December 2015
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Introduction to Biodiesel – Part 1

In this three part series, I will explain what biodiesel is, what you need to make it, how to make it, how to store it, and how to use it. In later posts, I’ll explain in more detail about the evolution of the processors I’ve built and other related projects. First, let’s get started with some basics.

What is biodiesel?
There are plenty of web sites out there explaining what biodiesel is, but simply put it is a fuel made from vegetable oils and used as a substitute for petroleum diesel. It can be mixed with petroleum diesel in any ratio of blends depending on your vehicle. Biodiesel is not vegetable oil. Vegetable oil can be burned in diesel engines, but only after making modifications to the vehicle. Biodiesel can be burned in many diesel engines without any conversion.

That being said, there are some things you still have to be careful about. Biodiesel hardens rubber and vehicles older than model year 1992 typically have rubber hoses and gaskets. These older vehicles would need the rubber hoses and gaskets replaced with more modern synthetic ones. Many vehicles this old would have already had the rubber replaced by now due to normal maintenance but you should still check before using biodiesel. On the other hand, in 2007 the EPA changed the requirements for vehicles sold in the US that make it more difficult to run high biodiesel blends. These newer model year diesel vehicles have an additional piece of equipment called a Diesel Particulate Filter (DPF) that causes foaming of the oil with high biodiesel blends. Vehicle manufacturers typically recommend that blends no higher than 5% biodiesel be used.

The sweet spot is model years 1992-2006. I personally have a 2005 Jeep Liberty CRD. I started with low biodiesel blends and gradually ramped it up. I’ve run 100% biodiesel on many occasions without a problem. I typically run lower blends like 33% to 50%, but that is mostly due to how much time I have to process batches.

Biodiesel can also be used in diesel generators or as a substitute for heating oil. It is useful as a cleaning solvent for oil and grease, not to mention a fantastic fire starter.

Before we proceed, some disclaimers are in order. Making biodiesel is a dangerous process. If you’re careless, don’t do it. Follow common sense safety procedures. It is legal to make your own biodiesel and use it in your vehicles. The federal government requires that you file a form and pay taxes on what you consume in your vehicles. You are responsible for that so do your own research and make your own decision. That being said, let’s get to the fun part.

How is biodiesel made?
Biodiesel is the product of a chemical reaction. It is most commonly made from vegetable oil. The lipids in the oil react with an alcohol, typically methanol, to form fatty acid esters more commonly known as biodiesel. A catalyst, usually either potassium hydroxide or sodium hydroxide, is used in the reaction. The main byproduct of the reaction is glycerin, which can be used to make soap. It can also be composted for use in the garden and is sometimes used in animal feeds. This all sounds complicated, but it really isn’t. In later posts, I’ll get into the nitty gritty details of the process and the processors I’ve built. But for now, we’ll stick to the basics. Next let’s look at what raw materials are needed.

It is important that the oil is of fairly good quality. Commercial operations often use new oil which has never been used for cooking. But that wouldn’t be in the spirit of sustainability, would it? Most home brewers collect used fryer oil from restaurants, which comes in a wide range of qualities. The quality of the used oil depends on what type of oil it was to start with and how the restaurant used it. Certain oils are better than others. Soybean oil is very common and is what I use. Peanut oil is not a good source because it will gel at very high temperatures. If the oil was over-used at the restaurant, it can become more acidic or have a higher water content. Acidity can be dealt with during the processing as we’ll talk about later. Water is a different issue. The oil needs to be dry. Water bonds with methanol and that will ruin the reaction. There are ways to dry the oil, but it is best for the home brewer to find sources with low water content. If you have to dry it, you can do so by heating it up. Some people just leave the cap off and exposed to the air for a few days when the humidity is low. I am lucky enough to have a source that is very focused on their food quality, so the oil I get from them is also of high quality. If you get bad oil, you can smell it. Rancid oil stinks and you’ll know it is bad so don’t use it. Oil can be stored in large containers like IBC totes. I get my oil in the five gallon jugs that come inside a cardboard box. The boxes stack nicely so I store it right in those boxes. I top the jugs off so there isn’t much air in them and seal them up tight. I label the boxes with the date I got it for future reference.

Methanol is the alcohol of choice for most home brewers. It can be a challenge to acquire in large quantities. You can order it but shipping is expensive because of the hazardous chemical requirements. You can find methanol near race tracks because it is used in racing fuels. Methanol is also known as wood alcohol and can be made in a distillation process, but that is more complicated than processing the biodiesel itself. The big box stores used to sell methanol is small containers, but they’ve been pulled from the stores since apparently you can make other illegal things with it. I am lucky enough to have a biodiesel supply company in town where I can get it in 55 gallon drums. For early test batches, you can get methanol in the form of automotive fuel treatment called HEET. It comes in a yellow bottle and can be purchased at auto parts stores or Walmart. This would be a very expensive way to buy methanol but is ok when you’re learning with small batches.

The two most common catalysts are sodium hydroxide (NaOH) and potassium hydroxide (KOH). Sodium hydroxide can be easier to acquire but is less desirable. The main reason is that the glycerin byproduct will gel and that’s a problem in your processor. Sodium hydroxide is good for test batches when you’re learning the process in a beaker. You can acquire it in small amounts at hardware stores. It is sold as lye drain cleaner. Just make sure you find one that is 100% pure NaOH. Potassium hydroxide is a better choice because the glycerin byproduct stays liquid, making it much easier to drain out of the processor tank after it settles to the bottom. I order my KOH on the internet ten pounds at a time. That’s enough to last a long time for the size of batches I process. Both types of catalyst will absorb moisture so you need to store them tightly sealed. I tighten the lid well and then store the bottle inside a plastic bag.

What’s next?
Learn more in the next part of this series: Introduction to Biodiesel – Part 2. I’ll explain in more detail how the chemical process works and safety procedures you need to follow.

Resources for this post:
Biodiesel Web Site:

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