Document ID: EPA-HQ-OAR-2014-0537-0001
Agency: epa
Document Type: Notice
Title: Lifecycle Greenhouse Gas Emissions for Renewable Fuels Produced From Biomass Sorghum
Posted Date: 2014-12-31T05:00Z

[Federal Register Volume 79, Number 250 (Wednesday, December 31, 2014)]
[Notices]
[Pages 78855-78861]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2014-30712]

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ENVIRONMENTAL PROTECTION AGENCY

[EPA-HQ-OAR-2014-0537-; FRL-9921-15-OAR]

Notice of Opportunity To Comment on the Lifecycle Greenhouse Gas 
Emissions for Renewable Fuels Produced From Biomass Sorghum

AGENCY: Environmental Protection Agency.

ACTION: Notice.

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SUMMARY: In this Notice, the Environmental Protection Agency (EPA) is 
inviting comment on its preliminary analysis of the greenhouse gas 
(GHG) emissions attributable to the growth and transport of biomass 
sorghum feedstock for use in making biofuels such as ethanol or diesel. 
This notice explains EPA's analysis of the growth and transport 
components of the lifecycle greenhouse gas emissions from biomass 
sorghum, and describes how EPA may apply this analysis in the future to 
determine whether biofuels produced from such biomass sorghum meet the 
necessary GHG reductions required for qualification under the Renewable 
Fuels Standard (RFS) program. Based on this analysis, we anticipate 
that biofuels produced from biomass sorghum could qualify for 
cellulosic biofuel renewable identification numbers (RINs) if certain 
fuel production process technology conditions are met.

DATES: Comments must be received on or before January 30, 2015.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2014-0537, by one of the following methods:
     http://www.regulations.gov. Follow the on-line 
instructions for submitting comments.
     Email: a-and-r-docket@epa.gov, Attention Air and Radiation 
Docket ID No. EPA-HQ-OAR-2014-0537.
     Mail: Air and Radiation Docket, Docket No. EPA-HQ-OAR-
2014-0537, Environmental Protection Agency, Mail code: 28221T, 1200 
Pennsylvania Ave. NW., Washington, DC 20460.
     Hand Delivery: EPA Docket Center, EPA/DC, EPA WJC West, 
Room 3334, 1301 Constitution Ave. NW., Washington, DC 20460, Attention 
Air and Radiation Docket, ID No. EPA-HQ-OAR-2014-0537. Such deliveries 
are only accepted during the Docket's normal hours of operation, and 
special arrangements should be made for deliveries of boxed 
information.
    Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-
2014-0537. EPA's policy is that all comments received will be included 
in the public docket without change and may be made available online at 
www.regulations.gov, including any personal information provided, 
unless the comment includes information claimed to be Confidential 
Business Information (CBI) or other information whose disclosure is 
restricted by statute. Do not submit information that you consider to 
be CBI or otherwise protected through www.regulations.gov or email. The 
www.regulations.gov Web site is an ``anonymous access'' system, which 
means EPA will not know your identity or contact information unless you 
provide it in the body of your comment. If you send an email comment 
directly to EPA without going through www.regulations.gov, your email 
address will be automatically captured and included as part of the 
comment that is placed in the public docket and made available on the 
Internet. If you submit an electronic comment, EPA recommends that you 
include your name and other contact information in the body of your 
comment and with any disk or CD-ROM you submit. If EPA cannot read your 
comment due to technical difficulties and cannot contact you for 
clarification, EPA may not be able to consider your comment. Electronic 
files should avoid the use of special characters, any form of 
encryption, and be free of any defects or viruses. For additional 
information about EPA's public docket visit the EPA Docket Center 
homepage at http://www.epa.gov/epahome/dockets.htm.
    Docket: All documents in the docket are listed in the 
www.regulations.gov index. Although listed in the index, some 
information is not publicly available, e.g., CBI or other information 
for which disclosure is restricted by statute. Certain other material, 
such as copyrighted material, will be publicly

[[Page 78856]]

available only in hard copy. Publicly available docket materials are 
available either electronically in www.regulations.gov or in hard copy 
at the Air and Radiation Docket, EPA/DC, EPA West, Room 3334, 1301 
Constitution Ave. NW., Washington, DC. The Public Reading Room is open 
from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal 
holidays. The telephone number for the Public Reading Room is (202) 
566-1744, and the telephone number for the Air and Radiation Docket is 
(202) 566-1742.

FOR FURTHER INFORMATION CONTACT: Jon Monger, Office of Transportation 
and Air Quality, Mail Code: 6406J, U.S. Environmental Protection 
Agency, 1200 Pennsylvania Avenue NW., 20460; telephone number: (202) 
564-0628; fax number: (202) 564-1686; email address: 
monger.jon@epa.gov.

