Vegetable Oil Used as a Fuel

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Many vegetable oils have similar fuel properties to [Diesel fuel], except for higher viscosity and lower oxidative stability. If these differences can be overcome, vegetable oil may substitute for #2 Diesel fuel, most signicantly as engine fuel or [home heating oil].

For engines designed to burn #2 diesel fuel, the viscosity of vegetable oil must be lowered to prevent poor atomization of fuel, incomplete combustion, carbon buildup and ultimately damage to the engine. Many enthusiasts refer to vegetable oil used as fuel as Waste Vegetable Oil (WVO) if it is oil that was discarded from a restaurant or Straight Vegetable Oil (SVO) to distinguish it from [[1]].

Contents

History

The first known use of vegetable oil as fuel for a diesel engine was a demonstration of an engine built by the [Otto company] and designed to burn [mineral oil], which was run off of pure [peanut oil] at the [1900 World's Fair]. While there is no record of [Rudolph Diesel], himself, ever experimenting with the use of vegetable oil as a fuel for his engines, he was certainly aware of the possibility. In a 1912 presentation to the British [Institute of Mechanical Engineers], he cited a number of efforts in this area and remarked, "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."<ref>Knothe, Gerhard. "Historical Perspectives on Vegetable Oil-Based Diesel Fuels." Inform. 12, 11 (2001): 1103-1107. http://www.biodiesel.org/resources/reportsdatabase/reports/gen/20011101_gen-346.pdf</ref>

Application and usability

While engineers and enthusiasts have been experimenting with using vegetable oil as fuel for a diesel engine since at least 1900, in all the literature, only one peer reviewed study exists that compares long term use of vegetable oil and #2 Diesel as a fuels which shows no noticeable difference in rate of deterioration of the engine burning vegetable oil, for one particular model of engine, the German [Deutz] F3l912W .<ref>Hawkins, C.S.; Fuls, J.; and F.J.C. Hugo. "Engine Durability Tests with Sunflower Oil in an Indirect Injection Diesel Engine." SAE Paper 831357.</ref>

Most diesel car engines are suitable for the use of SVO with modifications. One common solution is to add an additional fuel tank, one for SVO and a separate tank of diesel ([petrodiesel] or [biodiesel]) and a three way valve to switch between them. The viscosity of the SVO is reduced by preheating it using heat from the engine or electricity; the engine is started on diesel, switched over to vegetable oil as soon as it is warmed up and switched back to diesel shortly before being switched off to ensure it has no vegetable oil in it when it is started from cold again. In colder climates it is often necessary to heat the vegetable oil fuel lines and tank as it can become very viscous and even solidify. Another common solution (the one-tank system) is to add electric pre-heating of the fuel and if necessary upgrade the injection pumps and glow-plugs to allow SVO fuel use with one tank.

With unmodified engines the unfavourable effects may be reduced by blending, or "cutting", the SVO with diesel fuel; however, opinions vary as to the efficacy of this. Some WVO mechanics have found higher rates of wear and failure in fuel pumps and piston rings due to partially-combusted WVO/SVO droplets carbonizing in those components. For normal use, without either blending or a second tank and associated modifications in a petrodiesel engine, vegetable oil has to be [transesterification|transesterified] to [biodiesel].

Properties

The main form of SVO used in the UK is rapeseed oil which has a freezing point of -10°C, however the use of sunflower oil which freezes at -17°C is currently being investigated as a means of improving cold weather starting. Unfortunately oils with lower gelling points tend to be less saturated (leading to a higher [iodine number]) and polymerize more easily in the presence of atmospheric oxygen.

[Cetane number] (combustion quality) is highest with coconut oil, palm stearine, palm kernel, palm oil, palm oleine, lard and tallow. Coconut oil, palm oil, palm stearine, tallow and lard have the lowest iodine numbers.

Examples

Some Pacific island nations are using [coconut oil] as fuel to reduce their expenses and their dependence on imported fuels while helping stabilize the coconut oil market. Coconut oil is only usable where temperatures do not drop below 17 degrees Celsius (62 degrees Fahrenheit), unless two-tank SVO kits or other tank-heating accessories, etc. are used. Fortunately, the same techniques developed to use, for example, Canola and other oils in cold climates can be implemented to make coconut oil useable in temperatures lower than 17 degrees Celsius. operational expertise

Taxation of fuel

Taxation on SVO as a road fuel varies from country to country, and it is possible the revenue departments in many countries are even unaware of its use, or feel it sufficiently insignificant to legislate. Germany offers 0% taxation, resulting in their leading on most developments of the fuel use. There seems to be no clear taxation system in the USA, however given the low rate of fuel taxation, it is unlikely to face anything unfavourable, although charges could vary from state to state. In Ireland a pilot scheme is currently running (as of April 2006) whereby eight suppliers have been approved to sell SVO for use as a fuel without the payment of excise duty (VAT at 21% still applies, SVO from any other source still attracts exise duty at 36.8058 cents per litre plus 21% VAT). Despite its use being common in France, it would appear there has been no legislation to cover this.

