Dr Tom Reed mulled over his interest in alternative fuels and in November, 1989, wondered what happened to all the good oil/fat when it was "used up". He found that there are about a billion gallons a year under the heading "yellow grease" which are used for soap and cattle feed, and has a very low value (<$1/gallon) relative to new oil/fat.
He wondered if it could be used to make the esters for fuel and went to a local McDonalds to get a gallon of "waste grease" from their grease dumpster. He took it back to his lab, made minor adjustments in his diesel recipe and made a gallon of beautiful fuel from waste grease. Wow! As a chemist he had a wonderful time for the next few months making "transesterified waste vegetable oil" from many feedstocks. He even made it from bacon grease at Christmas in his daughter-in-law's kitchen from grocery store components.
At that time the DENVER RTD bus company was considering alternate bus fuels. He approached the bus company to see if they were interested in this alternative clean fuel. They were, but they needed more than a gallon to test, so Dr. Tom went to the UNIT OPS laboratory at the Colorado School of Mines and made 100 gallons (2 drums) for testing by RTD.
He didn't think "transesterified waste vegetable oil" was a very good name, and considering the source, decided to call it MCDIESEL. He applied for a copyright and even approached McDonalds to see if they were interested. They were, but they said they would sue if that name was used. Later people came to call these fuels "BIODIESEL".
Dr. Tom formed a company with Prof. Mike Graboski (at CSM) and Ed Names (a lawyer) to make and promote MCDIESEL. They published a number of papers, talked to many people, and entered into an agreement with a chemical engineering company (later a source of much grief).
They discovered that there was NO political base for using low cost waste grease for an alternate fuel and there was a tremendous base for spending much more money to make Biodiesel from virgin Soy Oil. Now biodiesel is highly political and there is a newsletter telling of test results and of new companies hoping for government subsidies courtesy of global warming. Check them out at www.biodiesel.org
In February 1990, the biodiesel fuel was tested on a bus and it ran fine and had low emissions. A number of papers have been published on Biodiesel from waste grease, but no one is particularly interested. Meanwhile biodiesel from soy is still $3-4/gal.
Making biodiesel on a large scale is a task for chemical engineers. It is a relatively simple process, but requires purification and washing to make a commercial fuel, especially if you use waste vegetable oil. However, if you would like to try the reaction in your kitchen, here's the recipe for a simple demonstration using common household chemicals. REMEMBER TO HANDLE ALL CHEMICALS WITH CARE! While these are common "household" chemicals, the methanol generated will burn with an almost invisible flame, so to avoid starting fires you cannot see, extinguish all flames and fires. Also the lye used can burn your fingers or blind you. Read the warning labels on the packages and be careful!
• 500 ml (1 cup) vegetable oil. (cooking oils such as Mazola, New Maid etc.)
• 85 ml methanol. (The easiest source of methanol is Dri-Gas, obtainable from any automotive store. Be sure to get the one that contains methanol -, not the one containing iso-propyl alcohol.)
• 1/4 level tsp. of lye (sodium hydroxide). (Red Devil lye is carried by most grocery and hardware stores.)
• Measuring Cup showing both ml and cups.
• Wooden Spoon
• Blender, or mixing bowl that you will not use for food
• Cooking Thermometer
• Tall thin vessel used to allow a mixture to separate.
The reaction (transesterification) substitutes methanol (wood alcohol, dri-gas ...) for the Glycerine in triglycerides (fats, oils) to make the methyl esters called biodiesel. It uses lye as a catalyst. A junior chemist might write it like this:
Triglyceride (fats or oils) + Methanol ===> Biodiesel + Glycerine (Lye catalyst)
The lye converts a small amount of the oil to soap. After the reaction is over, the Glycerine and soap settle to the bottom of the vessel and the biodiesel floats on top.
1. Measure 500 ml (1 cup) of vegetable oil into a blender (or mixing bowl).
2. Heat the oil to 120 F (not critical) using a cooking thermometer while carrying out the next step.
3. In a separate cup measure 85 ml of methanol.
4. To the methanol add 1/4 level tsp. of lye (sodium hydroxide).
5. Stir well with a wooden spoon, crushing as needed until all the flakes disappear. (The mixture will be slightly cloudy and is called "sodium methoxide".)
6. Add the methanol-lye mixture to the warm oil while vigorously stirring, using a mixer, paint stirrer (electric drill with propeller) or blender. Stir for 30 minutes. The mixture at first thickens, then becomes thinner than the original oil.
7. Allow the mixture to settle for a day in a tall thin vessel. The biodiesel floats to the top and can be poured off into a container for display. The glycerine and soap go to the bottom and can be discarded (but can make a high glycerine soap).
You have now made biodiesel on a small scale and can appreciate the use of renewable fuels from farms!
This clear biodiesel contains a very small amount of soap. If you want to use it in your diesel vehicle, go ahead, but only in small quantities. However, if you want to make large quantities or for sale, European specifications require removal of the soap by washing or other effective means.
Waste vegetable oils used for cooking are an attractive source of biodiesel, but are more difficult to convert because they contain 2-10% free fatty acids (the cause of the rancid taste) and can make a big mess. First it is necessary to remove any water present in the waste oil. Heat the waste oil in an oven at 220° F for an hour or until no bubbles can be seen in the oil.
It is then necessary to titrate the oil to determine how much free fatty acids they contain.
To Measure Free Fatty Acid content of your oil:
1. Mix 1 ml oil with 10 ml isopropyl alcohol (available as the other dry-gas) + 2 drops phenolphthalien solution (available in a hobby shop or toy store selling chemistry set supplies).
2. Dropwise add 0.1% lye solution (1 g lye in 1 liter water) with vigorous stirring until the solution stays pink for 10 seconds. (20 drops = 1 ml) Record the milliliters of 0.1% lye solution used.
3. For each liter of waste vegetable oil you will need one gram of granular solid lye for each ml of 0.1% lye solution used to titrate the free fatty acids, plus the 3.5 grams required as a catalyst as described above for new oil.
4. Completely dissolve the proper amount of Lye in the methanol. This combined mixture makes the sodium methoxide.
5. Add the alcohol-lye to the oil, stir VIGOROUSLY, and separate, as in instructions above for new oil.
These are jobs for professional chemists and chemical engineers. If you would like to learn more, please take a course in chemical engineering at the Colorado School of Mines or your nearest technical college first.
Unprocessed oils and fats can also be used in diesel engines, but require adjustment to the engines and driving habits. They are too thick, so do not inject well. They become solid below about 50 ° F. If the engine is started on conventional diesel and converted to heated vegetable oils after it is thoroughly warmed up, then switched back to diesel for cooling, engine life is greatly extended.
Mr. Louis Wichinsky claims to have developed engine modifications that permit direct combustion of waste vegetable oils. If you are mechanically inclined, rather than chemically inclined you may prefer this route.