SUPPLEMENTARY INFORMATION: 
    This notice is organized as follows:

I. Introduction
II. Analysis of Greenhouse Gas Emissions Associated With use of 
Biomass Sorghum as a Biofuel Feedstock
    A. Feedstock Description, Production, and Distribution
    B. Summary of Agricultural Sector Greenhouse Gas Emissions
    C. Fuel Production and Distribution
    D. Cellulosic Content of Biomass Sorghum
III. Summary

I. Introduction

    As part of changes to the Renewable Fuel Standard (RFS) program 
regulations published on March 26, 2010 \1\ (the ``March 2010 rule''), 
EPA specified the types of renewable fuels eligible to participate in 
the RFS program through approved fuel pathways. Table 1 to 40 CFR 
80.1426 of the RFS regulations lists three critical components of an 
approved fuel pathway: (1) Fuel type; (2) feedstock; and (3) production 
process. Fuel produced pursuant to each specific combination of the 
three components, or fuel pathway, is designated in the Table as 
eligible for purposes of the Act's requirements for greenhouse gas 
reductions, to qualify as renewable fuel or one of three subsets of 
renewable fuel (biomass-based diesel, cellulosic biofuel or advanced 
biofuel). EPA may also independently approve additional fuel pathways 
not currently listed in Table 1 to Sec.  80.1426 for participation in 
the RFS program, or a third-party may petition for EPA to evaluate a 
new fuel pathway in accordance with 40 CFR 80.1416.
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    \1\ See 75 FR 14670.
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    EPA's lifecycle analyses are used to assess the overall greenhouse 
gas impacts of a fuel throughout each stage of its production and use. 
The results of these analyses, considering uncertainty and the weight 
of available evidence, are used to determine whether a fuel meets the 
necessary greenhouse gas reductions required under the Clean Air Act 
(CAA) for it to be considered renewable fuel or one of the subsets of 
renewable fuel. Lifecycle analysis includes an assessment of emissions 
related to the full fuel lifecycle, including feedstock production, 
feedstock transportation, fuel production, fuel transportation and 
distribution, and tailpipe emissions. Per the CAA definition of 
lifecycle GHG emissions, EPA's lifecycle analyses also include an 
assessment of significant indirect emissions such as emissions from 
land use changes, agricultural sector impacts, and production of co-
products from biofuel production.
    Pursuant to 40 CFR 80.1416, EPA received a petition from the 
National Sorghum Producers (NSP), submitted under a claim of 
confidential business information (CBI), requesting that EPA evaluate 
the lifecycle GHG emissions for biofuels produced using a biomass 
sorghum feedstock, and that EPA provide a determination of the 
renewable fuel categories, if any, for which such biofuels may be 
eligible. As an initial step in this process, EPA has conducted a 
preliminary evaluation of the GHG emissions associated with the growth 
and transport of biomass sorghum when it is used as a biofuel 
feedstock, and is seeking public comment on the methodology and results 
of this preliminary evaluation.
    After considering comments received, EPA expects to revise its 
assessment as appropriate and then use the information to evaluate 
petitions received pursuant to 40 CFR 80.1416 which propose to use 
biomass sorghum as a feedstock for the production of biofuel, and which 
seek an EPA determination regarding whether such biofuels qualify as 
renewable fuel under the RFS program. In evaluating such petitions, EPA 
will consider the GHG emissions associated with petitioners' biofuel 
production processes, as well as emissions associated with the 
transport and use of the finished biofuel, in addition to the GHG 
emissions associated with the use and transport of biomass sorghum 
feedstock in determining whether petitioners' proposed biofuel 
production pathway satisfies CAA renewable fuel lifecycle GHG reduction 
requirements.

II. Analysis of Greenhouse Gas Emissions Associated With Use of Biomass 
Sorghum as a Biofuel Feedstock

    To evaluate the lifecycle GHG emissions associated with the use of 
biomass sorghum feedstock to produce biofuels, we used a similar 
approach to that used for miscanthus in the March 2010 rule, in which 
GHG emissions associated with the growth and transport of miscanthus 
was determined by comparing feedstock-related GHG emissions to those of 
switchgrass. In the March 2010 rule, EPA determined that biofuel made 
from switchgrass using designated processes meets the GHG emissions 
reduction threshold for cellulosic fuels. For miscanthus, new 
agricultural modeling was deemed unnecessary; EPA ultimately determined 
that miscanthus would have similar lifecycle GHG emissions to 
switchgrass and therefore that biofuels made from designated processes 
using miscanthus as a feedstock would have similar lifecycle GHG 
emissions as similar biofuels made through the same processes with 
switchgrass. EPA also followed a similar approach in assessing GHG 
emissions associated with the use of energy cane, giant reed, and 
napier grass in rules published on March 5, 2013 (the ``March 2013 
rule'') \2\ and July 11, 2013 (the ``July 2013 rule'').\3\
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    \2\ 78 FR 14190.
    \3\ 78 FR 41703.
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    As described in detail in the following sections of this notice, 
EPA believes that new agricultural sector modeling is not needed to 
analyze biomass sorghum. Instead, we evaluated the agricultural sector 
GHG emissions impacts of using biomass sorghum by reference to 
switchgrass. Both biomass sorghum and switchgrass are grasses with high 
yields and high cellulosic contents. Our preliminary assessment 
indicates that on a per dry ton of feedstock basis indirect land use 
emissions would be lower, direct emissions associated with use of farm 
machinery, fertilizers and pesticides would be lower, and that 
emissions associated with feedstock transport would be the same as for 
switchgrass. Therefore, we propose in responding to petitions received 
pursuant to 40 CFR 80.1416 to assume that on a per dry ton of feedstock 
basis GHG emissions associated with biomass sorghum production and use 
are the same as those associated with the production and use of 
switchgrass for biofuel production. We believe that this is a 
conservative approach, and we invite comment on it.

