Waste Vegetable Oil Conversion for Diesel Bus

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Introduction: Waste Vegetable Oil Conversion for Diesel Bus

About: Tim Anderson is the author of the "Heirloom Technology" column in Make Magazine. He is co-founder of www.zcorp.com, manufacturers of "3D Printer" output devices. His detailed drawings of traditional Pacific...

Biotour.org's bus can get halfway across the country on a single fill of waste vegetable oil ( WVO ).
They get their fuel from the used oil tank behind restaurants.
All processing of incoming oil takes place right on the bus, mostly while it's in motion. That means heating, water separation and filtration. They get about 10 mpg on veggie oil, which is about the same as they do on diesel.

This bus is a VEGGIE DIESEL bus, that can burn straight vegetable oil, as well as regular diesel or biodiesel.
It's a "two-tank" system, which means the bus has a small tank of biodiesel (or diesel) to start the engine, and then they switch to straight vegetable oil when the engine is hot.

For the uninitiated, Biodiesel is veggie oil that's been subjected to a chemical process so it's thin and runny (lower viscosity) all the time and can be run in unmodified diesel engines. This bus runs on straight veggie oil, no reaction needed. It only requires biodiesel or diesel fuel except for starting and shutting down the engine.

Check out [www.biotour.org biotour.org's website] for the history of how their methods have evolved.

Here Ethan Burke shows the pre-filters.

In another side compartment is the collection hose. They park next to the restaurant's waste tank, dip the end of their collection hose into the top, and start pumping oil into their storaage tanks.

They dip a piece of cardboard into the oil and do other connoisseur stuff to see if they want that restaurant's oil or not.
They don't want the oil at the bottom of the waste tank because that's where water and dirt settles. Their collection hose has a screen on the end to filter out bits of french fries, dead leaves, etc.

Step 1: Storage Tanks

These three 55 gallon oildrums are strapped under the rear of the bus.
The incoming oil goes here. The transfer pump can empty either of the side tanks into the center tank.
The center tank is heated.

Step 2: Water Separation

Hot coolant from the engine is piped to a coil of copper tubing in the middle tank.
That heats the vegetable oil.
After heating it up and letting it cool down water separates out and sinks to the bottom.
Then they drain out the water at the bottom of the tank.

Step 3: Transfer Pump

This is the main pump. It runs on 110volts from the inverter. The valves let them pump into or out of any of the three oildrums, out to the main fuel tank after passing through some filters, or in from a waste oil container at restaurants.

Step 4: Pre-Filters

On the way from the rear drum to the main fuel tank the hot oil goes through these filters.

These filter housings are available at any hardware store or plumbing supplier.
They contain one-micron nominal bag filters.
"nominal" means the average pore size is one micron. They don't block everything larger than one micron. A lot of multi-micron sized chunks still get through.

The pressure guages on the top are to check when the filters are clogged and need to be replaced.
When there's too much pressure across the filter, it means its clogged.
These filters are in parallel, in other words some oil goes through one and some goes through the other.

Ethan intends to change this so oil goes through three filters in series for finer filtration. He expects his screw on fuel filters in fuel injection system will last longer that way.

They look for very clean oil that won't clog their filters.
Their best oil came from the Falafel fryer at an Arab restaurant.
Chinese restaurants often have good oil.
Oil from frying chicken, any oil with animal fat in it is harder to filter and clogs the filter sooner.

After going through this filter the fuel goes into the main fuel tank. That's the regular stock fuel tank that came with the bus. I don't have any pictures of it. It wouldn't look like anything anyway.

Step 5: The Engine Compartment

It's a stock diesel engine, stock injector pump, stock injectors, the same as when it was bussing kids to school.
A bunch of additional plumbing has been added to heat and filter the veggie oil.
The next few steps will explain in more detail the function each add-on part.

Heated fuel line
starting fuel pump
Heated screen filters
heated final filters
temperature sensor
various hot hoses.

Step 6: Heated Fuel Line

A hot coolant hose from the engine goes back to the main fuel tank. It runs into 30 feet of PEX brand tubing coiled up in the tank. That heats up the fuel in the tank.
PEX is a type of heat-resistant plastic tubing available at hardware stores.

Inside another hot coolant hose is the aluminum fuel line.
That way the fuel is kept hot all the way to the engine.
Here's the T fitting where the fuel line comes out of the hot coolant hose.

