FISH OIL BASED BIODIESEL TESTING

University of Alaska Fairbanks Institute of Northern Engineering

by Dennis E. Witmer

Jack Schmid

Supported by the Alaska Energy Authority Contract # ADNR0617

November 7, 2008

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Abstract One major issue with the use of biodiesel fuels is the propensity of these fuels to oxidize during storage and form lacquers, resulting in failure of fuel handling systems. During one season of testing of a fish oil biodiesel in Alaska, a total of six out of six engines failed, all caused by fuel system seizures from lacquer films from partially oxidized fish oil. In retrospect, the oxidation of the biodiesel was due to the lack of understanding by the test program participants of the need for anti-oxidant additives, and for the proper storage conditions and time. This raises the question of the possibility of rehabilitating fuel that has undergone oxidation sufficient to render the fuel questionable. Preliminary tests at the UAF diesel test bed indicate that oxidized fish oil biodiesel can be rehabilitated and used as a fuel in diesel engines. Background The benefits of using biofuels are many, perhaps most importantly the production of energy from a renewable resource, using technology developed and perfected for the use of fossil fuels. Much recent discussion has centered on the relative energy benefits of some of these fuels, particularly ethanol from corn, where the perceived benefits might well be larger than the real effects. [1] Fish oil is a natural product produced by heating fish until the oil is rendered. The highest value use of this product is a human food supplement, as the omega 3 fatty acids have been shown to reduce cholesterol. [2] Fish oil gel tablets are sold in many health food stores at a price of about $75 per pound ($500 per gallon), but raw fish oil purchased from processors for this use is obtained at about $4.50 per gallon. Fish oil is also sold for animal feed at a price of about $3.50 per gallon. However, in fishing communities in Alaska, more fish oil could be produced than the human or animal feed markets currently can sustain, and much fish processing byproduct is disposed without rendering the oil. The recent rise in the cost of diesel fuel has created interest in rendering this oil to replace diesel for the generation of electricity. Estimates are that approximately 30,000,000 gallons of fish oil could be produced in Alaska alone. In 2004, an initial study was done to evaluate the use of B100 fish oil biodiesel (B100 refers to pure biodiesel without conventional diesel added) for both on road and off road vehicles, and for stationary power generation. The National Park Service was interested in the use of B100 as a possible fuel for use in environmentally sensitive areas. (Spills might attract bears, but not the attention of the EPA, since fish oil is a food and not considered toxic.) Fuel for this study was created as follows: bulk fish oil was purchased from processors working in the North Pacific just off the Alaskan coast in 24000 liter lots (a full ISO shipping container). [3] This raw fish oil was then shipped to Hawaii for conversion to biodiesel, through the transesterification process by a commercial biodiesel plant. The biodiesel was then returned to the ISO containers for shipment to Alaska. The full containers were split into smaller lots in 300 gallon totes for shipment to the various testing sites.

