I am also interested in biodiesel
From the recent Cummins newsletter:
What Is Biodiesel?
Biodiesel. It’s a term we’re hearing more and more frequently these days, but what does it mean? And, how might biodiesel fuel affect your engine?
Biodiesel is the name for an alternative fuel made from renewable sources such as natural oils like soybean oil. It can also be made from used cooking oil and from animal sources such as tallow. Biodiesel fuel is biodegradable, nontoxic, and essentially free of sulfur and aromatics so it is mostly clean burning.
Although not yet widely available, biodiesel can be found in many areas. It can often be purchased directly from biodiesel producers and marketers as well as many petroleum distributors. There are even biodiesel pumps at gas stations in some parts of the country. Altogether, approximately 23 million gallons of biodiesel were sold in 2003.
Although biodiesel fuel contains no petroleum, it can be blended with petroleum diesel fuel to create a biodiesel blend. The blend is usually referred to with a “B” followed by a number - for example, 100% biodiesel fuel would be referred to as B100. B5 (a blend of 5 percent by volume biodiesel with 95 percent by volume petroleum diesel) has been used in some fleet operations and by consumers. This is perhaps the most readily available blend today. However, other blends are also available such as B2, B10 and B20.
Biodiesel is made from renewable resources so it’s easier on the environment. Compared to petroleum diesel, biodiesel fuel has lower emissions of particulate matter, hydrocarbons (HC) and carbon monoxide (CO). However, biodiesel increases nitrous oxides (NOx) emissions. Most fuel-grade biodiesel is produced to an industry specification (ASTM D6751). It is important to note that this specification does not currently have an oxidation stability requirement which makes it difficult to guarantee the quality of the product over time. The performance characteristics of this fuel have been registered with the Environmental Protection Agency, so it is a legal motor fuel. However, there are other variations of biodiesel fuel available to consumers. This diversity in fuel types complicates the evaluation of biodiesel as an energy source. In general, however, biodiesel provides approximately 10 percent less energy per gallon of fuel when compared to distillate fuels.
Can I Use Biodiesel?
Technically, biodiesel will burn in any diesel engine with little or no modification to the engine or the fuel system. However, neither DaimlerChrysler or Cummins currently recommends the use of biodiesel blends above 5 percent (B5) for a number of reasons. First, biodiesel has a solvent effect. So biodiesel fuel may release deposits accumulated on tank walls and pipes from previous diesel fuel storage. This can clog filters, so precautions should be taken. Water is naturally more prevalent in biodiesel fuels than in distillate fuels, so care must be taken to remove water from fuel tanks. Current water separation filters are not as effective with biodiesel. Biodiesel fuels can also pose low-ambient-temperature problems for both storage and operation due to a higher fuel waxing temperature. Filters can plug, and fuel in the tank can solidify at low ambient temperatures if precautions are not taken. Biodiesel tends to have a negative effect on elastometers which means many gaskets, seals and hoses may be at risk. It can also have a corrosive effect on brass and bronze, which means certain valves and fittings may become compromised. Additionally, biodiesel fuel is an excellent medium for microbial growth. Microbes can cause fuel system corrosion and premature filter plugging.
So how concerned should you be about using a biodiesel fuel? First, keep in mind that there is a major difference between operating on pure (100 percent concentration) biodiesel fuel and biodiesel/petrodiesel fuel blends. In general, it seems that a B5 blend has no negative effects on the engine. A 100 percent blend, however, is a different matter. 100 percent biodiesel fuel is more likely to create the negative effects associated with biodiesel. Blends below 20 percent may minimize some of the potential negative effects, however, this is still under investigation.
DaimlerChrysler is continuously trying to promote the use of properly blended renewable fuels as a means of reducing the nation’s dependence on petroleum. According to DaimlerChrysler, diesel-fueled vehicles can be safely operated on up to 5 percent biodiesel blended in conventional diesel. DaimlerChrysler’s recommendations state that the biodiesel portion of the blend (5 percent) should meet the requirements of ASTM D6751, and the petroleum diesel portion of the blend (95 percent) should meet ASTM D975. Pure biodiesel is not recommended.
The bottom line is that more research needs to be done on biodiesel fuels. Cummins and DaimlerChrysler are actively researching the most common biodiesel fuels and their effect on engine performance, durability and reliability. In addition, Cummins is also currently part of a task force seeking to develop an ASTM stability standard and testing method for biodiesel fuel. It is certainly clear that biodiesel may offer an important fuel alternative for the future.
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