In the UK, drivers using SVO have been prosecuted for failure to pay duty to Her Majesty's Revenue and Customs. The rate of taxation on SVO was originally set at a reduced rate of 27.1p per litre, but in late 2005, HMRC started to enforce the full diesel excise rate of 47.1p per litre. HMRC argued that SVOs on the market from small producers did not meet the official definition of "biodiesel" in Section 2AA of The Hydrocarbon Oil Duties Act 1979 (HODA), and consequently was merely a "fuel substitute" chargeable at the normal diesel rate. Such a policy seemed to contradict the UK Government's commitments to the Kyoto Protocol and to many EU directives and had many consequences, including an attempt to make the increase retrospective, with one organisation being hit with a £16,000 back tax bill. Such a change in the interpretation of excise duty effectively makes use of SVO in the UK nonviable by all but environmentalists, as the combined price of SVO and taxation for its use considerably exceeds the price of mineral diesel. HMRC's interpretation is being widely challenged by the SVO industry and the UK pure Plant Oil Association (UKPPOA)has been formed to represent the interests of people using vegetable oil as fuel and to lobby parliament. http://www.ukppoa.org.uk/ <ref>Source: http://www.biomotors.co.uk/fuel-duty.html</ref>

Home heating

Success adaptation of the residential gun-style burner, common to most US homes, to burn waste veg oil, was established in 2001 by Jesse Parris and Eric Klatt in New England. (Source Yahoo Forums, altfuelfurnace). A Yahoo forum group altfuelfurnace was establish at the time and formed to share all the information with members. This is the only current forum where the conversion and adaptation of the gun-style burner is shared freely with any member who wants to build a veg oil burner to burn either waste veg oil or setup an oil burner to run on biodiesel. The forum has over 5000 members now, is global and has groups of members who help other get started on getting off the dependence of petroleum.

The modification to the common gun-style oil burner is more complex and expensive than setting up the burner to run on biodiesel. In warmer climates, such as the South, the only modification for biodiesel can be as simple as increasing pump pressure and giving the burner more air. In colder climates, it as simple as adding a small preheater to the nozzle. The setup for waste veg oil entails adding a compressed air source, a pre-heater to bring the oil, and the compressed air up to the desired temperature to ignite and burn the filtered waste veg oil, a temperature controller and a couple of solenoids to start and stop the air and the oil.

Waste vegetable oil has been established to burn as clean or cleaner than home heating oil, based on a correct setup of the burner compared to a home heating oil setup burning at optimally. Waste veg oil burns as hot or hotter per btu as home heating oil. (Source: altfuelfurnace)

Many restaurants will give away their used cooking oil either free or at minimal cost, and processing to biodiesel is fairly simple and inexpensive. Biodiesel is the easiest of the two to use as a replacement for home heating oil, but making biodiesel adds an extra step to the process. (See: How to Make Biodiesel) Burning waste veg oil requires a conversion of the oil burner to pre-heat both the oil and the air to work properly Either can be accomplished with a bit of ingenuity. WVO has now been firmly established as a very economical heating option for those with a mechanical inclination and the drive to put a little work into it.

Simple Pipe Burner

Another type of burner that can be used for home heating is a simple Pipe Burner.

A Black Pipe vaporizing burner works well for a corn or pellet stove. The pipe burner just sits over the fire pot and vaporizes or gasifies the oil. Just start with the pellets and then let the stove get hot with the pipe burner in position. Once the burner is hot allow the oil to feed into the burner slowly. The oil vaporizes in the burner and ignites as if it was a gas burner. To save pellets and keep warm on WVO just turn the pellets to low, but leave the blower on high.

Although the pipe burner is simple to build, there has been enough interest to offer them online.

Pipe Burner Website: http://jommy99.webs.com/

Various WVO Videos: http://www.youtube.com/jommy99

Availability of Fuel

Waste Vegetable Oil

As of 2000, the United States was producing in excess of 11 billion liters of waste vegetable oil annually, mainly from industrial deep fryers in potato processing plants, snack food factories and fast food restaurants. If all those 11 billion liters could be collected and used to replace the energetically equivalent amount of petroleum (a rather utopical case), almost 1% of US oil consumption could be offset. Template:Citation needed However, usage of waste vegetable oil as a fuel competes with already established usages.

Pure Vegetable Oil

Pure vegetable oil, in contrast to waste vegetable oil, is not a byproduct of other industries, and thus its prospects for use as fuel are not limited by the capacities of other industries. The production of vegetable oils for the purpose of fuels is theoretically limited only by the agricultural capacity of a given economy.

Legal Implications

The conversion of an automobile engine to burn vegetable oil is not currently legal under US Environmental Protection Agency guidelines. The EPA has not fined anyone for doing so, but certain laws may have to change - or a certification process may need to be established - before VO conversions become more popular in the United States. (See a recent New York Times article on the subject: [2])

Further reading

  • From the Fryer to the Fuel Tank by Joshua Tickell ISBN 0-9707227-0-2 Published by Greenteach.
  • Sliding Home: A Complete Guide To Driving Your Diesel On Vegetable Oil by [Ray Holan]

References

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External links

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