[[Page 78857]]

A. Feedstock Description, Production, and Distribution

    Although all types of cultivated sorghum belong to the species 
Sorghum bicolor (L.) Moench, breeding for different purposes has led to 
significant variation within this species. Sorghum is native to Africa, 
but was introduced to the U.S. in the early 17th century. Historically, 
sorghum has been bred to be used as a grain, a source of sugar, and as 
animal forage. More recently, it has also been bred to increase 
biomass. Different types of sorghum have different characteristics and 
may therefore qualify as different types of renewable fuels under the 
RFS program, making it important to distinguish among the different 
types of sorghums.
    Grain Sorghum. In the U.S., grain sorghum is commonly used as 
animal feed similar to feed corn, although in other parts of the world 
it is used for human consumption. Pathways for ethanol produced from 
grain sorghum feedstock were approved in a rule published on December 
17, 2012 (the ``December 2012 RFS rule'').\4\
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    \4\ See 77 FR 74592.
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    Sweet Sorghum. Sweet sorghum has historically been bred to maximize 
sugar content, and is crushed to yield a juice that is high in sugars 
that are easily fermentable. Processing sweet sorghum is similar to 
processing sugarcane, and the resulting juice can be used to produce 
sorghum syrup for food consumption or as a biofuel feedstock.
    Forage sorghum. Varieties of forage sorghum are typically used for 
animal grazing. These varieties of sorghum have been bred for optimal 
nutrition, including high content of digestible nutrients and low 
lignin content.
    Sorghum bred for biomass content. Recently, producers have begun 
breeding sorghum as a feedstock for biofuel production, beginning with 
forage sorghum varieties. The goal of these breeding efforts has been 
to maximize the total biomass yield for use as biofuel feedstock. The 
resultant sorghum varieties generally have greatly enhanced biomass 
yields (plants can grow to be over 20 feet tall), longer growing 
seasons, and lower nitrogen demand because digestibility is not a 
concern.
    Differentiating the types of sorghum for purposes of the lifecycle 
analysis required under the RFS program is challenging because 
varieties bred for different purposes all belong to the same species 
and are often defined based on end-use, rather than based on specific 
physical characteristics.\5\ For purposes of this Notice, EPA considers 
biomass sorghum to be Sorghum bicolor that has been selected or bred to 
maximize cellulosic content rather than sugar or grain content, and 
which therefore has at least 75% cellulosic content. EPA also considers 
hybrids that are crosses of Sorghum bicolor and sudangrass \6\ to be 
biomass sorghum if they have 75% cellulosic content, but EPA does not 
consider hybrids that are crosses of Sorghum bicolor and Johnsongrass 
(Sorghum halepense) to be biomass sorghum, even if such hybrids have 
75% or higher cellulosic content. This approach is consistent with the 
NSP petition, which explicitly excluded Johnsongrass due to concerns 
regarding its potential to behave as an invasive species. See Section 
II.D. for further discussion of varieties considered biomass sorghum 
for purposes of this Notice.
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    \5\ E.g. Stefaniak, T.R., J.A. Dahlberg, B.W. Bean, N. Dighe, 
E.J. Wolfrum, and W.L. Rooney (2012). Variation in biomass 
composition components among forage, biomass, sorghum-sudangrass and 
sweet sorghum types. Crop Science, 52, 1949-1954.
    \6\ Sudangrass (Sorghum x drummondii) is a forage grass which is 
commonly crossed with Sorghum bicolor to produce hybrids. FAO 
Grassland Species Profile, http://www.fao.org/ag/agp/AGPC/doc/gbase/data/pf000494.HTM. Accessed 15 September, 2014.
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1. Crop Yields
    For the purposes of analyzing the GHG emissions from biomass 
sorghum production, EPA examined crop yields and production inputs in 
relation to switchgrass to assess the relative GHG impacts. For the 
switchgrass lifecycle analysis, EPA assumed national average yields of 
approximately 4.5 to 5 dry tons per acre.\7\ Based on field trials in 
nine states under a range of growing conditions, the 2012 average yield 
of sorghum grown for biomass content is approximately 11 dry tons per 
acre,\8\ suggesting that biomass sorghum will have significantly higher 
yields than switchgrass.
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    \7\ Kumar, A. and S. Sokhansanj (2007). ``Switchgrass (Panicum 
vigratum, L,) delivery to a biorefinery using integrated biomass 
supply analysis and logistics (IBSAL) model.'' Bioresource 
Technology, 98:1033-1044. A more recent study compiled switchgrass 
yield data from 45 studies from 1991-2010, and found an average 
yield of 4.9 dry tons per acre: Maughan, M.W. (2011) ``Evaluation of 
switchgrass, M. x giganteus, and sorghum as biomass crops: Effects 
of environment and field management practices.'' Ph.D. Dissertation, 
University of Illinois at Urbana-Champaign.
    \8\ Petition, based on data from 8 sources. A study of the yield 
of biomass sorghum in Illinois found yields from 10.1-13.4 dry tons/
acre: Maughan, M.W. (2011). ``Evaluation of switchgrass, M. x 
giganteus, and sorghum as biomass crops: Effects of environment and 
field management practices.'' Ph.D. Dissertation, University of 
Illinois at Urbana-Champaign.
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    Furthermore, EPA's analysis of switchgrass for the RFS rulemaking 
assumed a 2% annual increase in yield that would result in an average 
national yield of 6.6 dry tons per acre in 2022.\9\ EPA anticipates 
similar yield improvements for biomass sorghum as for switchgrass since 
both feedstocks are energy crops in the early stages of development, 
and improvements in farming practices or new hybrids could increase the 
yield over time.\10\ Given the potential for yield improvements, our 
analysis assumed an average biomass sorghum yield of 13 dry tons per 
acre in the southern United States by 2022, which was calculated using 
a 2% annual increase in yield.
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    \9\ A recently released switchgrass cultivar, ``Liberty'' has a 
yield of 8.1 tons/acre in Nebraska (7.3 dry tons/acre, assuming a 
dry matter content of 90%). As hybrids like this become more 
commonly used, average national yields will increase; Vogel, K.P., 
R.B. Mitchell, M.D. Casler and G. Sarath (2014). ``Registration of 
`Liberty' Switchgrass.'' Journal of Plant Registrations, 8:242-247.
    \10\ Progress is being made in developing new biomass sorghum 
hybrids with higher yields than the parents. Increased used of these 
hybrids will increase national average yields. Packer, D.J. and W.L. 
Rooney (2014). ``High-parent heteropsis for biomass yield in 
photoperiod-sensitive sorghum hybrids.'' Field Crops Research, 
167:153-158.
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    Because of its higher yield, biomass sorghum grown in areas with 
suitable growing conditions would require approximately 50% less land 
area compared to switchgrass to produce the same amount of biomass. 
Even without yield growth assumptions, the current higher crop yield 
means the land use required for biomass sorghum should be lower than 
for switchgrass. Therefore less crop area would be converted and 
displaced through use of biomass sorghum as compared to switchgrass.
2. Land Use
    Biomass sorghum is not currently grown at commercial scale in the 
United States for the purpose of biofuel production, although 
approximately 1.4 million acres of forage sorghum were planted in 2012. 
Biomass sorghum is currently grown in test plots as part of research to 
develop it as an energy crop, and currently has no other uses. Biomass 
sorghum can be planted as early as April and can continue growing until 
the fall.\11\ Production is expected to be concentrated in the South 
Central U.S. in Texas, Oklahoma and Kansas, as well as in Missouri and 
Arkansas.\12\

