uses for basic needs such as food and material , and they must prove that they are more viable than oil and other renewable energies. In the social domain, they also have to answer to complaints about land grabbing, rural poverty, social acceptance. Over the past twenty years, a large number of studies aimed to estimate the amount of bioenergy that can be produced in a sustainable manner. Results are very contrasted for many reasons mainly due to the heterogeneity of methodologies, definitions, assumptions and datasets employed. However, most studies agree that among all possible sources of biomass energy, energy crops are considered as the most important. Other crops and forest residues can also be good sources but do not reach the potential of energy crops. These studies lead to consider that the main potential contribution of biomass for energy production will depend on one hand of the energy crops yields and on the other hand on the quantity, the quality and the location of available land to cultivate. Considering that grassland, savannah or shrubland are idle or non-used land, most of the studies locate the majority of potentially available land in developing countries, in Sub-Saharan Africa and South America. But there is considerable debates about the availability of land in these regions and many authors point out the need for a clearer picture of what it means. Thus, land availability is maybe