This all started when my interest was sparked by Niels Anso posting a thoughtful response to the Ricardo Study of SVO emissions. In his response he mentioned the effects that phosphor in the fuel could have on combustion. This was the first time I had seen this discussed and I had since intended to do further research on this topic.
The Ricardo Engineering study was commissioned by the UK government Department for Transport and was recently used in their 'Towards a UK Strategy for Biofuels - Public Consultation' to show that "Biofuels potentially have some air quality benefits, provided the fuel is of appropriate quality (studies have shown that use of unprocessed vegetable oil can actually lead to considerable increases in emissions)." The Ricardo report is at http://www.dft.gov.uk/stellent/groups/dft_roads/documents/page/dft_roads _027622.pdf Niels response posted to the vegoil-diesel yahoo group http://groups.yahoo.com/group/vegoil-diesel Fri 18/06/2004 12:10 The Ricardo report is just another useless report! The Ricardo report, which evaluates emission performance of Straight Vegetable Oil(SVO, in Europe Pure Plant Oil, PPO), is based on fundamental mistakes made regarding combustion of SVO in diesel engines, and the Ricardo authors demonstrates that they know nothing about SVO engine conversions and SVO fuel requirements. <SNIP> To obtain good emissions results, it«s essential to have a real conversion, including optimisation of the engine performance, and to have a good quality fuel which meets the limits specified in fuel standards developed for that specific fuel. <SNIP> Ricardo report & SVO Fuel quality. Rape seed oil as created by nature is an excellent fuel, but can easily be spoiled by wrong processing, handling and storing. The report does not describe the SVO fuel well, just that it«s origin was food grade Canola and from retail supply. The SVO was analysed and compared to fossil diesel and biodiesel(appendix 2). But analysis according to fossil diesel standards do not include important fuel parameters for SVO, so therefore SVO should be analysed according to SVO fuel standard. Here we can all benefit from very fine German research work on SVO fuel quality, ending up with the German RK- standard for rape seed oil as engine fuel. The Ricardo Team found the data sheet for the RK standard (appendix 3), but they didn«t use it. If you compare appendix 3 with http://www.folkecenter.dk/plant-oil/RK-standard-DK.htm, it looks like they visited our page, so they could have asked for our support to understand numbers, principles, and maybe German. The RK-standard describes both characteristic properties and variable properties. The first group of properties is created by nature, so it makes no sense to check the SVO for density, viscosity and sulphur, as they did in the report. The really important properties are the variable, which are influenced by processing, handling and storing, but these properties were ignored by the authors. "Other parameters which are included in the German specification were not requested for analysis; but it is not expected that these parameters would have a major influence on emissions". One of the important parameters regarding emission from SVO, is the phosphor(P) content, which I will compare the Sulphur(S) content in fossil diesel. It«s well known that sulphur in fossil diesel creates SO2 and particle emission, and that the fossil industry fights to reduce S. In Denmark the fossil industry convinced the government at least once, to reduce the mineral oil tax on low sulphur diesel, to compensate for the expenses to reduce S. Now they are trying again because of the new requirements from EU. SVO contains from nature no Sulphur. Both P and S are "strangers" to the combustion process, which itself only includes C, H and O. If you study the final report from the German research on SVO fuel quality, Gelbes Heft 69 (link is included on http://www.folkecenter.dk/plant-oil/RK-standard-DK.htm ), you will find that the phosphor reduces the combustion temperature, and that it will create P layers in the engine. Reduced temperature could reduce the combustion efficiency leading to more unburned fuel and thereby more emissions. P-layers are naturally harmful to the engine, and the reduced temperature/combustion efficiency can also lead to cooking and polymerisation in the engine. Industrial produced non refined rape seed oil can easily contain 20 times the P limit specified in the RK-standard. Only cold pressed rape seed oil, or full refined industrial produced rape seed oil, can meet the P limit of 15ppm. The Ricardo report doesn«t mention if the canola oil was refined, and no phosphor test was carried out. <BIG SNIP> best regards Niels Ans¿ Folkecenter - DK Tel.: +45 97 95 66 00 Dir.: +45 97 95 66 55 mob +45 40 14 80 20 fax.: +45 97 95 65 65 ---------------- Anyway Niels mention of phosphor levels in the fuel effecting combustion got me thinking. It shows that it is crucial for fuel standards to be set to be able to provide any meaningful emissions/reliability results from SVO. The Weihenstephan rapeseed oil fuel standards which are the only SVO standards in existence were produced following extensive consultation