Bio diesel

[GillandMike]

Has anyone used Rape seed oil in their tow car? With diesel prices escalting this is beginning to look like an option. Apparantly you can add a percentage of rape oil to a tank full of diesel along with an additive. Not sure if price compares well with the current price of diesel yet.

 

[Lol1]

If I had an old diesel I would be sorely tempted to go out and buy up all the stocks of cooking oil I could find, and run the motor on that.

 

[rob_jax]

Advice can be a dangerous thing, so I'll try to explain my credentials:

My company in Rotterdam builds process analysers and robotics systems for the petrochemical industry, and in my spare time I'm secretary of an Institute of Petroleum technical committee, and the UK representative to CEN on technical aspects of motor vehicle fuels.

In summary:

1. Most diesel fuel in Europe is (or will be) a 5% blend of bio-diesel in petroleum diesel. All the car manufacturers have accepted this sitution. and the bio-diesel content will continue to increase.

2. Bio-diesel and diesel can be used in any percentage combination without modification to a modern diesel engine, but the car manufacturers have only validated long term operation with 5% levels (important if you car is under warranty)

3. Bio-diesel is not vegetable oil, but is made from veg oil.

4. A hot diesel engine will run on 100% veg oil, but read item 6. before you try this.

5. A cold diesel engine will not start on 100% veg oil, but a blend of 25% veg oil and 75% diesel will start, probably upto 50% 50% if you want to experiment on a hot day, but read the following first.

6. There is a real issue with straight veg oil that will cause premature engine failure. Veg oil is a chemical compound made up from one molecule of glycerol and three molecules of "fatty acid".

When you burn veg oil in a diesel engine, the fatty acids burn but the Glycerol does not completely combust and forms gummy residues in the injectors, cylinder head and around the exhaust valves. This means that eventually the engine will need a visit to the workshop, and consequently if you use veg oil in a diesel car this invalidates the warranty.

If you look at a used chip-pan, or even an old bottle of oil in the kitchen, the gummy (brown) resdiues you see come from the glycerol in the oil.

Bio-diesel is a processed form of veg oil, where it is heated with methyl alcohol and a catalyst, creating "fatty acid methyl esters" or FAME. FAME is bio-diesel. During the chemcial reaction, the glycerol splits off as a separate layer - like a bottle of oil and water - and the waste glycerol is run off and used in other products.

Summary:

1. There is a tax issue where you need to pay H.M. Customs if you add veg oil

2. There is an engine reliabilty issue with the use of veg oil - unburnt glycerol gummy residues in the engine

3. If you car is outside warranty and you can do the maintenenace yourself, then most days a 25% veg oil mix with diesel will start OK. In winter (freezing) a 10% mix should be OK

Robert

 

[GillandMike]

Many thanks for you very comprehensive and helpful reply. The car is a 4 year old Mazda diesel pick up, so a fairly crude engine when compared to modern diesels. Warranty is not a problem and what I can't do myself a local garage in the village is able to sort out in the way of repairs servicing etc. I may well give it a whirl and see what happens. An aquaintence is starting up a new business of cleaning old veg oil from resturants and chippies with a special devise and selling it back to them, but no doubt the VAT man and Gorden Brown will appear on the horizon if I tapped into that source (only joking, Gorden)

 

[rob_jax]

Mike,

Sounds like you'll give it a go, particulary as you car is out of warranty. I don't think anything will happen with the gummy glycerol residues for a number of years, but if you did have a warranty claim it's pretty easy for a trained engineer to see the gummy stuff.

Something to think about:

Vegetable oil is a natural product and will go off (rancid) on storage, if the veg oil has been heated then it also goes gummy - our glycerol friend again.

This can be a concern if you leave your car idle for long periods with high levels of veg oil in the tank - the fuel in the tank could turn to jelly

This is not a recommendation, but if you were to start with a 10% veg oil blend then any gummy residue that may form in the fuel tank should stay dissolved. Make sure this works to your satisfaction before increasing the veg oil content.

If you do a lot of miles, and you run the tank down to almost empty before refilling, this will make sure that old veg oil doesn't stay around to build up gummy residues in the tank and fuel lines. Probably an idea to fill the tank with 100% diesel from time to time.

