Come along as I share my recipe for making your Biodiesel the best that it can be! I’ll keep it simple and will give you links out to places where you can learn more about each step.
1) Start With Good Oil
Seems obvious, but if you’re using crappy oil, your Biodiesel will be more prone to poor reactions. My definition of crappy oil is oil that has lots of water in it, titrates above about a 9 (with a KOH based titration) and is loaded with junk (food particles, etc).
If you find that your oil fits the description above, it might be time to start looking for new sources. Murphys Machines has a great article on sourcing oil that I highly recommend reading if you’re thinking about looking for another source. Click here to check out the article
2) Test For And Remove Any Water
Before making Biodiesel, lower the water content in the oil down to 1500 PPM (0.15% water content) or below. Too much water will neutralize a portion of the catalyst and the methanol will suck it up like crazy too making it more difficult to react with the oil. It will also contribute to higher soap production.
While there are many ways to identify if water is present in oil, we’re a big fan of ourDeluxe Water Test Kit.
Instead of a “Yep! Looks dry!” You’ll know just how dry it really is right down to the parts per million.
3) Titrate The Oil Every Time You Brew
Titrate your waste vegetable every time you make Biodiesel. It’s such an easy thing to do, takes very little time, and will let you know if there’s a problem with a batch of oil. If it’s been a while since you’ve titrated, check out our article on titrating oil.
Also, titrate AFTER you dewater. You’ll be amazed to see how much dewatering can actually lower a titration value. Give it a try.
Need a titration kit? We offer three great kits that do the job well.
3) Pre-Treating The Oil To Lower FFA%
If your oil titrates fairly high (9 or above), it’s a great candidate for pre-treatment. By lowering the titration level, you’ll get less soap and possibly a higher yield. Here’s a few ways we recommend for lowing your titration.
A) Glycerin Pre-Treatment
Heat your oil up to about 120-130 deg F, add some glycerin (usually all of the glycerin from the last batch works), stir it for about an hour, let it sit for 5-8 hours, drain off the glycerin, and then retitrate the oil. There isn’t really a “right” way to do this one. Just add glycerin to your heated oil, mix it around a bit, and let it settle back out. This process can also reduce water content (the glycerin and excess methanol absorb the water and carry it away). Click here to learn more about pre-treating oil with glycerin (and why it works).
B) De-Water The Oil
If your oil is above 1500 PPM, then its possible that part of that water is suspending free fatty acids in the oil. By removing the water from the oil, free fatty acid levels (indicated by titration value) can potentially drop. In some cases the drop is quite significant (from 12 to 5 or 6).
Dewatering can be done by settling for several days, bubbling the oil with an air bubbler, heating the oil past the boiling point of water (about 212 Deg. F), or my personal favorite, heating the oil while circulating it back onto itself in an open top container with a fan blowing across the top.Here’s a great example of what I’m talking about. This method seems to be the most effective and one of the quickest ways to dewater that I’ve come across short of boiling the oil (which consumes a large amount of energy, and can be dangerous). I recommend dewatering in a metal drum for safety. We carry a metal barrel band heater that people have used with great success for dewatering.
C) Acid Esterification
Determine how much you want to reduce your titration. Figure out how much Sulfuric Acid that will take. Heat the oil up to 120-130 deg. F. Add the correct amount of methanol and sulfuric acid to the oil. Mix anywhere from 6 to 24 hours. Check titration to see if it’s lowered. Repeat if necessary. Once it’s dropped sufficiently, remove any water and proceed to process as normal. Learn more about this method in these two articles.Article #2.
4) 5% Pre-Wash
Just before you shut down your processor to allow the glycerin to settle out, add water to your processor and continue to mix for another 10-15 minutes. The water absorbs methanol and soap out of the mixture and accelerates how fast the Biodiesel will separate and also allows more soap to settle into the glycerin layer making it much quicker and easier to wash the remaining soap out of the Biodiesel.
To figure out how much water to add, add up the oil and methanol in the tank and times it by 0.05. For Example: 40 gal of oil + 8 gal of methanol = 48 x .05 = 2.4 gallons of water required.
Make absolutely sure you’ve mixed your Biodiesel long enough before adding the water though. Once you add it, the water will stop the reaction dead in it’s tracks. I recommend pulling a small sample of mixed Biodiesel from the processor before shutting down the mixing and letting the glycerin settle out of the sample for a few minutes and doing a quick 3/27 test on it. If it doesn’t pass, don’t do a 5% prewash, instead, let it mix longer & test again or plan on doing a re-reaction of the mix.
Click here to learn more about the 5% Pre-Wash Method
5) Bubble Washing (Without Water)
I learned about this trick to reduce soap levels prior to washing Biodiesel from Arbor Biofuels Company. It involves bubbling the Biodiesel AFTER you’ve removed the glycerin but BEFORE you water wash or dry wash the fuel.
Remove the glycerin, then insert a bubbler and bubble the Biodiesel for at least 6-10 hours in an open top container while heating the Biodiesel. It only needs to be heated to about 100 deg. F to work and can even work with less heat but takes longer.
After bubbling 6-10 hours, turn off the bubbler and allow the Biodiesel to sit for 1-2 hours. Come back & drain off any soap that’s fallen to the bottom and proceed with washing.
This method works by evaporating off residual methanol in the Biodiesel through aeration. Methanol helps to suspend soap in Biodiesel and when a large amount of it is removed, a large majority of the soap will fall out of the Biodiesel. By removing much of this soap, the Biodiesel may require fewer washes to fully remove the soap to ASTM levels. Because you’re evaporating methanol into the air, be sure the area is well ventilated. Click here to learn more about this method
6) Test Every Step Of The Way
My final tip is to test every step of the way. If you fail a test, don’t proceed until you have it fixed. ie. if the oil is still wet, dry it. If reacted biodiesel fails a 3/27 test, re-react it. If it fails a soap test, keep washing!
Here’s the list of steps I recommend:
– Test oil for water content
– Test oil for free fatty acid level (titration)
– Test reacted Biodiesel for full conversion (3/27 test)
– Test washed Biodiesel for soap content (especially if dry washed)
– Test finished Biodiesel for water content (if water wash is used)
7) Final Filter The Biodiesel
Before putting Biodiesel in a diesel engine, run it through a final filter. Filters are relatively inexpensive and they help to keep the diesel engine fuel filters from getting plugged.
We now offer 10 micron fuel filters and have been using them on our BioPro with great success! Check them out here
Check the fuel filter on your rig to see what micron size it is and buy accordingly. Generally, Dodge uses 10 micron, Ford uses 7 Micron, and GM uses 5 Micron fuel filters. I’d much rather plug a $16 filter than a $35 or $40 filter, which is why I pre-filter all of my Biodiesel.
And that’s it! My 7 tips for making great Biodiesel! Follow them religiously and you’ll find yourself making great Biodiesel batch after batch. They’re also a great set of trouble-shooting steps to use. If you find you’re having problems with your fuel, use the tests in step 6 to figure out where the problem is and then use the appropriate tip to remedy the situation.
I share these tips all the time with people that call in with problems with their Biodiesel. Many of them call back later and report the great successes they’re having after implementing these great tips. Give them a try today!