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Two batches of fish oil biodiesel were created: the first batch (one ISO container) from oil purchased in the fall of 2003, with the biodiesel conversion done in March of 2004, the second (two ISO containers) purchased in December 2004, converted to biodiesel in March 2005, and delivered to Anchorage in April, 2005. Oxidation of the fuel was not considered a problem. No anti-oxidants were added to the fuel, and no special attention was paid to preventing exposure to air. In the summer of 2005, the fish oil biodiesel was tested in a total of six diesel engines. Initial results were encouraging, as it appeared that the fuel burned well with no apparent difference with conventional diesel fuel. However, by late summer, numerous problems began appearing. Some of these issues involved the production of smoke and an increase in the crankcase oil level of diesel generators after about a week of operation, but the failures were all in the fuel handling systems. One engine failed due to the seizure of the injectors, while the other engines had fuel pump failures. Visual examination of the injectors and fuel pumps revealed that an orange film similar to varnish covered all surfaces inside the fuel systems, and that failure had occurred when this film prevented the movement of close tolerance parts. These types of issues have been noted by other experimenters [4-7]. At one site, the failure coincided with a switch in the fuel supply. [8] The engine had been operating for approximately 40 hours on B100 with no apparent problems, but when the supply was changed from one storage container to another, the engine failed within minutes. When the fuel was inspected, it was noted that the fuel used when the failure occurred had a yellow cast as compared to the more orange color of the initial fuel. It was also noted that fuel stored in tightly sealed jars tended to retain the orange color, but that open containers became more yellow over time. Based on these observations, it appeared that the oxidation and resulting polymerization of the oils to form polymers was the cause of the engine failures. The polymerization of vegetable oils has been observed for centuries, and is the basis of oil based paints. Boiled linseed oil is the carrier for these paints, which solidifies when the oxygen in the air reacts with the oils to form a solid polymer when the paint “dries”. [9] Spontaneous combustion of oily rags is also a well known safety hazard, associated with the linseed oils in inks used in printing. Cooking oils also will react with oxygen to form gummy solids. Experimental Methods The use of rehabilitated degraded fuel requires some means of assessing fuel quality both before and after processing. After initial testing, stocks of biodiesel were selected for rehabilitation and then processed for use. After processing the fuel was used in diesel electric generator operation. Initially B20 (20% biodiesel and 80% #2 fuel oil) was used in the diesel generator and then the final segment of diesel operation was with B50. The diesel generator was operated at a load of 108 kW or approximately 60% engine load for all tests. Lube oil analysis was performed on crankcase oil samples taken before operation on biodiesel and taken after operation on B50. Exhaust emission analysis was performed at the end of the operation on B50. Immediately after

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the B50 operation, the engine was operated on #2 fuel oil to provide a reference exhaust emissions analysis. The use of rehabilitated degraded fuel requires some means of assessing fuel quality both before and after processing. A measurement of the peroxide value of oxidized biodiesel was performed by Dr. Subramaniam Sathivel, (Assistant Professor of Seafood Processing and Engineering at the UAF School of Fisheries facility at Kodiak, Alaska). The peroxide value is a measure of the hydroperoxides formed during the oxidation of the biodiesel. The peroxide values provided a means to assess the degree of degradation of the biodiesel stock. The biodiesel on hand was stored in multiple 1000 liter intermediate bulk containers (IBC) and the bulk containers holding biodiesel with the lowest peroxide value became candidates for rehabilitation. A common industry practice for improving food oils is to use a process described as adsorption bleaching to remove free fatty acids and compounds causing discoloration. This process is one that exposes the oils to activated earth, a type of clay, for a given time and then the activated earth is filtered from the oil. This process was applied to the biodiesel samples and the peroxide values were measured again to demonstrate the amount of reduction in the peroxide value possible. The tests and adsorption bleaching performed at the UAF Fisheries facility used required only small quantities of materials for the laboratory tests. The quantities of activated earth required to rehabilitate larger quantities of biodiesel were not available in Alaska and the hypothesis of using commercial cat litter as a substitute was tested. Tests indicated adsorption bleaching using cat litter was as effective as using activated earth. After completing the adsorption bleaching process to rehabilitate the fuel, the biodiesel was diluted with #2 diesel in a ratio of 1:4 to make a B20 mix in 150 liter batches and then pumped into a 1000 liter bulk storage container. Mixing in small batches insured good mixing of the biodiesel and conventional diesel. Testing of rehabilitated fuel was started with B20 to be conservative with fuel of uncertain quality. Near the end of the testing period, the concentration was changed to B50 after gaining confidence with the B20. Descriptions of the diesel test bed, emissions analysis equipment and the adsorption bleaching process are contained in the appendix. Results The peroxide values of the biodiesel samples and the results of the adsorption bleaching tests are presented in Table 1. The biodiesel in IBC2 and IBC4 was the least degraded of the stored fuel and an adsorption bleaching process was initiated on the biodiesel in IBC2. Dr Sathival indicated that the addition of an antioxidant to the biodiesel would reduce further oxidation. Each IBC was dosed with approximately 400 ppm of ethoxyquin, a common antioxidant used for animal feed.

