As petroleum fuels costs rise, biodiesel fuel will gain popularity as a less expensive alternative to diesel fuel. But what are the current risks with using this environmentally friendly alternative. Do the advantages outweight the disadvantages?
The Advantages of Biodiesel Looking closely at biodiesel, we find that its physical and chemical properties are very similar to petroleum based diesel fuel in terms of operation in compression ignition engines (diesel engines). Therefore, biodiesel can be used in diesel engines without expensive alterations to the engine or fuel system. Besides the obvious cost savings, some other notable benefits of using biodiesel include the following:
- Biodiesel is biodegradable, non-toxic and essentially free of sulfur and aromatics. Safer to handle and transport
- Fewer noxious emissions than petroleum-based diesel, and virtually eliminating acid rain-causing sulfur dioxide
- Runs in any conventional, unmodified diesel engine
- Improved lubricity
- High cetane number
- Improved conductivity particularly compared to Ultra Low Sulfur diesel fuel
The best advantage is the fact that biodiesel is a renewable fuel source, where petroleum fuels are limited. This alone will be the reason for it's ever increasing popularity.
The Disadvantages of Biodiesel
LOWER ENERGY CONTENT
The energy content of neat biodiesel (100% biodiesel) is about 11% lower than that of petroleum based diesel fuel, resulting in a power loss in engine operation. Engine adjustment for the power losses could lead to violation of EPA anti-tampering provisions. Biodiesel can be blended with petroleum fuel to create biodiesel blends that can minimize the power loss. (Blends are designated as B
xx, where "
xx" is the percentage of biodiesel in the blend. Most generally accepted by engine manufacturers is a B5 blend (5% biodiesel and 95% diesel fuel) or less.
ENGINE OPERATION PROBLEMS
Todays engines are designed to operate with petroleum fuel. Neat biodiesel and higher percentage biodiesel blends can cause a variety of engine performance problems including:
- Fuel filter plugging,
- Injector coking (carbon deposits),
- Piston ring sticking and breaking,
- Elastomer seal swelling and hardening/cracking, and
- Severe engine lubricant degradation.
Studies found injectors and pumps failing at around 50,000 miles with neat biodiesel. There is little information on the use of biodiesel with engine durability over the mileage and operating conditions of heavy-duty diesel engines.
STORAGE and HANDLING
- Long-term storage problems occur from the poor oxidation stability of biodiesel fuels.
- Biodiesel fuel at low temperatures can thicken and plug fuel filters.
- Biodiesel is subject to microbial growth causing operation problems, fuel system corrosion and premature fuel filter plugging.
EMISSIONS
There is little negative to say about biodiesel emissions, except studies found increased nitrous oxide (Nox) emissions with higher concentrations of biodiesel.
BIODIESEL EFFECT ON DIESEL OIL
Biodiesel fuel is very hard on your engine lubricant (oil). The following detrimental effects are noted when concentrations of biodiesel exceed 5%:
- Fuel begins to dilute the oil resulting in a viscosity reduction
- Increased sludge and varnish formation
- Depletion of alkalinity reserve in the oil indicated by total base number (TBN) decrease
- Certain metals such as copper and lead leached from bearings due to biodiesel fuel in the lubricant
- Oil filter plugging from sludge
As a result, most diesel manufacturers recommend cutting their recommended oil drain interval in half when using biodiesel fuel.
SUMMARY
Short oil drain intervals and higher maintenance costs to users of biodiesel still outweigh the benefit of cheaper fuel. As long as auto manufacturers continue to make diesel engines to use petroleum fuels, the disadvantages will continue to outweight the advantages, However, the high cost of petroleum diesel fuel and pressure from environmental groups now has automakers willing to spend research dollars on this issue.
tweet this!