This instructable has more details on how to make hose-in-hose heated fuel lines.

Step 7: Heated Screen Filters

The heated fuel line carries the fuel through these two heated screen filters with a 20 micron asbolute rating. Unlike the sock filters seen earlier, this micron size actually means there won't be any particles in it larger than 20 microns.
They are Volkswagen motor oil coolers from a junkyard. Each unit has a water hose in and out and a fuel line in and out, so there are plenty of hoses to delight the senses.In the original car, the hot engine coolant is cooler than the hot motor oil, meaning the heat exchanger in this case will heat the engine cooant and cool the motor oil.
In this case, the hot engine coolant exchanges heat with the cooler vegetable oil, raising the vegetable oil temperature as it passes through the metal screen filters.
They work great for that.

The filters are plumbed in parallel to decrease resistance, that is some fuel goes through one filter and some through the other.

The first photo shows a filter with the can removed.
These pleated screen filters seen here are handmade and intended to be used for motor oil.

Step 8: Elsbett Heat Exchanger and Filters

Our bean-squeezins journey now takes it into the main heat exchanger where it's once again heated by hot coolant. Then it goes through a 8 micron "nominal" filter.


This is an Elsbett brand unit from Germany. There's a temperature sensor on top.
Next to it is a mysterious black dingus.
Ethan says: "The black thing is a primer pump in case you want to pull fuel into the fuel filter before starting the engine and getting air inside. We havent even used it."

Step 9: Temperature Sensor and Starting Fuel Pump

This bus starts on diesel or biodiesel when the engine is cold. There is a separate small fuel tank for the starting fuel. I don't have a picture of it. It's a 20 gallon red plastic tank strapped under the bus.

Once the engine and veggie oil have heated up to 170 farenheit this temperature sensor switches to the other fuel pump and the engine runs on veggie oil.
There's a manual fuel selector switch in the cab also. When shutting down the engine they switch back to the starting fuel tank for a few minutes before turning off the engine. That way there's no cold veggie oil in the engine or injection system the next time they start it.

When veggie oil is cool, it can put pressure on the fuel pump, doesn't atomize well, doesn't burn completely, and can leave carbon deposits in the engine.

Also it's too thick for the fuel injection pump to move it. In the former inadequate heatling and filtering system that came with the bus when they bought (which has since been replaced by the one being described). Their injector pump broke and had to be replaced once because the veggie oil going into it wasn't hot enough.

Step 10: Roof Rack

The bus has many other ingenous systems and features, but for now, here's the roof rack.
It's a really simple and good design.

So that's it, a proven veggie diesel system for a large vehicle.
Get good veggie oil, heat it, and filter it.
Make sure it's good and hot before entering the injector pump.
Start up and shut down your engine on something else, either diesel or biodiesel.

For more info or to buy a Biotour.org shuttle bus ticket from SF to Burningman, check out their website.

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    100 Comments

    Great bus! I do the filtering in 3 steps with 3 different filters, this helps lowering costs as there are filters for 20 mycron available which are reusable(cleanable).
    The steps are 20-> 5-> 1. If you were ever wondering what to do with the disgusting rest aka fat.
    Here is a solution. :-)
    This is a really powerful stove which has about 10 kw. It burns anything like fat, oil or even used engine oil and there will be NO=0! smoke!
    If you want details send me a mail

    cheers from Germany

    03012009.jpg
    6 replies

    metamart - this is coming to you 8 years after you posted this so hope it finds you! I would love the details on your stove build if the info action is still on offer

    Many thanks in advance!

    Hi Metamart

    I have got your detailed written plans but have you got any pictures of the steps that I can see or a youtube video?

    cheers Greenpig

    i do not have any picture amterial at the moment.. I will try to make some pictures next week. I am always happy to help but i am very busy at the moment.
    Just one thing to mention: be careful with the smoke if it dosent burn decent (white smoke etc.) it hurts in the lungs and is probably very bad.

    happy new year

    Hi there.
    I have been working on a waste oil heater for my workshop and saw this. Any chance you could share the design with me.
    Thanks in advance.

    why is it luminescent purple?

    Ethanol is widely used in South America as an aircraft and vehicle fuel; E85 biodiesel is common in Europe (not UK and Ireland); biodiesel from rapeseed is common in Europe; use of recycled engine oil as diesel is practised in the US as "black" diesel; Ireland allows 2500 litres of biodiesel tax-free per year; ethanol is now common in European petrol, to at least 10% per litre.....I saw Waukesha V-16 diesels running on natural gas in oil fields. Ran very clean as a result.