[[Page 78858]]

These areas are similar to the acres where our agricultural sector 
modeling projected switchgrass would be grown in the March 2010 rule. 
In addition, modeling results presented in DOE's Billion-Ton Update 
suggest that biomass sorghum and switchgrass will be grown in similar 
regions.\13\
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    \11\ Blade Energy Crops (2010). ``Managing High-Biomass Sorghum 
as a Dedicated Energy Crop.'' Available at: www.bladeenergy.com/Bladepdf/Blade_SorghumMgmtGuide2010.pdf.
    \12\ According to DOE's Billion-Ton Update, ``dedicated biomass 
sorghums grow well throughout the eastern and central United States 
as far north at 40[deg] latitude.'' Department of Energy (DOE) 
(2011). U.S. Billion-Ton Update: Biomass Supply for a Bioenergy and 
Bioproducts Industry, http://www1.eere.energy.gov/biomass/pdfs/billion_ton_update.pdf. DOE's Billion Ton study conducted a 
technical analysis of the amount of potential biomass that could be 
produced in the U.S. under a range of different conditions. This 
study showed that biomass sorghum and switchgrass have the potential 
to contribute enough biomass to exceed the volumes of cellulosic 
biofuel required by the CAA. The purpose of EPA's 2010 analysis was 
to estimate one potential scenario for meeting the biofuel volume 
requirements in the CAA, not to estimate the maximum potential 
volumes of biofuels that could be produced in the U.S.
    \13\ Department of Energy (DOE) (2011). U.S. Billion-Ton Update: 
Biomass Supply for a Bioenergy and Bioproducts Industry, http://www1.eere.energy.gov/biomass/pdfs/billion_ton_update.pdf.
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    In EPA's analysis for the March 2010 rule, switchgrass plantings 
were projected to primarily displace soybeans and wheat, and to a 
lesser extent hay, rice, grain sorghum, and cotton in the South Central 
U.S. Because biomass sorghum is likely to be grown on similar existing 
agricultural land in the same regions, as explained above, and because 
biomass sorghum yields are higher than yields of switchgrass (so should 
displace fewer total acres) EPA concludes that the indirect land use 
GHG impact for biomass sorghum per gallon should be no greater and 
likely less than estimated for switchgrass.
    In the switchgrass ethanol scenario done for the March 2010 rule, 
total cropland acres were projected to increase by 4.2 million acres, 
including an increase of 12.5 million acres of switchgrass and 
decreases of 4.3 million acres of soybeans, 1.4 million acres of wheat, 
and 1 million acres of hay, as well as smaller decreases in a variety 
of other crop acreages. This analysis took into account the economic 
conditions such as input costs and commodity prices when evaluating the 
GHG and land use change impacts of switchgrass. Given the higher yields 
of the biomass sorghum considered here compared to switchgrass, there 
should be ample land available for production without having any 
adverse impacts beyond those projected for switchgrass production.
    The indirect land use impacts for biomass sorghum are assumed to be 
similar to or less than those modeled for switchgrass. The 
justification for this assumption is that both crops are expected to be 
grown in the South Central U.S. and will likely displace the same types 
of cropland, but because of higher biomass sorghum yields, fewer total 
acres will be displaced per gallon of fuel produced.\14\ Furthermore, 
we believe biomass sorghum will have a similar impact on international 
markets as assumed for switchgrass. Like switchgrass, biomass sorghum 
is not expected to be traded internationally and its impacts on other 
crops are expected to be limited. Accordingly, indirect land use change 
GHG emissions associated with biomass sorghum would likely be smaller 
than such emissions for switchgrass. Thus, we believe that our proposal 
to assume in our lifecycle GHG emissions assessments that indirect land 
use change GHG emissions from biomass sorghum would be similar to 
switchgrass represents a conservative approach.
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    \14\ Department of Energy (DOE) (2011). U.S. Billion-Ton Update: 
Biomass Supply for a Bioenergy and Bioproducts Industry, http://www1.eere.energy.gov/biomass/pdfs/billion_ton_update.pdf.
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3. Crop Inputs and Feedstock Transport
    EPA also assessed the GHG impacts associated with planting, 
harvesting, and transporting biomass sorghum in comparison to 
switchgrass. Table 1 below shows the assumed 2022 commercial-scale 
production inputs for switchgrass modeled for the March 2010 rule and 
average biomass sorghum production inputs based on U.S. Department of 
Agriculture (USDA) projections and industry data. Available data 
gathered by EPA suggest that biomass sorghum requires on average less 
nitrogen, phosphorous, potassium, and pesticide than switchgrass per 
dry ton of biomass, but more herbicide and diesel per dry ton of 
biomass. The inputs were given to EPA from the petitioners based on 
field trials, verified by the USDA, and documented in peer-reviewed 
journals where possible. Since biomass sorghum is an annual crop and 
switchgrass is a perennial, some inputs required for growing biomass 
sorghum, such as herbicide and diesel, are slightly higher than inputs 
for switchgrass (see Table 1 below). Applying the GHG emission factors 
used for the March 2010 rule, biomass sorghum production results in 
lower GHG emissions per dry ton of biomass produced relative to 
switchgrass production, as shown in Table 1, below. More information on 
biomass sorghum inputs is available in the docket.

