Scientific discussion of the proper methodologies to measure GHG savings and the environmental sustainability of biofuel production is yet ongoing, with the final criteria to be adopted in 2010. The US Environmental Protection Agency is also currently debating the inclusion of default GHG emission values for different biofuels in the RFS II but has postponed its adoption for five years in order to agree on a standard methodology. Producing countries that aim for export to these regions, therefore, have the challenge to evaluate which biofuel option might best meet these criteria in the long term. Based on the default lifecycle emission values as defined in the California Low Carbon Fuel Standard and other available lifecycle assessments for biofuels (see chapter 8), second-generation biofuels appear to be a technology that will meet the above mentioned sustainability requirements, in particular when residues are used as feedstock.