Also if you use recycled oil, you need to be very careful about the fine particles of burnt chips or whatever still in the oil. Careful filtering of the oil is essential, and replace the engine fuel filter on a more regular basis than normal.

And don't forget the tax man.

Regards, Robert

 

[Lol1]

Mike,

Sounds like you'll give it a go, particulary as you car is out of warranty. I don't think anything will happen with the gummy glycerol residues for a number of years, but if you did have a warranty claim it's pretty easy for a trained engineer to see the gummy stuff.

Something to think about:

Vegetable oil is a natural product and will go off (rancid) on storage, if the veg oil has been heated then it also goes gummy - our glycerol friend again.

This can be a concern if you leave your car idle for long periods with high levels of veg oil in the tank - the fuel in the tank could turn to jelly

This is not a recommendation, but if you were to start with a 10% veg oil blend then any gummy residue that may form in the fuel tank should stay dissolved. Make sure this works to your satisfaction before increasing the veg oil content.

If you do a lot of miles, and you run the tank down to almost empty before refilling, this will make sure that old veg oil doesn't stay around to build up gummy residues in the tank and fuel lines. Probably an idea to fill the tank with 100% diesel from time to time.

Also if you use recycled oil, you need to be very careful about the fine particles of burnt chips or whatever still in the oil. Careful filtering of the oil is essential, and replace the engine fuel filter on a more regular basis than normal.

And don't forget the tax man.

Regards, Robert

I did say "sorely tempted", probably wouldn't, how would I fry my chips?

 

[Lol1]

I do remember a couple of years back, watching Mr Clarkson (another hero of mine) on "Top Gear", look into the practice of using Veggie oil as a replacement for diesel fuel.

I think he used an old Volvo, and it involved draining the tank and fuel lines of all fuel and then refilling with a vegetable oil mix. I say mix, as the other ingredient was something along the lines of white spirit, this itself had to be made from plant material and not mineral in origin, due to tax reasons. Approximately a capful added to each gallon, certainly not enough that you think it would make any difference to the fuel characteristics. It was then discussed that "used and filtered" oil is best, perhaps negating or reducing the effect of gummy residues. These test were overseen by a well-regarded motoring organisation and as such were not a flight of fancy. The Volvo started almost immediately, and ran as well as an elderly Volvo can. The commentary went on to state that many others run their vans/cars on this veg oil/spirit mixtures with perhaps one in every 4 tank fills done with diesel. Even when these people paid the tax on this fuel it was still considerably cheaper than ordinary diesel. I have recently worked on motorway communications necessitating long hours next to the hard shoulder, and believe you me; the amount of vans run on curried oils is on the increase. The problem is not what fuel we have or which is the better to run our cars on it is simply, if we all use bio fuels, we will all end up paying the same taxation on it that we do now on diesel. Mr treasury will not let a good thing go unnoticed. I hate to say it, role on the fuel protests, something has to be done!

 

[rob_jax]

I did say "sorely tempted", probably wouldn't, how would I fry my chips?

You could always go back to cooking the chips in dripping.

 

[Lol1]

You could always go back to cooking the chips in dripping.

Ok, the slimming world magazine in the bin....

 

[rob_jax]

Lol,

I remember that TopGear transmission too. You are right, it was an old Volvo estate - probably with the outsourced 5 cylinder Audi diesel engine.

The car was certainly pre-common rail technology, and I don't believe that a CDI would like 100% veg oil - too viscous and may not lubricate the high pressure pump, but for an older generation engine, why not?

They cleaned out the tank and fuel lines to prove that the engine would run on veg oil, modified with about 10% of vegetable origin white spirit to reduce viscosity - rather more than a cap full in a gallon.

Used and filtered oil will be the cheapest, but because it's been heated it's now chock full of gummy residues. I've mentioned the outside of a chip pan before, but if youwant another example, artists use "boiled linseed oil" as a varnish.

More and more bio-diesel will be added to diesel over the coming years, more ethyl alcohol to gasoline, but with China and India buying more and more oil...

Robert