The biodiesel education network that delivers up-to-date information, ideas and solutions

Frequently Asked Questions (F.A.Q.s)

As AskBEN continues to grow, our database of questions and answers continues to grow, giving us the ability to provide you with the answers to the most Frequently Asked Questions.
Here then, are the most Frequently Asked Questions:


Q. Does biodiesel gel in certain temperatures?

A. Biodiesel manufactured from soy has a cloud and pour point of approximately 32F while yellow grease and tallow ranges in the fifty degree area. When blending biodiesel manufactured from any feed stock it is equally important to access the best base stock (relating to cold properties) with your biodiesel.

Q. How much sulfur is in biodiesel?

A. There is virtually none.

Q. Are there specifications for biodiesel that can be compared against diesel fuel specifications?

A. Yes, compare ASTM D 6751 (biodiesel B100 specification) with ASTM D 975 (generic diesel fuel specification). You can find a biodiesel typical specification by clicking the biodiesel basic icon found on the bottom of either the Ask Ben website or Biodiesel website.

Q. What has been done to keep biodiesel blends flowing in the cold weather months?

A. Whereas fuel additives are not effective in neat biodiesel our outreach and communication efforts have included recommendation on adhering to appropriate storage, blending and distribution efforts. These recommendations include keeping the biodiesel heated to a minimum of ten degrees above the posted cloud point of the biodiesel while ensuring that the diesel fuel which it is blended is both additized and blended with kerosene to meet the expected low temperatures of the specific market which the product is being handled and sold.

Q. How many bushels of soybeans are required to manufacture one gallon of biodiesel?

A. One bushel equals approximately 1.5 gallons of biodiesel

Q. Have any oil burner manufacturers certified biodiesel for use in their products?

A. At this time no oil burner, boiler or fuel pump manufacturer has approved biodiesel for use in home or commercial oil applications. However with several years of field and laboratory studies well documented, the National Oilheat Research Alliance organization has continued to embrace an inclusion of 5% biodiesel as a blend stock into number two heating oil. The inclusion of biodiesel in heating oil has no drawbacks relating to combustion; however, in storage higher percentages of biodiesel has a similar drawback such as expeditious cleaning of dirty oil tanks, sedimentation formation from copper lines (which are common throughout the heating oil industry) and seal compatibility in the oil burner sealing compounds. At this time the National Biodiesel Board is working closely with NORA, burner, boiler and pump companies to arrest each of their concerns enabling safe usage of biodiesel as a heating oil blending stock.

Q. How do I become a Certified Bio-Diesel Marketer and what are the requirements? Who are the current marketers?

A. Contact the National Biodiesel Board at 800-841-5849 for instructions on how to apply and be approved for this status. You may also view existing suppliers at under buying biodiesel.

Q. I am a petroleum marketer, is there any incentive or credit to encourage me to start up a biodiesel program in my area?

A. See for information about federal and state incentives. Biodiesel affords you an opportunity to offer your customers a cleaner burning environmentally friendly liquid fuel option which would enhance your total offering to your valued customers. Visit to learn more about the exciting biodiesel industry.

Q. What if any additives can I add to biodiesel to keep it from gelling this winter?

A. Conventional fuel additives you have become dependent on just don’t perform with B100. My recommendation for attaining winter operability success with biodiesel is to start with the absolute best winterized generic fuel with an additive and kerosene, if necessary, in conjunction with your biodiesel. Just remember a 20% blend of soy biodiesel will impair the blend by only 2-7 degrees Fahrenheit, so work with the base stock and you will avoid any operational problems. One other note is keep your systems free of water, both bottom water and entrained. As you might be aware water freezes at 32F, so you may have great diesel fuel cold flow properties and the fuel still could cause issues if your water is not controlled.

Q. What is transesterfication?

A. It is the refining or processing method which raw soybean oil (or other feedstock) is taken and processed in ASTM D 6751 biodiesel. Biodiesel can be manufactured from vegetable oils, recycled cooking grease, or animal fats. These feedstocks are reacted with methanol in a chemical reaction called transesterfication to form fatty acids methyl esters (FAME). The various feedstock can contain up to 14 different types of fatty acid chains with specific fatty acids and their proportions varying with feedstock.

