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Several key indicators of the sustainability of biofuels are related to the land used to produce the feedstock. Most of the agronomic costs and energy use (fertilizers, herbicides, soil preparation, and harvesting) are more related to the cropped area than to the feedstock quantity produced; this is also the case of soil greenhouse gas (GHG) emissions (CO₂ and N₂O) and land use change (LUC) impacts, both direct (dLUC) and indirect (iLUC), socio-economic impacts (land tenure, land prices and traditional crop displacement), impacts on biodiversity and on the environment (soil, water and air). Today, biofuels use only a little more than 2% of the world arable land but if their use to displace fossil fuels increases, as indicated by some low carbon scenarios, the land demand for the production of feedstocks could become a constraint to the expansion. It is quite apparent that the biofuel yields, present and future, should be one of the main characteristics to be evaluated in the initial screening process. This work uses the cases of corn and sugarcane ethanol to draw some comparisons on the use of these biofuels to meet the targets of some of the International Energy Agency (IEA) biofuel use scenarios in terms of land demand and also will use some of the most important study results concerning the GHG emission reduction potential, including LUC and iLUC impacts, when meeting the Renewable Energy Directive (RED) of the European Union (EU) and the Renewable Fuel Standard (RFS2) of the USA. Some technology improvements will be considered including the integration of first and second generation technologies in the same site processing corn or sugarcane for ethanol. The results of the simulations indicated that the land demands for the 2030 projected ethanol production in the two alternatives seems not to give reasons for concern on a global scale, but are large enough to produce significant local impacts. The GHG abatement potential is strongly dependent on the biofuel alternative considered.
