Basics of Biodiesel Production

Linda Benedict, Carney, Jr., William A.  |  11/17/2009 2:08:44 AM

William A. Carney Jr.

You can make your own fuel to run in diesel engines for a fraction of what regular petroleum diesel costs. In fact, most people making biodiesel are making it for about $1 a gallon.

Biodiesel is most commonly made by chemically altering animal fats or vegetable oil through the use of a catalyst and an alcohol. The chemical reaction that occurs through this process breaks down the oil molecules and replaces the glycerin portion of the molecule with an alcohol molecule. To be successful at making fuel, the oil must be free from water and grit.

To make a batch of biodiesel, you heat the oil (triglycerides) to a designated temperature (130 degrees F to help with the chemical reaction) and then add a mixture of a catalyst (sodium hydroxide or potassium hydroxide) and an alcohol (methanol). The oil-catalyst-alcohol mixture is then agitated for two hours and allowed to settle, which can take 16-24 hours.

If the process is successful, the chemical reaction between the oil, alcohol and catalyst will have broken down the oil into several layers. The top layer will be biodiesel, chemically called an ester. The next layer may contain soap, and the bottom layer will be glycerin.

Once the layering has occurred, the glycerin and soap are drained off. The biodiesel is then washed with a water mist, a bubble wash or both. The washing removes any additional soap, alcohol or impurities.

After it’s been washed, the biodiesel is then dried to remove the water. Commonly, it is then filtered through fuel filters and made ready to use in any diesel engine.

Making biodiesel typically takes a couple of days to a week from start to finish. Most people making biodiesel make anywhere between 20 to 100 gallons at a time in a batch process.


Biodiesel can be made in anything from a 2-liter pop bottle to an elaborate processor complete with separate tanks for processing, washing, mixing, settling and filtering. Obtaining equipment is relatively easy. Most people get started by making small batches with minimal equipment and then gradually move up to making larger batches using processors built specifically for making biodiesel. Many home "brewers" either buy a variety of premade processors designed for biodiesel or make their own processors, either from kits or from plans found on the Internet. Professionally built processors can cost as little as $1,000 and as much as $15,000.

Using biodiesel

Biodiesel can easily be used in any diesel engine. Once processed, washed and dried, biodiesel can be poured into any diesel fuel tank. Biodiesel can also be mixed with petroleum diesel in any ratio. It easily mixes with petro-diesel and is most often sold commercially blended with petro-diesel. B20 fuel is common and consists of 20 percent biodiesel and 80 percent petro-diesel.

Within minutes of biodiesel being added to the fuel tank – and especially when used in high blend ratios of 50-100 percent – a noticeable difference begins. Most people report a reduction in engine noise, a smoothing of the engine and a noticeable change in the smell of the exhaust.

Research has compared biodiesel to petro-diesel across a wide range of parameters. One of the most significant differences is a drastic reduction in tailpipe emissions from biodiesel. Other significant reductions from use of biodiesel include hydrocarbons, carbon dioxide and particulate matter. For many, these reduced emissions are reason enough to use this alternative fuel. Biodiesel is good for the environment.

Besides better emissions, research has indicated an increase in engine longevity, a decrease in engine maintenance and a better-performing engine. Because biodiesel has solvent properties by nature, it acts as a cleaning agent on the fuel system in diesel engines. This means that it cleans things up the more it’s used. Because of these solvent properties, some people have noted that fuel lines in older diesel engines (pre-1993) may degrade because the biodiesel breaks them down. Particularly susceptible are fuel lines made from natural rubber. Most of the susceptible fuel lines can be replaced easily with inexpensive biodiesel-compatible fuel lines.

Diesel engines made after 1993 and sold in the United States typically won’t have this problem because the fuel lines are already biodiesel-compatible. This is because a reduction in sulfur in diesel fuel in 1993 in the United States caused manufacturers to change to non-rubber fuel lines.

Home brewers use biodiesel in varying blends, but most commonly it’s used in blends from 20 percent (B20) to 50 percent (B50). When the weather drops below 50 degrees, it’s recommended to blend biodiesel with petro-diesel, although a gelling effect does not occur much in Louisiana’s warmer climate.

Another thing most people do when getting started is to change their fuel filters before using biodiesel and then change them again a few thousand miles later. This is to prevent the filters from plugging because of biodiesel’s solvent properties. As it’s used, biodiesel may knock residue from the walls of older fuel tanks and fuel lines that has built up from the use of petro-diesel. Replacing the fuel filters is just a precaution to ensure the engines keep on running.

The LSU AgCenter’s W.A. Callegari Environmental Center is playing a vital role in meeting future domestic energy needs, such as for biodiesel. It produces alternative, renewable fuels as part of its waste-recycling and waste-minimization program. The center produces biodiesel from used vegetable oil from LSU campus food service operations for use in heavy equipment and transportation vehicles.

As part of the AgCenter’s bioenergy research program, the Callegari Center plays an active role in developing alternative fuels. The center features a biodiesel plant that’s used in conjunction with established laboratory procedures to characterize biodiesel and evaluate quality control procedures. Along with traditional food crops such as corn, soybean, sugarcane, sorghum and sunflowers, scientists are evaluating nonfood crops such as rapeseed, Chinese tallow and palm oil as feedstocks for biofuels.
Precautions in biodiesel production 

  • Biodiesel production includes dealing with caustic chemicals, an alcohol called methanol, fair amounts of heat and the transferring of flammable fluids from one container to another. You need to have a fire extinguisher handy that is capable of putting out an oil-based fire.
  • Biodiesel should always be made using proper safety equipment in a well-ventilated area away from children and pets. 
  • Using homemade biodiesel in a diesel engine may void a manufacturer’s warranty. Read your warranty.
  • Biodiesel is considered a fuel, so if it’s used in a vehicle for on-road use, it may be subject to taxes. Check with state and federal taxing agencies if you have a question.
  • Biodiesel itself, when properly made, is actually quite safe. It’s less toxic than table salt and degrades faster than sugar. It has a higher flash point (the temperature at which it ignites) than regular petro-diesel, and if it’s spilled, it isn’t considered toxic.

William A. Carney Jr., Associate Professor and Head, W.A. Callegari Environmental Center, LSU AgCenter, Baton Rouge, La.

(This article was published in the fall 2009 issue of Louisiana Agriculture.)

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