On December 19, 2007, the President signed into law the Energy Independence and Security Act of 2007 (EISA). This law (PL 110-140) includes an increase in the national Renewable Fuel Standard (RFS) mandating the production of 36 billion gallons of renewable fuels by 2022. Within the total mandate, 21 billion gallons must qualify as advanced biofuels -- fuels made from renewable biomass other than corn starch. There are additional carve-outs for biomass-based diesel and fuels made from cellulosic feedstocks, such as wood, grasses, and agricultural residues. An important component of the RFS is a series of greenhouse gas emissions screens, essential safeguards that ensure renewable fuels will meet minimum verifiable reductions in greenhouse emissions. For renewable fuels (from new facilities) to qualify under the RFS, they must achieve at least a 20 percent reduction in direct and indirect lifecycle emissions compared to equivalent petroleum fuels. Advanced fuels and cellulosic fuels are subject to a 50 percent and 60 percent emissions screen, respectively. Because of these stringent safeguards and the large quantity of fuel mandated, it is paramount that we not rule out potentially important feedstocks without valid reasons. The definition of 'renewable biomass' included in the law, however, does rule out a number of feedstocks, including thinning materials and woody residues from federal forests.