Biodiesel has many uses and can be produced from various starting materials using diverse techniques and processes. Find below a healthy mixture of some helpful introductory and advanced information, as your interests dictate.

 

What is Biodiesel?

Biodiesel is a diesel replacement fuel that is manufactured from vegetable oils, recycled

cooking greases or oils, or animal fats. Because plants produce oils from sunlight and air,

and can do so year after year on cropland, these oils are renewable.

Animal fats are produced when the animal consumes plant oils and other fats, and they too are renewable. Used cooking oils are mostly made from vegetable oils, but may also contain animal fats. Used cooking oils are both recycled and renewable.

The biodiesel manufacturing process converts oils and fats into chemicals called long chain mono alkyl esters, or biodiesel. These chemicals are also referred to as fatty acid methyl esters or FAME. In the manufacturing process, 100 pounds of oils or fats are reacted with 10 pounds of a short chain alcohol (usually methanol) in the presence of a catalyst (usually sodium or potassium hydroxide) to form 100 pounds of biodiesel and 10 pounds of glycerine. Glycerine is a sugar, and is a co-product of the biodiesel process.

 

Note well or Nota bene (N.B.): Raw or refined vegetable oil, or recycled greases that have not been processed into biodiesel, are not biodiesel and should be avoided.

 

Research shows that vegetable oil or greases used in CI engines at levels as low as 10% to 20%, can cause long-term engine deposits, ring sticking, lube oil gelling, and other maintenance problems and can reduce engine life. These problems are caused mostly by the greater viscosity, or thickness, of the raw oils (around 40 mm2/s) compared to that of the diesel fuel for which the engines and injectors were designed (between 1.3 and 4.1 mm2/s).

To avoid viscosity-related problems, vegetable oils and other feedstocks are converted into biodiesel. Through the process of converting vegetable oil or greases to biodiesel, we reduce viscosity of the fuel to values similar to conventional diesel fuel ( biodiesel values are typically between 4 and 5 mm2/s).

 

Registration and Regulation

ASTM International is a consensus based standards group comprised of engine and fuel injection equipment companies, fuel producers, and fuel users whose standards are recognized in the United States by most government entities, including states with the responsibility of insuring fuel quality.

The specification for biodiesel (B100) is ASTM D6751-03. This specification is intended to insure the quality of biodiesel to be used as a blend stock at 20% and lower blend levels. Any biodiesel used in the United States for blending should meet ASTM D6751 standards.

The definition of biodiesel within ASTM D6751 describes long chain fatty acid esters from vegetable or animal fats that contain only one alcohol molecule on one ester linkage. Raw or refined vegetable oils contain three ester linkages and are therefore not legally biodiesel.

 

So, running your engine on Straight Vegetable Oil (SVO) is not advisable, unless you intend to rebuild and clean out your engine and other parts of your equipment on a very-short-notice basis!

 

 

BIODIESEL (B100)

This section will describe the basic properties and blending considerations for B100 fuels. The considerations for storing, handling, blending and using B100 are very different than for B20 or lower biodiesel blends, but for some readers the B100 information may help you further understand B20 use. If you are only interested in using or handling finished B20 or lower biodiesel blends, you may want to skip the B100 section and go directly to the B20 section.

 

B100 has physical and chemical properties similar to petroleum based diesel and can in some cases be used in existing diesel applications with little or no modification to the engine or fueling system. While B100 can be used as a pure fuel in diesel applications, there are important differences between B100 and conventional diesel fuels that must be taken into consideration when handling or using B100. Using B20 and lower blends significantly reduces or eliminates the issues described here (see the following section on using B20).

 

1. B100 is a good solvent. It may loosen and/or dissolve sediments in fuel tanks and fueling systems left by conventional diesel over time. If your system contains sediments, you should clean your existing tanks and fuel system before handling or using B100.

 

2. B100 freezes at higher temperatures than most conventional diesel fuel and this must be taken into account if handling or using B100. Most B100 starts to cloud at between

35°F and 60°F, so heated fuel lines and tanks may be needed even in moderate climates.

As B100 begins to gel, the viscosity also begins to rise, and it rises to levels much higher

than most diesel fuel, which can cause increased stress on fuel pumps and fuel injection

systems. Cold weather properties are the biggest reason many people use biodiesel

blends.

