Rudolf Diesel, in 1912, at a presentation given to the British Institute of Mechanical Engineers, stated "The fact that fat oils from vegetable sources can be used may seem insignificant today, but such oils may perhaps become in course of time of the same importance as some natural mineral oils and the tar products are now."
Most people think that the use of waste or fresh vegetable oil is a new phenomenon, but the reality is that this has been in use for quite some time. The use of vegetable oil as a fuel is appealing to many because it frees them of the reliance on petroleum and gives them a sense of independence.
There is tremendous confusion, however, over the use of vegetable oil in diesel engines. For example, there is biodiesel, recycled vegetable oil, and straight vegetable oil; all different in properties and how the engine reacts to the fuel. Whichever fuel is selected, vegetable oil pollutes less, and is therefore favored by environmentalists. It is also sustainable because vegetable oil can come from a myriad of sources, including, but not limited to corn, oil palm, soybean, safflower, peanut, and a number of other plants.
Types of Vegetable Oil
There is a lot of confusion surrounding vegetable oil. What is it? How is it used? Are there any adverse effects resulting from its use? These are all good questions. However, before all of those questions are addressed, the difference between the types of vegetable oil needs to be understood.
The most prominent use of vegetable oil is biodiesel, which is typically sold as B20, 20% vegetable oil and 80% diesel. The second most widely used vegetable oil is oil that is sought from fast food joints that would rather give away their oil to people that use it as a fuel than to pay to have it recycled. Lastly, there is straight vegetable oil. Straight vegetable oil is vegetable oil that is produced from plants grown for the sole purpose of creating a fuel.
Vegetable Oil Issues
The major issue with vegetable oil are the properties. Vegetable oil is much more viscous than diesel, on the order of 11 to17 times. According to Biodiesel.org, there are some adverse effects that occur as a result of using vegetable oil as a fuel due to its high viscosity, its reactivity to oxygen, and its higher pour and cloud points.
It is reported that the use of vegetable oil causes reduced engine life due to the build up of carbon deposits and the mixing of vegetable oil with the lubricant. The number one technique employed to battle the high viscocity found in vegetable oil is to pre-heat the oil, therefore reducing its viscosity to an acceptable level.
Sources of Vegetable Oil
The most interesting aspect surrounding the use of vegetable oil is the fact that it seems as if there are an infinite number of vegetable sources for extracting oil from. However, not all sources are the same in terms of the oil output. Corn, for example, only yields 18 gallons/acre, while oil palm yields 635. This is an obvious and huge difference. The issue at hand is that not all vegetables can be grown in all climates, therefore giving certain geographic climates a distinct advantage in terms of growing capability, and subsequently manufacturing capability of vegetable oil fuel.
Given all that is known about using vegetable oil as a fuel, either straight, or as a mixture of diesel and vegetable oil, it can be seen that the advantages far outweigh the disadvantages. Despite the high viscosity of vegetable oil, it has many highly desirable characteristics, particularly in the area of emissions. When compared to emissions from diesel fuel, vegetable oil pollutes less hydrocarbons, carbon monoxide, and particulate matter. This is an alternative fuel that should be watched closely in the years to come as it is a top contender in the race for the next fuel to replace petroleum.
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