Q. Do you have any information on the cost of producing biodiesel and on setting up a commercial production facility?

A. Assistance with plant technology/production is outside the scope of NBB activities. We normally recommend that a company contact a biodiesel technology company or biodiesel consulting firm for assistance. See for directory listings.

Q. What is the minimum and maximum flash point of B20?

A. The definition of flash point is the lowest temperature at which the application of the ignition source causes the vapors above the liquid to ignite. Biodiesel flash point can be close to 300F but has been as low as 200F. Diesel fuel on the other hand is rated to be 140F. To determine the actual flash point for B20 you would have to average the blends accordingly or better yet, have the sample professionally tested once blended to determine or validate your calculations. Any ASTM testing laboratory can perform flash point testing.

Q. What is the truth about seals? Does everything need to be Viton?

A. B100 will have a negative impact on Buna and Nitrile seals; however, Teflon and Viton are more suitable for higher blends or neat biodiesel. If you plan on using biodiesel at 20% or under, you most likely will have negligible headaches with sealing compounds. See the NREL Handling and Use Guidelines for more information.

Q. Are there any emission studies of biodiesel blended with ultra low sulfur diesel? I wish to know how biodiesel effects emissions on ULSD.

A. Because ULSD is still not readily available throughout the nation testing documentation with this blend is probably not readily available. I would suggest visiting and using the advanced search engine on the site to seek this type of data, if available. Other than the reduction in sulfur oxides you could really depend on all the testing currently available with 500 ppm sulfur fuel currently in the markets which you operate.

Q. What is the best method to test for storage stability of a B20 blend? Does the acid value number tell you anything useful for B20? What would a typical B20 acid number be?

A. Fuel aging and oxidation can lead to high acid numbers, high viscosity and the formation of gums and sediments that clog filters. If the acid number, viscosity or sediment measurements exceed the limits in ASTM D 6751, the B100 is degraded to the point where it is out of specification and should not be used. Most B20 fuel could be a candidate for use of stability additives if fuel is being stored in excess of six to eight months. As biodiesel and biodiesel blends are stored the acid number tends to increase and go out of specification, gums and varnish can form and the viscosity can increase. The ASTM standard to evaluate acid value is ASTM D664 and Kinematic Viscosity, ASTM D445.

Q. What can you tell me about micro-organisms and biodiesel fuel? Does it cause black, stringy gunk in a fuel tank? How can it be avoided?

A. I can tell you that if you keep your fuel systems (diesel fuel, kerosene and biodiesel fuel) free of water then you will have no incidence of microbial contamination. Before bugs can become an issue, water must be present along with warmer temperatures. For the record biodiesel is no more an incubator for microbes than any other fuel left unprotected from water contamination. Water can enter through the vent cap, in the fuel itself and through the delivery process. Micro-manage your fuel for water before and after each delivery and execute at a bare minimum a quarterly fuel management program which will help you have a positive experience with your liquid fuels in general.

Q. Recently two purchases of B20 in the Denver area marked B20 were not biodiesel, only generic diesel. Where is the standards process at this time? Dealer was subsequently stripped of all B20 signs by the suppler.

A. It is unfortunate that you have experienced this situation. BQ9000 which is the biodiesel quality certification program is voluntary as you may be aware and at this time only one registered fuel supplier has committed to applying for certification. It appears with the tax incentive now in place you will see more and more suppliers taking the initiative to follow this supplier lead. With many years of petroleum experience behind me I must advise you that the BQ9000 program like ASTM D 975 quality standards is just one element of our industry that you must be cognizant of. The fact is you can have two fuels meeting quality specifications but are not blended properly which was the case in this circumstance which is just plain embarrassing. My suggestion is that you work cooperatively with your suppliers to make sure they are aware of BQ9000 protocols and work towards adhering to them. Human nature plays a big role in this probably as much as accessing quality diesel fuel or biodiesel. Good work in observing what you did and I’m sure you will see marked improvement from the mutual industries that offer biodiesel to the end-user.

Q. Can you tell me the problems with B100 and yellow metals? Are there any modifications someone can make in order to run it in your home heating oil system?