 

3. B100 is not compatible with some hoses and gaskets. B100 may soften and degrade

certain types of rubber compounds found in hoses and gaskets (i.e. buna N, nitrile, natural

rubber) and may cause them to leak and become degraded to the point they crumble and

become useless. This could cause a fuel spill on a hot engine, could ruin a fuel pump, or

could result in filter clogging as the hose material gradually wears away. If using B100,

extreme care should be taken to ensure that any part of the fuel system that touches the

fuel is compatible with B100. Some systems already have biodiesel resistant materials

(i.e. Viton™) but many do not because these materials are usually slightly more

expensive.

 

4. B100 is not compatible with some metals and plastics. Biodiesel will form high

sediment levels if contacted for long periods of time with copper or copper containing

metals (brass, bronze) or with lead, tin, or zinc (i.e. galvanized surfaces). These high

sediment levels may cause filter clogging. Diesel systems are not supposed to contain

these metals, but sometimes they can occur anyway.

USING 20% BIODIESEL BLENDS

This section is focused on blending B100 with petrodiesel to make a B20 blend, but the approach is similar for other blend levels such as B2 or B5. Blending biodiesel into petroleum diesel is a way to minimize these property differences while still retaining some of the benefits of B100. We are not going to repeat the information provided in the B100 section, just elaborate where it specifically applies to blends.

B20 is popular because it represents a good balance of cost, emissions, cold weather performance, materials compatibility, and solvency. B20 is also the minimum blend level that can be used for EPAct compliance for covered fleets.

A blending level above 20% can provide higher emission reduction benefits for CO, PM, and HC; with the impact on NOx depending on the application (increases in most diesel engines, decreases in boiler or home heating applications). Higher blend levels of biodiesel significantly reduce polycyclic aromatic hydrocarbons and other toxic or carcinogenic compounds found in diesel exhaust. High blend levels also promote faster biodegradation should a spill occur. However, at biodiesel levels above 20%, cold flow management is a more significant issue, the cleaning effect is more severe, and hoses and gaskets will be more affected.

 

B20 Cold flow

This is probably the largest concern for blenders and users alike. Blending biodiesel with petroleum diesel moderates cold flow problems by dilution. The blend also makes the use of cold flow additives practical, since these are effective in the petroleum portion of the blend. When biodiesel is blended with diesel fuel, the key variables are the cold flow properties of the diesel fuel you blend with, the properties of the biodiesel, the blend level, and the effectiveness of cold flow additives.

The same is true of diesel fuel. No. 2 diesel fuel may have cloud points that range from –10oF to 10oF on average (some fuels can be higher or lower than these figures). No 1 diesel, jet A, or kerosene may have cloud points that range between –40oF to –60oF.

Blends of No. 1 and No. 2 diesel fuel are frequently used to meet customer cold flow specifications. Adjusting the blend of kerosene (or No. 1 diesel) in the diesel fuel alone or with additives can modify the cloud and pour point temperatures of B20. An accurate estimate of how B20 will perform in the winter months will require mixing the biodiesel with the winter diesel typically delivered in your area and testing the mixture.

Your petroleum distributor or refinery may already be blending No. 1 and No. 2 diesels in the winter, using cold flow additives, or both. So ask your diesel distributor to provide some samples of winter diesel.

 

 

WARRANTY ISSUES

There are a variety of statements about biodiesel use from engine/vehicle manufacturers, including some that make reference to warranty. Engine and vehicle manufacturers provide a material and workmanship warranty on their products. Such warranties do not cover damage caused by some external condition.

Thus, if an engine that uses biodiesel experiences a failure unrelated to the biodiesel use, it must be covered by the OEM’s warranty. Federal law prohibits the voiding of a warranty just because biodiesel was used—it has to be the cause of the failure. If an engine experiences a failure caused by biodiesel use (or any other external condition, such as bad diesel fuel), the damage will not be covered by the OEM’s warranty.

Many engine OEMs are acknowledging biodiesel use by stating their observations about

harmful effects (or the lack of effects) with various blends in their equipment. Most

OEMs declare a lack of harmful effects for B5 and lower blends based on a statement by

the leading fuel injection equipment suppliers, as long as the biodiesel meets D6751

and/or the European biodiesel specification.

Some OEMs recognize higher blend levels. More evaluation is underway in the diesel engine industry related to biodiesel and its effects on diesel engines. Damage directly attributable to biodiesel will not be covered by an engine OEM’s warranty, but should be covered by the fuel supplier’s general liability insurance.

New biodiesel users should be sure that their biodiesel suppliers provide liability coverage on

the biodiesel and its blends. For an updated list of OEMs and their positional statements, visit the National Biodiesel Board Web page at URL http://www.biodiesel.org/.

