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Regulation of Fuels and Fuel Additives: Changes to Renewable Fuel Standard Program
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PDF Version (41 pp, 712K, About PDF) [Federal Register: May 26, 2009 (Volume 74, Number 99)] [Proposed Rules] [Page 25103-25143] From the Federal Register Online via GPO Access [wais.access.gpo.gov] [DOCID:fr26my09-25] Regulation of Fuels and Fuel Additives: Changes to Renewable Fuel Standard Program [[Continued from page 25102]] [[Page 25103]] concerns such as Gulf of Mexico hypoxia, large corn production, and numerous ethanol production plants. For more details on the analysis, see Chapter 6 in the DRIA. On average the UMRB contributes about 39% of the total nitrogen loads and 26% of the total phosphorus loads to the Gulf of Mexico.\527\ The high percentage of nitrogen from the UMRB is primarily due to the large inputs of fertilizer for agriculture and the 60% of cropland that is tile drained. Although nitrogen inputs to the UMRB in recent years is fairly level, there is a 21% decline in net inputs from humans. The Science Advisory Board report attributes this decline to higher amount of nitrogen removed during harvest, due to higher crop yields. For the same time period, phosphorus inputs increased 12%. --------------------------------------------------------------------------- \527\ Mississippi River/Gulf of Mexico Watershed Nutrient Task Force, supra note 6. --------------------------------------------------------------------------- 1. SWAT Model EPA selected the SWAT (Soil and Water Assessment Tool) model to assess nutrient loads from changes in agricultural production in the UMRB. Models are the primary tool that can be used to predict future impacts based on alternative scenarios. SWAT is a physical process model developed to quantify the impact of land management practices in large, complex watersheds.\528\ --------------------------------------------------------------------------- \528\ Gassman, P.W., Reyes, M.R., Green, C.H., Arnold, J.G., 2007, The soil and water assessment tool: Historical development, applications, and future research directions. Transactions of the American Society of Agricultural and Biological Engineers, v. 50, no. 4, p. 1211-1240. http://www.card.iastate.edu/environment/items/ asabe_swat.pdf.--------------------------------------------------------------------------- 2. Baseline Model Scenario In order to assess alternative potential future conditions within the UMRB, EPA developed a SWAT model of a Baseline Scenario against which to analyze the impact of increased corn production for biofuel. For simplicity's sake, we refer to the baseline as 2005, but like most water quality modeling, we had to use a range of data sets for the inputs. As noted above corn acres did not increase significantly until the 2007 crop year. While this baseline does not directly quantify the impacts of this proposal on water quality, it is useful in understanding the magnitude of the impacts of corn production for biofuels. EPA plans to conduct additional analyses for the final rule that will compare the reference case biofuel volumes to the RFS2 volumes. The SWAT model was applied (i.e., calibrated) to the UMRB using 1960 to 2001 weather data and flow and water quality data from 13 USGS gages on the mainstem of the Mississippi River. The 42-year SWAT model runs were performed and the results analyzed to establish runoff, sediment, nitrogen, and phosphorous loadings from each of the 131 8- digit HUC subwatersheds and the larger 4-digit subbasins, along with the total outflow from the UMRB and at the various USGS gage sites along the Mississippi River. These results provided the Baseline Scenario model values to which the future alternatives are compared. 3. Alternative Scenarios SWAT scenario analyses were performed for the years 2010, 2015, 2020, and 2022 with corn ethanol volumes of 12 billion gallons a year (BGY) for 2010, and 15 BGY for 2015 to 2022. These volumes were adjusted for the UMRB based on a 42.3% ratio of ethanol production capacity within the UMRB compared to national capacity. The resulting UMRB ethanol production goals were converted into the corresponding required corn production acreage, i.e. the extent of corn acreage needed to meet those ethanol production goals. Annual increases in corn yield of 1.23% were built into the future scenarios. Fewer corn acres were needed to meet ethanol production goals after the 2015 scenario due to those yield increases. Table X.B.3-1 and Table X.B.3-2 summarize the model outputs both within the UMRB and at the outlet of the UMRB in the Mississippi River at Grafton, Illinois for each of the four scenario years: 2010, 2015, 2020, and 2022. It is important to note that these results only estimate loadings from the Upper