Adjusting the Quality Spec Won't Alleviate Post-Production Concerns

The possibility of imposing a monogylceride limit for biodiesel to comply with ASTM guidelines was discussed at the National Biodiesel Conference. It's a sensitive issue, according to industry insiders. In fact, several sources contacted by Biodiesel Magazine either had no comment or asked to remain anonymous when the conversation was about tweaking the quality parameters.
By Nicholas Zeman | June 09, 2009
The fact that one of the world's biggest oil companies had a problem with plugged fuel dispensers in Washington state last year has driven the creation of an ASTM working group to consider imposing a limit for monoglycerides in biodiesel. The ASTM biodiesel quality spec, D6751, already has a 0.24 percent limit for total glycerin free and bound, the test procedure for which some say is awkward and cumbersome. Quality has long been an issue affecting the growth and development of the biodiesel industry, though some producers
believe that it's unnecessary to take the ASTM specifications further.

"There's speculation that monoglycerides can cause filter plugging at or above cloud point," says a biodiesel producer and distributor, who asked to remain anonymous. "I don't see why the biodiesel spec has to be more stringent than the petroleum spec," the source says, with a hint of indignation. "The real issues right now are in the field with tank maintenance. That's where the real problem is-with tank maintenance and lack of education."

A consensus among sources, however, says that while improving fuel quality is important, most of the ongoing problems are occurring post-production, during fuel handling and storage operations. Supporting this claim is the fact that the call to introduce an ASTM limit for monoglycerides is not coming from the original equipment manufacturers (OEMs). "We were notified of the intention to [include a] limit for monoglycerides, and agreed it sounded good," says Brent Calcut, fluids engineer for Detroit Diesel Corp. "We're always willing to support stricter quality guidelines, but we don't have any real issues with the ASTM specs currently in place."

The official inclusion of a mono limit for biodiesel is only speculation, and one that the industry is reluctant to talk about. The National Renewable Energy Laboratory is involved with ongoing work to improve biodiesel fuel quality, yet NREL engineer Teresa Alleman had little to say about particular modifications of the ASTM spec when Biodiesel Magazine asked her for details. "Currently, there is no proposal before ASTM to add a monoglyceride specification to D6751-although specific members of ASTM have discussed this possibility," she says.

Attention on furthering the development of a monoglyceride spec has caused the proliferation of a lot of misinformation, which hurts the industry more than it helps; and it likely will not improve relations between producers, wholesalers, distributors and fleet operators either. Monoglycerides have been seen as a contributing cause for certain biodiesel samples to fail the cold-soak test, but the situation is more complicated than solely attributing the problem to monos. One producer cited the fact that certain products, such as Schroeder Biofuels' recently marketed Cold Clear filter, can bring biodiesel that fails the cold-soak spec into compliance while improving cold weather operability at the same time. "After this process does its work, there is the same level of monos," says the producer. "The filter system eliminates the problems associated with longer cold-soak time biodiesel without reducing monos, so I don't see the problems as being related."

Excessive monoglycerides present in finished B100, however, has been viewed by some observers as the single most influential component effecting filter plugging. The reason there might be more problems with plugged filters in the storage and distribution chain than there are in vehicle operations is that, in diesel vehicles, the fuel heats up as it circulates from the tank to the engine, maintaining the flowability of the fuel. This means that handlers and tank farm operators have to be educated on how to properly heat outside storage tanks to administer biodiesel.

Canadian Mandate, Study
In Canada, cold weather is naturally a concern. As a result, Shell Canada Ltd., along with the biodiesel industry and the Alberta Climate Change Central organization, conducted a study testing biodiesel blends under very harsh conditions to help ease concerns from potential methyl ester users. Milligan Bio-Tech Inc., a 2 MMgy biodiesel plant in Foam Lake, Saskatchewan, states that exceeding quality standards is important to building the biodiesel industry in Canada, not to mention its importance in developing relationships with customers.

Zenneth Faye of Milligan Bio-Tech participated in the Alberta study and says biodiesel performed very well under a variety of conditions and operating procedures. Aside from one early filter change, no fleets reported any fuel-related loss of service or mechanical operability challenges during the winter months, even when temperatures reached minus 40 degrees Celsius (minus 40 degrees Fahrenheit).

