VEGETABLE OIL-BASED FUELS, ADDITIVES AND COPRODUCTS
Location: Bio-oils Research Unit
Title: Efficacy of fatty acid profile as a tool for screening feedstocks for biodiesel production
Submitted to: Biomass and Bioenergy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 21, 2011
Publication Date: January 25, 2012
Citation: Moser, B.R., Vaughn, S.F. 2012. Efficacy of fatty acid profile as a tool for screening feedstocks for biodiesel production. Biomass and Bioenergy. 37:31-41.
Interpretive Summary: This research reports that a simple screening tool can be used to select the best alternative feedstocks for biodiesel production. Feedstocks for biodiesel production are normally commodity vegetable oils or animal fats that are regionally available, such as soybean oil. However, feedstock acquisition may account for up to 80% of the overall costs associated with biodiesel production. Consequently, the search for alternative low-cost feedstocks is of paramount importance for the economic viability of the biodiesel industry. Fuel properties depend on the chemical composition of the feedstock from which biodiesel is prepared. Screening potential alternative feedstocks based on their chemical composition identifies feedstocks that will provide biodiesel with the best fuel properties. Such a screening tool accelerates the exploration of alternatives to traditional commodity oilseed crops (like soybean), as time is not wasted working on feedstocks that don’t have the best chemical compositions. The screening tool utilizes a method known as gas chromatography that identifies all of the fatty acids contained in the potential feedstock. The objective of this study was to determine whether or not the screening tool was effective at identifying which feedstocks would provide biodiesel with fuel properties that were in accordance with accepted biodiesel fuel standards. The results indicated that the tool was effective at identifying feedstocks that would provide biodiesel compliant with the biodiesel fuel standards. These results will be important to biodiesel producers, distributors and end-users (customers) because insight was obtained on improving the availability and properties of biodiesel. This research may ultimately improve market penetration, availability and public perception of domestically produced agricultural fuels, such as biodiesel, thus affording greater national independence from imported petroleum-based fuels.
Fuel properties are largely dependent on the fatty acid (FA) composition of the feedstock from which biodiesel is prepared. Consequently, FA profile was employed as a screening tool for selection of feedstocks high in monounsaturated FAs for further evaluation as biodiesel. Those feedstocks screened included ailanthus (Ailanthus altissima L.), anise (Pimpinella anisum L.), arugula (Eruca vesicaria L.), cress (Lepidium sativum L.), cumin (Cuminum cyminum L.), Indian cress (Tropaeolum majus L.), shepherd's purse (Capsella bursa-pastoris L.), and upland cress (Barbarea verna (Mill.) Asch.). Other selection criteria included saturated content, iodine value (IV), content of FAs containing twenty or more carbons, and content of trienoic FAs. Anise oil satisfied all selection criteria and was therefore selected for further investigation. Arugula, cumin and upland cress oils were selected as antagonists to the selection criteria. Preparation of FA methyl esters (FAME, = 92 wt % yield) following conventional alkaline-catalyzed methanolysis preceded fuel property determination. Of particular interest were oxidative stability and cold flow properties. Also measured were kinematic viscosity (40oC), IV, acid value, free and total glycerol content, sulfur and phosphorous content, cetane number, energy content, and lubricity. FAME prepared from anise oil yielded properties compliant with biodiesel standards ASTM D6751 and EN 14214 whereas the antagonists failed at least one specification contained within the standards. As a result, FA profile was an efficient predictor of compliance with biodiesel standards and is therefore recommended as a screening tool for investigation of alternative feedstocks.