The Dark Side of Biodiesel

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2,053
Location
Sequim, WA
Here's the summary of a study we did on biodiesel that returned some unexpected results. Those running biodiesel thinking that they are doing the environment good my be dead wrong. The author stated that a good title for the report would be: The Road to He!! is Paved with Good Intentions. EXECUTIVE SUMMARY Biodiesel is a fuel created by reacting oils and fats with alcohols. The reaction produces 2 products: an ester and a glycerin phase. Upon complete separation, the ester [biodiesel] can be used directly as fuel for diesel engines. Biodiesel is an attractive supplement or alternative to petroleum diesel because [1] it is a renewable energy source, [2] it is less toxic to humans than petroleum diesel, and [3] it has a low sulfur content and will not degrade catalytic or particle trap emission control systems. Numerous controlled laboratory studies have been conducted to quantify differences in exhaust emissions attributable to switching to biodiesel fuel from petroleum diesel. A comprehensive EPA analysis of dynamometer emission tests on engines found that biodiesel emissions are lower for particulate matter [PM], hydrocarbons [HC], and carbon monoxide [CO]. This same analysis also showed a slight increase in nitrogen oxide [NO] emissions when biodiesel is used. These emissions differences were found to increase with the relative quantity of biodiesel mixed with petroleum diesel. The Community Planning Association [COMPASS] of Southwest Idaho contracted the Desert Research Institute [DRI] to measure the change in exhaust emission factors associated with switching the Meridian Joint School District [MJSD] #2 School Bus fleet from 100% petroleum diesel to 20% biodiesel/80% petroleum diesel [i.e. B20]. The MJSD operates a fleet of 205 school busses with model years ranging from 1983 to 2004. The field study took place on Lanark Road in Meridian, ID outside of the MSBD parking lot. The study was conducted in 2 phases: the first between January 11 and January 15, 2004 and the second between March 1 and March 4, 2004. During the first phase, the busses were operating on 100% petroleum diesel. The refueling tank at the school bus depot was filled with B20 on January 16, and all busses refueled with B20 until April 1, 2004. The average school bus odometer increase between January 16, 2004 and March 1, 2004 was approximately 3,000 km corresponding to 3 or 4 refuelings during the period. A commercial vehicle exhaust remote sensing system [VERSS] augmented with an ultraviolet Lidar was used to measure the emissions from all vehicles traveling on Lanark Road during the study. Using optical beams oriented across the roadway, the system measured the column content of CO2, CO, HC, NO, and PM. By calculating the ratio of each pollutant to the total carbon content of the exhaust, the measurements were converted into fuel based emission factors with units of g pollutant per kg fuel burned. Since there was no outlet on the eastern end of the street [i.e, a dead end street], the vehicles traveling eastbound were operating under hot stabilized conditions, while the westbound vehicles were generally operating under cold-start conditions. Between 230 and 540 valid measurements of school bus emission factors were collected for each pollutant during each phase and each operating condition. Motor vehicle emissions [especially those from light duty gasoline vehicles] are usually skewed due to a small number of vehicles causing the majority of the emissions. The diesel bus emission factors tended to have less skewness than gasoline powered vehicles. Analysis of emissions factors by model year showed that busses with the newer engines [model years 1998 to 2000] emitted less CO and PM than the older engines [model years 1995 to 1998]. These differences are likely due to computer controlled fuel injection systems on the newer busses that optimize both power and combustion efficiency. For the school busses, cold start emissions of CO were 34% +/- 7% higher after the switch to B20. Average hot-stabilized CO emissions factors were not significantly different after the switch to B20. Average hot-stabilized HC emission factors increased 23% +/- 11% after the switch to B20, but cold-start HC emission factors were indistinguishable based on fuel type. Emission factors of NO for busses running on both fuels were not significantly different <1%. The largest change in emission factors were observed for PM. Hot stabilized PM emission factors were 88% +/- 11% higher with B20 and cold start PM emission factors were 65% +/- 8% higher after the busses has switch to B20. All noted differences in emissions were deemed statistically significant via a t-test with alpha = 0.05. Emission factor measurements of CO, NO, and PM from both sampling phases were corroborated by a redundant set of measurements using a novel in-plume sampling system. These results are in disagreement with the majority of dynamometer biodiesel studies that show a decrease in CO, HC, and PM emission factors with biodiesel use. In addition to the higher PM emission factors observed after the switch to biodiesel, a number of mechanical problems forced 6 busses out of service. Each bus had failures of the lift pump or fuel pump that delivers the fuel to the injectors. One failure occurred prior to the fuel swith on one of the control busses that had been using biodiesel for ~1.5 years. These conflicting results prompted the analysis of the fuels used in the busses during the study. Samples of B100, B20, and petroleum diesel were collected directly from a manufacturer and at several distribution points in the Treasure Valley. The samples were sent to Caleb Brett Laboratories in Deer Park, Texas for testing. Analyses of these fuels indicated that the biodiesel used in the Treasure Valley was not in compliance with the newly published ASTM standard for B100 [D6751]. All of the biodiesel samples collected in the Treasure Valley had elevated levels of glycerin [a byproduct of the biodiesel trans-esterification process]. In addition, one of the B100 samples had a low flash point that is usually associated with residual methanol in the biodiesel. Based on the DOE’s “Biodiesel Handling and Use Guidelines”, these deficiencies can cause fuel system failure and poor combustion characteristics. The findings of increased PM emission factors and fuel systems failures are consistent with B20 made from off-specification biodiesel fuel. This study differed from many previous laboratory studies in that the effects of a fuel switch under real world conditions were tested. The analysis identified that the use of off-spec fuel can reverse the some of beneficial effects of using biodiesel. Ed
 