The Canadian government is scheduled to introduce a national on-road biodiesel mandate as early as 2010 and no later than 2012, as long as "all practical and technical issues involving the interaction compatibility, availability and distribution of biodiesel with heavy trucks are addressed" prior to the introduction, reported the Canadian Trucking Association in May. "I've been very surprised by the comments made by the Trucking Association, because we addressed most of these issues during the Alberta study," Faye says. "I think this is just another way to delay the implementation of the mandate, which I think is primarily being pushed by the petroleum companies."

Milligan Bio-Tech's canola biodiesel will retain a pour point of minus 15 C (5 F), whereas biodiesel made from other feedstocks have difficulty flowing at temperatures below 0 C. Many of the current protocols in place regarding cold flow operability and other issues have been based on soy biodiesel, and there are currently no feedstock-specific standards, which might be needed to address fuel variability. "They're painting a picture of the biodiesel industry with one stroke," Faye says. "Petroleum from different areas or different sources, like tar sands or underground wells, is often blended together during the refining process, and in the future, I think biodiesel will also be made from a variety of feedstocks." Clearly, in many instances this is already happening.

Water and Sediment Changes
NREL reports that even though it was an extremely cold winter, biodiesel distributors reported far fewer problems last season. It is difficult to prove exactly what some of the improvements were based on, though. "One reason is that, in Minnesota, we've been educating people on proper fuel handling and storage practices," says Kelly Strebig with the Center for Diesel Research at the University of Minnesota. "Most of the problems we've had here haven't been fuel quality related, but have been caused by microbial growth in fuel tanks along with sediment and water contamination."

The Karl Fischer Moisture Specification doesn't have an official position in ASTM biodiesel guidelines at the moment, though there is a crude water and sediment testing method currently in place. The problem with water content in fuel is that it can adversely influence the calorific value and, above all, the storage life of the fuel. Biodiesel with excess water clearly has less oxidative stability, which means that there is a good chance for the formation of deposits during storage, along with the increased likelihood of frozen fuel lines and other engine components.

The water test right now can only measure free water; it can't measure dissolved water. B100 can contain up to 1,500 parts-per-million of dissolved water before it separates out.

One drawback of replacing the current water test with Karl Fischer, however, is that the latter does not address sediment levels. The testing for water and sediment falls under the same umbrella, however, there's no correlation between the tests. "People are more willing to accept the new water test than they are the sediment test, because the sediment test has no real pass-fail threshold," Calcut says. "So if you replace the water test, you also have to replace the sediment test because the two are combined right now."

There have been concerns from the OEMs that dissolved water in the fuel could increase its corrosivity, so Detroit Diesel and others support stricter methods for testing water. That, however, might be an exercise in futility if storage and handling procedures aren't improved.

"The water problem is difficult to control because it doesn't happen at the refinery," says another producer. "The fuel picks up water during transportation so it's particularly difficult to guarantee dry fuel-there's hesitancy among the industry to put in a strict limit because it's so hard to control." Dirty tanks or those that are ill-maintained can contain large amounts of condensation, so some water problems are clearly post-production issues. "Making the spec more stringent won't alleviate the problem," the source says. "The water test is plenty sufficient without making biodiesel producers invest in heavy equipment." Petroleum diesel has water problems too, and some see it as unfair that biodiesel gets blamed for problems that have long been a part of the traditional fuel infrastructure.

Faye agrees with fellow producers who complain that adding another test on the front-end designed to address water contamination cannot control what happens to the fuel after it leaves the plant. "They certainly have a legitimate complaint," he says. "But we've found that the Karl Fischer method has not been that expensive to implement and it's the most efficient way to test for water." Faye adds that while post-production issues involving handling and storage are often out of the hands of producers, refineries must send out the driest, highest-quality fuel possible to their customers.

Ultimately, ongoing adjustments to ASTM D6751 may consider issues besides monoglycerides, water and sediment. Detroit Diesel says that another area of concern is with allowable ash contamination. The current spec in place allows calcium and magnesium a combined five parts per million, while phosphorous has an allowance of .01 percent. "We are concerned that at those levels too much ash is being contributed to the diesel particulate filter and could cause premature filter plugging," Calcut says.

Nicholas Zeman is an associate editor for Biodiesel Magazine. Reach him at (701) 738-4972 or nzeman@bbiinternational.com.
 
 
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