and discussion between scientists, oil mill operators and SVO engine converting companies. I'd looked into the standards some years ago and come across a few German documents which at the time I could not use and having become proficient with the use of googles' web based translation tools could not find. Earlier this year Niels put me onto some documents relating to the fuel standards which included:- http://www.stmlf-design2.bayern.de/tfz/tec/oel/pdf/gelbesheft69.pdf It is only now that I have had time to run some parts in the text through a translator giving the following results:- For the measurement of the phosphorgehalts in rapeseel oil the organic portion in the sample is unlocked by strong heating in presence of zinc oxide. The arrears will become solved in sulfurous acid, Ammoniummolybdat and Hydraziniumsulfat in addition-given. Spectrophotometrically the adsorption is based on the molybdenum blue complex, which runs proportionally to the phosphorus concentration in the sample. In the testing method ASTM D3231-99 for the phosphorgehalt the unit is used mg/l. The measuring range of the testing method is appropriate for 40 between 0,2 mg/l and mg/l. The repeatability amounts to for the limit value 1.05 mg/l, the reproductibility 1.95 mg/l. In the planned company ME standard the regulation takes place from phosphorus according to the method NF T60-705 with ICP. The phosphorgehalt of rapeseel oil fuel is a variable characteristic. It affected by process parameters during the oelgewinnung. A high phosphorgehalt has negative effects on the motor burn by the formation of deposits. In addition phosphorus is a catalyst poison. Illustration 26 shows the phosphorgehalt of rapeseel oil fuels of different origin. The phosphorgehalt varies with the high standard deviation of 15,6 around the average value of 11,8 mg/kg. The median is with 5,0 mg/kg. With three samples a phosphorgehalt is not provable in the oil. In illustration 27 the influence of sort and cultivation on the phosphorgehalt is represented. Clear sort differences do not show themselves. With the two measured values, which exhibit over 40 mg/kg, the analysis was repeated, in order to exclude an analysis error. These two high phosphorus values are not explainable. The median of 8,0 mg/kg the samples from the cultivation attempts shows that the limit value is well stopable. On very low level the phosphorgehalte of the rapeseel oil samples from the interlaboratory test are, represented in illustration 28. It is to be noted that for the determination of the phosphorgehalts the testing method DIN 51363-1 [ 25 ] was used. Phosphorus phosphorus is present in vegetable oils and FAME in the form of phospholipiden. With rising portion of phospholipiden oxidation stability is reduced, in addition phospholipide are inclined to the Hydratisierung (swelling in water) and can cause thereby for example filter blockage. Phosphorus lowers the burn temperature, can in the combustion chamber to deposits lead and possibly a change of the emission behavior cause. Oxidation catalysts exhibit besides a high sensitivity in relation to phosphorus connections regarding its shifting rate and/or continuous function. The phosphorgehalte in vegetable oils depend on the refining degree. Phosphorgehalte in not refined vegetable oils can be kept low by appropriate processing [ 59 ]. [ 59 ] WIDMANN, B.A. (1994): Production and cleaning of vegetable oils in decentralized plants - factors of influence on the product quality and the production process. "yellow booklet" No. 51. Munich: Self-publishing house BayStMELF. Research report: DO Munich, Institut and Bavarian national institute for agricultural engineering, Freising Weihenstephan (310 sides) Phosphorgehalt?? A lower limit value than so far would be possible, since in the meantime with the testing method ASTM D 3231-94 a method is available, which makes a substantially higher resolution possible (detection limit 0.2 mg/kg). Phosphorus in the fuel caused in rotochamber engines of fewer problems, there the phosphorus?staubartig? arises and over the valves from the combustion chamber one removes. Problems arise with certain pre-chamber engines and directinjecting engines. Therefore a limit value is demanded by max 10 mg/kg phosphorus, stated as example a passenger car engine, which was defective after 7000 km with a fuel, which exhibited a phosphorgehalt of 26 mg/kg. The rapeseel oils analyzed so far point % phosphorgehalte to 90? 