Vegetable Oil Road Trip

A while back, I received the following question:

Hey, I just wanted to say hello and ask you if you have any suggestions about procuring the vegetable oil. My bus is about ready and I heard there are good establishments to get oil from relatively painlessly. Any advice is appreciated.

Supposedly there are organizations who will sell the oil- already filtered for cost but this is anecdotal. I am perfectly happy climbing in the grease traps and sucking it out and filtering it myself, but I need to know where to actually get it.

Cheers,
adam

Sadly, when I replied to the email address Adam gave, my reply bounced. Here is my answer:

Hi Adam,

Gosh, that’s the million-dollar question: where do you get vegetable oil?

First, a few warnings about dumpsters:

1. Once oil is placed into a dumpster, it legally belongs to the company that owns the dumpster. If you pump oil from the dumpster (even with the restaurant’s permission), you are stealing. There have been prosecutions of people running their cars on veg oil who pumped oil from dumpsters in Texas and other states.
2. Can you really, guarantee that some brainiac hasn’t decided to dump their old engine oil into that “oil only” dumpster? You can’t filter engine oil out of veggie oil, and I guarantee that engine oil will cause damage to your engine.

Now, on to your question: where do you get used oil?
Most restaurants pay a waste removal service to dispose of their used fryer oil. If you offer to pick up their oil for free, most restaurants will be happy to help you out.

What you want:

• Vegetable oil without animal fats that has been used at relatively low temperatures (~300-350F). Preferably canola or soy oil.
• Absolutely no hydrogenated oils – the words “creamy fryer shortening” on oil containers are a tip-off that their oil is hydrogenated.

Best places to try:

• Mexican restaurants that only use fryers for making tortilla chips
• sushi restaurants that use fryers for making tempura with vegetables and fish
• vegetarian or middle eastern restaurants that use fryers for making falafel and french fries
• chip factories (only approach them if you can handle the volume – otherwise, they will drown you in oil)

Tips to prevent you from ruining it for the rest of us:

• Be professional, polite, and dependable – the restaurant is depending on you to remove their oil. If you can’t do it reliably, they’ll wish they had could just pay Waste Management to do it. Establish a day/time to get the oil, and stick to it. Even during the winter.
• Get the manager’s name and contact info; give them yours.
• Be clean: bring a tarp, lots of rags, rubber gloves, funnels, and lots of absorbent material in case of spills. Leave your workspace (their kitchen or alleyway) as clean as you found it.

If all of this sounds like too much work (and it is a lot of work), try fillup4free.com, or look for a biofuels co-op, conversion shop, or other vegetable fuel organization near you.

I hope this helps.

I just received the following question from Jim:

I have a question. Being interested in using VO for diesel fuel, and knowing that air and reactive metals cause degradation of the oil (polymerization – and also putrifaction), I am wondering if an inert atmosphere would help. Would nitrogen do the trick (or air purged of oxygen), or would argon be necessary?

Jim

Jim,

Thanks for your question!

Yes, a nitrogen or argon blanket would significantly slow the rate of oxidation. Unless you have an extremely problematic storage situation, using either nitrogen or argon is unnecessary (and expensive).

In my experience, vegetable oil doesn’t degrade that quickly from oxygen unless there is a lot of heat and a lot of oxygen present (such as if your oil is constantly shaken or has air bubbling through it). In a heated fuel tank, you do have this situation, but the oil doesn’t stay there long enough to degrade enough to be a problem.

In my experience, storing fuel in a dark, dry place is more than good enough. Make sure to rotate your stored oil so it doesn’t sit for too long (this applies to all fuel supplies, actually). I once stored waste vegetable oil for over 6 months in a hot and humid storage shed (in a sealed container), and it was fine. If your supply is so large that you’re storing your fuel for more than six months before using it, consider giving some away on fillup4free.com or craigslist.org.

The real culprit in storing vegetable oil isn’t oxygen, reactive metals, or heat: it’s light and moisture. Light and moisture promotes algae and bacteria growth – which causes clogged filters and general fuel system nastiness. So, keep your fuel dark and dry. Luckily, this isn’t a biofuel-specific problem, it’s a problem for petroleum diesel fuel, too – this means that petroleum diesel biocide additives work well for treating biodiesel and vegetable oil algae and bacteria problems.

