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United States Department of Agriculture

Agricultural Research Service

Research Project: VEGETABLE OIL-BASED FUELS, ADDITIVES AND COPRODUCTS

Location: Bio-oils Research Unit

Title: Impact of fatty ester composition on low temperature properties of biodiesel-petroleum diesel blends

Author
item Moser, Bryan

Submitted to: Fuel
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 18, 2013
Publication Date: September 3, 2013
Citation: Moser, B.R. 2014. Impact of fatty ester composition on low temperature properties of biodiesel-petroleum diesel blends. Fuel. 115:500-506.

Interpretive Summary: This research revealed that biodiesel composition does not affect cold flow properties at low blend levels in conventional petroleum diesel fuel. Although biodiesel negatively affects cold flow properties when blended with diesel fuel, the composition of biodiesel does not play a role at low blend levels. Biodiesel may be produced from a number of different feedstocks, each of which possesses a unique chemical composition. Fuel properties of biodiesel largely depend on chemical composition. Among the properties of biodiesel affected by chemical composition is cold flow, which describes the tendency of a fuel to undergo unwanted solidification at cold temperatures. According to the fuel standard that governs the quality of petroleum diesel fuel (ASTM D975), biodiesel may be blended at low blend levels (5% or less) with diesel fuel. The objective of this study was to determine whether or not different biodiesel fuels (soybean, canola, palm, etc.) with different chemical compositions caused cold flow properties of blends with diesel fuel to vary from one another. In other words, does the chemical composition of biodiesel matter if it is blended at low blend levels with petroleum diesel fuel? The answer was “no” because, in most cases, the chemical composition of biodiesel does not influence cold flow properties of blends with diesel fuel. These results will be important to biodiesel producers, distributors, and end-users (customers) because insight was obtained on how biodiesel performs in blends with petroleum diesel fuel. This research may ultimately improve market penetration, availability, and public perception of domestically produced agricultural fuels such as biodiesel, thus affording greater independence from imported petroleum-based fuels while simultaneously enhancing rural economies across America.

Technical Abstract: Several biodiesel fuels along with neat fatty acid methyl esters (FAMEs) commonly encountered in biodiesel were blended with ultra-low sulfur diesel (ULSD) fuel at low blend levels permitted by ASTM D975 (B1-B5) and cold flow properties such as cloud point (CP), cold filter plugging point (CFPP), and pour point (PP) were measured. The objective was to determine whether or not the fatty acid composition of biodiesel affects cold flow properties of blends at low levels such as B1 to B5. Statistical methods such as least squares regression and one-way analysis of variance coupled with Tukey’s Studentized Range test were applied to the resulting cold flow property data. Statistical analysis revealed the fatty acid profile did not affect cold flow properties at low blend levels unless the biodiesel sample contained a high percentage (> 48%) of long-chain saturated FAMEs. Other important conclusions were that variances in cold flow property data at low blend levels (B1 to B2) were minimal and generally statistically equivalent regardless of fatty acid composition. Lastly, application of least-squares statistical regression to CP, CFPP, and PP data revealed distinct mathematical relationships between cold flow properties and blend ratio. Specifically, CP was best fit to an exponential decay model whereas PP exhibited linearity and CFPP provided the highest R2 values when fitted to polynomial equations. In summary, this study demonstrated that, in most cases, feedstock selection for biodiesel fuel had minimal impact on cold flow properties at low blend levels permitted by ASTM D975, the U.S diesel fuel standard.

Last Modified: 7/28/2014
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