I have several 55 gal drums of Bio that I made last March. I have it filled to the lid with no space and air tight. How long is the shelf life? Any one know?

If it's clean, dry, ASTM-spec bio (especially on acidity), then there's no reason to believe that it would have gone bad. I've seen fuel go over a year and still be okay when it was stored well.

If the fuel was perfectly converted (i.e.: meet all ASTM specs, 3/27, etc) when it was put into the steel drums, within a month or two it will no longer meet all of the specs. That doesn't mean it's not good useable fuel, only that the clock is ticking despite being well stored. I've found it instructive to repeat 3/27 tests on my oldest stored fuel, and it always fails. I still use it, up to 2 years after making it, but then my VW and Mazda have IDI engines that tolerate off-spec fuel. My storage conditions are different from yours - vented steel tanks, exposed to sun and weather (hot summer, cold winter), yet my fuel works well for my vehicles after more than a year. My oil feed stock is likely quite different from yours, as well, so that's another variable. Mine is mostly creamy soy, with some canola and some animal fats. Cottonseed oil, peanut oil, and lard will make biodiesel that stores either better or worse than mine. It may also be influenced by the cooking process. Mine isn't heavily used before I get it.

Aging biodiesel (and oil) develops a characteristic "paint" odor as it begins to oxidize and polymerize. The odor develops before the viscosity has changed much, so it's a pretty good warning indicator that the fuel is "about to go bad". In my experience, the fuel fails 3/27 long before it even develops the paint odor, so there's a sort of progression of symptoms that might give you plenty of indication of fuel usefulness - 1) fails 3/27, 2) paint odor, 3) increase in viscosity, 4) polymerized to form a gelatinous mass, 5) fully polymerized and unable to extract from storage drums without power tools. These 5 steps take years.

I have 8-year old biodiesel samples in pop bottles that smell strongly of paint and have the viscosity of straight oil, but haven't gelled yet. At one time I also had a metal can of boiled linseed oil that was 15 years old that had completely gelled into a solid rubbery mass. Linseed oil is one of the fastest polymerizing oils, much faster than soy, if that helps give you as sense of the speed of polymerization.

I think your drums of fuel are safe for a year or two, but don't expect them to pass 3/27. If they smell of paint, further tests are needed before using it in your car, if it is sensitive to fuel quality.

Cheers,
JohnO

Johno,

I assume that when you say the smell of paint, you are using oil base paint as your comparison? I know latex paint smells totally different than oil paint.

If the BD polymerizes to some extent, is it possible to just filter out the bad part and use the rest?

Yes, it smells like oil-base paint, and for a good reason. The drying process of oil-based paints is a faster version of biodiesel and veg oil aging. Soy oil is the most common oil used for oil-based paint now-days. In the old days (15 years ago and older), linseed oil was the common oil-based paint. To prepare the oil for paint use, it was boiled in the presence of heavy metals, such as lead (thus lead in paint), copper and iron. This initiated the polymerization ("drying") process. It didn't happen quickly as long as the paint was kept away from open air, but once it was painted onto a surface, it quickly oxidized and polymerized to form a tough, flexible film called "paint".
Soy doesn't polymerize and oxidize as readily as linseed oil, but it's cheaper now-days. If you boil soy oil or biodiesel in the presence of heavy metals, it will not store long with oxygen present, and won't store as long as if it wasn't boiled first.

Cheers,
JohnO

I recently had a nasty experience involving polymerized oil that led to an IP rebuild, and what a lot it taught me including how expensive rebuilds are.

From what I have read a host of by-products occur in the oxidation/polymerization process including a brown gum that may coat fuel tank, fuel lines, and everything inside your IP. It easily gets past the fuel filter. As a result your IP will cease functioning although not be "damaged" as such simply because freely moving parts cease moving freely. This is what happened in my case.

This gum only seemed to precipitate in the presence of mineral diesel, and a guy who is setting up biodiesel plants in island states in the Pacific told me the exact reason why (which I forget for now.)

However he did say that this gum may be removed from bio by two processes.

The first is mixing with methanol and allowing the gum to settle out, then draining off, and treating the remaining biodiesel with steam. I cant recall if it involved methanol recovery, and have been unable to contact him recently.

The second was just treating the biodiesel with steam but this was not as effective as treating with methanol first.

I havent tried either to date, but he seemed to know what he was talking about.

Incidentally he told me that storing biodiesel in steel drums can accelerate polymerization of biodiesel, it's something in the steel itself.



Paul

Thanks for the input. No smell of Paint or others. I think I read somewhere a couple of years ago that by filling drums completely full to the spout removes unwanted air amd may help in premature aging.?.?

Always leave room for expansion. A completely full drum will rupture when heated enough, such as in direct sunlight in Florida. Oil expands more than water with heat, so it tends to surprise people. It's important to minimize air circulation over stored oil, but the small amount of air sealed into the top of a drum shouldn't worry you too much. If you really want the "best" storage conditions, don't use a steel drum, use black plastic, and use an intert gas (nitrogen for example) for the expansion space gas.

I have an unproven theory that biodiesel frozen solid may last forever.

Cheers,
JohnO