                         Table 1--Direct Inputs for Switchgrass and Biomass Sorghum \15\
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                                             Switchgrass \16\                      Biomass sorghum \17\
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            Category                Inputs (per dry   Emissions (per dry   Inputs  (per dry   Emissions (per dry
                                    ton of biomass)    ton of feedstock)    ton of biomass)    ton of feedstock)
----------------------------------------------------------------------------------------------------------------
Yield (Projected)...............  6.6 dry tons/acre.  ..................  13 dry ton/acre     ..................
Nitrogen Fertilizer.............  15.2 lbs/dry ton..  25 kg CO2eq.......  4.6 lbs/dry ton...  8 kg CO2eq
N2O.............................  N/A...............  136 kg CO2eq......  N/A...............  105 kg CO2eq
Phosphorus Fertilizer...........  6.1 lbs/dry ton...  3 kg CO2eq........  1.2 lbs/dry ton...  0.6 kg CO2eq
Potassium Fertilizer............  6.1 lbs/dry ton...  2 kg CO2eq........  0.5 lbs/dry ton...  0.2 kg CO2eq
Herbicide.......................  0.002 lbs/dry ton.  0.02 kg CO2eq.....  0.4 lbs/dry ton...  5 kg CO2eq
Insecticide.....................  0.02 lbs/dry ton..  0.3 kg CO2eq......  0.003 lbs/dry ton.  0.05 kg CO2eq
Lime............................  0 lbs/dry ton.....  0 kg CO2eq........  0 lbs/dry ton.....  0 kg CO2eq
Diesel..........................  0.4 gal/dry ton...  6 kg CO2eq........  0.7 gal/dry ton...  9 kg CO2eq
Electricity (irrigation)........  0 kWh/dry ton.....  0 kg CO2eq........  0.0 kWh/dry ton...  0 kg CO2eq
                                 -------------------------------------------------------------------------------
    Total GHG emissions.........  ..................  173 kg CO2eq......  ..................  128 kg CO2eq
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[[Page 78859]]

