Turn gasoline into fuel fit for diesel use

[ccw]

.
With the widening gap between 90 octane gasoline price and diesel fuel price here in the U.S., is there a successful and cost effective additive, treatment, etc. to rescue diesel drivers from being raped at the gas pump?

 

[globi5]

http://www.greasecar.com/

 

[ccw]

Thanks globi5, but I did not see where 90 octane gasoline was involved or treated in any way in your greasecar process.

What I had in mind was filling up your 1.9 TDI VW bug with 90 octane gasoline, then throwing in a $5 bottle of something that degraded or performed some kind of organic chemistry to turn the gasoline into a suitable diesel fuel.

 

[rmw]

Well.....

Once when I drove a diesel pickup truck and I managed to run the tank(s) to dry not in the vicinity of a diesel pump I put 4 quarts of ATF in the tank and that got me to a diesel pump and on another occasion I put a mixture of 50% motor oil and 50% gasoline in-about 2-3 gallons and limped it to a diesel source.

However, I wouldn't recommend it on a regular basis.

rmw

 

[globi5]

Sorry, I thought you were just looking for a possibly cheap diesel alternative.

 

[ccw]

There has been many a VW run for some distance on 1/2 and 1/2 gasoline/diesel. Diesel is cut with gasoline in northern climes. I know that for a fact. So, with the state of organic chemistry such as it is, why is there not a cheap additive to change gasoline fuel to diesel fuel?

The price difference between gasoline and diesel here in the U.S. is $1/gal in places. So, this is a big dis-incentive to switch to the more efficient (40%) diesel propulsion, at least here in the U.S. This ought not be, since diesel traditionally required less processing than gasoline.

 

[romke]

there is no way you can turn gasoline into diesel that might be called succesful and costeffective. gasoline and diesel are both mixtures of hydrocarbons, but there the similarity ends. they differ fundamentally in boiling range, chain length, type of chains (branched or not), ignition capabilities and lubricity.

and in cold climates it is usually a kerosine fraction that is used to enhance the cold flow properties of diesel and not gasoline. gasoline used to be recommended for that purpose, but with modern injection systems (injection pump lubricated by the fuel) the inclusion of gasoline is a definite nono.

 

[JSteve2]

ccw,
A certain fraction of a barrel of oil "wants" to be diesel and a certain fraction wants to be gasoline. It depends upon the specific oil. The reason diesel pushes higher than gasoline in times like the present is that the demand for diesel is less flexible than the demand for gasoline. A greater percentage of gasoline consumption is voluntary relative to diesel.

Gasoline can be converted to diesel, but it requires industrial scale synthesis. Therefore, this can't or won't be done on a regular basis unless there were a permanent switch from gasoline to diesel that would require it and justify the expense. The fact that diesel requires less processing than gasoline only accounts for a few cents per gallon, where the current prices are being driven by the supply-demand balance, refining capacity, and the delivery logistics required to make sure that gasoline and diesel are uniformly available.

 

[patprimmer]

It is easier to break molecules down than to build them up, so it is relatively easy to break diesel down to petrol, but harder to build petrol up to diesel, although this has changed a bit with the advent of higher octane unleaded where aromatic hydrocarbons are mostly used in significant quantities to boost the octane.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[rmw]

Any grade of petroleum crude oil below gasoline can be cracked down to gasoline plus some other heavier component, but diesel is a straight distillate cut from the crudes composition (leaving making #2 distillate from synthesis gas out of this discussion).

#2 Distillate is also used in addition to engine (stationary and automotive) fuel in home heating oil in a large portion of the USA as well.

Point being that the #2 cut that is taken from a given barrel of crude is limited and the demand right now seems to be unlimited.

rmw

 

[drwebb]

Thermodynamically, reforming small hydrocarbons from gasoline (or better yet- stranded natural gas sources) into bigger ones of diesel requires a significant decrease in entropy that can only be driven by high temperature & pressure. Catalysts help, but it's much easier to do in a refinery continuouos process than batch it in your tank.

US highway diesel has reduced the sulfur content in the past few years, and the additional refining as well as any additive treatments to maintain lubricity has added some cost.

If diesel maintains a 40% mileage advantage, even a 25% price premium may not keep US consumers from reconsidering their disdain for diesel light duty engines. That would leave Detroit behind EU diesel technology the same way they were caught out by the Japanese hybrid technologies . . .

 

[dcasto]

even the price of used oils and grease is approaching the same. By the time you buy all the filters, add the equipment, and then worry that the grease isn't hot enough and the engine coming to a complete stop, even the grease car isn't anymore cost effective.

 

[bvanhiel]

If there was a cheap way to make diesel out of gasoline without much capital investment, then their prices wouldn't be different. That's just how economics works.

-b

 

[crysta1c1ear]

I've heard of a farmer replacing diesel with a mixture of oil and petrol, where the oil is probably mainly rapeseed oil, but maybe some sunflower oil.

The aim was not to use petrol as an alternative to the diesel, but to use the oil which came from his own crops. I don't remember the defficiency in the oil as a fuel that required petrol to be added to overcome the problem.

As I remember it a significant amount of petrol needed to be added. (If that weren't the case, there would be no point in mentioning it here.) So that raises the question then of whether amounts of oil can be added to petrol, presumably to aid with ignition since petrol is designed to resist autoignition to a certain extent, and compression ignition engines requires it. So that might make the fuel more like diesel.

As far as the farmer is concerned, I was completely sceptical as it was not anything I had heard of before, and diesel is supplied cheap to farmers, whereas he would presumably be paying pump prices for petrol, so it didn't seem to make economc sense even if it worked.