How Is Biodiesel Made?
By Mark Allen
Biodiesel is a clean burning substitute for petroleum based diesel fuel. Biodiesel is made of vegetable oil. Most modern diesel burning engines can use Biodiesel with few or no modifications. Biodiesel is making inroads at the gas pump too where it can be found more and more as an option when it's time to fill up the tank. But, how is Biodiesel made?
To make, or manufacture, Biodiesel you must first start with raw materials. The raw materials needed in the production of Biodiesel are a small amount of Methanol and a ready supply of vegetable product. One of the most common vegetables used in the production of Biodiesel is corn, although depending on the geographic location of the manufacturing facility many other plants are used as well (rapeseed, soybeans, flaxseed, etc.). The first step is to use the raw vegetable product to make vegetable oil. Vegetable oil by itself will not be what you need to power a car, from here it has to be processed into Biodiesel.
The process for converting vegetable oil into Biodiesel is sometimes called ester interchange. To complete this process the vegetable oil has to be combined with a smaller amount of Methanol and then put in the presence of a small quantity of an alkaline catalyst (for example, .5% to 1% sodium hydroxide). Vegetable oil is made up of so-called triglycerides, which is a compound of the trivalent alcohol glycerin with three fatty acids. The goal of ester interchange is to separate, or detach the glycerin molecule from the three fatty acids and replace it with three methanol molecules. This process then yields roughly 90% Biodiesel and 10% of a glycerin byproduct. The glycerin byproduct can be used in a number of other chemical processes for different industries. There are also studies being done to see if the glycerin byproduct, since it is vegetable based, can be used as feed for animals. This makes the production of Biodiesel produce virtually no waste products at all.
The production of Biodiesel is done in a large manufacturing facility like those being built around the world to take advantage of this relatively new fuel source. These facilities are built much like their oil refinery cousins with the intent of putting out hundreds of thousands, if not millions, of gallons of fuel. Unlike the manufacturing process of standard mineral based fuel, Biodiesel can also be manufactured in smaller home or farm units, or kits. The process remains the same but on a much smaller scale. There is also the option of making Biodiesel at home from used vegetable oil gathered from restaurants and delis. To achieve this the oil first has to go through another process to clean it of any impurities.
One of the main benefits of Biodiesel is that it burns cleaner than standard mineral based fuel. An additional benefit is that it also pollutes less during the process of making Biodiesel than it does during the manufacture of standard mineral based fuel like diesel and gasoline. Cleaner to burn and cleaner to make, Biodiesel is truly a viable alternative energy source.