Thanks again for your question, good luck, and if you’re ever in Chicago, drop me a line!

Sacha

I recently received the following questions from Scott via email:

Hello:
I am thinking of going with a WVO system in my 2000 Jetta TDI. I would like to know what kind of storage container (metal or plastic) I should get? Is one better than the other?

Also, I live in an area that gets very hot and humid in the summer. Should this be a concern?

What should I do for long term storage of filtered and de-watered WVO?

I have also been told that burning WVO (filtered and de-watered) causes Sulfuric Acid to be created and that will damage the valve train and exhaust system. Is this true? How can it be prevented? Thank you very much.

Best regards,
Scott H.

Hi Scott,

Thanks for your message!

As far as storage goes, I always used the standard 4.5 gallon plastic “cubies” that restaurants purchase their oil in. They’re light weight, (usually) free, and recyclable.

The downside is that they aren’t as strong as other storage containers. I never had a problem, but I was always careful to store them on a cloth tarp instead of bare concrete (to prevent punctures), and I never stacked them.

Despite my personal practice, I really like Lovecraft Biofuels’ home fueling station/storage container (they don’t seem to have them in stock at the moment). It’s just a barrel, wheels (for the barrel), a hand pump, and a sock filter (link). You could probably remake one of these with parts from Harbor Freight and McMaster for pretty cheap.

Hot and Humid Climate: While I owned Minnie, we traveled through many hot and humid environments (including a swamp), and I didn’t have many issues. My advice is pretty standard: keep your fuel in a dark place, keep a lid on your fuel, remove fuel from the top or middle, never the bottom (that’s where water settles!), if you’re worried or if you see stuff growing in your fuel, use a biocide in the summer to treat your fuel (ask your local diesel mechanic or farmer’s supply).

Sulfuric Acid: I wonder where you heard that rumor about sulfuric acid coming from veggie oil because there is zero sulfur in vegetable oil, so no sulfuric acid can possibly be produced when it is burned.

On the other hand, petroleum does contain sulfur, so sulfur oxides are produced when you burn petroleum diesel. When those sulfur oxides react with atmospheric water, sulfuric acid and acid rain are formed. Notice that none of that acid is formed in your valve train or exhaust system. Note: in 2007, new ultra-low sulfur fuel was introduced in the US, but there is still some sulfur present in all petroleum diesel fuel.

There are (of course) other issues with burning veggie oil, but sulfur isn’t one of them. Religiously change your engine oil every 3,000 miles and give your engine a few doses of diesel purge every once in a while and you’ll probably be fine.

I hope this helps, and good luck with converting that Jetta!

On Monday, we visited with the 5th, 6th, 7th, and 8th graders at the St. Mary’s School in Goldsboro, NC.

A common questions we get from students – almost always from boys – is: does adding the vegetable oil tank in the trunk of the car increase the risk of explosion during car accidents?” I then have to convince everyone that adding a vegetable oil tank does not make Minnie The Car a rolling stick of dynamite, and that vehicle explosions pretty much never happen outside of Hollywood, California.

While trying unsuccessfully to explain this fact (much lamented by 8th grade boys everywhere), Miss Caroline from the 5th grade raised her hand and asked a question that completely stumped me: “what is the flammability of vegetable oil?”

I sputtered for a moment and managed to say that “well, it’s much less than gasoline, and less than diesel, but I don’t know how much less.” I congratulated her on stumping me, and promised her a much more thorough explanation in a Q&A post.

So, let’s first look at what flammability means, a good way of measuring it, and finally, we’ll compare the flammability of vegetable oil to other common liquids and fuels.

Flammability
By asking how flammable something is, we are asking how easily can it catch fire. The best way to look at the flammability of a liquid fuel is to look at its flashpoint. The flashpoint is the temperature above which a liquid can form an ignitable vapor above the surface of the fuel.

Without going into the science of vapor pressure, if a fuel is warmer than its flashpoint, if you hold a match to the surface, it will catch fire and burn. The lower the flashpoint, the easier it is to catch a fuel on fire. Gasoline, with a flashpoint of -43F is extremely flammable, while Canola oil with a flashpoint of 600F is flame retardant by comparison.

Flashpoint is measured by slowly heating a sample of the fuel in a chamber with a spark plug. As the temperature rises, the spark plug makes sparks – the temperature where the first flames form is the flash point.