    The lifecycle GHG emissions associated with distributing biomass 
sorghum feedstock are expected to be similar to EPA's estimates for 
switchgrass feedstock. One major difference is that switchgrass has a 
longer harvest window than biomass sorghum. Biomass sorghum is 
typically harvested in the fall, whereas switchgrass can be harvested 
from July to March. This suggests that for fuel production purposes, 
harvested switchgrass would not need to be stored as long as biomass 
sorghum because it would be available directly from the field for a 
longer period of time.\18\ However, harvesting switchgrass just once 
per year, in the fall, can maximize yield and minimize nutrient 
inputs.\19\ Therefore, even though switchgrass could be harvested more 
often, in practice it may just be harvested once per year in the fall, 
like biomass sorghum. In addition, the biomass sorghum harvest window 
can be extended by staggering planting times, using a range of hybrids 
with different harvesting times, or using multiple cuttings, which 
would reduce storage needs.\20\ When switchgrass and biomass sorghum 
need to be stored, both can be stored in bales.\21\
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    \15\ The IPCC equations for N2O emissions were 
updated since our earlier analysis of switchgrass. We use the 
updated equations here.
    \16\ Beach, R.H. and B.A. McCarl (2010). U.S. Agricultural and 
Forestry Impacts of the Energy Independence and Security Act: FASOM 
Results and Model Description. Docket EPA-HQ-OAR-2005-0161-3178.
    \17\ Input data are from petitioners, peer-reviewed literature, 
and USDA. Details on the sources of input data can be found in the 
docket. Emissions are calculated based on the input data and 
emission factors.
    \18\ Haque, M. and F. M. Epplin (2012). ``Cost to produce 
switchgrass and cost to produce ethanol from switchgrass for several 
levels of biorefinery investment cost and biomass to ethanol 
conversion rates.'' Biomass and Bioenergy, 46:517-530.
    \19\ Mitchell, R. B., and M. R. Schmer (2012). ``Switchgrass 
harvest and storage.'' Switchgrass. A. Monti (ed.), London: 
Springer-Verlag, 113-127; Garland, C. D., et al. (2008). ``Growing 
and harvesting switchgrass for ethanol production in Tennessee.'' 
University of Tennessee Agricultural Extension Service.
    \20\ Turhollow, A. F. E. G. Webb, and M. E. Downing (2010). 
``Review of sorghum production practices: Applications for 
Bioenergy.'' Oak Ridge National Laboratory, Oakridge, TN. Available 
at: http://info.ornl.gov/sites/publications/files/Pub22854.pdf; 
Blade Energy Crops (2010). ``Managing high-biomass sorghum as a 
dedicated energy crop.'' Available at: http://www.bladeenergy.com/Bladepdf/Blade_SorghumMgmtGuide2010.pdf.
    \21\ Blade Energy Crops (2010). ``Managing high-biomass sorghum 
as a dedicated energy crop.'' Available at: http://www.bladeenergy.com/Bladepdf/Blade_SorghumMgmtGuide2010.pdf; 
Sanderson, M. A., R. P. Egg, and A. E. Wiselogel (1997). ``Biomass 
losses during harvest and storage of switchgrass.'' Biomass and 
Bioenergy, 12(2):107-114.
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    Biomass sorghum is expected to achieve higher yields and thus the 
feedstock distribution radius around a similar sized biofuel production 
plant, or biomass collection hub, could be lower for biomass sorghum 
than for switchgrass. Therefore, even though there can be differences 
in the harvest period of switchgrass and biomass sorghum, our analysis 
makes the simplifying assumption that both crops require similar 
transport, loading, unloading, and storage regimes, and have the same 
GHG emissions for feedstock distribution, on a per dry ton of feedstock 
basis. Harvesting, storage, and distribution were a small fraction of 
the total GHG emissions for switchgrass, so we do not believe this 
simplification substantially affects our lifecycle analysis.

B. Summary of Agricultural Sector Greenhouse Gas Emissions

    Based on our comparison of biomass sorghum to switchgrass, EPA 
proposes to use, in its future evaluations of petitions proposing to 
use biomass sorghum as feedstock for biofuel production, an estimate of 
the GHG emissions associated with the cultivation and transport of 
biomass sorghum that is the same as that which we have used for 
switchgrass, on a per dry ton of feedstock basis. EPA solicits comment 
on this proposed approach.

C. Fuel Production and Distribution

    Biomass sorghum is suitable for the same conversion processes as 
approved cellulosic feedstocks such as switchgrass and corn stover. 
After reviewing comments received in response to this Notice, we will 
combine our evaluation of agricultural sector GHG emissions associated 
with the use of biomass sorghum feedstock with our evaluation of the 
GHG emissions associated with individual producers' production 
processes and finished fuels to determine whether the proposed pathways 
satisfy CAA lifecycle GHG emissions reduction requirements for RFS-
qualifying renewable fuels. Based on our evaluation of the lifecycle 
GHG emissions attributable to the growth and transport of biomass 
sorghum feedstock, EPA anticipates that fuel produced from biomass 
sorghum feedstock through the same biochemical or thermochemical 
process technologies that EPA evaluated for the March 2010 RFS rule for 
biofuel derived from switchgrass feedstock would qualify for cellulosic 
biofuel (D-code 3) renewable identification numbers (RINs) or 
cellulosic diesel (D-code 7) RINs depending on the type of fuel 
produced.\22\ However, EPA will evaluate petitions for fuel produced 
from biomass sorghum feedstock on a case-by-case basis.\23\
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    \22\ The biochemical and thermochemical processes that EPA 
evaluated for the March 2010 RFS rule for biofuel derived from 
switchgrass feedstock are described in section 2.4.7.4 (Cellulosic 
Biofuel) of the Regulatory Impact Analysis for the March 2010 RFS 
rule (EPA-420-R-10-006).
    \23\ Similarly, EPA anticipates that naphtha produced from 
biomass sorghum feedstock through any of the gasification and 
upgrading processes that EPA evaluated in the March 2010 RFS rule 
(78 FR 14190) for biofuel derived from switchgrass feedstock would 
likely qualify for cellulosic biofuel (D-code 3) RINs, but EPA 
intends to evaluate petitions for naphtha produced from biomass 
sorghum feedstock on a case-by-case basis.
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D. Cellulosic Content of Biomass Sorghum

