Biodiesel Frequently Asked Questions

Question

What is biodiesel?

Answer

Biodiesel is made from vegetable oils, recycled cooking greases or oils, or animal fats. The manufacturing process, called transesterification, separates the oils or fats into two products: methyl esters (biodiesel) and glycerin (used in soaps).

   

Question

Technical Definition:

Answer

Biodiesel, n – a diesel fuel composed of mono-alky esters of long chain fatty acids derived from vegetable oils or animal fats, designated B100, and meeting the requirements of ASTM (American Society for Testing & Materials) D 6751.
-Source: http://www.nbb.org/resources/definitions/default.shtm

   

Question

What are the benefits of biodiesel?

Answer

  • Biodiesel reduces global warming gas emissions such as carbon dioxide (CO2) and tailpipe particulate matter (PM).
  • Biodiesel improves lubricity. Even low level blends such as 2% can improve lubricity of diesel fuel for the on-road market.
  • Biodiesel is easy to use. No new equipment or modifications are necessary in vehicles.
   

Question

What are the drawbacks of biodiesel use?

Answer

Biodiesel (B100) has less favorable cold flow properties compared to conventional diesel. Both conventional diesel and biodiesel can start to freeze or gel as the temperatures get colder. If the fuel gels, it can clog filters and eventually become thick enough that it cannot be pumped from the fuel tank to the engine. Biodiesel blends of 5% or less have very little impact on cold flow. Be sure the biodiesel blended fuel will meet the cold flow properties adequate for the climate and time of the year the fuel is going to be used.

   

Question

How does biodiesel affect a vehicle engine performance?

Answer

Biodiesel blends of 20% or less should not change the engine performance. Some users have noticed reductions in soot, and carbon monoxide (CO) and hydrocarbon (HC) emissions.

   

Question

Does a vehicle need to be modified to use biodiesel?

Answer

No vehicle modifications appear to be necessary for blends of biodiesel up to 5% or B5. 20% blend (B20) or higher may require modifications.

The solvency effect of biodiesel may cause the release of deposits on a vehicle’s fuel tank walls or pipes. These deposits may end up in the fuel filters and cause the filters to plug. Fuel filter should be checked more frequently during the initial use of biodiesel.

   
Question

Does biodiesel use void my engine warranty?

Answer Biodiesel use in existing diesel engines does not void parts and materials workmanship warranties of any major U.S. engine manufacturer. Most major engine manufacturers have approved the use of up to 5% biodiesel blends. Check with your engine manufacturer for more details.
   
Question

Does dispensing equipment need to be modified to use biodiesel?

Answer

No modifications need to be made on biodiesel blends of 20% biodiesel or lower. However, some elastomers are not compatible with B20 blends or higher.

   
Question

Does biodiesel have a cleaning affect on my diesel fuel storage tank?

Answer

Methyl esters have been used as cleaners and solvents for decades. The methyl esters will tend to dissolve sediments in the tank and fuel delivery system that can eventually plug dispenser filters and vehicle fuel filters.

The level of cleaning depends on the amount of sediment in the tank and the blend level of biodiesel. Storage tanks should be monitored and the frequency of dispenser filter changes may need to increase to counter the solvency effect of the biodiesel fuel.

   
Question

How should I prepare for my retail location for the first load of biodiesel?

Answer
  1. Check tank bottoms. If water and/or sediment are present, pump out the bottoms to assure complete removal.
  2. Prior to the first delivery of the biodiesel blended fuel, it is recommended that proper identification signs are in place at the fuel storage tank, inlet pipes taking product, at the station dispenser, and at the dispenser nozzle handle. These locations should be marked with the special biodiesel symbol showing biodiesel blended fuel is being sold. Please check with your state regulations for labeling requirements.
  3. During every transport delivery, ensure the sump well is free of standing water. This will prevent the entry of water into the underground storage tank.
  4. Maintain a checklist record with a defined periodicity to check the functionality of underground fill pipes, pipe caps, vent valves, and catch basins surrounding the fill pipe openings. Water and dirt should be removed from the catch basin to prevent drainage back into the storage tank.
  5. Testing for free water, acid number, and microbial activity is recommended if product has not turned for a period greater than three months.
   
Question

What do I need to do if I find microbial activity?

Answer

Biodiesel is an excellent food source for microbials. Microbial contamination is caused by living microscopic cells that feed off the hydrocarbons in the fuel and use the water in the fuel as their oxygen source. Once established, microbials can double in population every twenty minutes. Eventually they will form a slime which can clog filters, corrode metal, and cause gaskets and hoses to swell and blister.

Prevention is the key to controlling microbial infestation. Good housekeeping, as mentioned above, and using biocides on a regular basis is a good start to avoiding problems. Biocides are recommended treatment for conventional and biodiesel fuels wherever microbial contamination has been a problem.

   
Question

Is there any benefit to in-line blending versus splash blending?

Answer

In splash blending the biodiesel is loaded into the tank truck first, followed by the diesel fuel. This allows some mixing to occur. The fuel will continue to mix as the truck moves to the delivery point, providing the roads are a bit rough and the route is long enough. Difficulties in mixing can also be encountered if the biodiesel is loaded on the transport first under very cold temperatures. Under these conditions the two fuels may mix poorly or not at all. There is also a risk of potential fuel spill from overflow.

In-line blending uses metered pumps and dual fuel injection system. Blending occurs when the biodiesel is added to a stream of diesel fuel as it travels through a pipe or hose. Mixing is achieved through the turbulent movement through the pipe and when it is loaded into the transport truck. It is the most accurate and reliable system for guaranteeing specific fuel blends and better fuel quality.

   

Comparison of Number 2 Ultra Low Diesel Fuel and Biodiesel

Property ASTM
Method
No. 2
ULSD
100% Soy
Biodiesel
5% Blend
or B5
BTU/US gallon D240 ~138,000 117,000 130,000
Density, 15 C D4052 0.85 0.88 0.85
Vicosity D445 2.7 4.1 2.7
Cetane Number D613 ~45 ~50 45
Total Aromatics D5186 ~30 0 ~28
Cloud Point, ºC Q2500 -15 0 -15

Updated: Friday, January 18 2008