Biodiesel Chemistry

How can I make biodiesel? There are two ways to make biodiesel and dozens of feedstocks to make it from. If you’re interesting in brewing your own biodiesel in the backyard then start learning about Backyard Biodiesel.

  1. Industrial Renewable Diesel – Hydrotreating Hydrotreating of feedstock fatty acids (soy bean oil, palm oil, canola oil, jatroph oil, sweet sorghum, chinese tallow, grease, etc.). However, this method lends itself to large scale industrial facilities with access to reformers or hydrogen pipelines and you will not find someone making biodiesel in their backyard using this method. The products made from hydrotreated fatty acids are jet fuel, diesel, and light-ends such as methane, ethane, propane, and butane.

  2. Backyard Biodiesel – Transesterification Reaction The transesterification or alkali method of making FAME biodiesel can be found in backyards across America and in commercial facilities. This method requires the use of an acid followed by a base to complete the transesterification reaction to produce biodiesel. In order to “officially” call the fuel you brewed in your backyard “biodiesel” it must meet American Society for Testing & Materials (ASTM) 6751 requirements.

The simple chemistry reaction known as transesterification illustrated on the left has an oil (vegetable oil) being mixed with a solvent (methanol) over a catalyst (KOH potassium hydroxide, which is also commonly referred to as potash) to make biodiesel and the byproduct glycerol. To actually make biodiesel you would simply mix the solvent (methanol) with the catalyst (KOH) to form a mixture called “methoxy”. Then you mix the methoxy with the oil at an elevated temperature for a given period of time to make biodiesel.


Feedstocks used to make biodiesel can be sourced from land-based crops-for-food (food crops), land-based crops-not-for-food (energy crops), liquid waste, solid waste, algae raceways (open air lagoons), or algae photo bio-reactors (PBRs). However, the most common feedstocks for anyone interested in making their own biodiesel in the backyard are waste and crude vegetable oils. Waste vegetable, fryer, and cooking oils can be found at your neighborhood restaurant next to the garbage dumpster, inside the kitchen in 5 gallon jugs, or from your neighbor’s leftover oil used in the turkey fry last weekend.

Okay, so I now get the “theory” of making biodiesel, but how do I actually make it? To actually make Backyard Biodiesel first make sure you have access to every item in the brewer’s checklist below:

  1. You own a diesel car, truck, tractor, yard mule, or forklift (on or offroad)
  2. Waste cooking oil supply to make it worth your while
  3. You have access to a biodiesel mechanic or know how to change your fuel filter and make sure your fuel line is made from Viton®
  4. Biodiesel Processor
  5. Biodiesel Course Training & Successful Completion
  6. Access to methanol and KOH
  7. Access to test kits or fuel testing laboratory
  8. Safety goggles, eye-wash station, gloves, apron, and fire extinguisher
  9. Disposal facility for your waste glycerol byproduct

Now you understand the reason why not too many people brew their own biodiesel in the backyard… It takes a lot of preparation and sourcing of the required ingredients just to get your Backyard Biodiesel operation off the ground!