    For biomass sorghum-derived biofuels to qualify as cellulosic 
biofuel under the RFS program, the fuel must achieve a 60% lifecycle 
GHG reduction as compared to the 2005 baseline fuels, and must also be 
derived from cellulose, hemicellulose and lignin. This section of the 
Notice discusses our preliminary analysis of the extent to which fuel 
made from biomass sorghum may qualify as derived from cellulose, 
hemicellulose and lignin. For simplicity, these three chemicals are 
hereafter referred to as ``cellulose,'' and their presence in feedstock 
as the feedstock's ``cellulosic content.''
    In the rule published on July 18, 2014 (the ``July 2014 
rule''),\24\ EPA determined that fuel generated from feedstocks with an 
average adjusted cellulosic content \25\ of 75% or more is eligible to 
generate cellulosic biofuel RINs for the entire fuel volume. EPA 
examined the biochemical composition of different feedstocks commonly 
understood to be ``cellulosic,'' including corn stover and other crop 
residues, switchgrass, miscanthus, energy cane, giant reed, napier 
grass, and various woods and tree branches. Based on this work, EPA 
found that roughly 75-90% of the organic biomass of these feedstocks 
was cellulosic, and the balance was comprised of other constituents, 
such as starches and sugars.\26\ EPA considered in the July 2014 rule 
the extent to which fuel made from these and other feedstocks with some 
amount of cellulosic content

[[Page 78860]]

should be considered ``cellulosic biofuel,'' and determined in the rule 
that the entire volume of fuel derived from feedstocks with at least 
75% adjusted cellulosic content should be considered cellulosic 
biofuel. Fuel made from feedstocks having less cellulosic content could 
qualify for the generation of cellulosic biofuel RINs for a portion of 
the finished fuel.
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    \24\ ``Regulation of Fuels and Fuel Additives: RFS Pathways II, 
and Technical Amendments to the RFS Standards and E15 Misfueling 
Mitigation Requirements.'' 79 FR 42128.
    \25\ Adjusted cellulosic content is the percent of organic 
material that is cellulose, hemicellulose, and lignin.
    \26\ See ``Cellulosic Content of Various Feedstocks--2014 
Update.'' Docket EPA-HQ-OAR-2012-0401.
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    In the July 2014 rule, EPA described in more detail why we believed 
that setting the threshold at 75% percent appropriately implements the 
statutory requirements while not imposing excessive administrative 
burden on industry. In that rulemaking, EPA also explained that we 
would apply the 75% threshold to feedstocks that we evaluated in the 
future, and finalized a definition of energy cane, which can have a 
wide range of cellulosic contents. Consistent with that rulemaking, we 
have evaluated the cellulosic content of biomass sorghum. The results 
of chemical analyses of biomass sorghum and other types of sorghum are 
shown in Table 2 below and derive from two scientific studies and 
industry data. One study found that sorghum selected or bred for 
enhanced biomass content was composed of 61-72% cellulosic materials, 
with an average of 67% cellulosic material, whereas the other found an 
average composition of 59% cellulosic material. When these values are 
adjusted to remove the ash content (which will not yield biofuel),\27\ 
the adjusted cellulosic contents are 75% and 63%, respectively, from 
the two studies (Table 2). Compared to traditional forage sorghums, one 
study found sorghums selected or bred for biomass content had greater 
cellulosic content, whereas the other found they had lower cellulosic 
content. These differences likely reflect both the natural 
heterogeneity within crops and the fact that breeders are still 
experimenting with sorghum to find which varieties are best for biofuel 
usage, and thus have not yet settled on any particular sets of 
``ideal'' properties or compositions for this crop. Breeding of sorghum 
to enhance biomass content is in the early stages, and it is likely 
that in the future, these feedstocks may be bred to contain greater 
proportions of cellulose, hemicellulose and lignin. Data submitted by 
NexSteppe and available in the docket indicate that newer hybrids of 
sorghum do have higher percentages of cellulose, hemicellulose, and 
lignin, in the range of 75-81%, with a range of 77-89% for the adjusted 
cellulosic content. Some of the sorghum samples also contained 
significant proportions of sugar (0.3-19%) and starch (0-12%), as shown 
in Table 2.
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    \27\ Adjustments are also made to account for percent recoveries 
less than 100%. If all chemical components of a feedstock are 
analyzed, the total recovery should equal 100%. However, recoveries 
may be lower than 100% because of losses during sample processing. 
For recoveries less than 100%, the percent concentration of each 
component was adjusted so that the total percent recovery equaled 
100%. For more information, see ``Cellulosic Content of Various 
Feedstocks--2014 Update.'' Docket EPA-HQ-OAR-2012-0401.
    \28\ Dahlberg, J., E. Wolfrum, B. Bean, and W.L. Rooney (2011). 
Compositional and agronomic evaluation of sorghum biomass as a 
potential feedstock for renewable fuels. Journal of Biobased 
Materials and Bioenergy. 5, 1-7. Values include additional data 
provided by J. Dahlberg on October 22, 2013.
    \29\ Stefaniak, T.R., J.A. Dahlberg, B.W. Bean, N. Dighe, E.J. 
Wolfrum, and W.L. Rooney (2012). Variation in biomass composition 
components among forage, biomass, sorghum-sudangrass and sweet 
sorghum types. Crop Science, 52, 1949-1954.
    \30\ For more information, see ``14-10-09 NexSteppe EPA 
submission.pdf.'' Docket EPA-HQ-OAR-2014-0537.

