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 demonstrate that they know nothing about SVO engine conversions and SVO fuel requirements.
To people who do not know better, the report looks serious, nice and decent, but it is completely opposite, and the results are useless. I will explain why. My background is 6 years working intensely to convince the Danish and European systems to accept that SVO engine technology, and SVO as a fuel, is 100% reliable. I have learned that the "old system" including Energy Agencies, Institutes specialised in engine and combustion technologies etc, know nothing about SVO technology, but they do not hesitate to talk about it as if they knew everything.
It is common knowledge that basically all diesel engines will run on SVO for a short while even without conversion, but that is far from optimised and no solution. Then you can compensate for cold start problems with a 2-tank system, and compensate for the higher viscosity by heated fuel system and larger fuel pipes, but this is not all that you will need for a real and reliable conversion. What I call a real conversion also includes injectors, injection parameters, glow plugs, and a lot of simple and practical considerations regarding the fuel supply.
To obtain good emissions results, it is 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.
Ricardo report & Engine conversion
The report does not describe the conversion kit well, but it seems that the only thing there was done, was to heat the fuel near the injection pump. There is no diagram and/or parts list for the kit. The report does not mention who supplied the kit, and which knowledge and references they had in this field. But the report shows a nice photo (figure 2) of a shiny heat exchanger, and the text stresses, that "The Conversion was completed to a high standard, with attention paid to cleanliness of components fitted". What´s the point that it looks nice??
On page 4 the reports says "Since vehicles are unable to start up on VVO100... ". Excuse me, but they have never seen a converted vehicle then. Over here it is common to run round the year always on "VVO100", without additives, 2-tank diesel start, or other help - the cold engine starts well on cold VVO100 in cold weather. Personally, I have completed 5 years with my VW Golf 1.9 IDI, literally always on VVO100, and never filled a single drop of fossil diesel or other additives. We have also converted VW TDI engines with 1-tank system, and even where it is not optimal, they can start the cold engine on cold VVO100 in cold weather. To protect the engine, reduce emission etc., the TDI models should preheat a little before cold starts below 5-10 deg C. That can be done by a comfort heater, which also starts to come in new diesel cars. IDI engines do not need to be preheated to start even down to -10 deg C.
Ricardo report & SVO Fuel quality
Rapeseed 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 its 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 does 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 did not 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 variables, 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 emissions from SVO, is the phosphorus (P) content, which I will compare with the Sulphur (S) content in fossil diesel. It is well known that sulphur in fossil diesel creates SO2 and particle emission, and that the fossil industry fights to reduce sulphur. 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 sulphur content. Now they are trying again because of the new requirements from EU. SVO contains from nature no sulphur.
Both phosphorus and sulphur 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 phosphorus reduces the combustion temperature, and that it will create phosphorus layers in the engine. Reduced temperature could reduce the combustion efficiency leading to more unburned fuel and thereby more emissions. Phosphorus layers are naturally harmful to the engine, and the reduced temperature/combustion efficiency can also lead to coking and polymerisation in the engine.
Industrially produced non refined rapeseed oil can easily contain 20 times the phosphorus limit specified in the RK-standard. Only cold pressed rapeseed oil, or fully refined industrially produced rapeseed oil, can meet the phosphorus limit of 15ppm. The Ricardo report does not mention if the canola oil was refined, and no phosphorus test was carried out.
Interpreting the Ricardo report figures & results
NOx emission: From figure 3, it appears that the NOx was clearly reduced by SVO compared to the other fuels. My idea is that it could be related low combustion temperature due to high phosphorus content in the fuel, and/or bad combustion/adjustment.
PM: There is often a reverse relation between NOx and PM emission. I believe that it is related to engine load and combustion efficiency, which can be adjusted by optimisation. Figure 4 shows higher PM emission from SVO, which confirms this.
T.HC: There is a high level of unburned fuel, which match the above mentioned.
CO2: The direct CO2 emission is normally proportional to the fuel consumption. The CO2 emission is shown in figure 5 and 6, and the fuel consumption in figure 7. The CO2 emission from SVO is higher than for the other fuels, but the fuel consumption is less, so these figures don't match.
Fuel consumption: The emission levels in general from the VW Passat, indicate low combustion efficiency, which logically should lead to higher fuel consumption, but the result shows the opposite.
