Category: Homebrew BioDiesel

I’m cooking up a batch of BioDiesel today. Filled up the processor last night and and turned it on to heat up. Obviously my thermostat is off calibration as it is supposed to stop at around 55°C. Easy fix.

For the past year I’ve been doing a two stage process, with an 80% load of the catalyst going in first, followed by an overnight settle, then a re-heat and the remaining 20% going into the mixture. This seems to get better conversion rates, though slightly lower yields – which even to my pea-brain understanding of Chemistry seems to be logical. Since I started doing this two-stage process I have yet to have a batch go bad in the wash process. Nothing worse than watching 100+ liters of fuel turn into a vat of pancake batter, or soap!

The downside is that it takes twice as long to do the processing as you have two overnight settling times. I’m happy to see 2—5% lower yields since I’m getting better fuel in the end. Warmer temperatures are coming soon, which means I can run the cars on more home-brew and less pump fuel. The old TDI gets switched to B100 as soon as ambients hit the 60s (F), but Sue’s CRD tops out at around B80. I just haven’t worked up the courage to commit her car to 100% home-brew.

This winter it thankfully never stayed too cold here so I was able to keep at least 20% BD in the tanks of both cars, which keeps the fuel systems clean and avoids filter clogging that inevitably haunts us if any car has reverted to 100% #2 Diesel. That stuff coming out of the pump just coats the tank with crud without some good veggie solvent to keep it clean.

Since it is summer and the weather is warm, and since I’m planning to be away for about 10 days I figured the time was right to do a “summer cleanup” in the BioDiesel refinery. This is easier said than done, as shutting down is a difficult process. From start to finish BioDiesel takes several weeks to make. Cleaning any part of the system requires that it be offline and empty for the cleanup. So over the past several weeks I’ve been doing a sort of ‘rolling shut-down” of the system. I started at the beginning – the settling tanks. This is where waste oil goes into two large barrels to sit and settle out. Water and food particles settle to the bottom. The barrels are inverted and have twin drains, one set flush with the bottom of the barrel, the other extended up about 6 inches or so above the bottom. One at a time I emptied them out (making BD all the way) and cleaned them when done. I actually took the opportunity to swap in a new barrel for my oldest setting tank. I used to have a 30 gallon poly barrel, now it has been replaced by a 55 gallon olive oil barrel. You can see it at the back, it is the blue one on the right. I fill from the left side via a large funnel, and the barrels self-level between themselves. Next I dismantled the wash and dry tanks and cleaned them up a bit. Neither were in bad shape, unlike the settling tanks. Finally I Drained the MeOH recovery system and am in the process of transforming it from a prototype to a finished and refined item. This means relocating it to a position near enough to the processor to plumb it directly downstream from it. This will clean up the process a lot. That will have to wait until I get back though.

What I’ve done recently though is wash down the whole area. Due to veggie oil spills the area where I work was filthy. You could literally no longer see concrete on the floor, it was one big stain, combined with a lot of ground-in dirt and oil-absorbent that I’ve used to clean up spills. I pressure-washed, which did a fair job. But the miracle trick was taking a bit of the Potassium Hydroxide (KoH) used in the BioDiesel process and spreading it on the wet floor. KoH is a cleaning agent used in brewing and wine-making. It does an AMAZING job of breaking up the oil in the surface of the concrete and allowing it to be washed away. I used probably less than a cup of the stuff, just lightly sprinkling it around the wet floor and sitting overnight. Gently hosing it off in the morning, followed by a second application where I missed the first time. After a few days I went back and pressure-washed again. Look how clean it is:

I’ve started re-filling the settling tanks, with the goal of being able to start refining again upon my return. Of course what did I do to my nice clean floor already? Spilled some veggie oil of course! sigh.

“Nuke & Pave”… it is a systems administration term for deleting the data off a hard drive and rebuilding the system software and user environment from scratch (with some data restored from backups of course.) The idea is to just blow away any crufty buildup and start anew.

That is what I’m planning on doing to my home brew BioDiesel setup in a few weeks. The system has grown organically over the past several years with me constantly tinkering, modifying, and adding to the design. Additionally the handling of waste vegetable oil (WVO) in the area has made things… messy. So I figure I’ll drain my tanks, get out the pressure washer, and give everything a good washing to get it cleaned up. Everything from the settling tanks to the concrete slab. I’ll then disassemble the plumbing and reconfigure it to my liking.

The only thing that will not get washed out are my BioDiesel storage tanks. This is a pair of 55 Gallon drums (that started life as my original WVO filtering system) that I can’t really risk getting water into. I’ll tighten them up with good seals and wash their exteriors though.

I’ll also plumb in the new methanol recovery still to the processor. My little test with a prototype has gone very well and I’ve learned how to (and how NOT to) extract methanol from my glycerol BioDiesel by-product. I haven’t built a new recovery still yet, but I plan to do so very soon. Plumbing it into the processor will allow me to clean up a messy step in the process, namely draining the by-product off the bottom of the processor. Right now I do this into buckets and hand carry it to the still. I’ve gone through this process with each expansion of the system: either doing something by hand, or using temporary plumbing to bridge a gap, and eventually building a cleaner, more efficient system to reduce labor to turning valves and operating pumps. The less I touch this stuff, the less I spill on myself, the ground, etc. Ideally I’d like to do as little manually as possible.

I often find myself sitting in the middle of this Rube Goldberg setup, looking around and just thinking about how I can improve it. Step One however always involves dropping that nuke and getting this part of the barn cleaned up. I’m a designer, not an engineer, so I work somewhat intuitively and through iteration. The time for that is now, while the weather is dry and warm and I can let things dry for a week or so before using them again.

I few weeks ago one of the guys in my small BioDiesel co-op dropped off a barrel of waste oil he collected from a restaurant. I was a bit taken aback when I looked at the oil as it had… some odd coloration. Usually a barrel of oil settles in a way so that the top few inches look like new. That is clear, bright golden-yellow oil. When I looked at this stuff it was sort of shocking orange, and very opaque… almost milky. I though perhaps it had been shaken up in transit and have left it sitting out by the barn for a few weeks to settle. My worst fear was that it wasn’t really oil at all. Next in line was that it had been contaminated with something. Water if of course the usual waste oil contaminant, but this looked… weird. So last weekend I took a 1-liter sample and made a small test-batch. The oil had settled and was mostly clear, but still VERY orange. The test batch is done at ambient temps so it takes a long time. I let it sit for five days and above is how it looks today. Still not “clear” (it is unwashed though) and still… very orange.

Next I’ll subject some to the 3/27 Conversion Test and see how it does. My gut feeling says it is “good” and that the coloration is just some artifact of whatever it is they are cooking. The oil comes from a Mexican food place, so perhaps it is excess paprika, or maybe Chorizo, which are the only Mexican cuisine items I can recall that are unusually orange in color.

If it tests out well I’ll mix it with the rest of my (normally colored) waste oil and make some BioDiesel from it. Maybe my exhaust will make people think of nachos instead of french fries now? We’ll see.

Speaking of Home Brew BioDiesel I figured I’d share one of the risks of this activity: Shoe dissolving.

BioDiesel is one of the world’s great solvents. It attacks rubber with the ferocity of a shoal of slow-motion piranhas. Exposure directly to vegetable oils literally makes rubber vanish. I only wear one pair of shoes when I work out in the barn around the waste oil and BioDiesel, and the above is a photograph of their current state. This is of course after many years of use, but I think it is time to retire them.