            Table 2--Chemical Composition of Different Types of Sorghum Samples, as Determined by Two Research Studies and From Industry Data
[The adjusted cellulosic composition was calculated by adjusting the reported content of cellulose, hemicellulose and lignin for the ash content and for
                                                                    the total yields]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                     Source                                                        Chemical composition (%)                                   NexSteppe
--------------------------------------------------------------------------------------------------------------------------------------------     \30\
                                                      Dahlberg et al. (2011) * \28\             Stefaniak et al. (2012) [dagger] \29\       ------------
                                                 -------------------------------------------------------------------------------------------
                 Sorghum variety                                  Sudan/                   Biomass       Sudan/                                Biomass
                                                   High-yield    sorghum       Forage      [caret]      sorghum       Forage       Sweet       [caret]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Number of samples...............................            5            4           15           51            6           41           54            7
Sucrose (sugar):
    Average.....................................          2.9          2.7          1.0          9.0          2.4          1.1          9.8          4.5
    Range.......................................      1.6-4.6      0.4-3.5      0.2-1.7       0.3-19      0.4-4.6      0.2-3.0     0.2-23.9      1.2-8.5
Starch:
    Average.....................................          0.8          5.6         18.1          5.6          1.1          1.8          7.3          3.4
    Range.......................................          0-4         0-15       0-25.2       0-12.0        0-4.0        0-8.9       0-16.6      0.3-8.1
Cellulosic Components:
    Average.....................................         66.7         62.0         54.9         59.2         63.9         66.4         58.3         77.5
    Range.......................................    61.3-72.3    53.8-67.5    46.8-73.6  ...........  ...........  ...........  ...........    75.3-80.5
Adjusted Cellulosic Composition:
    Average.....................................         75.4         70.0         60.5         63.2         72.5         70.1         61.8         83.7
    Range.......................................    68.9-82.8    61.2-75.8    50.5-84.4  ...........  ...........  ...........  ...........    77.4-88.6
--------------------------------------------------------------------------------------------------------------------------------------------------------
* This paper analyzed 22 samples of forage sorghum, including some high-yield varieties that could be used for biomass purposes. The four sudan/sorghum
  varieties include two samples that were also counted in the high-yield category. The remaining varieties fall into the forage sorghum category.
[dagger] This study separated 152 samples of sorghum into groups based on end use, with samples being harvested at different growth stages and
  containing various tissue types depending on how the material would ultimately be used. See the original source for more information about the
  different classes of sorghum.
[caret] These sources refer to certain hybrids as ``biomass'' sorghum. However, this does not necessarily mean that these varieties meet EPA's 75%
  adjusted cellulosic content threshold.

    In the July 2014 rule, EPA considered the cellulosic content of 
energy cane. Like biomass sorghum, cane can be bred for a wide range of 
cellulosic and sugar contents. In that rule, EPA defined ``energy 
cane'' as cultivars containing at least 75% adjusted cellulosic 
content. EPA also indicated that in the future, feedstocks that could 
be bred for a wide range of uses and fiber content would have 
registration requirements similar to energy cane, in order to 
demonstrate that the adjusted cellulosic content of varieties used is 
at least 75%. Therefore, for the purposes of the cellulosic content 
issue, EPA intends to treat biomass sorghum similar to energy cane. For 
purposes of this Notice, we consider biomass sorghum to include 
varieties containing at least 75% adjusted cellulosic content. If, as a 
result of a complete lifecycle assessment in response to individual 
producer petitions EPA determines that a given fuel product made from 
biomass sorghum satisfies the 60% lifecycle GHG reduction requirement 
for cellulosic biofuel, 100% of the fuel in question would qualify for 
cellulosic biofuel RINs, provided the producer can

[[Page 78861]]

demonstrate that the varieties they use as a feedstock contain at least 
75% adjusted cellulosic content and satisfy all other applicable 
definitional, registration, recordkeeping, and reporting requirements. 
We would consider any cultivars with an adjusted cellulosic content 
less than 75% to be forage sorghum, which we are not addressing in this 
Notice. See the discussion regarding energy cane in the July 2014 rule 
and accompanying memo to the docket \31\ for a description of the 
methodologies and data EPA considers suitable for demonstrating that 
the average adjusted cellulosic content is at least 75%. We expect that 
any approved petition for cellulosic biofuel made from biomass sorghum 
would contain registration requirements comparable to those set forth 
at 40 CFR 80.1450(b)(1)(xiv).
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    \31\ 79 FR 42128; ``Cellulosic Content of Various Feedstocks--
2014 Update.'' Docket EPA-HQ-OAR-2012-0401.
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III. Summary

    EPA invites public comment on its preliminary analysis of GHG 
emissions associated with the cultivation and transport of biomass 
sorghum as a feedstock for biofuel production. EPA expects to revise 
its analysis as appropriate in light of public comments received, and 
to thereafter use the analysis as part of its evaluation of the 
lifecycle GHG emissions of biofuel production pathways described in 
petitions received pursuant to 40 CFR 80.1416 which use biomass sorghum 
as a feedstock.

    Dated: December 17, 2014.
Christopher Grundler,
Director, Office of Transportation and Air Quality.
[FR Doc. 2014-30712 Filed 12-30-14; 8:45 am]
BILLING CODE 6560-50-P