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Table 1 Peroxide Value of Stocks of Fish oil Biodiesel Peroxide Values expressed in milliequivalent peroxide/kg biodiesel Fish Oil – sample of untreat

ed raw fish oil % of activated earth to biodiesel were by weight There was a visible difference between biodiesel samples before and after the adsorption bleaching process. Photos 3 and 4, appendix, “samples of antioxidant treated biodiesel before and after adsorption bleaching”, illustrates the difference in clarity of fuel that has undergone adsorption bleaching. The four cylinder Series 50 Detroit Diesel operated normally on B20 for 262 hours, which exhausted the first batch of rehabilitated biodiesel. The a second batch was processed by adsorption bleaching and diluted with #2 diesel in a ratio of 1:1 to make a B50 mix. Operation continued for 92 hours on B50 with no signs of problems. Biodiesel B50 operation resulted in the production of less CO and increased NOx in the exhaust emissions, as reported in Table 2. The changes in the emissions indicate the B50 fuel mix results in a higher flame temperature and more complete combustion resulting in lower CO emissions and elevated NOx concentrations. Table 2 emissions results Fuel O2 (%) CO

(ppm) NO2 (ppm)

NO (ppm)

NOx (ppm)

B50 9.5 189 52.5 1401 1454 D2 9.4 330 44.8 1234 1279

The lube oil analysis at the end of the trial indicated no abnormal wear or that any corrective action was necessary. The report from the Detroit Diesel Power Trac analysis laboratory described the concentrations of the compounds found in the lube oil as being in the normal range. The lube oil sample taken after operating 92 hours on B50 and 15 hours on D2 showed

Biodiesel samples

Peroxide Value of biodiesel

(untreated)

Peroxide Value of biodiesel

treated with 3%

Activated earth

Peroxide Value of biodiesel

treated with 1%

Activated earth

Peroxide Value of biodiesel

treated with 1.5 %

cat litter

Peroxide Value of biodiesel

treated with 3 %

cat litter

Peroxide Value of biodiesel

treated with 5 %

cat litter

IBC1 50.2+2.2 45.7+0.4 IBC2 35.4+0.7 27.3+1.6 28.7+2.2 27.7+2.5 29.4+0.8 27.3+1.1 IBC3 51.1+1.2 55.5+3.6 IBC4 38.0+1.4 29.8+1.0 IBC5 53.3+5.2 40.8+4.4 IBC6 42.0+4.6 31.7+1.5 IBC11 51.3+1.8 40.3+0.6 Fish Oil 19.7+0.9

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concentrations of boron and molybdenum, twice that found in the sample taken before the biodiesel operation, and potassium was found after biodiesel operation while there was no potassium detected prior to that. The presence of potassium after biodiesel operation suggests the source was the biodiesel fuel. The increases in boron and molybdenum concentrations require more research to explain since these constituents were present in the lube oil during operation on D2. Biodiesel characteristics After completing operation on biodiesel, the biodiesel adsorption bleaching system remained charged with some biodiesel. The effect of biodiesel on fuel hoses demonstrated a striking difference between biodiesel and conventional mineral diesel. Over time a fraction of the biodiesel remaining in the hoses migrated through the hose wall. This component of biodiesel appeared as a waxy oily substance on the surface of the fuel hose. Hoses containing mineral diesel for a similar length of time had no evidence of fuel migration through the hose. The hose was “Parker Hi-Temp Push-Lok 836” with a synthetic rubber liner. The manufacturer’s specifications note that the hose lining is resistant to petroleum base oils and does not specify resistance to biofuels. This materials issue is an important factor when considering operating engines on biodiesel, although since the mid 1990’s engine manufacturers have been using biofuel compatible materials in their seals and hoses. Photos 5 and 6 in the appendix show examples of biodiesel that has migrated through the hose material. Conclusion It is likely that older biodiesel fuel may be used as a fuel with proper rehabilitative treatment. The effort is time consuming and requires handling the fuel multiple times. Whether this is a practical endeavor is another question. A more practical strategy for the use of fish oil biodiesel would be to use it in a timely manner, minimizing the potential for oxidation. If the fuel required storage, the addition of an antioxidant and reducing the exposure to air is recommended. These precautions could reduce the need for rehabilitation efforts.

