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MEMORANDUM TO: Air and Radiation Docket EPA - HQ - OAR - 2014 - 0537 FROM: EPA Office of Transportation and Air Quality DATE: December 1 7 , 2014 SUBJECT: Agricultural Inputs and Cellulosic Content of Biomass Sorghum This memo randum provides information on sources of data used for EPA’s anal ys is of the greenhouse gas emissions associated with the cultivation of biomass sorghum . Italso provides information on the data used to calculate the adjusted cellulosic content of biomass sorghum. **A. AGRICULTURAL INPUTS**  **AND EMISSIONS** To determine the greenhouse gas emissions associated with growing biomass sorghum, EPA used data from the petition, literature, and USDA. The data and sources are summarized here, and details of how the data were used to calculate greenhouse gas emissions are provided in a spreadsheet available on the docket. a 1. Yield To estimate an average yield i n 2022, w e started with an assumed biomass sorghum yi eld of 11 dry tons / acre in 2012 . This value is based on an average of data from several sources , which showed results of field trials in Indiana, Texas, Kentucky , Mississippi, North Carolina, Kansas, Io wa, Michigan, and Illinois . 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 Trials took place between 1979 and 2010, and used a range of growing conditions. The average yi eld based on all of these studies was 10.77 dry tons/acre, with a range of 5.84 to 26.32 dry tons/acre. Values in the higher end of this range came from a single study. 5 If this study is excluded, the range in yi eld is 5.84 - 15.66 dry tons/acre.

a See “Biomass sorghum data

– for docket.xlsx” placed in docket EPA - HQ - OAR - 2014 - 0537.2

We assume d that the yield for biomass sorghum would increase by 2% per year , based on similar yi eld improvements that were projected for switchgrass. Based on this yield improvement, we calculated a biomass sorghum yield of 13 dry tons / acre in 2022 . This value was used for subsequent emissions calculations. 2. Fertilizers We used fertilizer input values of 60 lbs nitrogen/acre , 15 lbs phosphorus /acre, and 7 lbs potassium/acre. These values are based on data provided by the petitioner, which cited Forest and Agricultural Sector Optimization Model ( FASOM) documentation as a source. b Using a yi eld of 13 dry

tons / acre, the fertilizer inputs per dry ton are: 4.6 lbs nitrogen/dry ton, 1. 2 lbs phosphorus /dry

ton, and 0. 5 lbs potassium/dry ton. 3. Other i nputs The petition provided two diesel input value s: 9.2 gal/acre , based on FASOM documentation , and 7. 35 gal/acre based on GREET 2011 and two reports . 9 , 10 We used the more conservative value of 9.2 gal/acre , which is 0.7 gal/dry ton feedstock. For herbicide inputs, we use d USDA’s estimate for energy

cane, which is 5.5 lbs/acre , or 0.4 lbs/dry ton feedstock . c For pesticide s , the petition provided the greenhouse gas emissions based on FASOM data, rather than the quantity of pesticide used. We used this value (0.0006 tons CO 2 e/acre) to calculate the quantity of pesticide used , based on our emission factor for pesticides. This calculation resulted in a pesticide input of 0.044 lbs/acre, or 0.003 lbs/dry ton feedstock . 4. N 2 O emissions

b For more information about FASOM, see Beach, R.H. and B.A. McCarl (2010). “U.S. Agricultural and Forestry Im pacts of the Energy Independence and Security Act: FASOM Results and Model Description.” RTI International, and Beach, R.H. et al. (2010). “Model d ocumentation for the Forest and Agricultural Sector Optimization Model with Greenhouse Gases (FASOMGHG).” RTI International. c The petitioner did not estimate herbicide use in their petition. As a conservative estimate, we use d the value of herbicide use for energy cane, as provided by the USDA. Information on the energy cane analysis is available on docket EPA - HQ - OAR - 2011 - 0542.3

N 2 O is emitted from sy

nthetic nitrogen fertilizer, as well as from the decay of crop residues. The Intergovernmental P anel on C limate C hange (IPCC) provides equations for direct emissions from these sources, and indirect emissions from the v olatilization of sy nthetic fertilizer , and leaching/runoff of all nitrogen sources. 11 The IPCC also provides emission factors for these N 2 O sources. To calculate the amount of crop residues, we used equations and factors in the IPCC. With these equations , the crop yi eld is used to calculate the amount of above - ground residue, and the ratio of below - ground residue to a bove - ground biomass (including harvested material) is used to calculate the amount of below - ground residue . The IPCC provides a table of fa ctors to calculate crops residues and the nitrogen content of crop residues for a variety of crops. d Because factors for biomass sorghum are not included in this table, we used the factors provided for “Perennial grasses . ” We chose this value because the harvesting of biomass sorghum is likely to be similar to the harvesting of perennial grasses