    1 reply

    Hey all and TimAnderson, grateful for the awesome information resource you got here, I just purchased a 1990 diesel ford f250 2wd lariat ext cab, and was looking for anyone who is selling converted and filtered quality waste oil for cheap as I'm sure someone around the Ottawa Ontario area has made a little filtration chemical setup for waste oil somewhere, with all the micronl filters and potassium and sodium hydroxide chems they need to obtain a pure product... if anyone knows of someone like that or if that's you, please contact me, Jonathan or Johnny for short at 613 741 6648, or email jonny_blaze_et@hotmail.ca , looking forward to doing business thanks!

    Hey all and TimAnderson, grateful for the awesome information resource you got here, I just purchased a 1990 diesel ford f250 2wd lariat ext cab, and was looking for anyone who is selling converted and filtered quality waste oil for cheap as I'm sure someone around the Ottawa Ontario area has made a little filtration chemical setup for waste oil somewhere, with all the micron filters and potassium and sodium hydroxide chems they need to obtain a pure product... if anyone knows of someone like that or if that's you, please contact me, Jonathan or Johnny for short at 613 741 6648, or email jonny_blaze_et@hotmail.ca , looking forward to doing business thanks!

    Ok, I love this but I will share a life experience of mine. I am 100% for reducing waste, BUT a bus ran on vegetable oil will only run so long, and by "so long" I mean not long. I am the general manager of a truck repair shop, and one day a group of kids from an unspecified Ivy League school barely roll into my shop with a dying bus. We soon found out that this bus was powered by vegetable oil. This engine was destroyed on a trip that started in New Hampshire and ended at my shop in the southeast. The damage was so bad to the engine, we had to do extensive repairs and then convert the bus back to diesel power. I do believe it is possible to build an engine from scratch that can run on vegetable oil, but an engine designed for diesel is not going to last long converted to vegetable oil. So.... Before trying this yourself, keep this in mind. And be ready for a hefty repair bill to get you going again when you get stuck. Sorry to be a bummer!!

    Wow, it's incredible that you can power a whole bus with this waste oil. I wonder if the exhaust smells like chicken fingers and egg rolls! This conversion must have taken some serious smarts and a lot of patience.

    Working with an application as big as that and such a rarely used energy source must have been intimidating. I just finished up my Instructable on converting an air compressor to a larger capacity by adding air receiver tanks and thought THAT was intense.

    I can't imagine how much work went into performing this task and THEN logging onto this website to show everyone how you did it. Anyone else crazy enough to try a conversion like this one?! LOL

    can any body tell me that how can i get fuel from waste plastic

    i saw some videos about " convert waste plastic into fuel diesel patrol, gasoline".But i don't know the equipment. (i want to do it at home.)

    waiting for your reply

    can any body tell me that how can i get fuel from waste plastic

    i saw some videos about " convert waste plastic into fuel diesel patrol, gasoline".But i don't know the equipment. (i want to do it at home.)

    waiting for your reply

    You have done a very nice job and explanation of all your work. I see this was posted a few years ago and I live in Calif. I believe you have to have a recycling permit or certificate to take used frying oil in this state. How do you handle this?

    That honestly is pretty cool, turning old cooking oil that no one knows how to dispose and running your vehicle off of it.

    Going Green has never been cooler! It is truly remarkable with the energy shortages of the world that it took this long to realized fuel could be made from waste vegetable oil, brown oil, or the grease from grease traps. Biodiesel makes sense!

    VegSamples.jpg
    1 reply

    For more information about how Grease and Oil Rendering is converted to biodiesel and where to sell your grease and WVO visit Hulsey Environmental

    It's cool to see people trying to change the way we run cars on gas, but its sad to say that if everyone started doing this biodiesel project to their cars, that the price of vegetable oil would clearly start to run higher than gasoline. Still an awesome project! How much does a gallon or OJ cost or a gallon of Ocean Spray? Think about it

    1 reply
    user

    It is fallacious to think that any one fuel solution will be "the" solution to our transportation and energy needs. Each one has it's trade-offs. We are already seeing the result of subsidized ethanol (corn oil) on the wider agricultural economy. Using recycled oil isn't for everyone, but it's much better than no one using it and it going right down the tubes, isn't it?