Mississippi River basin, not the entire Mississippi River watershed. As noted earlier, the UMRB contributes about 39% of the total nitrogen loads and 26% of total phosphorus loads to the Gulf of Mexico. Due to the timing of this proposal, we were not able to assess the local impact in smaller watersheds within the UMRB. Those impacts may be significantly different. The decreasing nitrogen load over time is likely attributed to the increased corn yield production, resulting in greater plant uptake of nitrogen. Table X.B.3-1--Changes in Nutrient Loadings Within the Upper Mississippi River Basin From the 2005 Baseline Scenario ---------------------------------------------------------------------------------------------------------------- 2005 Baseline 2010 2015 2020 2022 ---------------------------------------------------------------------------------------------------------------- Nitrogen................................ 1897.0 million lbs........ +5.1% +4.2% +2.2% +1.6% Phosphorus.............................. 176.6 million lbs......... +2.3% +1.1% +0.6% +0.4% ---------------------------------------------------------------------------------------------------------------- About 24% of nitrogen and 25% of phosphorus leaving agricultural fields was assimilated (taken by aquatic plants or volatilized) before reaching the outlet of the UMRB. The assimilated nitrogen is not necessarily eliminated as an environmental concern. Five percent or more of the nitrogen can be converted to nitrous gas, a powerful greenhouse gas that has 300 times the climate-warming potential of carbon dioxide, the major greenhouse. Thus, a water pollutant becomes an air pollutant until it is either captured through biological sequestration or converted fully to elemental nitrogen. Total sediment outflow showed very little change over all scenarios. This is likely due to the corn being modeled as well-managed crop in terms of sediment loss, primarily due to the corn stover remaining on the fields following harvest. Table X.B.3-2--Changes From the 2005 Baseline to the Mississippi River at Grafton, Illinois From the Upper Mississippi River Basin ---------------------------------------------------------------------------------------------------------------- 2005 Baseline 2010 2015 2020 2022 ---------------------------------------------------------------------------------------------------------------- Average corn yield (bushels/acre)....... 141....................... 150 158 168 171 [[Page 25104]] Nitrogen................................ 1,433.5 million lbs....... +5.5% +4.7% +2.5% +1.8% Phosphorus.............................. 132.4 million lbs......... +2.8% +1.7% +0.98% +0.8% Sediment................................ 6.4 million tons.......... +0.5% +0.3% +0.2% +0.1% ---------------------------------------------------------------------------------------------------------------- After evaluating comments on this proposal, if time and resources permit, EPA may conduct additional water quality analyses using the SWAT model in the UMRB. Potential future analyses could include: (1) Determination of the most sensitive assumptions in the model, (2) water quality impacts from the changes in ethanol volumes between the reference case and this proposal, (3) removing corn stover for cellulosic ethanol, and (4) a case study of a smaller watershed to evaluate local water quality impacts that are impossible to ascertain at the scale of the UMRB. EPA solicits comments on the scenarios developed for this proposal and additional future analyses. At this time, we are not able to assess the impact of these additional loadings on the size of the Gulf of Mexico hypoxia zone or water quality within the UMRB. EPA also solicits comments on the significance of the modeled increases in nitrogen and phosphorus loads. C. Additional Water Issues Water quality and quantity impacts resulting from corn ethanol production go beyond our ability to model. The following issues are summarized to provide additional context about the broader range of potential impacts. See Chapter 6 in the DRIA for more discussion of these issues. 1. Chesapeake Bay Watershed Agricultural lands contribute more nutrients to the Chesapeake Bay than any other land use. Chesapeake Bay Program partners have pledged to significantly reduce nutrients to the Bay to meet water quality goals. To estimate the increase in nutrient loads to the Bay from changes to agricultural crop production from 2005 to 2008, the Chesapeake Bay Program Watershed Model Phase 4.3 and Vortex models were utilized. Total nitrogen loads increased by almost 2.4 million pounds from an increase of almost 66,000 corn acres. As agriculture land use shifts from hay and pasture to more intensively fertilized row crops, this analysis estimates that nitrogen loads increase by 8.8 million pounds. 