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BioDiesel Class 101

Class # 10 - What to do with Waste Glycerol

    As you now know the waste byproduct of making BioDiesel is raw Glycerol. This is the raw form of Glycerin which is used in many chemical applications from explosives to soap. Many people ask what to do with this raw waste by product. Commercially glycerin is distilled or purified by a high temperature high pressure steam distillation process which is well beyond the scope of most home BioDiesel brewers. Below are some of the uses that this Raw Glycerol product has been put to use by others.

  1. You can make Presto style logs by mixing small amounts of Glycerol with coarse sawdust & then press it into an paper old milk carton & after it sets up & dries they burn these in a fireplace insert or wood stove in place of wood logs. A 1 Quart milk carton holds about 450 gm of wood shavings and 750 gm of glycerol by-product. When used for heating, three milk cartons will burn for about 45 minutes and heat 20 gallons of water from room temperature to 140 deg F. Glycerol is a dense fuel and these Presto style logs will give off more heat than about 2 times these weight in wood.

  2. After a lengthy conversation with our local waste management services about how BioDiesel is made & what it is made out of, they stated that raw glycerol is not considered hazardous waste & provided it is hard & not liquid they will accept it in the regular waste stream. They suggest mixing the raw glycerol with sawdust or wood chips & allowing it to harden then wrap it in paper before disposing of it. They mentioned this is the same method suggested for latex paint before disposing of it in the regular waste stream. Check with your local waste management services before disposing of it in this manor if this is the method you choose.

  3. Glycerol made from KOH (Potassium Hydroxide) contains potassium and can be diluted with water to be used as lawn fertilizer.

  4. Glycerol made from NaOH (Sodium Hydroxide) contains a salt so it tends to kill grass & can be used if slightly diluted with water as a weed or grass killer.

  5. Glycerol when added in small amounts to an Anaerobic Digester boosts Methane production. If too much is added at one time it can cause excess foaming.

  6. Heating NaOH Glycerol to 120F and adding in the appropriate amounts of NaOH Lye & water it makes for a good quality brownish colored Bar hand soap for the shop. Look HERE for the recipe.

  7. Heating KOH Glycerol to 120F and adding in the appropriate amounts of KOH Lye & water it makes for a good quality brownish colored Liquid hand soap. Use the same recipe as for Bar soap above.

  8. Commercial Power generation plants can burn waste Glycerol as fuel. It requires high temperatures to burn glycerin so that toxic acrolein fumes are not produced. Toxic acrolein fumes, mainly form when boiling glycerin between 200 and 300 deg C (392-572 deg F) to prevent this you need a really hot fire.

  9. Waste oil contains huge amounts to BTU. We have heard that some people construct a Babington or a Turk burner and burn waste glycerol for heating greenhouses, however we have not personally witnessed any of these in operation and have heard that they may coke up. Another way to go is with a commercially made BioDiesel glycerin & waste oil boiler such as the one at to dispose of any waste glycerol.

  10. It has been reported but not confirmed by us that since raw Glycerol is a sugar, it makes for good Bovine cattle feed. Waste Glycerol contains a reasonable amount of Methanol which is toxic to humans but has been reported to be non-toxic to Bovine cattle due to something about their different digestive system and metabolism being able to break down the Methanol without incurring the toxic effects that humans have with it. It must be stressed however that this claim has not been substantiated & if you try this it is at your own risk. If anybody can locate any official data indicating this it true, please contact the webmaster of this web site & give us the source information so we can publish it here for every ones benefit.

  11. Waste Glycerol also contains a reasonable amount of Methanol and as such some find it worth while to attempt Methanol recovery by Vacuum distillation. According to our sources, 10 gallons of fresh waste Glycerol may contain as much as 3 gallons of Methanol. At current prices this amounts to around $9 worth of Methanol.

And you thought we forgot.....

  1. How much Methanol can you expect to recover if you use vacuum distillation on 10 gallons of fresh Glycerol?

  2. Can Glycerol be burned in a commercial power plant as fuel?

  3. What kind of Hand Soap can you make out of Glycerol recovered from BioDiesel made with KOH?

  4.  Can Glycerol be used to make another renewable fuel, Methane gas?

  5. How would you make Presto Style logs?

  6. What kind of Glycerol is used to make Bar Soap?

  7. What color soap is made from waste Glycerol?

  8. Can the average home brewer make purified Glycerin?


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Last modified: 11/26/16