– most of the plant will be harvested, with little residue remaining, in contrast to crops like corn or grain sorghum where onl y the grain is harvested . However, because perennial grasses have a more developed root s ys tem than annual crops, it is likely that our calculations overestimat ed the below - ground biomass, and therefore overestimat ed the N 2 O emissions from below - ground biomass. We calculated an above - ground residue of 3.9 tons/acre and a below - ground residue of 13.5 tons/acre for a yield of 13 dry tons/acre. Total direct and indirect N 2 O emissions from nitrogen fertilizer and crop residues are 105 kg CO 2 e/dry

ton. Further details of these calculations can be found in the associated spreadsheet on the docket. e 5. Total e missions from chemical and energy inputs and crop residues We used the emission factors documented in the March 2010 rule to calculate the emissions from fertilizers, her

bicides, pesticides, and diesel . f These results are shown in the spreadsheet posted

d Ta ble 11.2 in 2006 IPCC Guidelines for National Greenhouse Gas Inventories. e See “Biomass sorghum data

– for docket.xlsx” pl aced in docket EPA - HQ - OAR - 2014 - 0537. f 75 FR 14670 and associated material in Docket EPA - HQ - OAR - 2005 - 0161.4

on the docket. g Total emissions from agricultural inputs and crop resi dues (including N 2 O emissions) are 128 k gCO 2e/dry ton feedstock. **B. CELLULOSIC CONTENT**  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 derive d from cellulose, hemicellulose and lignin . h In the rule published on July 18, 2014 (the “July

2014 rule”) , i EPA determined that fuel generated from feedstocks with an average adjusted cellulosic content j of 75% or more is eligible to generate cellulosic biofuel RI Ns for the entire fuel volume. In that rulemaking, EPA also explained that we would appl y 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, based on two scientific studies and industry data. Data and calculations can be found in the spreadsheet posted to the docket. k One study presented compositional data for 22 varieties of forage sorghum. 12 The c omposition was measured using N ational R enewable E nergy L aboratory (NREL) Laboratory

Anal yt ical Procedures. 13 The samples included photoperiod sens itive (PS) varieties l as well as non - PS varieties. Data in the paper show ed that the PS varieties had higher yields than the other varieties, and that these higher yi elds were similar to the yields of other bioenergy crops. For our calculations, we separated the varieties into “high - yi eld” (the PS varieties), “sorghum/sudangrass” (which includes two of the PS varieties), and “forage.” Although the paper did not specificall y categorize an y of the samples as biomass sorghum, w e assume d that g See “Biomass sorghum data

– for docket.xlsx” placed in docket EPA - HQ - OAR - 2014 - 0537. h For simplicity, these three chemicals are hereafter referred to as “cellulose,” and their presence in feedstock as the feedstock’s “cellulosic content.” i “Regulation of Fuels and Fuel Additives: RFS Pathways II, and Technical Amendments to the RFS Standards and E15 Misfueling Mitigation Requirements .” 79 FR 42128 j Adjusted cellulosic content is the percent of organic material that is cellulose, hemicellulose, and lignin. k See “Biomass sorghum data

– for docket.xlsx” placed in docket EPA - HQ - OAR - 2014 - 0537. l Photoperiod sensitive sorghums flower when the length of the day is below a certain threshold (12 hours and 20 minutes). This is in contrast to non - photoperiod sensitive varieties that flower when a certain amount of time has passed. Photoperiod sensitive sorghums can have a longer growing season, which means mo re biomass will be produced. See, e.g. Pennington, D. 2011. Photoperiod sensitive sorghum for bioenergy. Michigan State University Extension. Available at: http://m sue.anr.msu.edu/news/photoperiod_sensitive_sorghum_for_bioenergy . Accessed December 12, 2014.5

the high - yi eld , photoperiod sensitive varieties are most similar to biomass sorghum , based on information from the petitioners . This paper showed data for ash, protein, soluble sucrose, soluble starch, total solubles, lignin, glucan, x yl an, galactan, arabinan, and total structurals. In addition, we received supplementary data from the authors for water extractives, ethanol extractives, and acetyl . m These data (published and supplementary) are included in the spreadsheet on the docket. n Us ing methods detailed in a separate memorandum, o we calculated the adjusted cellulosic content of the samples (Table 1) . We found that “high - yi eld” varieties had an average adjusted cellulosic content of 75.4% (with a range of 68.9 - 82.8%) , sorghum/sudangra ss had an average adjusted cellulosic content of 70.0% (with a range of 61.2 - 75.8%) , and forage sorghum had an average adjusted cellulosic content of 60.5% (with a range of 50.5 - 84.4%) . Another study presented data from 152 sorghum samples. 14 51 of these samples were categorized as “biomass sorghum.” These samples were “photoperiod sensitive and produce [d] little to no grain.” This study also presented data from 41 forage sorghum samples, 54 sweet sorghum samples, and 6 sorghum/sudangrass s amples. The composition of the samples was anal yz ed using NREL Laboratory Anal yt ical Procedures. T his paper presented data on ash, protein, sucrose, lignin, xylans, glucans, and starch. Using these data, we found that the biomass sorghum samples had an average adjusted cellulosic content of 63.2%, the forage sorghum samples had an adjusted cellulosic content of 70.1%, the sweet sorghum samples had an adjusted cellulosic content of 61.8%, and the sorghum/sudangrass samples had an adjusted cellulosic conte nt of 72.5% (Table 1) . We also received data from NexSteppe , a developer of sorghum hy brids that have been recentl y released or are under development, and for which there is not yet published data available . NexSteppe provided data from seven samples gro wn in four locations. 15 NRELL aboratory Analy tical P rocedures were used to measure the composition of the samples . NexSteppe provided data on the free sugar content, starch content, total cellulosic content, and adjusted

