B100 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 (see Table 1) 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. In addition, B100 may permeatesome typical types of plastics (polyethylene, polypropylene) over time and they should not be used for storing B100.
There are other physical or chemical properties where biodiesel is substantially different from petroleum diesel and where these differences provide significant benefits. Biodiesel has significantly lower sulfur than today’s diesel fuel, while providing a significant increase in lubricity.
Most B100 already meets the EPA’s new rule requiring all on-road diesel fuel to contain less than 15 ppm sulfur in 2006. The future 15 ppm diesel—Ultra low sulfur diesel or ULSD—can create lubricity problems as the new refining processes tends to reduce the natural lubricity of diesel. Pure biodiesel, or biodiesel blended with ULSD restores fuel lubricity in levels as low as 1% or 2% biodiesel. Biodiesel also contains 11% oxygen by weight, as well as a slightly higher cetane number, which provides for more complete combustion and a reduction in most emissions.