 

 

TAXES AND INCENTIVES

Biodiesel is not exempt from federal excise taxes, and it is not exempt from most state or local taxes. That means that biodiesel and biodiesel blends are taxed at the same rate as diesel fuel. Some states have passed legislation that either reduces fuel excise taxes or provides other incentives. For local exceptions to this statement, please contact local tax authorities.

The federal government currently offers some incentives related to biodiesel. There are a number of grant programs available, as well as tax credits for blending biodiesel, and investment opportunities in certain refueling infrastructure. DOE’s Clean Cities Program maintains a Web site that summarizes state and local laws and incentives related to alternative fuels. This can be accessed at www.eere.energy.gov/cleancities/vbg/progs/laws.cgi. 

Another good resource for information on federal incentives is the National Biodiesel Board’s Web site at www.biodiesel.org. If you are using biodiesel in a vehicle that uses any public road (B100 or any blend of biodiesel), then you are responsible for remitting federal, state, and local taxes on the fuel, including the biodiesel fraction, to the appropriate agencies in a timely manner.

This requirement applies to biodiesel you make yourself and to B100 that you purchase and use in your own operations. If you are blending B100 that you purchased, and either using the B20 yourself, or selling it to others, you are responsible for remitting the federal, state, and local taxes in a timely way to the appropriate agencies. Most B100 is sold on a pre-tax basis, which leaves the blender responsible for collecting and remitting taxes.

For most commercial blend users, the blenders have already included the taxes owed in the sale price of the fuel. Check your invoice or with your supplier if you have questions. The customer has the responsibility to ensure that the appropriate taxes have been paid.

 

 

INFORMATION RESOURCES

The National Biodiesel Board has compiled an impressive library of online documents

located at http://www.biodiesel.org/resources/reportsdatabase/. It can add detail to these

guidelines. The search engine is set up by market segment. You have to be creative and

use a variety of key words to search on specific non-market topics or call 1-800-841-5849

for information.

The U.S. Department of Energy has some technical documents located at

http://www.eere.energy.gov/biomass/document_database.html.

The EPA has reviewed many emission reports and has summarized them at

http://www.epa.gov/OMS/models/biodsl.htm.

Iowa State University has an online tutorial on biodiesel at

http://www.me.iastate.edu/biodiesel/Pages/biodiesel1.html. They also offer classes in

biodiesel production, analytical test methods, and business management for producers

and marketing firms.

Department of Defense A-A-59693A Biodiesel Commercial Item Description (CID) is

located at http://assist.daps.dla.mil/docimages/0004/29/73/AA59693.PD0 in PDF format.

Also contact your Clean Cities representative, biodiesel suppliers, and others for

information.

 

 

GLOSSARY/DEFINITIONS

 

additive: material added in small amounts to finished fuel products to improve certain properties or characteristics.

antioxidant: substance that inhibits reactions promoted by oxygen aromatic compound: a hydrocarbon based on a six-carbon benzenoid ring

biodiesel: methyl esters of fatty acids meeting the requirements of ASTM specification D6751.

biodegradable: capable of being broken down by the action of microorganisms

boiling range: the spread of temperature over which a fuel, or other mixture of compounds, distills.

cetane index: an approximation of cetane number based on an empirical relationship with density and volatility parameters such as the mid-boiling point. This approximation is not valid for biodiesel or biodiesel blends.

cetane number: a measure of the ignition quality of diesel fuel based on ignition delay in an engine. The higher the cetane number, the shorter the ignition delay and the better the ignition quality.

chelating compound: a fuel additive that deactivates the catalytic oxidizing action of dissolved metals, notably copper, on fuels during storage.

CI: compression ignition, i.e. a diesel engine cloud point: the temperature at which a sample of a fuel just shows a cloud or haze of wax (or in the case of biodiesel, methyl ester) crystals when it is cooled under standard test conditions, as defined in ASTM D2500.

detergent: a fuel detergent is an oil-soluble surfactant additive that maintains the cleanliness of engine parts by solubilizing deposits or materials likely to deposit in the engine fuel system.

dispersant: a surfactant additive designed to hold particulate matter dispersed in a liquid.

elastomer: synthetic rubber-type material frequently used in vehicle fuel systems (but not necessarily natural or synthetic rubber, may also apply to other polymers).

energy content: the heat produced on combustion of a specified volume or mass of fuel, also known as heating value or heat of combustion.

 

SOURCE: http://www.eere.energy.gov