PROBABLY THE MOST important input in any discussion around the complex issue of biofuels is what the vehicle and engine manufacturers are saying and permitting for use in their equipment without impairing warranties and expected useful life. 

Max Braun spoke to David van Graan, marketing director at MAN Truck & Bus SA, who is substantially involved in developing and communicating MAN’s biodiesel strategy. His objective is to keep MAN owners fully in the picture regarding current and emerging biodiesel trends and developments, how they impact on past, present and future models and what MAN believe needs to be done to ensure all concerned get the perceived benefits of biodiesel. Here is a verbatim synopsis of his talk with Van Graan: 

FW: What are MAN’s requirements in terms of blend (%) and must it be derived from any particular feedstock? 

A: MAN approves the use of a 5% blend of bio-diesel in its engines as per DIN EN 590. 

FW: According to reports, all European OEMs stipulate biodiesel blends must be from rapeseed oil. Can you confirm or elaborate on this? 

A: MAN engines can use a biodiesel blend where the biodiesel component must be a Fatty Acid Methyl Ester (FAME). A rapeseed Methyl Ester (RME) is recommended, which complies with the DIN EN 14214 standards. 

FW: Does MAN require the biodiesel to have a minimum cetane rating - or conform to a particular spec such as B100 or EN14214? 

A: MAN requires compliance with DIN EN14214. The DIN 14214 standards contain an elaborate number of values which need to be complied with – inclusive of a minimum cetane value of 51 (measured by using the EN ISO 5165 testing method). 

FW: How do you cope with the hygroscopic problem? Surely fuel stocks cannot be blended in bulk storage tanks?

A: Blending and storage conformance standards are certainly an area of concern - and are out of the hands of OE suppliers of vehicles and engines. As such, we do not have experience on the extent of the problem in our region. Storage of biodiesel is clearly a problem, evident through the need for a parkoff procedure: MAN recommends for any vehicle to be parked for four weeks or longer, that it be run with at least two tanks of non-biodiesel prior to parking it. This avoids any blockages in the fuel system. Furthermore, MAN recommends certain additives to be used to combat the formation of microorganism build-up in tanks. 

FW: Tests conducted by Golden Arrow confirm a significant increase in fuel consumption. This seems a high price to pay to promote questionable environmental issues? 

A: There is currently not a good database of facts regarding fuel consumption impacts in local operations. We are advised by other markets that there is definitely a deterioration in fuel consumption results when biodiesel blends are used but conversely, certain fuel companies suggest that there are theoretical merits for a slight fuel consumption improvement (density of fuel versus energy content values, assuming a 100% bio diesel blend). 

FW: When biodiesel blends are used, do you see the need to shorten service intervals with the objective of replacing fuel filters earlier and to deal with any other issues that may result? 

A: Yes, we certainly recommend that service intervals are shortened when a biodiesel blend is used – dependent on the application, this could mean a reduction of between 50% and 75% in intervals. This is because FAME has more unfavourable evaporation properties than diesel which in turn causes thinning of the oil and consequently lower viscosity of engine oils. Fuel filters also require more frequent replacement due to clogging caused through oxidation. 

FW: Can it be used when engines are electronically managed and/or with EU4 and EU5 motors? 

A: Biodiesel can be used on all MAN modern electronic engines, subject to certain FAME-compatible product options being fitted. Examples are larger fuel filters and deletion of pre-filters such as SEPAR. Biodiesel can also be used with engines where on-board emission diagnostics and NOx monitoring is required to ensure emission standards. 

Not a new event 
Marc Bataille, manager Industry Liaison at Mercedes-Benz SA, reminds us that biodiesel is not a new event. It’s just that the South African specification has not yet been finalised, he says. As we would expect, rapeseed oil, if it complies with a recognised standard, is favoured by Mercedes-Benz when used as a 5% blend. 

“When a larger percentage blend is desired, modifications are required. Typically these could be filters, water traps and early drains. Fuel consumption will be compromised due to oxidisation and shelf life will be lower, adds Bataille - not to mention hygroscopic and precipitation issues. SANS 342 is not compulsory for fuel retailers according to M-B. 

Operators must beware of claimed compliance as we can expect many small manufacturers to struggle with consistent quality control. Once again, the question of storage as a critical factor raised its head. Vehicle manufacturers and fleet owners are concerned about problems associated with regular diesel distribution channels – the presence of dirt, sediment and water are the main issues. 

Scania is excited about the test results achieved using bio-based synthetic diesel. A reduction in NOx emissions is said to be down by 20% and particulates by 30%, CO2 by a huge 80%. Working with Neste Oil Corp of Finland, tests will continue to 2010. Scania has a fleet of buses operating on different diesel fuels and bio-blends as part of its practical tests. It seems Scania is not saying much about feedstock until its test programme is completed.