Biodiesel

Biodiesel is a petrodiesel replacement fuel that is manufactured from vegetable oils, recycled cooking greases 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.

You get 3.4 units of fuel energy from biodiesel for every unit of fossil energy used to produce the fuel.  Substituting biodiesel for petrodiesel reduces life-cycle carbon dioxide emissions by 78%. Engine manufacturers depend on lubricity to keep moving parts, especially fuel pumps, from wearing prematurely. Even 2% biodiesel can restore adequate lubricity to dry fuels such as kerosene and low petrodiesel. 

And last, but maybe not least, the biggest benefit to using biodiesel is that it is easy. In blends of B20 (20% biodiesel and 80% petrodiesel) or less, it is literally a “drop in” technology. No new equipment and no equipment modifications are necessary.

Using Biodiesel
Biodiesel blends of 20 percent and below will work in any diesel engine without the need for modifications.  These blends will operate in diesel engines just like petroleum diesel.  If the blend has been properly treated by the petroleum company, it will work year round, even in cold climates.  B20 also provides similar horsepower, torque, and mileage as diesel.
There are a few PRECAUTIONS to take when making the switch to B20:

Biodiesel Feedstocks
The predominant biodiesel feedstock used in the United States is soybean oil. Other vegetable oils, such as corn, cottonseed, canola (rape seed), palm, sunflower, flax, and peanut, also can be used.  Animal-derived products such as tallow, choice white grease (lard), poultry fat and yellow grease are also triglycerides and are used as a biodiesel feedstock.

There is a substantial amount of research and development into new biodiesel feedstocks such as jatropha and algae.  algae have emerged as one of the most promising sources especially for biodiesel production, for two main reasons (1) The yields of oil from algae are orders of magnitude higher than those for traditional oilseeds, and (2) Algae can grow in places away from the farmlands & forests, thus minimizing the damages caused to the eco- and food chain systems. There is a third interesting reason as well: Algae can be grown in sewages and next to power-plant smokestacks where they digest the pollutants and give us oil!

The third main source of triglycerides is recycled oil and grease, usually from restaurants and animal food processing plants. Although more pre-treatment is required for this feedstock compared to virgin vegetable oils, economically it can be a very attractive feedstock. The use of a recycled product such as used cooking oil is an environmentally friendly process since it solves a waste disposal problem.

Market Drivers
The EPA mandate to reduce sulphur in transportation diesel fuel from 500 parts per million (ppm) to 15 ppm causes lubricity problems in diesel fuel injection systems. Adding 1 to 3 percent biodiesel to the petroleum diesel can restore the lubricant qualities of the fuel. Based on approximately 35 billion gallons of diesel fuel used in over-the-road transportation, this addition, using a B2 blend, would require 700 million gallons of biodiesel just for this program. This represents 500 million bushels of soybeans (based on 1.4 gallons/bushel).

Other biodiesel market drivers such as the Energy Policy Act, Renewable Fuel Standard Two (RFS2), energy bill and various environmental programs—for school buses, marinas, ski lifts, etc.—will continue to influence biodiesel consumption.   RFS2 targets the use of biofuels to increase from approximately 12 billion gallons in 2009 to 36 billion gallons in 2022.  However, the big looming potential for biodiesel is the use of biodiesel blends for transportation fuel. Minnesota has a B5 mandate (5% biodiesel) year around and a B20 mandate (20% biodiesel) in the summer.  Other states and regions are considering similar mandates.

Processing Considerations
All biodiesel feedstocks, including soybean oil, require some amount of pre-conditioning, often chemical refining, before being processed into biodiesel. For example, crude soybean oil must be degummed to remove sources of phosphorous, which degrades the catalysts employed in biodiesel production.

Free fatty acids should also be removed from the feedstock before transesterification, especially if recycled cooking oils, which are high in free fatty acids due to their exposure to high temperature during frying, are used. Free fatty acids are corrosive, and therefore hard on fuel storage facilities, fuel systems and engines. ASTM standards set forth tight tolerances on the allowable levels of free fatty acids in biodiesel.

A common approach for removing free fatty acids from the feedstock is via acid catalyzed esterification in the presence of methanol. This converts the free fatty acids to methyl esters (e.g., biodiesel). Acid esterification equipment requires the use of stainless steel equipment due to the corrosive nature of the process.

Crude oil from a crushing operation also may be pre-treated by caustic refining to remove free fatty acid. The soapstocks generated in this step are then removed by washing the oil with hot water. The oil must be dried to remove the water before transesterification, since water inhibits the biodiesel-producing reaction.

Useful Links
NBB is the national trade association representing the biodiesel industry
http://www.biodiesel.org/            

A very good source to learn about biofuels in general and biodiesel specifically. http://www.afdc.energy.gov/afdc/fuels/biodiesel.html        

List of publications about biodiesel
http://www.afdc.energy.gov/afdc/fuels/biodiesel_publications.html

New Holland Web Page about biodiesel use in their products.
http://agriculture.newholland.com/us/en/information-center/Biodiesel-Support/Pages/default.aspx

John Deere Web Page about biodiesel use in their products.
http://www.deere.com/en_US/rg/infocenter/biodiesel/index.html


The Biodiesel Standard (ASTM D 6751)
All engines are designed and manufactured for a fuel that has certain characteristics. In the US, the industry organization that defines the consensus on fuels is the American Society for Testing and Materials (ASTM). In the case of diesel fuel (and biodiesel), the responsibility for setting standards lies within ASTM Committee D02 on Petroleum Products and Lubricants. In order to assure that the standards are rigorous and robust, ASTM committee D02 is comprised of fuel producers, engine equipment manufacturers, and third party interests (users, government agencies, consultants). ASTM also uses a complicated ballot process in which a single negative vote is enough to defeat a ballot, so this is a true consensus organization. An ASTM standard is not easily achieved. Some standards can take over 10 years to gain agreement and be issued by ASTM. This rigorous, time-consuming process is why ASTM standards are recognized and adopted by others worldwide.
ASTM fuel standards are the minimum accepted values for properties of the fuel to provide adequate customer satisfaction and/or protection. For diesel fuel, the ASTM standard is ASTM D 975. All engine and fuel injection manufacturers design their engines around ASTM D 975. In cooperative discussions with the engine community early in the biodiesel industry's development, engine manufacturers strongly encouraged the biodiesel industry to develop an ASTM standard for biodiesel fuel which would allow them to provide their customers with a more definitive judgment on how the fuel would affect engine and fuel system operations compared to ASTM D 975 fuel for which an engine was designed.
In June of 1994, a task force was formed within ASTM Subcommittee E on Burner, Diesel, Non-Aviation Gas Turbine, and Marine Fuels of ASTM Committee D02, with the expressed objective of developing an ASTM standard for biodiesel. The biodiesel standard, ASTM PS 121-99, was approved by Subcommittee E, and subsequently issued by ASTM in June of 1999 (for copies, see the ASTM web site at www.astm.org). In December of 2001, ASTM approved the full standard for biodiesel, with the new designation of D-6751 (succeeds PS 121-99). This standard covers pure biodiesel (B100), for blending with petrodiesel in levels up to 20% by volume. Higher levels of biodiesel are allowed on a case-by-case basis after discussion with the individual engine company, since most of the experience in the US thus far has been with B20 blends.