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United States Department of Agriculture

Agricultural Research Service

Research Project: IMPROVING THE PERFORMANCE OF ALTERNATIVE FUELS AND CO-PRODUCTS FROM VEGETABLE OILS
2008 Annual Report


1a.Objectives (from AD-416)
Biodiesel is an alternative diesel fuel derived from vegetable oils, animal fats or used oils. While it is competitive with (in some aspects even technically superior to) conventional, petroleum derived diesel fuel, its use is still affected by several technical issues that hinder more widespread commercialization. Therefore, this project proposes to improve the combustion characteristics and fuel properties of vegetable oils (emphasizing soybean oil) and their derivatives as alternative diesel fuels, extenders, and additives in the operation of compression ignition (diesel) engines for on road and off road applications. Fatty derivatives will be utilized for performance enhancement and exhaust emission reduction (e.g. nitrogen oxides). Specific objectives for this project include: 1) Improved cold weather start up and operability performance. 2) Novel fuel formulations that reduce regulated exhaust emissions such as nitrogen oxides. 3) Improvement of fuel quality through enhanced oxidative stability and development of new, rapid analytical methods for assessing biodiesel fuel quality. 4) Development of specialty chemicals from biodiesel co-products.


1b.Approach (from AD-416)
Improve the fuel properties and combustion characteristics of vegetable oils (emphasizing soybean oil) and their derivatives as alternative fuels, extenders, and additives in the operation of compression ignition (diesel) engines for on road and off road applications. Address technical problems identified by stakeholders and customers. Specific objectives for this project include: develop new alternative fuel formulations with improved cold weather start up and operability performance without compromising fuel quality as defined by appropriate standard fuel specifications; develop alternative fuel formulations with improved combustion performance that reduces harmful, regulated exhaust emissions such as nitrogen oxides, carbon monoxide and particulate matter; develop new biodiesel formulations with improved storage stability with respect to oxidative degradation; develop rapid instrumental methods for monitoring effects of degradation on biodiesel fuel quality during storage, as defined by appropriate standard fuel specifications; identify and develop novel specialty chemicals that may be prepared from glycerol, mono, and diacylglycerols as marketable co products of biodiesel production.


3.Progress Report
Research continued towards the overall goals of enhanced understanding of factors governing biodiesel fuel properties and of developing biodiesel fuels with improved fuel properties. In this area, numerous factors were investigated, including low-temperature behavior (cloud point, pour point, melting point, freezing point depression, kinematic viscosity, effects of contaminants), effects of blending with ultra-low sulfur diesel (ULSD) fuels, oxidative stability analysis by three separate methods and cetane number as indicator of fuel ignition and combustion. New additives for improving cold flow properties were developed. Optimum fatty ester components of biodiesel were defined. Other work included monitoring of the transesterification reaction through which biodiesel is produced, assessing the composition of used cooking oils, and investigating alternative vegetable oils as potential biodiesel feedstocks. Collaborated with Alternative Aviation Fuels LLC (Rye Brook, NY) on development of a pilot-scale dry fractionation process for improving the cold flow properties of biodiesel. Collaborated with Iowa State University/University of Idaho on biodiesel education courses. Collaborated with the National Renewable Energy Laboratory, Department of Energy (DOE) on exhaust emissions evaluation of partially hydrogenated soybean oil methyl esters. Collaborated with Southwest Research Institute (SwRI) on cetane testing of fatty esters. This research progress addresses National Program 307, Component 2 of the Action Plan.


4.Accomplishments
1. Optimum fatty ester components of biodiesel defined. Using new and existing fuel and physical properties of fatty esters, optimum components of biodiesel were determined. Data used for this determination related to cetane numbers and combustion, viscosity, oxidative stability and cold flow. It was shown that esters of palmitoleic acid and decanoic acid may be the most preferable fatty ester components of biodiesel, possessing advantages compared even to esters of oleic acid. These results will eventually guide interested parties in preparing biodiesel fuels with optimized properties and help solve the technical problems associated with use of biodiesel without extensive use of additives. This accomplishment directly addresses NP307/213, Component 2, Problem Area 3c3 of the Action Plan.