Other studies
You can find hundreds of similar studies, which have used unconverted or badly converted engines, with undefined or badly defined SVO. A similar test was made in Finland with mustard oil, which was not tested for the variable SVO fuel properties. That report even mentioned that they had problems with the filter blocking because of dirt in the oil, so it says something about the quality level. The worst case I know is the Swedish study, which did not even test in an engine, but in an oven, and also used non-defined SVO. The press release from the Chalmers University was later retracted by the university, and Volvo UK, which had used the Swedish results to promote their Natural Gas Cars, also had to send out a new press release with retractions. See:
http://www.folkecenter.dk/plant-oil/press/pressr_rapeseed_18012001.htm
Other emission tests
Through my work during the last 6 years, first of all trying to convince the Danish and European Systems that SVO is a reliable technology when used in proper vehicles, I have had unofficial emission tests from different vehicles converted to and running on SVO. The first one is a test of a VW Golf, 1.6 (IDI) from 1984, tested according to the EURO1 norm. The results are all very fine, and shows that the vehicle after the conversion could even meet the EURO2 limits.
The other is a test of a VW LUPO 1.2 (PDI) 3L, which shows very fine results for particles (PM) of 86% of EURO3 limit, but the NOx emission exceeded the EURO3 limit by 80%. It corresponds with the reverse relation between PM and NOx emission. The test shows a consumption of 3.6 liters/100km, but the test was by mistake carried out with too high rolling resistance for the converted car (Fa(80km/h)=3,53kW) compared to the reference test with a non-converted car (Fa(80km/h)=2,93kW). Therefore emissions and consumption was relatively higher for the converted car than for the reference car. If the numbers for consumption and CO2 emission is corrected with factor 2,93/3,53, both the consumption and CO2 emission matches the numbers for the reference car.
The test results are available at:
http://www.folkecenter.dk/plant-oil/publications/PPO-emissions.htm
Fuel and emission standards
As described above, SVO fuel should be tested according to SVO fuel standards, and not to fossil diesel standards. Therefore larger attention should be paid to develop SVO fuel standards further, and take care that these standards are followed by the consumers.
The VW Passat DI car used for the Ricardo test was first registered on 1/1/1999, and should therefore be tested according to the EURO2 standard specially for DI engines, which have larger limits than the EURO2 for IDI engines. This is just an example where standards are developed to the purpose, in this case to meet the difficulties for DI engines. In the same way it would be natural to develop emission standards for biofuel cars, which consider both challenges/difficulties and the advantages for e.g. SVO.
Future
In May 2003 the new EU biofuel directive was adopted, including SVO (PPO) as one of the options as biofuel. The first draft of the directive (naturally) did not include SVO, but we from Folkecenter.dk and an informal international group including Holland, France, Germany, Belgium, Ireland etc., succeeded in convincing first the Parliament, and later the European Commission, that SVO belonged to the list of Biofuels mentioned in the directive. The greatest challenge was to convince the officials of the Commission, who naturally had to take care that SVO was a serious option, if they should include it in the directive. They were only convinced by references to a lot of well functioning examples in Germany, Denmark etc., and by documentation from literature. This literature is usually not found through traditional sources, you have to search for them in the quite limited numbers of research environments, such as in Germany. The SVO sector is in a large vacuum of research money, but has a huge potential, and deserves more attention and financial support. SVO accepted in the EU Biofuel directive confirms that we can count on that technology, but it needs much more attention and financial sources for relevant studies done by qualified institutions. It´s an illusion to believe that the existing institutions linked to the fossil sector, can and will think alternative, and come out with qualified studies.
Read more about the EU Biofuel directive here:
http://www.folkecenter.dk/plant-oil/news/PPOnews_20052003.htm
Request
Let us all spend our efforts to present convincing results with SVO engines and SVO fuel, rather than spend the time to discuss bad results from useless studies. Convincing results requires large attention to engine conversion and optimisation, and to the quality of the SVO fuel. Both things are quite simple, but they need attention and require discipline. Let's move the attention and money from the fossil and nuclear sectors to the future sector, Renewable Energy.
With best regards
Niels Ansø
Folkecenter
Denmark
July 2004
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