image

FIGURE G.1 Mandated consumption target for different categories of biofuels under the Energy Independence and Security Act of 2007.

NOTE: The line shows the consumption target under the Energy Policy Act of 2005 (EPAct05 RFS).

SOURCE: NRC (2011).

starch that is not from corn, biomass-based diesel, and coprocessed renewable diesel.1 The mandate requires 4 billion gallons per year of advanced biofuels measured in terms of ethanol equivalent gallons in 2022.

Cellulosic biofuels are renewable fuels derived from any cellulose, hemicellulose, or lignin from renewable biomass that achieve at least a 60 percent reduction in life-cycle GHG emissions. In general, cellulosic biofuels also qualify as renewable fuels and advanced biofuels. The mandate requires 16 billion gallons per year of cellulosic biofuels measured in terms of ethanol equivalent gallons in 2022.

Biomass-based diesel, including biodiesel2 made from vegetable oils or animal fats and cellulosic diesel, achieves at least a 50 percent reduction in life-cycle GHG emissions—for example, soybean biodiesel and algal biodiesel. Co-processed renewable diesel is excluded from this category. The mandate currently requires 1 billion gallons per year of biodiesel expressed as gallons of methyl ester-based biodiesel energy equivalents.

While corn-grain ethanol is only allowed to fulfill the conventional biofuels volume, biofuels from other categories could also fill the conventional biofuels volume if cellulosic biofuels become less expensive than corn-grain ethanol. There is not a specific mandate for corn-grain ethanol.

RFS2 also defines the energy equivalence of various biofuels relative to ethanol. One gallon of biodiesel is worth 1.5 gallons of ethanol. One gallon of renewable diesel3 is worth 1.7 gallons of ethanol. One gallon of biobutanol is worth 1.3 gallons of ethanol. Other fuels are rated by petition to EPA based

_____________________________

1 Co-processed renewable diesel refers to diesel made from renewable material mixed with petroleum during the hydrotreating process.

2 Biodiesel is a diesel fuel consisting of long-chain alkyl esters derived from biological materials such as vegetable oils, animal fats, and algal oils.

3 Renewable diesel is they hydrogenation product of triglcerides derived from biological materials.



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement