Background

The vegetable oil in its pure form, used as diesel replacement in diesel engines is known as PPO, SVO, JPO. This is  contrary to bio-diesel which is esterified oil, treated with chemical ingredients.

Oil qualities in relation to use in diesel engines.

From first literature research in the project [attachment 1, 2] it became clear that using oil as fuel in diesel engines is not so simple. Various experiments done by people showed that running any diesel engine on oil for 24 hours is not a problem. But problems often occur after that within the first 500 hours in which total breakdowns of engines occurred.

The experiences with rape seed oil, as reported from Denmark and Germany gave good guidelines for JPO.

The variables which might  cause difficulties with JPO are:
  • Much higher viscosity of PPO in comparison with fossil diesel,

  • Too high values of contents of phosphor, acid, water, contamination with particles, oxidation, etc.
There exist also a great variety between diesel engines, both in type, the DI (Direct Injection) types and IDI (Indirect Injection) types and with different types and makes of fuel pumps. The result is that each engine has to be modified and tuned in its own way to let it run smoothly on PPO.

A very good description of all these facets is given by Niels Ansø in section 5.2 of the Jatropha Handbook  [see www.fact-foundation.com]

After some surveys in QNP many different diesel varieties were discovered see [Diesel Survey, Cabo Delgado]. Unfortunately this means that the development of a standard engine conversion kit as originally anticipated was not feasible.

The high viscosity of the PPO can be reduced to the level of fossil diesel, by increasing the temperature of the PPO before injection. Diesel engines can be modified, making use of surplus heat, like exhaust or cooling water to increase the temperature of the PPO. Start up problems, when the engine is still cold, can be overcome by mounting a second tank, with fossil diesel, so that the engine can be started on normal diesel and after some minutes, when it has got heated up, the fuel can be switched to PPO. This is commonly known as ”dual fuel mode”.

There exist diesel modification kits in Europe (like delivered by Elsbett) but they are too expensive for the diesel owners of the maize mills in QNP to be earned back in a short time.

Therefore, within the project funds were re-directed to develop a technical investigation program to find out if a cheap kit to modify the most suitable diesel engine could be developed. Then consequently some diesel engines should be modified and some endurance tests be done to check if the engines were performing well on PPO.

This needed to be done before diesel engines of real users were to be modified. Some guarantee has to be given and demonstrated to the potential clients.

From the survey in QNP it emerged that most of the recently bought diesel engines were of the Chinese Feidong make. It was decided then to develop a modification kit for this type of engine.
The first modification kit was developed in The Netherlands by Ger Groeneveld of PPO Groenveld. It was based on building a heat exchanger around the exhaust pipe of the engine a Lister type air cooled engine with Indirect Injection. This engine did run over 600 hrs on all kind of PPO without problems, which was encouraging.
The second kit was consequently made in Mozambique at Evretz, a farm of a Zimbabwean farmer who was experimenting with biofuels. First a Chinese Feidong diesel engine, which is a typical engine used in QNP was bought by the project in Cabo Delgado and transported to Chimoio. Ger used the same principle of using the heat of the exhaust to pre-heat the PPO, but in a different way. [see Development of a modification kit for diesel engines suitable for PPO, By G.J. Groeneveld., December 2008]

He used as much as possible local materials and the diesel could run on it, driving a water pump for the farm. As fuel cotton oil was being used, which was pressed at Evretz. During a visit after one year by Niels Ansø and Jan de Jongh, it was found that the engine with the water pump was not running at all. Logistic problems was the reason. Also the modification was no longer in order. The cheap plastic hoses used for the fuel had become brittle and were broken. After repair by Niels the engine ran again and the farmer promised to resume the testing. Unfortunately, this experiment failed in the end, as the number of planned hours were not made.

At the BBC two Feidong diesel engines were modified by Niels using imported parts from Denmark. The principle was to use the cooling water to pre-heat the PPO.