A. Use of tanks or lines made of brass, bronze, copper, lead, tin or zinc may cause high sediment formation and promote filter clogging. They are not recommended with B100, or for that matter generic heating oil as well. This is why additive companies are including metal deactivators in premium heating oil packages to tie up the yellow metals so as not to accelerate corrosive act ivies within the storage tanks which the fuel is stored.

Blends of 5% up to 20% are less of an issue but this is one area that NBB is working on to evaluate the impact of yellow metals with biodiesel. Unless you are prepared to pretty much change your oil lines from copper to stainless, your fuel pump seals to Viton or Teflon I would suggest sticking with B5 as a minimum to a max of 20% biodiesel. There is a comprehensive overview of heating oil and biodiesel at for your review.

Q. I have heard that biodiesel has 300 percent more lubricity than petroleum diesel. Is this true and if so where can I get information sources to back it up?

A. Biodiesel is a well known lubricity enhancer. Go to and type in lubricity and you will be recipients of reams of data on the subject. Small amounts of biodiesel as low as 2% can increase a fuels lubricity up to 65%.

Q. We have been told by some that biodiesel is more corrosive for storage tanks over time than traditional diesel fuel. Is this true and if so why?

A. This is not true. Both diesel fuel and heating oil as well as biodiesel (independently or blended as one fuel) are all susceptible to numerous fuel quality deficiencies. In short, if fuel systems have water ultimately the diesel fuel user will face microbiologics, corrosive activity and fuel instability. The number one contaminant in fuel is water and it is very important that you make sure if water is in a fuel tank that you immediately get rid of it. Biodiesel is no more a driver in this phenomenon than diesel fuel itself.  For more information, see the NREL Handling and Use Guideliness document, as it does a great job addressing issues such as this.

Q. If we blend clear biodiesel into dyed diesel will it change the federal dye concentration specification?

A. IRS regulations (26 CFR 48.4082-1) require that all non-taxed diesel and kerosene be dyed with the dye solvent red 164 (and no other dye) at concentration spectrally equivalent to at least 3.9 pounds of the solid dye standard solvent red 26 per thousand barrels of diesel fuel or kerosene or any dye of a type and in a concentration that has been approved by the commissioner. Without actually performing dye concentration or lack of it would be purely guess work which is strongly not recommended when dye concentration penalties are at stake. Bottom line all clear product necessitating dye be dyed and at the recommended IRS declared values as shown above.

Q. What is the difference between Biomass-based diesel fuel vs. other renewable diesel fuels?

A. All biodiesel fuels are biomass based. The difference between biodiesel, renewable biodiesel and synthetic diesel is as follows. Renewable Diesel is not made through a chemical reaction it is refined much like crude oil and it produces a fuel identical to petroleum based. It is very expensive to produce and shares many of the feed stock limitations as biodiesel. Synthetic diesel or BTL biomass to liquid is similar to ethanol production, it also is very expensive and complex to produce but utilizes many feedstock products that we currently throw away.

Q. How about the DSE additive I see advertised? They say it works with no processing. Please, explain.

A. I am aware of Diesel Secret, however it is a proprietary product and I really do not know how it works. This is not revealed on the Diesel Secret web site. It simply states the additive (chemical) known as Diesel Secret is added to WVO and it chemically transforms the WVO into a biomass product.

Q. Which marine diesel engine manufacturers have approved biodiesel as a fuel for their engines?

A. If you go to the Biodiesel web site home page ( look under the USING BIODIESEL tab and OEM Information. There is an OEM Statement document that lists all of the OEM recommended and approved biodiesel blends by OEM.

Q. I am interested in getting started making biodiesel and selling it commercially. Where's the "best" information?

A. I would suggest contacting the NBB office at 1-800-841-5849.

Q. What are the best references for tracking the cost of biodiesel and biodiesel blends?

A. I would suggest trying:
Alternative Fuels Index
Jacobsen's Publishing
ICIS Pricing (
BiofuelsConnect Biodiesel Price Sheet (
Ethanol and Biodiesel Commentary-Biofuel Markets Daily (
Argus Biofuels (
US DOE Alternative Fuels Price Report
USDA Bioenergy Market News Report