2. Biodiesel from various vegetable oils. Since there is only a limited amount of feedstock available for producing biodiesel, the search for additional oils or fats that can serve as feedstocks or improvement of current production procedures is critical. Oils that were evaluated for biodiesel applications under these aspects included cottonseed and moringa. Such oils can be used as biodiesel feedstocks. As is the case with biodiesel from other oils, some technical problems exist in terms of properties requiring optimization. Overall, such work will contribute to enhancing the supply of biodiesel and reduce dependence on petroleum-based diesel fuel. This accomplishment directly addresses NP307/213, Component 2, Problem Area 3c1 of the Action Plan.

3. Fuel properties of biodiesel/ultra-low sulfur diesel (ULSD) blends. There is a general lack of reliable data on how fuel properties are affected by blending biodiesel with recently mandated ultra-low sulfur diesel (ULSD; less than 0.000015 percent sulfur content). Cold flow properties (cloud point, pour point and cold filter plugging point), viscosity (thickness), density, American Petroleum Institute (API) gravity, and refractive index were measured for various blend levels (volume percentages) of biodiesel derived from soybean oil and used cooking oil in ULSD. Cold flow property and API gravity data will be particularly useful to fuel producers, blenders and distributors as well as other scientists and engineers research biodiesel/ULSD blends. This accomplishment directly addresses NP307/213, Component 2, Problem Area 3c3 of the Action Plan.

4. Modeling crystallization of biodiesel at low temperatures. There is a need to develop better fundamental understanding of how low temperatures affect crystallization of different compounds present in biodiesel. A thermodynamic model based on freezing point depression of mixtures was employed to predict the behavior of prescribed mixtures of compounds found in biodiesel. Results from the model were compared to those from experimental data on crystallization temperatures of biodiesel formulations. Results from this work will be useful on modifying crystallization mechanism in biodiesel at low temperatures, such development of cold flow improvers, and in determining effects of minor impurities on cold storage stability of biodiesel. This accomplishment directly addresses NP307/213, Component 2, Problem Areas 3c3 and 3c4 of the Action Plan.

5. New cold flow additives for biodiesel. Several fatty derivatives with bulky moieties were synthesized from oleic acid by treatment of alkyl oleates with a variety of alcohols in the presence of sulfuric acid catalyst to provide a series of branched-chain ethers. The materials were analyzed for low temperature behavior through cloud and pour point determination. Generally, the 2-ethylhexoxy ethers of oleates containing bulky head groups were found to have the best low temperature performance. These results demonstrate that agricultural-based materials may serve as cold flow additives for biodiesel. This accomplishment directly addresses NP307/213, Component 2, Problem Area 3c3 of the Action Plan.

6. New oxidative stability additives for biodiesel. The search for technically competitive natural antioxidants for use as oxidation inhibitors of biodiesel which are not derived from petroleum has resulted in the discovery that myricetin, a naturally occurring flavonoid derived from a variety of fruits, vegetables, and other botanical sources, significantly delays autoxidation of biodiesel. This result will contribute significantly in devising biodiesel fuels with improved storage stability. This accomplishment directly addresses NP307/213, Component 2, Problem Areas 3c3 and 3c4 of the Action Plan.

7. Partially hydrogenated soybean oil methyl esters. Partially hydrogenated soybean oil methyl esters (PHSME) were prepared in a two step sequence (catalytic partial hydrogenation followed by transesterification) in an effort to satisfy the European Union biodiesel standard (EN 14214) with regard to oxidative stability and iodine value. It was concluded that PHSME is acceptable for use as a biodiesel fuel in the European Union and in the United States according to relevant reference standards. Exhaust emissions evaluation revealed a small reduction in nitrous oxide (NOx) exhaust emissions in comparison to non-hydrogenated soybean oil methyl esters. These results demonstrate that soybean oil-derived biodiesel, after partial hydrogenation, is acceptable for use in the large European biodiesel market. This accomplishment directly addresses NP307/213, Component 2, Problem Areas 3c3 and 3c4 of the Action Plan.