10 mg/kg up. The boundary conditions of the sampling are questioned. It is suggested to provide the limit value with 25 mg/kg too left and the limit value with a footnote that a reinsurance must be caught up with the engine manufacturers. Doubts exist over it whether generally phosphorgehalte can be guaranteed of under 10 mg/kg by the oil producers. A limit value of 20 mg/kg is suggested. It is assumed that the output product oil seed already exerts a substantial influence on the phosphorgehalt in the oil. The new method of analysis offers the chance to receive more accurate values over the phosphorgehalt in the rapeseel oil. On the part of the oil mill operators it is doubted whether a limit value can be kept of 10 mg/kg without subsequent treatment of the oil, through for example Saeureentschleimung. The phosphorgehalt is very critical for the motor enterprise of evaluating. Phosphorgehalte of 100 mg/kg with full load enterprise do not cause problems, only with intermittent enterprise or partial load operation already arise with substantially smaller phosphorgehalten damage to the engine. Possibly these damage is favoured by low burn temperatures and an engine oil dilution exerted by it. The damage to the engine by phosphorus is temperature and pressure independent. It is considered to indicate graduated limit values for the phosphorgehalt for differently targeted applications of the engine. The task of the adjustment of the engine to the natural fuel does not lie on sides of the engine manufacturers, after present level of knowledge is suitable for example directinjecting engines for the use of vegetable oils as fuel. Different oil mills are to be kept able a limit value of 10 mg/kg. A limit value of 10 mg/kg is to be only accepted for the oil mills, if over interlaboratory tests the stop barness of the limit value is examined. The sampling must be specified exactly. In addition a if possible low phosphorgehalt is to be demanded with the use from catalysts to, since phosphorus?Katalysatorgift as? works. Appendix 3: Minutes to 5. Ltv working group meeting 187?? It is discussed whether a limit value is to be fixed, or whether the phosphorgehalt in arrangement between supplier and engine manufacturer can be specified. Influences of the oil production process on the phosphorgehalt discusses. A proposal for compromise for the limit value reads max.15 mg/kg. The influence of the phosphorgehalts in the fuel on the motor enterprise is to be examined by the engine manufacturers more near. A footnote to the limit value max. 15 mg/kg?25 mg/kg with the employment in stationary engines? as meaningfully one does not judge. For the retention of the past limit value of max. 25 mg/kg one pleads, since the past data basis is too small due to the insufficient analysis procedure. It will suggested, which methods of analysis to test and examine whether the limit value can be kept, afterwards is the limit value again to be discussed. The limit value max. 15 mg/kg phosphorus proves as consentable phosphorgehalt?? variable characteristic?? In place of the testing method DIN the more highly dissolving testing method ASTM D 3231-94 steps 51,363 T1. The limit value is lowered on max. 15 mg/kg. Phosphorgehalt: For engine damage frequently the phosphorus in the vegetable oil is made responsible. Also phosphorus works as catalyst poison. The analysis of practice oil samples results in that with an exception all phosphorgehalte lie underneath the limit value of 15 mg/kg. More as 2/3 of the oil samples have a PGehalt of less than 6 mg/kg. 13.Phosphorgehalt collection of the statements and suggestions of the participants: From an engine manufacturer the demand of a limit value of 10 is present ppm for phosphorus. Indications exist for a direct connection of phosphorus deposits in the engine compartment and the phosphorgehalt in the fuel. Phosphorus lowers the burn temperature in the engine, the vegetable oil burns therefore incompletely, deposits themselves at walls and can by the piston rings into the engine oil be brought. In particular during low engine extent of utilization abrasive materials can develop. It must be paid attention to the fact that no defaults are made for the oil mill operators, which are not stopable in practice therefore are a participant against a sinking of the limit value and points out that certain engines stand also substantially more phosphorus, than the past limit value permits. It is reported that the p-content in the vegetable oil depends strongly on the contamination and is influenceable by the sampling. Schleimstoffe do not have to be specially limited, since the Schleimstoffe settles as phospholipide in the p-content. One agrees to maintain the limit value for phosphorus. Resolution: Phosphorgehalt?? Testing method ASTM D 3231-99?? The limit value remains unchanged on max. 15 mg/kg --------------- It appears from the translated notes above that the 15mg/kg was a compromise between the conversion companies wishes for 10mg and the oil mills worrying about feasibility of providing fuel at a level below 20mg. DI engines are more likely to suffer from high P levels. Also the report contains a table of biodiesel specifications from around the world that show that most limit phosphor to 10mg/kg, Austria and Czech 20mg and USA has no requirements. This report was written August 2000 so things may well have changed. Also Of note one of the most advanced SVO conversion companies United Vegetable Oil Workshops - VWP suggests using only oils with less than 10mg/kg phosphor - see FAQs at www.pflanzenoel-motor.de Still this is, I think, an important issue which has gone largely unreported. Best Darren _______________________________________________ Biofuel mailing list [EMAIL PROTECTED] http://wwia.org/mailman/listinfo.cgi/biofuel Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuel archives at Infoarchive.net (searchable): http://infoarchive.net/sgroup/biofuel/