Daniel P. Geller

DSC studies to evaluate the impact of bio-oil on cold flow properties and oxidation stability of bio-diesel.

This paper describes the use of Differential Scanning Calorimetry (DSC) to evaluate the impact of varying mix ratios of bio-oil (pyrolysis oil) and bio-diesel on the oxidation stability and on some cold flow properties of resulting blends. The bio-oils employed were produced from the semi-continuous Auger pyrolysis of pine pellets and the batch pyrolysis of pine chips. The bio-diesel studied was obtained from poultry fat. The conditions used to prepare the bio-oil/bio-diesel blends as well as some of the fuel properties of these blends are reported. The experimental results suggest that the addition of bio-oil improves the oxidation stability of the resulting blends and modifies the crystallization behavior of unsaturated compounds. Upon the addition of bio-oil an increase in the oxidation onset temperature, as determined by DSC, was observed. The increase in bio-diesel oxidation stability is likely to be due to the presence of hindered phenols abundant in bio-oils. A relatively small reduction in DSC characteristic temperatures which are associated with cold flow properties was also observed but can likely be explained by a dilution effect.

Rheological characterization of animal fats and their mixtures with #2 fuel oil

To aid in the development of biomass fuels based on waste animal fats, as of yet unpublished rheological properties of these fats and their mixtures with petroleum-based fuels are needed. The viscosities and densities of beef tallow, choice white pork fat, poultry fat and yellow grease were experimentally determined to examine their potential use as fuel substitutes or additives. The viscosities of 30% mixtures of these fats with #2 fuel oil fuel were also examined. Dynamic viscosities of these agricultural oils were measured for shear rates of 0.65– at temperatures between 54.4°C and 85°C. The resulting measurements were fitted to a power law model to obtain values for the consistency coefficient and the flow behavior index. These results indicated pseudoplastic flow behavior for all products, with increasingly Newtonian behavior at higher temperatures and shear rates. The mixtures of these fats with fuel oil exhibited even more encouraging rheological properties very near those of pure fuel oil.

Fuel properties of oil from genetically altered Cuphea viscosissima

Abstract A genetically altered plant strain ( Cuphea viscosissima VS-320) was identified which produces an oil with elevated levels of medium- and short-chain triglycerides. Previous studies have suggested that such an oil may be appropriate for use as a substitute for diesel fuel without chemical conversion of component triglycerides to methyl esters. This oil is also of interest for other industrial applications. This paper discusses the oil composition of C. viscosissima VS-320 and presents the analysis of several important alternative fuel screening properties of this oil: dynamic viscosity for shear rates of 1.617–64.69 s − 1 at temperatures of 25–80°C, boiling point at atmospheric pressure, temperature dependence of vapor pressure (from 40 to 760 mmHg for the 300–400°C temperature range), and heat of vaporization (Δ H v ). These properties have been established as indicators of fuel performance and can be used for initial screening of possible diesel fuel substitutes. These properties are compared to those of diesel, biodiesel, and vegetable oils. Analysis of these properties suggests that further genetic development of this plant as a source of diesel fuel is warranted.

Rapid thermogravimetric measurements of boiling points and vapor pressure of saturated medium- and long-chain triglycerides

In developing compositional models for biomass-based diesel fuel extenders, volatility properties of medium- and long-chain saturated triglycerides are essential to predict the impact of low levels of these compounds in mixtures with short-chain triglycerides. A thermogravimetric analysis (TGA) method for rapid measurement of boiling points and vapor pressure was used to obtain data for four pure medium- and long-chain triglycerides. Normal boiling points at 1 atm and the temperature dependence of vapor pressure from 760 mm down to 25 mm Hg were obtained for trilaurin (C12:0), trimyristin (C14:0), tripalmitin (C16:0), and tristearin (C18:0). The data showed good agreement with the Clausius-Clapeyron model for temperature dependence of vapor pressure up to 1 atm pressure. The results of this study were consistent with those obtained using differential scanning calorimetry (DSC) and with data previously reported for reduced pressure.

RAPID SCREENING OF BIOLOGICALLY MODIFIED VEGETABLE OILS FOR FUEL PERFORMANCE

A process for the rapid screening of alternative diesel fuel performance was applied to analogues of genetically modified vegetable oils and a mixture with no. 2 diesel fuel. The oils examined contained 60 to 80% of low molecular weight, short-chain, saturated triglycerides compared to the 1 to 2% found in traditional vegetable oils. These oils have relatively low viscosity that is predicted to enhance their performance as alternative diesel fuels. The screening process utilizes an engine “torque test” sequence that accelerates the tendency of diesel fuels to coke fuel injectors, a key indicator of fuel performance. The results of the tests were evaluated using a computer vision system for the rapid quantification of injector coking. The results of the screen were compared to those using no. 2 diesel fuel as a baseline. Coke deposition from the modified vegetable oil analogues was not found to be significantly different than deposition from diesel fuel. Suggestions are made to guide further modification of vegetable oil biosynthesis for the production of alternative diesel fuel.

ATOMIZATION OF SHORT–CHAIN TRIGLYCERIDES AND A LOW MOLECULAR WEIGHT VEGETABLE OIL ANALOGUE IN DI DIESEL ENGINES

To aid in the development of chemical composition models for diesel fuel substitutes based on vegetable oils and their derivatives, atomization properties of pure short–chain triglycerides were studied using a TK Solver and a previously developed model. The atomization of a simulated low molecular weight oil from the plant Cuphea VS–320 was also analyzed. This analysis required the measurement of density and surface tension for this oil, which are presented here. The atomization properties were compared to those of peanut oil, peanut oil methyl ester, and diesel fuel to provide reference. The low molecular weight triglycerides and simulated Cuphea oil exhibited atomization properties between those of standard No. 2 diesel fuel and more common vegetable oils such as peanut oil. This suggests better fuel performance with short–chain oils and triglycerides than with traditional vegetable oils containing predominantly long–chain triglycerides.

Biodiversity conservation in biofuel production: are we doing enough?

1Environmental Policy Program, Carl Vinson Institute of Government, University of Georgia, 201 N. Milledge Avenue, Athens, GA 30602, USA 2Engineering Outreach, College of Engineering, University of Georgia, Driftmier Engineering Center, Athens, GA 30602, USA *Author for correspondence: Tel.: +11 706 542 2808; Fax: +11 706 542 9301; E-mail: jme@uga.edu

Multicomponent Bio-oil/Biodiesel Based Fuels

Pyrolytic bio-oils have great potential as diesel fuel extenders. However, most bio-oils are not readily miscible in petroleum diesel fuel due to their high water content and abundance of hydrophilic components. This prevents their direct use as a component in diesel fuel blends. This study sought to develop inexpensive methods to upgrade bio-oil and utilize its components as a diesel fuel extender.