Bethany Fisher M.S. final exam and defense
Tuesday, November 10, 2009, 10:00 AM
EECL Conference Room

"Characterization of Gaseous and Particulate Emissions from Algae-Based Methyl Ester Biodiesel"

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Bethany Fisher will give a M.S. final exam and defense at 10 a.m. on Tuesday, Nov. 10 in the EECL Conference Room.

Advisor: Anthony Marchese, Ph.D.

Committee: Daniel Olsen, Ph.D., John Volckens, Ph.D.

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Abstract

The many advantages to using biodiesel in place of petroleum diesel are typically accompanied by the disadvantages. Oil-producing microalgae is a favorable alternative to the more common biodiesel feedstocks (soy, canola, etc.) because it does not compete with food sources, does not require arable land to grow and has the potential to produce significantly more oil per area per year than soy or canola crops.

However, the fatty acid composition of the oil produced by algae species currently under consideration for fuel production differs from that of the more common vegetable oils in that it often includes high quantities of long and highly unsaturated fatty acids.

When transesterified into fatty acid methyl esters (i.e. FAME biodiesel), the unique fatty acid composition could have a substantial impact on tailpipe emissions such as NOx and particulate matter (PM). Accordingly, the goal of this study was to examine the effect of the chemical structure of algal methyl esters on pollutant emissions from a diesel engine operating on algae-based FAME biodiesel.

Tests were performed on a 2.4 L, 56 HP John Deere 4024T, non-road diesel engine meeting USEPA Tier 2 emissions regulations. The engine was fitted with a unique, low-volume fuel system that enable emissions tests to be conducted with very small specialty fuel samples. Tests were performed on 9 different fuel blends at 2 different engine loading conditions.

Exhaust gas measurements were made using 5-gas emissions analysis system that includes chemiluminescence measurement of NO, NO2 and total NOx, flame ionization detection of total hydrocarbons, paramagnetic detection of oxygen and non-dispersive infrared detection of CO and CO2. Particulate matter was characterized on-line, using an Aerodyne Aerosol Mass Spectrometer (AMS), which is capable of direct measurement of particle composition.

Smaller PM size distributions (10 to 1000 nm) were measured using a Scanning Mobility Particle Sizer. Total PM mass emissions and the ratio of elemental carbon to organic were measured using gravimetric sampling. Experiments were performed with ultra-low sulfur diesel, soy biodiesel (B20 and B100), canola biodiesel (B20 and B100), and two synthetic algal methyl ester formulations (B20 and B100 for each).

The algal methyl esters were found to result in decreased NOx relative to both canola and soy biodiesel and ULSD, in contrast to previous research that examined the effect of fatty acid saturation and chain length on NOx emissions. A correlation was found between NOx emissions and premixed burn fraction, which provides an explanation for these results.

Total hydrocarbons, formaldehyde and the organic carbon particulate matter were found to be slightly elevated with the two algal fuels in comparison with the traditional feedstocks. The other tests, including particle size distribution, total PM mass, and CO and acetaldehyde levels, showed similar results between the different types of biodiesel.

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Event Contact: Denise Morgan can be reached at (970) 491-0924

Sponsored by The Department of Mechanical Engineering.