Been talking about this offlist with Jon Van Gerpen of Iowa State University. I sent him my "Conversation with the EPA Tome". Here's some more info. I actually had brought up with Jim Caldwell "the lowest possible biodiesel viscosity issue" as compared with the lower temps of diesel's viscosity- but didn't get far with it.
In fact the more I think about it, the more bothered I am about the problem of 'biodiesel doesn't meet diesel specs'. Of course it doesn't, but it works fine just the same, and the faster this comparison stops being made, the faster we stop having problems such as the California CDFA issue (please search the archives here), where oil company representatives successfully lobbied to have B100 'must meet petrodiesel specs' in California- effectively outlawing it since it can't- though how much that's enforced we haven't seen yet. Quote from Jon Van Gerpen: Mark: Jim Caldwell is the person at EPA that I contacted through email. It sounds like you got more from him than I could. This is the first time that I have heard that their concern was viscosity. In the past, I have heard that they were concerned about the distillation points. <snip> There is some slight justification for being concerned about viscosity. The fuel injection system on a diesel engine will inject more fuel if the fuel has a higher viscosity (due to less internal leakage in the pump). We have measured this effect when comparing diesel fuel and biodiesel. However, since biodiesel has a lower energy content, the effect is such that the engine still produces less power and operates at a lower overall fuel-to-air ratio with biodiesel than with diesel fuel. You might be familiar with this issue in the context of maximum engine power. Since biodiesel has about 8% less energy per unit of volume, we would expect about 8% less maximum power from the engine. However, reported results are usually in the 6-8% range. This slight discrepancy is due to viscosity. The viscosity of soybean-based biodiesel varies from 4-12 cSt over the temperature range from 40 deg C to 0 deg C. Since the biodiesel solidifies at about 0 deg C, the value of 12 is the lowest viscosity we would expect to see for this feedstock. Grease-based biodiesels can be higher but I don't have any low temperature viscosity data for them. They also will not go to as low of a temperature before gelling. Regular diesel fuel will have a viscosity of 12 cSt at about -13 deg C. Since this is within the normal operating range for the engine, I see no reason to expect deleterious effects from the higher viscosity of biodiesel. Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://archive.nnytech.net/index.php?list=biofuel Please do NOT send Unsubscribe messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Yahoo! Groups Links To visit your group on the web, go to: http://groups.yahoo.com/group/biofuel/ To unsubscribe from this group, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