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Bibliography [1] Wikipedia, "Biofuel," 2007. [2] Wikipedia, "Fish Oil," Wikipedia, The Free Encyclopedia., 2007. [3] J. Steigers, "Alaska Fish Oil as a Bidiesel Feed Stock," in Alaska Rural Energy

Conference Valdez, Alaska: AETDL, 2005. [4] J. Scherpenzeel, "The use of biofuel in diesel engines: tests on a Fiat 160/90 DT tractor,"

1999. [5] "Standards and Warranties: The Biodiesel Standard (ASTM D 6751)," National

Biodiesel Board, 2007. [6] D. Seddon, "Standardising Diesel/Biodiesel Blends." vol. 2007: Australian Government,

Department of the Environment and Heritage, 2006, p. 113. [7] L. The Associated Octel Corporation, "Impact of Biodiesel on Fuel System Durability,"

in NREL/TP-540-39130. vol. 2007: NREL, 2005, p. 149 pages. [8] K. Sastry, CS Lin, DE Witmer, "Testing of Synthetic Diesel Fuel Suitable for Alaska," in

Alaksa Rural Energy Conference Valdez: AETDL, 2005. [9] Wikipedia, "Linseed Oil," 11 May 2007 02:49 UTC ed: Wikipedia, The Free

Encyclopedia., 2007.

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APPENDIX Diesel Electric Generator The diesel test bed is a 4 cylinder Detroit Diesel Series 50 Heavy Duty diesel engine. The engine is rated at 180 KW and operates at a constant speed of 1200 rpm. The engine is coupled to a generator rated at 125 kW at 1200 RPM. Load to the generator was supplied through a programmable LoadTec resistive/reactive load bank rated at 250 KW. The load bank employed a digital interface, located inside diesel engine enclosure, which allowed the load to be varied in 5 kW increments. The electrical load for the series of tests reported here was 108 KW, this was comprised of load bank setting of 100 kW and additional parasitic loads of operating the load bank of 8 kW. Emissions Analyzer Testo Model 350 XL flue gas analyzer. Emissions constituents reported: O2 CO NO NO2 NOx Biodiesel adsorption bleaching system The adsorption bleaching process was comprised of plastic bleaching column filled with cat litter, a circulating pump, filter and reservoir. The flow through the column was maintained until the volume of the reservoir was recirculated through the column a minimum of ten times. This resulted in a cumulative residence time of approximately 50 minutes for all of the biodiesel in the reservoir. During the adsorption bleaching process the headspace biodiesel bulk storage container was kept washed with nitrogen to minimize additional oxidation. Photos 1 and 2 show the setup. Column: 10 foot 4” ID ABS with a 4” cleanout and cap at the top for introducing clay/cat litter biodiesel is introduced to the top via a ½” JIC flare to ¼” NPT thread screwed into a 1/4” NPT tapped hole in the ABS pipe. The bottom of the column has a 4” to 2” reducer. Fastened to the top of the reducer is a 4” bronze drain grate covered with 2 layers of steel screen with 1/8” spacing sandwiching a layer of fiberglass screen with 1/8” spacing. The 2” reducer is reduced to 1 ½” with a bronze 1 ½” to ½” NPT bushing to accommodate a ½” NPT ball valve. Media in the column was 50 lbs of Premium Choice brand cat litter ( 100% clay) Pump: Oberdorfer 991M gear pump Hoses: Parker PushLok 836 high temperature hose, ½” ID Pump: Oberdorfer 991M gear pump delivering approximately 1 gallon per minute Relief valve: ½” relief valve manufactured by ProPlumber, set to open at 75 psi

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Schematic of for 1000 liter bulk storage tank at UAF, June 2007

1000 liter bulk storage (polyethylene intermediate bulk container)

Gear pump 1 gpm

Relief valve

Pressure meter

Shut off valve

Clay filled column

Nitrogen flow to maintain oxygen free headspace

N2

Filter

Flow

Flow

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PHOTOGRAPHS

Photo 1 Adsorption Bleaching column

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Photo 2 Adsorption bleaching apparatus

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Photo 3 samples of antioxidant treated biodiesel before and after adsorption bleaching

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Photo 4 Color differences of biodiesel at different stages of oxidation

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Photo 5 Biodiesel leached through fuel hose

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Figure 6 Discoloration on fuel hose resulting from biodiesel