Document ID: EPA-HQ-OAR-2015-0093-0001
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2015-04-23T04:00Z

MEMORANDUM
TO: 		Air and Radiation Docket EPA-HQ-OAR-2015-0093
FROM: 	EPA Office of Transportation and Air Quality
DATE:		April 15, 2015
SUBJECT: 	Supporting Documentation for Emissions Related to the Production and Transport of Carinata.

The document "Carinata data and calculations  -  for docket.xlsx" contains data and calculations used in the analysis of greenhouse gases attributable to the production of carinata oil for biofuel. This memorandum provides additional explanation of these data points and calculations including:

   * Assumptions about fertilizer use and other inputs for growing carinata.  
   
   Current literature and research suggests a range of fertilizer inputs that have been applied for growing carinata. Therefore, to capture the range of conceivable impacts, we used a range of fertilizer estimates that may be appropriate in a variety of conditions. The petitioner, Agrisoma Biosciences, Inc., recommended 60 lbs/acre of nitrogen based on application rates for their research plots. On these research plots, the carinata is grown in a continuous cropping system, whereas for commercial production carinata will likely be grown in fallow rotation which requires less fertilizer input as there is generally residual soil nutrient from the primary crop. As a low nitrogen estimate we assume 40 lbs/acre based on recommended rates for camelina, a Brassicaceae that is similar to carinata. As a high nitrogen estimate, we are assuming 80 lbs/acres. In recent trials, USDA has applied a range of 50  -  70 lbs/acre, however other studies have shown increases in yields at higher application rates. These studies did not attempt to assess these yield tradeoffs against the economic costs and returns from varied nitrogen application or recommend an optimal application rate (or rates). Therefore, we believe 80 lbs/acre is a reasonable upper estimate.  
   
   As the upper bound for phosphorus and potassium inputs, we used 30 lbs/acre and 10 lbs/acre, respectively.  The phosphorus value is based on guidance from the petitioner: 30 lbs/acre is the application rate used for the carinata continuous cropping system test plots. The petitioner did not recommend potassium fertilizer for carinata production, claiming that the land expected to be used for carinata growth generally has sufficient levels of potassium for carinata production. However, to capture regional variability in soil quality, we assume 10 lbs/acre as a high estimate of the amount recommended for camelina production.  According to the U.S. Department of Agriculture, sulfur can also be a beneficial fertilizer component for oilseeds such as carinata and soybeans, dependent on local soil characteristics, at application rates of up to 10-20 lbs/acre. There are multiple options for sulfur application as part of a liquid or dry granular mixture that also contain phosphorus and nitrogen.  The emissions for fertilizer rates provided in Table 3 of the preamble capture the likely range of impacts associated with the variety of application options, including ones containing sulfur.

   * Carinata yield
   
   We project 1,865 pounds of carinata seed per acre as the 2022 average yield. This is based on the average yield from 15 test plots across the U.S. and Canada between 2009 and 2012. As research plots produce higher yields than commercial production, we believe this is a reasonable approximation of the average 2022 commercial yield. Other studies show a range of yields similar to those of the petitioner based on experiments varying factors such as nitrogen application, water stress, and seed spacing. One such study showed a yield ranging from 552 to 2,434 lbs of seed/acre. We believe a projected yield of 1,865 lbs of seed per acre in 2022 is reasonable for the purposes of evaluating the GHG emissions associated with growing carinata as a biofuel feedstock.  
   

   * Calculations of the nitrous oxide (N2O) emissions from fertilizer and crop residues, for carinata and soybeans. 
   
   Equations for direct and indirect emissions from these sources are from the Intergovernmental Panel on Climate Change.  To calculate the amount of crop residues from carinata, and the nitrogen content of these crop residues, we used data on canola as a substitute for carinata, because data on carinata were not available, and both canola and carinata are oilseed plants in the Brassicaceae family.  
      
   * Net returns for growing carinata

   Planting, harvesting, and price per pound of carinata seed assumptions were based on information from the petitioner.  The petitioner also provided information on the amount of seed that would need to be planted to achieve the current technically feasible  - and 2022 projected average  - yield of 1,865 pounds of seed per acre.  
	
   * Energy inputs and greenhouse gas emissions from extracting oil from carinata seeds

   Estimates of the energy requirements for the crushing of carinata seeds were based on information submitted by the petitioner. The petitioner based their data on a survey of 10 canola crushing plants in the US and Canada, with the results normalized for the oil content of carinata. EPA then used emissions factors from the RFS2 Final Rule (2010) to produce estimates of associated emissions.