How to make biodiesel

What is biodiesel? Simply put, it is diesel fuel that is made from vegetable oil. It will run in any unmodified diesel engine. It has many advantages over petroleum diesel fuel such as: 1) It burns cleaner 2) It has a higher cetane rating (less knocking) 3) It has better lubricity 4) You can make it yourself from used vegetable oil (a waste product) often for less than the cost of petroleum diesel.
You will need the following things to make your first batch:
  1. At least 1 Litre (1.1 Quart) vegetable oil. Canola oil, corn oil, soybean oil, etc will suffice.
  2. A variable speed blender with a slow speed option. Use one with a glass pitcher only. The methanol that is used in this process will "eat" a plastic pitcher. Make sure that this blender will never be used for food products again.
  3. A scale that will accurately measure 3.5 grams (.12 oz). I use a triple beam balance available through Edmund Scientific. Search the site for the keyword "balance". A good scale will cost between $100 and $200 and is a good investment. However, if you are on a budget, you can get the Edmund Scientific "Carry-With-You Twin Beam Balance" (Stock Number: CR30360-28) which will weigh up to 4 grams. This costs $25.
  4. 1 bottle Red Devil Lye Drain Cleaner (Sodium Hydroxide) available from you local hardware store. Make sure the label says "contains sodium hydroxide". Most other drain cleaners are chlorine (Calcium Hypochlorite) based and will NOT work! Notice: Lye is poisonous! Take all necessary safety precautions!!
  5. At least 200 milliliters (6.8 fl. oz) of methanol (Methyl Alcohol or "Wood" Alcohol). Methanol is widely available in 12 oz. quantities as "gas tank antifreeze" in auto parts stores, hardware stores and even some grocery stores. Popular brands include "Heet" and "Pyroil". Read the label carefully and make sure it says "contains methanol"! Many gas line antifreeze products contain isopropyl alcohol or "isopropanol" and will NOT work! Methanol is available in larger quantities as racing fuel through some racetracks that cater to drag racers and some "high performance" auto parts stores. Keep in mind that Methanol is both poisonous and flammable. Take all necessary safety precautions!!
  6. A glass container that is marked for 200 milliliters (6.8 fl. oz). We like to use a beaker.
  7. A glass or plastic container that is marked for 1 liter (1.1 Quart)
  8. A wide mouth glass or plastic container that will hold at least 1.5 litres
  9. A common spoon (preferably plastic or stainless steel).
  10. Safety Glasses and Rubber Gloves! Methanol and Lye are extremely poisonous and must not come into contact with skin or eyes! Methanol is a poison that attacks the eyes (ocular nerves) even if it comes into contact with your hands. Use extreme care when blending the methanol and lye, as the blender can spash the chemicals around. Put on your glasses and gloves BEFORE opening the chemicals! Do your work close to a sink or hose, or have a bucket of water handy to wash any part of your body immediately if it comes in contact with these chemicals.
Get organized in a well lit, well ventilated area! This process is best done at or above room temperature (70 degrees F or 21 Degrees C). Temperatures lower than 60 F or 15 C may cause an incomplete reaction. Plan for spills by spreading paper or plastic on your work surface. Put your safety glasses and gloves on before opening any chemicals!

What you work
  • Measure 200 milliliters (6.8 fl. oz) of methanol
  • Pour the methanol into the blender. Notice the glass pitcher on the blender.
  • Weigh out 3.5 grams of lye on your scale. Notice that we use a white piece of plastic to hold the lye. The weight of the plastic is 4 grams, so we set the scale to 7.5 grams.
  • Turn the blender on "slow" speed and slowly add the lye to the methanol. You now have a mixture called "sodium methoxide". The methoxide must be used right away to make biodiesel. Do not plan on making a large batch of methoxide and storing it for use later. It loses its potency over time.
  • After the Lye has completly dissolved into the methanol (about 2 minutes), add 1 liter of vegetable oil to the blender. Blend on low speed for 20 to 30 minutes. The ideal speed for this process just barely creates a vortex or "tornado" in the oil without spashing the mixture around or frothing it up.
  • After the blending is complete, pour the mixture into the wide mouth jar. It is advisable to label all containers used in this project as "POISON"! And of course, keep all of this stuff away from children!
  • After about 30 minutes to 1 hour, you will notice a layer of darker colored glycerin settling to the bottom of the container. The lighter layer on top is biodiesel. Wait another few hours for complete settling. At that point, you can carefully pour off the lighter biodiesel from the top and discard the glycerin (or save the glycerin to use in soapmaking). An alternative would be to use a pump to remove the biodiesel from the jar. You are done!
It is always wise to use a "diesel fuel filter/water separator" with any diesel engine. These are available through some auto parts stores or A good model is the Racor 120AS diesel fuel filter/water separator (West Marine # 411348).

Biodiesel has a solvent effect on natural rubber hoses and seals. While newer diesel engines have polymer hoses and seals (such as Dupont's "Viton" brand), older engines may need to be outfitted with new hoses and/or seals made of viton. Since most diesel injector pumps don't have rubber parts directly in contact with the fuel, it is usually easy to replace hoses and seals without any major dissasembly. A fuel mixture of 20% biodiesel and 80% petroleum diesel (called "B20") will have no effect on older natural rubber hoses.

Biodiesel will "cloud" at temperatures below 55 degrees F (13 degrees C). While this "clouding" is easily reversible by raising the temperature of the fuel again to above 55 degrees, it may cause temporary clogging of your fuel system, thus stopping your engine. Petroleum diesel fuel (Diesel #2) can be used down to -10 degrees F (-24 degrees C). It is advisable to use a blend of at least 50% petroleum diesel with your biodiesel if you are going to be operating in cold weather. You can experiment with different blends of biodiesel and petroleum diesel to determine what works best. Simply mix up batches of fuel with different ratios of petroleum diesel and biodiesel in glass jars and put in a freezer. Use a thermometer to determine the temperature of the fuel. Periodically check on the fuel to determine at what temperature it gets cloudy. This temperature is the "cloud point". It is best to determine this point at home before you head out on the road and get stranded in a snowstorm because your mixture is too rich in biodiesel. Of course, if you are going to be operating during the warm months, or in a warm climate, you can use 100% biodiesel with no problems.