On this page, you will see some of the equipment that we fabricated to allow us to experiment with making Biodiesel fuel, some of the process, and the product that resulted.

 

A group of mini batches settling out. The two layers that you see are the glycerin —the darker layer on the bottom—separating from the Biodiesel—the clearer layer on the top. After they've had time to separate completely, we'll measure the specific gravity of each mini in order to determine how much sodium hydroxide we need for the entire batch of waste vegetable oil (WVO). Alternately, a titration method is used, and a Ph test performed to insure that all of the sodium hydroxide has been reacted. This indicates that the finished product is Ph neutral and that all of the available esters in the waste oil have been reacted.

After determining which mini batch has the best specific gravity, The amount of reactants used to produce the mini-batches is extrapolated to indicate how much sodium hydroxide and methanol to add to the entire batch of WVO. For our usual 40 gallon batch, this generally works out to about 8 gallons of methanol, and 1,300 or so grams of sodium hydroxide, assuming used vegetable oil.

 

Our sodium methoxide (the product of combining methanol and sodium hydroxide) mixer at work! The piece of tubing on the right that extends out of the picture is venting the toxic sodium methoxide fumes to the outside. A commercial chemical mixer is used to insure that the lye is completely dissolved before the compound introduced to the reactor vessel on the left. A vat of finished fuel is visible on the right, undergoing water washing to remove unreacted lye and methanol. After washing, the fuel will be decanted to 5 gallon fuel containers for storage and eventual use.

 

The large batch of WVO mixing after we've added the sodium methoxide. The waste oil has been heated to about 90°F before being mixed with the reactant.. After we finish stirring, the same type of settling will occur here as in the mini batches above: glycerin falls to the bottom, Biodiesel rises to the top. The reaction is mostly completed after two hours, and the batch will be allowed for settle for a total of 8 hours before being transferred to the wash barrels, where tap water will be used in conjunction with compressed air bubbles to finish the fuel.

 

The finished product, ready to use. This batch of fuel had an uncharacteristically rich amber color. Usually, depending on the condition of the used vegetable oil, the fuel comes out more of a straw or wheat color. Many factors can affect used oil, including how long it had been used in the fryer, what types of foods were cooked in it (and whether they were burned as a result of inattention or mistakes), the frying temperature and many other variables. Of course, combustible fuels should never be stored or transported in glass containers, this fuel was decanted into the container strictly for the purpose of this photograph.