Flashpoints of some common fuels:
Gasoline: -45F/-43C
Diesel: 143F/62C
Biodiesel: 300F/149C
Canola Oil: 600F/320C
Soybean Oil: 491F/255C

So, Miss Caroline, if you look at the numbers above, you’ll see that vegetable oil is much less flammable than gasoline, diesel, or biodiesel.

Source research:
Wikipedia: Vapor_pressure

Wikipedia: Flammability

Wikipedia: Flash_point

MSDS definition of flashpoint

biodiesel.org.au’s biodiesel facts

biodiesel.org’s safety FAQ

Update:
Looks like I messed up the flashpoint for biodiesel – it is actually 260 to 300F, not 212F as I previously wrote. Thanks anonymous commenter for keeping me on my toes!

However, I believe that 143F is the correct flash point for petroleum diesel – can you please tell where you found 77F?

I met Eric over dinner in Indianapolis, and he asked me a very good question:

What is the Cetane number of Vegetable Oil as compared to Petroleum- and Bio-Diesel?

Having no idea what a cetane number was, my response was: “hmm, that would make a great Q&A post. Watch our blog for my answer!”

So, two and a half weeks later, I finally have the time to investigate and post a response to his question.

I found the answer in several places: Wikipedia’s Descriptions of Cetane Number and Cetane, Journey to Forever’s comparison of Vegetable Oil, Bio Diesel, and Petroleum Diesel, ChemFinder, the NIST chemistry web book, and FuelMagic’s cetane discussion.

The short answer is this: the cetane number of vegetable oil varies depending on type and quality of oil, but it doesn’t vary far from the cetane number of petroleum diesel.

Here is the data (from Journey to Forever):
Diesel 45
Canola Oil 40-50
BioDiesel 45-65

This is all well and good, but who the heck is cetane, and why do I care about her number?
Cetane (AKA: hexadecane) is a fuel that experiences autoignition very easily. If you were to test a fuel for use in an autoignition engine (like a Diesel engine), and it behaved exactly like cetane, the fuel’s cetane number would be 100. If it were slightly worse than cetane, it would have a cetane number of 99, and so on. If the fuel does not autoignite, it has a cetane number of 0. Diesel fuel has a cetane number of about 45. Most Diesel engines run well when using fuels with cetane numbers between 40 and 55 (please note that Canola Oil is well within that range).

So, simply put: The cetane number is a fuel’s ability to combust in a diesel engine, as compared to cetane.

A cetane molecule. Image taken from NIST.

Don’t confuse cetane number with octane number – these are NOT equivalent measurements.
If you put 100% octane (or a fuel with a octane number of 100) into a gasoline engine it would run very well. If you put 100% cetane (or a fuel with a cetane number of 100) into a diesel engine, it would either not run at all, do some terrible damage to itself, or both.

Fuel Magic says:

There is no benefit to using a higher cetane number fuel than is specified by the engine’s manufacturer

and

Diesel fuels with cetane number lower than minimum engine requirements can cause rough engine operation.

So, any fuel that has a cetane number of 40-55 will work just fine. This means that Vegetable Oil works just great as a diesel substitute (if you can deal with the viscosity).

I hope that answers your question Eric!

Please keep your questions coming – just use the contact us page to send us questions!

Rebeccalin continues with this question:

Are there any other disadvantages to using biodiesel?

Well, I found this document on Extraordinary Roadtrip that I feel details the advantages and disadvantages of biodiesel pretty well.

I’m an optimist, so let’s cover the advantages first:

• Biodiesel is a renewable energy resource. Biodiesel can extend the supplies of fossil fuels that rely on carbon-based compounds.
• Biodiesel can be made in the US. This would improve energy security by reducing the reliance on imported oil.
• Biodiesel has a higher cetane and lubricity rating than pure petroleum based diesel fuel, which improves engine efficiency and operating life cycle.

