Land-use-change and the "food-versus-fuel debate" are contentious issues related to the adoption and use of biofuels in many countries. As a way to mitigate potentially adverse impacts related to the use of food-based bioenergy crops and associated land-use changes, many national biofuel policies are geared toward (1) the use of non-food-based feedstocks for bioenergy crop cultivation; and (2) the utilization of marginal lands as cultivation areas. A question about the availability of these lands and whether these are sufficient for cultivating biofuel crops to meet global demand has been raised. To answer these questions, researchers from the University of Illinois at Urbana-Champaign and the University of Central Florida (both in the United States) attempted to assess land availability in areas with "major agricultural capacities". These areas include Africa, China, Europe, India, South America, and the continental United States. The researchers first assessed land availability from a physical perspective, using the best available data. Fuzzy logic modeling was also used "to address uncertainty and ambiguity in analysis where researchers considered multiple scenarios for land availability". Among the highlights of the study are: (1) regions with major agricultural production capacities have an estimated 320 million hectares to 702 million hectares land available for bioenergy crop cultivation, if only abandoned or degraded cropland is used; and  (2) cultivating second generation biofuel feedstocks on these lands can supply 10% to 52% of world energy consumption. The full results are published in the journal, Environmental Science and Technology (URL above).