m See “ Sorghum cellulosic content data from J. Dahlberg ” placed in docket EPA - HQ - OAR - 2014 - 0537. n See “Biomass sorghum data

– for docket.xlsx” placed in docket EPA - HQ - OAR - 2014 - 0537. o “Cellulosic Content of Various Feedstocks

– 2014 Update” available in docket EPA - HQ - OAR - 2012 - 0401.6

cellulosic content for each sample . The average adjusted cellulosic content was 83.7% , with a range of 77.4 - 88.6% (Table 1) . **Table 1**  **— Chemical composition of different types of sorghum samples, as determined by**  **two research studies and from industry data**  **. The adjusted cellulosic compo sition was**  **calculated by adjusting the reported content of cellulose, hemicellulose and lignin for the ash content and for the total yields.** 

Chemical Composition (%) Source Dahlberg et al. (2011) Stefaniak et al. (2012) NexSteppe Sorghum variety High - Yield Sudan/ Sorghum Forage Biomass Sudan/ Sorghum Forage Sweet Biomass 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

Ran ge 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 Average 0.8 5.6 18.1 5.6 1.1 1.8 7.3 3.4 S tarch 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 In the July

2014 rule , EPA considered the cellulosic content of energy cane. Li ke 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 cellulos ic 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 th e Notice, we consider biomass sorghum to include varieties containing at least 75% adjus ted cellulosic content . REFERENCES 1 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.7

2 Prophe ter, J.L ., S.A. Staggenborg, X. Wu, and D. Wang (2010). “Performance of annual and perennial biofuel crops: Yield during the first two years.” Agronom y J ournal , 102 (2):806 - 814 . 3 Pennington, D. (2011) . “ Photoperiod sensitive sorghum for bioenergy . ” Michigan State University

Extension. Accessed December 9, 2014, http://msue.anr.msu.edu/news/photoperiod_sensitive_sorghum_for_bioenergy 4 Rooney , W. L. (2009). “Sorghum Feedstock Performance Tests.” AgriLife Research. P owerPoint, Texas A&M University . 5 Olson, S.N. et al. (2012) . “ High biomass yi eld energy sorghum: developing a genetic model for C4 grass bioenergy

crops. ” Biofuels, Bioprod. Bioref. , 6:640 - 655. 6 Cherney , J.H. et al. (1990) . “ Evaluation of potential herbaceous bio mass crops on marginal crop lands: 1) Agronomic potential. ” ORNL/Sub/85 - 2741/5&P1. Oak Ridge National Laboratory , Oak Ridge, TN . 7 Johnson, K.D., J.H. Cherney , D.K. Greene, and J.J. Volenec (1992) . “ Evaluation of switchgrass and biomass sorghum potential. ” Oak Ridge National Laboratory , Oak Ridge, TN. 8 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 9 Blade Energy

Crops (2010). “Managing high - biomass sorghum as a dedicated energy crop.” Available at: http://www.bladeenergy .com/Bladepdf/Blade_SorghumMgmtGuide2010.pdf . 10 Grisso, R. et al. ( 2010 ) . “ Predicting Tractor Diesel Fuel Consumption. ” Virginia Cooperative Extension, Publication 442 - 073. 11 Intergovernmental Panel on Climate Change ( 2006 ) . “N 2 O emissions from managed soils, and CO 2 emissions from lime and urea application. ” 2006 IPCC Guildelines for National Greenhouse Gas Inventories, Volume 4: Agriculture, Forestry , and Other Land Use. Egg leston, H.S., Buendia, L., Miwa, K., Ngara, T., and Tanube, K (eds). Published: IGES, Japan. 12 Dahlberg, J., E. Wolfrum , B. Bean, and W.L. Rooney (2011) . “ Compositional and agronomic evaluation of sorghum biomass as a potential feedstock for renewable fue ls. ” Journal of Biobased Materials and Bioenergy , 5: 1 - 7. Additional data provided b y J . Dahlberg on October 22, 2013. 13 N ational Renewable Energy L aboratory (2011) . “ Standard Biomass Analy tical Procedure . ” Accessed December 9 , 2014 , http://www.nrel.gov/biomass/analy tical_procedures.html8

14 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. 15 NexSteppe ( 2014 ) . “ 14 - 10 - 09 NexSteppe EPA submission. ” Docket EPA - HQ - OAR - 2014 - 0537.