5.Significant Activities that Support Special Target Populations
None.


6.Technology Transfer

Number of Non-Peer Reviewed Presentations and Proceedings1
Number of Other Technology Transfer2

Review Publications
Knothe, G.H., Steidley, K.R. 2007. Kinematic viscosity of biodiesel components (fatty acid alkyl esters) and related compounds at low temperatures. Fuel. 86:2560-2567.

Kenar, J.A., Knothe, G.H., Gunstone, F.D. 2007. Chemical properties. In: Gunstone, F.D., Hardwood, J.L., Dijksta, A.J., editors. Lipid Handbook with CD-ROM, 3rd edition, Boca Raton, FL: Taylor & Francis Group LLC. p. 535-590.

Dunn, R.O. 2008. Effect of temperature on oil stability index (OSI) of biodiesel. Energy and Fuels. 22:657-662.

Knothe, G.H. 2008. Fuel and physical properties of biodiesel components. In: Nag, A., editor. Biofuels Refining and Performance. Chapter 5. New York, NY: McGraw Hill. p. 149-164.

Knothe, G.H. 2008. Evaluation of ball and disk wear scar data in the HFRR lubricity test. Lubrication Science. 20:35-45.

Knothe, G.H. 2008. "Designer" biodiesel: optimizing fatty ester composition to improve fuel properties. Energy and Fuels. 22:1358-1364.

Kenar, J.A., Knothe, G.H. 2008. 1,2-isopropylidene glycerol carbonate: preparation, characterization, and hydrolysis. Journal of the American Oil Chemists' Society. 85(4):365-372.

Levinson, W.E., Kuo, T., Knothe, G.H. 2008. Characterization of fatty amides produced by lipase-catalyzed amidation of multihydroxylated fatty acids. Bioresource Technology. 99:2706-2709.

Moser, B.R., Erhan, S.Z. 2008. Branched chain derivatives of alkyl oleates: tribological, rheological, oxidation, and low temperature properties. Fuel. 87:2253-2257.

Moser, B.R., Sharma, B.K., Doll, K.M., Erhan, S.Z. 2007. Diesters from oleic acid: synthesis, low temperature properties, and oxidation stability. Journal of the American Oil Chemists' Society. 84:675-680.

Moser, B.R., Cermak, S.C., Isbell, T. 2008. Evaluation of castor and lesquerella oil derivatives as additives in biodiesel and ultralow sulfur diesel fuels. Energy and Fuels. 22:1349-1352.

Moser, B.R. 2008. Review of cytotoxic cephalostatins and ritterazines: isolation and synthesis. Journal of Natural Products. 71:487-491.

Doll, K.M., Moser, B.R., Erhan, S.Z. 2007. Surface tension studies of alkyl esters and epoxidized alkyl esters relevant to oleochemically based fuel additives. Energy and Fuels. 21:3044-3048.

Holser, R.A., Willett, J.L., Vaughn, S.F. 2008. Thermal and physical characterization of glycerol polyesters. Journal of Biobased Materials and Bioenergy. 2(1):1-3.

Holser, R.A., Harry O Kuru, R.E., Vaughn, S.F., Himmelsbach, D.S. 2008. Preparation and characterization of 4-methoxy cinnamoyl glycerol. Journal of the American Oil Chemists' Society. 85(4):347-351.

Dunn, R.O. 2008. Antioxidants for improving storage stability of biodiesel. Biofuels, Bioproducts, & Biorefining (Biofpr). 2:304-318.

Last Modified: 9/10/2014
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