This is the gist of an article in the german magazine mot (1/2000). It gives a brief summary on the need for sulfur in diesel, and the possible solution of replacing the sulfur content with biodiesel and the advantages of biodiesel.
All diesel fuels are NOT the same today. Many engines that could use alternative variations of diesel fuel still are fueled with the standard,
sulfur-containing kind . That is no longer necessary.
Variations in fuel quality were of concern to the drivers of gasoline cars only. Until 1996, when the inferior lubricational qualities of de-sulfurized diesel fuel damaged a lot of injection pumps. In contrast to the outcry in the media about this desaster, the introduction of a standard for Biodiesel (DIN EN 51606) in 1997 didn´t cause that much of a reaction. This standard was necessary to provide the basis for the manufacturers allowance to use biodiesel in their engines. But until now, only Volkswagen allows the use of biodiesel for the majority of their diesel engines:
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>
How car manufacturers and biodiesel figure :
Audi/VW: all TDI since MY 1996, before that date modification is in most cases possible
Seat/Skoda: all TDI since MY 1996
Peugeot: Only 5% biodiesel (like in every French diesel-engine)
BMW: Extra for 525td and 525tds for 330 DM, retrofitting/other engines not possible
Citroen: Up to 30% possible, over that at own risk
Mitsubishi: Not allowed, say that ABE (=the allowance to use the car in public traffic) is void when using biodiesel (absolutely BS of course - Claus)
Mercedes: E-Class 200 and 220 is available with biodiesel-kit, which is standard on all Taxi-models. No retrofitting for older cars possible.
Volvo: S/V 70 TDI and S 80 TDI since January 1998 (these are all Audi engines). V/S 40 not possible (=Renault engines). Retrofitting not possible.
Nevertheless the interest has steadily increased: today there are over 900 filling stations in Germany that sell biodiesel.
But only few people here know that the low-sulfur diesel produced for Sweden is available here, too. It is called Greenergy. His advantage is that everybody can use it without modifications.The drawback is that it is only available at 32 stations in Germany and while it costs 6 Pfennig more than conventional diesel, there are no taxation benefits for it.
Engine developers favour the general introduction of Greenergy, because only with the low-sulfur-content fuel can low emmissions be achieved.
Warnings, Allowances, Promises: Diesel does not equal diesel any more. What should the diesel-driver fill in today ?
Standard diesel has a maximum sulfur content of 500ppm and has a Cetane number of 49.
From 01.01.2000 the content has to be reduced to 350ppm and from 2005 onwards a maximum of 50ppm is allowed. Cetane # has to be 51 or more.
The low sulfur-content needs to be equalized by the addition of additives, to keep up the lubricational qualities.
Greenergy is a low-sulfur-diesel (<10ppm sulfur) from mineral oil. Special additives enhance lubrication over the minimum HFRR-result of 460 µm. Usually the Greenergy has a HFRR of 400 µm and a Cetane # of 54. It is usable down to -32 degrees Celsius. It can be used in all cars using diesel without any modifications.
Tests at Volkswagen showed, that with Greenergy CH-emmissions dropped more than 25%, CO-emmissions dropped by 30% and particle emmissions were reduced by a third. The low-sulfur-content is good for a better longetivity of the Oxidation-Catalytic Converter and for better emmissions right after cold-start.
Volkswagen issued a clear statement:
"Emmissions of all Otto- and Diesel engines could be reduced immediatedly with the mandatory introduction of low-sulfur-fuel."
Biodiesel however has nothing to do with mineral oil. The name "Rapsmethylester", abbreviated RME, gives a hint to its origin from plants. Currently 100.000 tons Biodiesel are sold in Germany annually. This fuel is usable down to -22 degrees Celsius. RME has a Cetane # of 58, a Oxygene contents of 11% and is nearly free of sulfur. Several tests, including TÜV (southern Germany) and Volkswagen, have shown that this fuel together with a Oxidation-Catalytic Converter can reduce particle emmissions by up to 50%.
Catalyst-retrofitter HJS claims that emmissions of Greenergy and biodiesel are nearly similar. Only CO-emmissions are 1-10% more with biodiesel.
Both fuels are allowed with the retrofitted catalysts.
Biodiesel has a very good lubrication. Tests have proved (http://www.biodiesel.de
) that even without additives the wear is reduced. RME can even be used as an additive itself to provide the necessary lubrication for low-sulfur-diesel. RME is non-toxic, biodegradeable and can be mixed with other diesel fuels without any problems. But it is like a solvent which on the one hand keeps the fuel system clean, but on the other hand can be harmful to the paint and can attack gaskets and tubes made from regular materials. This negative feature is the only reason for the trouble with the manufacturers allowing the use of RME in their cars. Only vehicles equipped with a RME-resistant fuel system should be fueled by RME. Most cars though can be converted for cheap money.
(Ingenieurbüro Liphardt, Tel.: 0049 6175 3522)
In contrast to Greenergy, RME is a renewable source of energy. Rapeseed is planted in areas which would be not used otherwise to avoid over-production. The plant covers the ground for 11 months a year, collecting CO2 from the soil and saves the ground from being eroded. (there are negative side effects also - like monoculture and some animals being poisoned thru grazing by the rapeseed - Claus).
Biodiesel is CO2-neutral. Until beeing harvested, the plant has taken the amount of CO2 out of the soil which is emmissioned when the fuel is burned.
Why do we use standard diesel, then ? The answer is simple: If all areas possible in Germany would be used to grow Rapeseed, the average amount of 1500 litres per hectare would lead to a production of 1.200.000 tons of biodiesel per year. That would be only 5% of the diesel fuel used in Germany per year.
In France 5% biodiesel is added to all diesel-fuels already. This reduces emmisions and provides a constant market for the farmers, while the need for government subsidies to the farmers decreases.
Should you want to try biodiesel yourself, two to three tanks later the fuel-filter should be changed. Therefore, it is better to wait until a filter change before the use of biodiesel is begun, to avoid further cost and inconvenience. If you car needs to be converted first, "Ingenieurbüro Liphardt" can provide you with a kit, so you can use biodiesel in older cars, even when the manufacturer doesn´t encourage the use of RME.
One last thought: 5% of biodiesel must be tolerable by all engines, whatever the manufacturer says - or do they forbid you to drive to France at all ?
Growing Interest in Biodiesel and low-sulfur diesel (mot 01/2000)
Info on biodiesel: http://www.biodiesel.de
(A branch of the German union of farmers)
Retrofitting RME-safe fuel tubes:
Ingenieurbüro Liphardt, Tel.: 0049 6175 3522
´92 VW Polo G40 - 1272ccm / 113bhp
´97 Audi A6 Avant 2.5 TDI - 2461ccm / 140bhp Ad: "Why settle for moving with the times, when you can OVERTAKE them ?"
[This message has been edited by CFriedriszik (edited December 28, 1999).]