biodiesel questions

I'm going to make a big mistake and try to answer based on my memory of the subject, Don.

Viscosity, low temperature stability, and volatility are some of the problems with these esters which blending with a little petroleum diesel helps to iron out.

Biodiesel is based upon natural fatty oils which can range from 14 to about

18 carbons in chain length. They come from the plant or animal sources as a triester with glycerine, and are rather viscous. They can be refined including such processes as splitting the triglyceride ester, releasing the glycerine which is removed and forming a new monoester.

The new materials are usually methyl, ethyl, or isopropyl esters of the same fatty acids. They are chemically a bit different from normal petroleum hydrocarbons.

The chemically unsaturated esters (oleic, for example) are more likely to stay liquid than a saturated ester like stearic. Both oleic and stearic have 18 carbons and are the principal products of many plant and animal oils. The stearic ester would be more likely to form waxy precipitates in cold weather, and the petrodiesel would also help prevent this from happening. If you dont distill the natural oils (which you dont want to do for reasons of cost) you would invariably have a mix of oil types, some desirable, others not.

It's not needed. It's there because at this point, biodiesel is more expensive than petro diesel.

Actually, the gasoline in E85 is primarily added for safety reasons: Ethanol burns with invisible flames in the daylight; gasoline colors the flames bright yellow-orange.

True, at the moment, it is cheaper in the USA. Was just in Europe for my sons wedding, and we all know that European taxes and practices lead to higher fuel costs. That, coupled with the still rather low value of the dollar, reflected in a gasoline price of nearly US$8 per US gallon at the end of July.

If things continue as they are, alcohol and biodiesel may become more interesting. In fact, if the government incentivated this industry with tax benefits, it might be much closer now...payoffs should include increased domestic jobs for the production of these fuels, savings of petroleum for more strategic uses, lessening of demand from unfriendly foreign sources, etc... Big oil might not like it, and they hold a powerful stick.

Well said.

There are a couple of reasons. One is that biodiesel doesn't like to ignite in a cold engine very well. Once the temperature drops down below

60 degrees or so it doesn't ignite very well. Another reason for the blend is that biodiesel turns into a solid mass (think crisco) at temperatures below 40 degrees unless you heat it up, since very few vehicles have heated fuel tanks they add regular diesel to keep it flowing in the cold. I have also been told by a few diesel mechanics that the biodiesel is hard on the injectors so the added diesel acts as a buffer for the injectors.

But cold weather starting with alcohol is a problem isn't it? Maybe it wouldn't be with port injection, but I suspect it would be with TBI or carbs. I know my race car starts like crap until it is warmed up first time for the evening. That is methanol, but thought volatility of ethanol is similar to methanol. I need to get pushed a long way before I start first time each day, even in middle of summer.

There are no E85-capable TBI or carbureted cars.

Ah, that pretty well takes care of that. Are TBI cars pretty much obsolete now?

I think they were obsolete when they were introduced. You can't get as fine a mixture control with TBI as with multiport, the manifold interferes too much.

Ted