[Federal Register Volume 79, Number 250 (Wednesday, December 31, 2014)]
[Notices]
[Pages 78855-78861]
From the Federal Register Online via the Government Publishing 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: [email protected], 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:
[email protected].
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)
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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
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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]
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Source Chemical composition (%) NexSteppe
-------------------------------------------------------------------------------------------------------------------------------------------- \30\
Dahlberg et al. (2011) * \28\ Stefaniak et al. (2012) [dagger] \29\ ------------
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Sorghum variety Sudan/ Biomass Sudan/ Biomass
High-yield sorghum Forage [caret] sorghum Forage Sweet [caret]
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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
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* 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