Messages
894
Location
Sudbury, Ontario
The buses were showing lift pump failures after 3000 km? I don't understand how this could have happened unless the pumps had cheap rubber parts in them, school buses are only allowed to be on the road for 10 years (15 in some areas) and they put on very very few miles during this time. Increased nitrogen output is a known issue but you can fix that by changing the fuel injector timing. I talked to the Sudbury Transit employee responsible for running B20 in their busses and he has not had any problems. The busses probably put a couple thousand km under their belts weekly. The busses in Sudbury probably aren't running biodiesel made in somebody's back yard but the buses in the EPA article certainly were. The author must have some sort of agenda. His Executive Summary tells the reader that his findings are very flawed. That's pretty funny. [LOL!] Steve
 

MolaKule

Staff member
Messages
21,909
Location
Iowegia - USA
It sounds if they have a Quality Control issue.
quote:
The analysis identified that the use of off-spec fuel can reverse the some of beneficial effects of using biodiesel.
 
Messages
2,187
Location
Arizona
quote:
Originally posted by MolaKule: It sounds if they have a Quality Control issue.
quote:
The analysis identified that the use of off-spec fuel can reverse the some of beneficial effects of using biodiesel.

Exactly. This had nothing to do with the fuel itself being "evil" or having a "dark side." Similar things will happen to emissions levels of any engine when you change the fuel out of spec.
 

edhackett

Thread starter
Messages
2,053
Location
Sequim, WA
You are right that there is nothing wrong with biodiesel. In "pure" form it is a very promising fuel all the way around. The dark side is that off-spec biodiesel is being sold, and the customer has no way of knowing. The ASTM specification has just been adopted, and as far as I know, compliance is voluntary. The cost of doing the testing is expensive. The major suppliers might eventually test each batch, but you can bet that the smaller and "back yard" producers will not test. This applies to the current U.S. situation. I understand that some other contries have better controls in place currently. The biodiesel in this study was supplied by a national company with production facilities in the midwest and southeast. All of the samples that were tested from the southeast facility were bad, and the samples from the midwest facility were fine. The same glycol contaminated biodiesel used in this test was being sold at a public pump in Boise. How many people around the country were buying this biodiesel thinking they were doing good for the environment, yet in reality were harming the environment more than using full petroleum diesel? They were also risking expensive damage to their vehicles. The glycol and methanol are byproducs of the process and are literally washed out of the biodiesel. The biodiesel is mixed with water and the water soluble glycol and alcohol dissolve in the water. The water separates from the biodiesel, sometimes with the aid of a centrifuge, removing the contaminates. If this extraction is not complete you end up with a fuel that harms rather than helps. The B20 in this case contained more glycol than is allowed by ASTM for B100. What this study points out is the need for strict quality control and monitoring of biodiesel if the benefits of using biodiesel are to be realized. We are currently waiting for one more test result to come in to fill in the data tables. Once that is here I will make the paper available to anyone who would like a copy of the full report, all 142 pages of it. Ed
 
Messages
43,667
Location
'Stralia
ed, thanks for the offer, I'll certainly take it up. Oz has introduced some pretty impressive/strange legislation on the production of biodiesel. Some things I think protect the consumer, some protect business, and also protect taxation revenue. Anyone producing biodiesel must be registered with the customs and exise people, whether you are producing it for sale, or for your own use. You must keep auditable records of your vegetable oil inputs and biodiesel outputs, and pay an exise of 43c for every litre that you produce. You WILL be audited. You must subject your product to a NATA approved laboratory for testing twice per year (about a grand per test). And the specs pretty much rule out second hand oil, almost but not quite specifying first use canola oil. So Oz consumers who purchase a biodiesel product can be pretty much 100% guaranteed that they are safe. (The government can be guaranteed that they get their revenue.) Backyard brewers beware...testing for esters is on the way.
 
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