The Pros and Cons of Running Your Vehicle on Biodiesel

the pros and cons of bio-diesel

Help save the world. It’s a message we hear every day and while it is a noble idea, there are definite things that should be considered before choosing to run your vehicle on biodiesel.

Our desire to continually increase engine performance while also reducing exhaust emissions, has created new generations of diesel fuel injections systems that meet government legislated emissions targets. With an increase in performance, there is a correlating increase in operating temperature and pressures, as well as reduced clearances. Maintaining these critical tolerances requires a minimum standard of fuel quality, both to achieve emissions compliance and to ensure reliable operation of your diesel vehicle.

While the manufacturers of diesel fuel injection equipment certainly support the development of alternative fuel sources by engineering components compatible with biodiesel fuels, many vehicles are simply not designed to run on alternative fuels.

It is becoming easier for the end-user to access biofuels. In Canada, Europe and the United States, these fuel sources include rapeseed methyl ester (RME), soybean methyl ester (SME), palm oil methyl ester (PME). These, as well as a few others, are collectively known as fatty acid methyl esters or FAME. FAME fuel sources are being used as alternatives and ‘extenders’ to add to mineral oil derived fuels.

It is important to understand that the chemical and physical characteristics of biofuel components are very different from conventional fuels and great care must be taken in their use. Here are several things to consider:

FAME STABILITY

The long-term stability of FAME is of a particular concern. Aged or poor quality fuel sources contain organic acids (like formic acid) and polymerization products. These acids actually attack many engine components leading to plugged filters, sediment build-up and a stickiness to moving parts; drastically reducing the life of a fuel system.

FAME IMPURITIES

As FAME is being produced from an ever increasing number of new feedstocks, there is potential for additional impurities to be “hidden” until the vehicle is in operation. An additional point of concern is that the minor components of FAME with higher molecular weight may lead to filter plugging. Furthermore, FAME additive with interacting chemistries could create undesireable results.

FAME COMPATIBILITY

There are also compatibility and performance issues on older vehciles that were manufactured before the use of FAME was considered. As FAME concentrations increase so do issues with filters, hoses, gaskets and seals which are most commonly affected by swelling or distorting.

Bio-diesel fuel does not like long periods of inactivity. This is especially applicable to equipment that has seasonal usage such as harvesters, emergency generators and even vehicles being exported overseas. For this reason, FAME-free fuel is highly recommended for a “first fill” or during extended periods of inactivity.

BIO-DIESEL HYGROSCOPIC

Diesel fuel is highly hygroscopic which means it is able to easily absorb water from moisture in the air. We all know that water contamination in diesel fuel is a major concern because it leads to corrosion of the steel components as well as the potential for microbial growth in the fuel tanks. Water contamination of bio-diesel is very common as it absorbs water at x100 the rate of regular mineral based diesel. For this reason, it is critical that a fuel filter with a water-separator be installed to remove moisture from the system.

MICROBIAL GROWTH

Microbial growths that occur naturally in diesel fuel can form a layer of organic debris that, as the fuel ages, attaches itself to the inside of the fuel tank or storage. They flourish by living in or around the water line and feed off the rich hydrocarbons present in the asphaltene layer of the fuel. Be aware: adding fresh fuel to a contaminated fuel supply accelerates the development of these growths; they may break away from the sides and float freely in the fuel, clogging fuel lines or filters.

REPOLYMERIZATION AND OXIDATION

These are the natural processes by which diesel molecules lengthen and bond, producing varnishes and insoluble gums. These particles then drop to the bottom of the tank to form asphaltenes or “diesel sludge”.

The North American standards for bio-diesel (B0 to B5) do not contain mandatory stability requirements and the standards for B6 to B20 blends (and for pure FAME) do not include sufficient stability safeguards.

The manufacturers of modern fuel injection equipment do not agree with the use of un-esterified plant oil (waste veggie oil – WVO), even when this fuel meets existing national standards.

The bottom line:  you CAN run your diesel engine on bio-fuel, but there are a lot of caveats to be aware of:

  • THE PROs
  • • Reduced emissions
  • • Abundant lubricity
  • • Gasket and seal reaction and/or distortion
  • • Lower BTUs of energy from bio-diesel
  • • Organic acids can attack engine components
  • • Additional water-separator filter is required
  • • Increased filter change intervals
  • THE CONs
  • • Poor long-term storage stability
  • • High water absorption rate promotes algae growth
  • • Gasket and seal reaction and/or distortion
  • • Lower BTUs of energy from bio-diesel
  • • Organic acids can attack engine components
  • • Additional water-separator filter is required
  • • Increased filter change intervals

So… when you consider all these variables, are you actually reducing your carbon footprint? Or, in reality, will you end up spending more money on maintenance in an effort to increase reliability and engine life?

So, will you be running your vehicle on biodiesel?

The decision is yours.

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