One engine is the drive engine of the BBC generator set, the other the drive engine of the maize mill of the EPF school. Since there was not yet Jatropha available in sufficient quantities, cooking oil was used to do the tests. Data loggers were attached to the engines to measure the exhaust temperature, as indicator for the load, against time.

Due to a number of set backs the endurance test could not be finished before the end of the project. Up to now however no problems were experienced. It might well be that this kit at a total cost of around € 200, is suitable for these types of engines. Apart from this, thermostats were needed, since the engine did not heat up sufficiently. Also for one of the engines the injection pressure has been slightly adapted by Niels.

Since these test have not been concluded, and therefore no guarantee can be given yet, potential clients could not be approached yet for modification.

Modification of the Nissan 4Wd car.

The project car, a Nissan 4wd was repaired and modified by Niels in Oct 2009, to run on PPO. 

The system is a 1-tank system enabling the car to start and run on 100% PPO without starting first on diesel. Niels provided the parts from Denmark, costing around € 700., which is rather costly. The purpose was mainly to demonstrate that driving on PPO with a normal modern car is also possible.
The car was driven to Maputo on sunflower PPO (over 2000 km) and was present at the one day Seminar on the 25th of November where the project results were presented to the public. The car modification was shown and got a lot attention. In future when JPO of good quality will be available, the car can drive on it, meanwhile it still can drive on fossil diesel.

Oil quality

As soon as the first oil had been pressed, around Dec 2009, Flemming Nielsen took a bottle and send it to ASG, a recognized laboratory in Germany for testing. (see results)

The test gave very negative results. Nearly all the critical variables were far too high to make the oil valuable for using as PPO in engines. It was decided to use this oil for making soap and continue the endurance test with the diesels with cooking oil.

The quality of oil is to be controlled during the whole production chain, from soil preparation to oil storage and distribution.  For example: harvesting green unripe seeds results in too high phosphor contents, bad for diesel engines, while storage in galvanised tanks leads to creation  of polymers, blocking fuel filters. Also during pressing the quality can change, e.g. too high pressing temperature increases the phosphor contents in the oil.

It was clear that a quality control method of checking the oil quality had to be established. From the neutralizing experiments with the cotton oil by Evans it was learned that the acidity could be neutralized by adding caustic soda and heat, resulting in clean cotton oil and soap residues. Samples of both untreated cotton oil and treated oil were also sent by us to ASG and results compared [¨...*] Apart from the lowering of the acidity, also the other variables lowered, within acceptable values for PPO. See [Note on cotton oil]

Experiments were done at BBC by Jan de Jongh with this method [mission report July 2010] and indeed the JPO acidity could be lowered from 17 to 3.  However a lot of oil is lost on sediments after neutralization. It is better to use non chemical treated plant oil, i.e. only pressing, sedimentation and filtering to be done.
 
With help of titration the level of acidity can be determined. Therefore some staff members were trained to do this titration to find out the JPO acidity in future. If from time to time an JPO sample could be send to ASG for the full testing, then together with this titration for checking the acidity, the JPO quality can be reasonably well controlled. Even better would be to build up a small laboratory and attract a chemical engineer who could be trained at Diligent in Tanzania to execute the required for testing of the PPO on the standards as set in DIN V 51605.

Alternatively it could be explored if for instance the laboratory at Pemba hospital could undertake the tests for a fee.

SelectionFile type iconFile nameDescriptionSizeRevisionTimeUser
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ASG (2009): Test of Jatropha oil from BBC.  98k v. 1 16 Feb 2011, 04:36 Banana hill Consultants
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Thijs Adriaans (2008): duurtesten met minimaal omgebouwde DI motoren op PPO  96k v. 2 15 Feb 2011, 07:47 Banana hill Consultants
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Niels Ansø (2007): Short note regarding Pure Plant Oil, PPO, as engine fuel  31k v. 3 15 Feb 2011, 07:51 Banana hill Consultants
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Jan de Jongh & Thijs Adriaans (2007): Jatropha oil quality related to use in diesel engines and refining methods  103k v. 2 15 Feb 2011, 07:51 Banana hill Consultants
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