Wednesday, September 3, 2008

Q&A: Vegetable Oil Storage 2: Inert Gases

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?


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 or

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!


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