Why not make Biodiesel instead?

Well, why convert the car to run on waste vegetable oil (WVO)? Why not just make Biodiesel? After all, the 300D runs fantastically well on Biodiesel with no modifications required...

Good questions. It was originally my intention to make a small scale biodiesel production plant to make fuel for my own use. But first, what IS "Biodiesel" and how is it different to veg oil?

Biodiesel is essentially vegetable oil that has had the glycerine and "soap" stripped out from it by a process of transesterification. This process reduces the viscosity of the veg oil to approximately that of dino-diesel. This is why it is not usually necessary to make any modifications to run a diesel engine on biodiesel. It also has excellent lubricity, better in fact than dino-diesel. The only real problem that might arise in some vehicles is that the seals in some injection pumps and the fuel lines might degrade. All veg oils and biodiesel will soften ordinary rubber. To combat this effect, seals, membranes and fuel lines made from nitrile or viton rubbers are usually used.

Now the chemical processes involved in the manufacture of biodiesel are quite simple, and around the world there are many home mini-plants in operation. It is so simple, that you can make it in your kitchen using nothing but a PET softdrink bottle. See: http://en.wikibooks.org/wiki/How_to_make_biodiesel
Please heed the cautions!!!

OK, it's so simple to make biodiesel, why not? Personally, I have two reasons not to tread this path: -

1. Here in Australia, biodiesel is now officially a fuel. Now we all know what governments do with fuel don't we? Yes, they tax them! Excise tax in fact. So to legally make biodiesel for your on consumption, you have to register as a fuel producer. Not only do we have to register and toe the line with reams of paperwork to satisfy the tax man, we also have to jump through hoops in order to comply with local government regulations, State government manufacturing, as well as storage and material handling issues.

As Senator Allison said: "Home-brewers will not produce biodiesel, or if they do, they'll be doing it outside the law [and] they'll be effectively tax cheats," she said.

"One of the reasons they won't continue to produce biodiesel is the cost of licensing and testing which means thousands of dollars in many cases.

"Not only will it not be viable but it would be very, very expensive."

2. The main reagent in the biodiesel making process is a chemical called Sodium Methoxide. It is the product of mixing two chemicals that can be found in many households, ie. methanol (methyl alcohol/methylated spirits)and sodium hydroxide (drain cleaner), yielding a solution of sodium methoxide in methanol. When sodium methoxide is mixed with vegetable oil at the right temperatures, the glycerine and soap components are stripped out, leaving behind.........Biodiesel! OK, what's the problem? Well, a big one as far as I'm concerned......

Sodium methoxide in methanol is a liquid that kills human nerve cells before any pain can be felt…… Yikes!!!!

No such problems with WVO. WVO, also known as UCO (Used Cooking Oil) is classified as a food, so no excise applies :)

Converting a 1976 Mercedes Benz 300D to run on WVO

About 2 years ago I purchased a 1976 Mercedes 300D with the intention of one day running it on 100% vegetable oil.

Why?

Well, there are environmental benefits of burning veg oil rather than petro-diesel. Petro-diesel is a fuel that was laid down tens of millions of years ago. Burning it is releasing all the stored CO2 into today's atmosphere at a far greater rate than plants took to make it. Veg oil, whether in Biodiesel form, straight vegetable oil (SVO), waste vegetable oil (WVO) or used cooking oil (UCO) forms, is a renewable resource and its CO2 output fom combustion is theoretically balanced with the plant's intake from the atmosphere. In other words, veg oil is a "green" fuel with a much reduced impact on our atmosphere.

I don't wish to post too much detail on these fuels here on this blog. A quick search using words like: biodiesel, WVO, SVO, bio-fuels will produce plenty of reading matter on the subject. A good, quick reference to biofuels is http://www.nrel.gov/docs/fy00osti/25876.pdf

For those unfamiliar with Benzs, my 300D is a model W123. Technical details are as follows: -

(All technical data reproduced with kind permission of Carfolio.com
Reproduction free under the terms and spirit of the GNU GPL)

Code: OM 617 D 30 / 617.91
Manufacturer: Mercedes-Benz
Type: 5 cylinders SOHC
10 valves total
2 valves per cylinder
Main bearings: 6
Bore x stroke: 91.00mm × 92.40mm
Bore / stroke ratio: 0.98
Displacement: 3005 cc 183.37 cu in
Compression: 21.00:1
Fuel system: Bosch diesel inj.
Aspiration: Normal D.
Catalytic Converter: N
Max. output: 81.1 PS (80.0 bhp) (59.7 kW)@4000 rpm
Max. torque: 171.0 Nm (126 lbft) (17.4 kgm)@2400 rpm
Coolant: Water
Specific output: 26.6 bhp/litre
Specific torque: 56.91 Nm/litre

Performance
Top speed: 148 km/h (Yeah, right, they're dreaming...!)
Power to weight: 55.36 bhp/ton

Chassis
Engine location: Front
Engine alignment: Longitudinal
Steering: recirculating ball PAS
Suspension front: I.W.CS.
Suspension rear: I.STA.CS.
Brakes: Disks front/Disks rear
Transmission: 4 spd Auto
Drive: RWD
Top gear ratio: 1
Final drive ratio: 3.46

Why a 300D Benz?

The W123 model Mercedes Benz is widely considered as the most bullet-proof and reliable Benz models ever made. Around the world, stories of these cars reaching 500,000km are commonplace. A million km on the clock hardly raises an eyebrow. All W123s are a tribute to Mercedes Benz engineering, and their diesel engines in particular, are legendary.

More so than their petrol (gasoline) counterparts, the diesel W123 models hold sway as being even more long-lived. The Bosch in-line injection pump that feeds the 5 cylinders is just as tough. Moreover, unlike most other diesel injection pumps which rely heavily on the diesel fuel itself for lubrication , the Bosch pump is lubricated by sump oil from the engine. Therefore it is not as prone to the effects of low-sulphur fuel as most pumps are these days. It has a reputation as being particularly resistant to the effects of bio-fuels on newer fuel system elastomers, seals, and metals.

Watch my week by week progress on the conversion of this vehicle to use used cooking oil as a fuel!

Cheers
OZTayls