Climate policy, concerns about energy security, and the search for alternative sources of agricultural income have greatly increased interest in bio-energy as an alternative to fossil fuel. Many scenario studies with and without climate policy constraints project substantial increase in bio-energy use, and thus significant transformation of both energy systems and land use. However, the implications of bio-energy is the subject of long-standing and fierce debate. The outcomes of this debate may critically influence the rationale for bio-energy and ultimately determine the future use of this energy source. Crucial issues include the greenhouse gas balance of bio-energy and the environmental implications of large-scale bio-energy use.
Potentials for bio-energy have been estimated earlier on the basis of estimates of potentially available land, excluding certain types of land use or land cover (land required for food production and forests). In this paper, we explore how such estimates may be influenced by other factors such as land degradation, water scarcity and biodiversity concerns. Our analysis indicates that of the original bio-energy potential estimate of 150, 80 EJ occurs in areas classified as from mild to severe land degradation, water stress, or with high biodiversity value. Yield estimates were also found to have a significant impact on potential estimates. A further 12.5% increase in global yields would lead to an increase in bio-energy potential of about 50%. Changes in bio-energy potential are shown to have a direct impact on bio-energy use in the energy model TIMER, although the relevant factor is the bio-energy potential at different cost levels and not the overall potential.