2. Ethanol Production There are three principal sources of discharges to water from ethanol plants: Reject water from water purification, cooling water blowdown, and off-batch ethanol. Most ethanol facilities use on-site wells to produce the process water for the ethanol process. Groundwater sources are generally not suitable for process water because of their mineral content. Therefore, the water must be treated, commonly by reverse osmosis. For every two gallons of pure water produced, about a gallon of brine is discharged as reject water from this process. Most estimates of water consumption in ethanol production are based on the use of clean process water and neglect the water discharged as reject water. The largest source of wastewater discharge is reverse osmosis reject water from process water purification. The reverse osmosis process concentrates groundwater minerals to levels where they can have water quality impacts. There is really no means of ``treating'' these ions to reduce toxicity, other than further concentration and disposal, or use of instream dilution. Some facilities have had to construct long pipelines to get access to dilution so they can meet water quality standards. Ethanol plants also discharge cooling water blowdown, where some water is discharged to avoid the buildup of minerals in the cooling system. These brines are similar to the reject water described above. In addition, if off-batch ethanol product or process water is discharged, the waste stream can have high Biochemical Oxygen Demand (BOD) levels. BOD directly affects the amount of dissolved oxygen in rivers and streams. The greater the BOD, the more rapidly oxygen is depleted in the stream. The consequences of high BOD are the same as those for low dissolved oxygen: Aquatic organisms become stressed, suffocate, and die. Older generation production facilities used four to six gallons of process water to produce a gallon of ethanol, but newer facilities use less than three gallons of water in the production process. Most of this water savings is gained through improved recycling of water and heat in the process. Water supply is a local issue, and there have been concerns with water consumption as new plants go online. Some facilities are tapping into deeper aquifers as a source of water. These deeper water resources tend to contain higher levels of minerals and this can further increase the concentration of minerals in reverse osmosis reject water. Geographic impacts of water use vary. A typical plant producing 50 million gallons of ethanol per year uses a minimum of 175 million gallons of water annually. In Iowa, water consumption from ethanol refining accounts for about seven percent of all industrial water use, and is projected to be 14% by 2012--or about 50 million gallons per day. a. Distillers Grain with Solubles Distillers grain with solubles (DGS) is an important co-product of ethanol production. About one-third of the corn processed into ethanol is converted into DGS. DGS has become an increasingly important feed component for confined livestock. DGS are higher in crude protein (nitrogen) and three to four times higher in phosphorus relative to traditional feeds. When nitrogen and phosphorus are fed in excess of the animal's needs, these nutrients are excreted in the manure. When manure is applied to crops at rates above their nutrient needs or at times the crop can not use the nutrients, the nutrients can runoff to surface waters or leach into ground waters. Livestock producers can limit the potential pollution from manure applications to crops by implementing comprehensive nutrient management. Due to the substantially higher phosphorus content of manure from livestock fed DGS, producers will potentially need significantly more acres to apply the manure so that phosphorus will not be applied at rates above the needs of the crops. This is a particularly important concern in areas where concentrated livestock production already produces more phosphorus in the manure than can be taken up by crops or pasture land in the vicinity. Several recent studies have indicated that DGS may have an impact on food safety. Cattle fed DGS have a higher prevalence of a major food-borne [[Page 25105]] pathogen, E. coli O157, than cattle without DGS in their diets.\529\ More research is needed to confirm these studies and devise methods to eliminate the potential risks. --------------------------------------------------------------------------- \529\ Jacob, M. D., Fox, J. T., Drouillard, J. S., Renter, D. G., Nagaraja, T. G., 2008, Effects of dried distillers' grain on fecal prevalence and growth of Escherichia coli O157 in batch culture fermentations from cattle, Applied and Environmental Microbiology, v. 74, no. 1, p. 38-43, available online at: http://aem.asm.org/cgi/content/abstract/74/1/38