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Veggie Oil Powered Toy!

Children, you musn't play with fire. This is serious business. HEY! Wipe that smirk off your face, this is for real. What we have here is a truly vegetable oil powered vehicle. Not new oil of course, it's premium quality used, rancid, and nasty canola oil. Otherwise known as WVO, or waste vegetable oil. You know how a candle smells when you blow it out? Nice! Well, this one smells like cat barf when you blow it out.

New in package

This is how the project began. I went to the store in quest of a battery-powered car of some sort. One that preferrably used only one or two AA batteries. This one took two AA's in the transmitter, two in the receiver. Perfect. I'll explain the low voltage requirement later.

Let the hacking begin

Some disassembly required. Further progress required dissassembly. This unit was very cheap, held together with only a few phillips screws. Thank you, New Bright™! (I wonder if their oil lamp logo is any coincidence.)

Getting ready to modify

Down to the elecronics. I chose to leave the radio control stuff intact, in case they would be of any use. My intentions were to modify the unit so it would be easy to power the entire system with the thermoelectric module--including radio control, or just power the motor for basic propulsion.

New wires soldered in

A twisted pair of red and black straight off of the battery terminals, and a pair of yellow and green straight up off the motor terminals. I'll let you guess where these wires came from. (Give up? Okay, they're telephone wires.)

Marlow thermoelectric module

Originally intended to provide refrigeration in 12 volt portable coolers, these modules will also generate electricity when heated on one side and cooled on the other. And a handsome quantity, too--not just microvolts. Together, they will produce about 3.2 volts open circuit with the grease burner under them. Powering the jeep with drive wheels raised, that drops to about 2.4 volts--the same as two NiCD AA's.

I got these on ebay a while ago for around $15 each as I recall.

Mounting thermoelectric modules to heatsink

I used two of the Marlow SP2348 modules in series for the heat to electricity converter. I used white heatsink grease to make a good thermally conductive bond between the two heatsinks. Actually, the bottom heatsink (the hot side) was just a flat plate of aluminum, about 1/16" thick.

The cooling side was a leftover heatsink from an old UPS (uninterruptible power supply), you know, the type they use for power backup on computers.

Flame box for vegetable oil burner

Since the cheap plastic construction of the donor car would not be able to stand up to much heat, I took some aluminum flashing and folded up a box which fit neatly into the passenger compartment (roll bars, seats, and dashboard had to be removed). The thermoelectric module assembly is visible to the left.

Tea light holder

I didn't want the tea light bouncing around in here and sloshing putrid oil all over the pristine interior of my newly converted grease car, so a simple holder was devised, also of aluminum flashing.

Used tea light cup for burner

My wife burns these at an approximate rate of 2.88732987234 per month, so she was happy to donate one to the cause.

Fill 'er up with grease, Charlie!

Boy this stuff is nasty. It was sorta cold from being out in the garage, so it poured out in chunks. Note to self: The same thing would happen in the fuel tank of an automobile.

Tea light, in holder

I got some votive wicks at a local craft store to use as the wicks. I knew it would take more than just one wick, from some preliminary testing with an ordinary white-wax tea light.

Six wick oil burner

Simpler is better. I've tried all sorts of different ways to vaporize and burn veggie oil. Lots of failures. This one works. Not very serviceable though, because the wicks burn down as the oil level drops, and they need to be replaced.

Complete unit with heatsink

The heatsink/thermoelectric module unit is held on with some heavy duty spring clips. It can easily be unclipped and attached to other heat-powered projects. (An oil-powered transistor radio is next on the list!)

Motoring under its own power

Here's a movie clip (9.63MB quicktime .mov, Sorensen 3 codec) of the Jeep spinning its wheels on the test bench, and then motoring under its own power. There didn't end up being enough power to operate the radio control system, so all it can do is drive in a straight line. I think that with some gear reduction and steering servo upgrades, this could be overcome also.

(For best results, right-click the link for the movie clip and choose "save link target as" to save it to your desktop.) More...