And here are the disadvantages listed by Extraordinary Roadtrip:

• Biodiesel acts like a solvent, similar to methanol, and more pronounced than gasoline. Therefore, any sediment in the fuel delivery system (storage tanks, hoses, vehicle fuel tank, etc.) can be washed into the diesel engine’s filters and fuel injectors, potentially causing reduction or stoppage in fuel flow.
• This solvent effect can be overcome by changing filters more often initially, as well as ensuring storage tanks are kept free of sediment and other deposits.
• Hoses and other fuel delivery connectors must be inspected regularly for deterioration, particularly when higher blends are used because material compatibility is an issue.
• Biodiesel can harm painted surfaces when excess fuel is spilled. Reducing the concentration of the biodiesel blend to B05 or lower can alleviate this risk.
• Biodiesel is more likely than petroleum diesel to attract moisture, which can cause problems in cold weather (fuel freezing, deposit of water in the vehicle fuel delivery system, fuel cold flow, clouding, and increased corrosion for example) and increase the risk of microbial growth (which can also clog engine filters).

Rebeccalin writes:

Hi, I was wondering why viscosity is a concern when using biodiesel. Is it because it will freeze in lower temperatures and the car would not run?
Also, what can be added to biodiesel to reduce the problem of viscosity?

Thanks!

Hi Rebeccalin,

That’s a great question!

Before we begin: viscosity is a measure of how fast a liquid flows. Something with a low viscosity (like water) flows very quickly. Something with a high viscosity (like honey or pancake syrup) flows very slowly. Also keep in mind: viscosity can change a lot with temperature. for example: cold honey barely moves at all, but if you warm it up, it flows very easily.

Viscosity of biodiesel fuel is actually pretty similar to petrodiesel fuel.

Here’s how they compare at 40C (I know, it rarely reaches 40C during the winter, but bear with me, that was the only data I could find) – I threw in the values for canola oil and water for comparison, so you can see how close biodiesel really is to petrodiesel.

The reasons the petrodiesels have a range of values here because the viscosity varies depending on the different blend of petrodiesel used – (I’ll discuss that in a second). Biodiesel also has varying viscosities, depending on the source of the grease used to make biodiesel. Pretty much, if you use very viscous grease, you get very viscous biodiesel.

Really, as long as biodiesel stays liquid, it should have no problem going through your diesel engine. Viscosity isn’t the problem.

The real problem with using any diesel engine fuel at low temperatures isn’t the viscosity – it’s what is called the cloud point. The cloud point is the temperature below which little crystals form in the fuel.

If the temperature drops below the cloud point, those little crystals grow into bigger crystals and your tank and fuel lines are filled with a solid “gel” of fuel. That sounds bad, and it is bad. Gelled fuel will prevent your car from starting, and will probably damage your fuel filters. Incidentally, the viscosity of gelled (or even clouded) fuel is way off the top of the viscosity chart above.

The cloudpoint of commercially available petrodiesel is controlled by blending – it can range from -34F to +41F.

Depending on where you are and what time of year it is, the petrodiesel available commerically will be blended differently to have a cloudpoint appropriate for the weather. This is done to save money for the oil companies. The higher (or warmer) the cloudpoint is, the less expensive the fuel is.

For example, in Minnesota in January, the cloudpoint of diesel at the pump is -34F. In Louisiana during the same month, the cloudpoint will be +25F. In June, it may be as high as +41F.

100% biodiesel has a cloudpoint of +31F to +51F, depending on what kind of grease the biodiesel was made from.

Now we’re beginning to see the problem with biodiesel in the winter. Unless you live in Louisiana, you might have problems using 100% biodiesel in the winter.

So, it’s very cold outside, but you want to drive greeen – what can you do?
The easiest solution is to blend your biodiesel with petrodiesel. I’d suggest a B20 blend (20% biodiesel/80% petrodiesel).

With regard to winter use, the National Biodiesel board says that over seven years of testing:

“The cold flow properties of biodiesel and biodiesel blends have been thoroughly tested with a variety of diesel fuels, both with and without cold flow enhancing additives. Biodiesel blends (primarily B20) have also been used in a variety of climates—including some of the coldest weather on record—without cold flow problems.”

“High concentrations of biodiesel (i.e. blends over 20%) may not be appropriate for use in cold climates without blending…with proven cold flow improvers specific to conventional diesel fuels.”

There are some people who have had success using antigel additives with higher blends of biodiesel (and even 100% biodiesel). The best source of info would be your biodiesel supplier or people with lots of experience using biodiesel in cold weather.

I hope this helps!

Sources: ASTM, National Biodiesel board, Wikipedia