Biodiesel Overview

by Martin Stenflo

Introduction
What is Biodiesel
Emissions of Biodiesel
Problems with Biodiesel
How to Make Biodiesel
The Titration
Making Biodiesel
How to make 1 liter of biodiesel

Introduction
Driving diesel vehicles on vegetable oil is not a new concept, Rudolph Diesel actually invented the engine to be used with a variety of vegetable oils, most notably peanut oil. However, due to the availability of cheap petroleum, the phyto-fuel was largely ignored. We are now finally encountering the costs associated with our petroleum dependence, whether it is fighting over the last reserves or the impacts of local and global pollution. The post-fossil fuel economy is approaching and we must do all we can to accelerate this transition.

Biodiesel is a domestic, non-toxic, biodegradable fuel that can be made from used cooking oil. As a society, we will use up our fossil fuels much sooner than we will transcend towards a healthy raw food diet; fried foods and waste vegetable oil are not a scarcity. There is also a huge transformation that happens when you are in control of your own fuel and energy needs. Being able to harness ones own energy in a sustainable manner is one of the best things we can do to support our fragile planet.

Confused about the terms I am using? Check out our Glossary of Biodiesel terms

What is Biodiesel?

Biodiesel is made from used or new vegetable oils or animal fats

Used oils are abundantly available at major restaurants and diners

In addition to vegetable oils, biodiesel is made from Methanol and Lye

Biodiesel can be used in any diesel vehicle without modification of the engine

Biodiesel can be used alone or reliably mixed with any proportion of petroleum diesel

Biodiesel is safe to handle and store and is biodegradable and non-toxic

Biodiesel reliably cuts emissions on all diesel engines

Biodiesel is considered an alternative fuel under EPAct, as long as it contains a minimum of 20% biodiesel, 80% diesel mix

Biodiesel has been tested at major universities and is being used by the U.S. Postal Service, the U.S. Departments of Energy and Agriculture, countless school districts, transit authorities, national parks, public utility companies, and garbage and recycling companies

Emissions of Biodiesel

Reduction of net carbon dioxide (CO2) emissions by 100%

Reduction of sulfur dioxide (SO2) emissions by 100%

Reduction or increase of nitrous oxide (NOx) emissions by 5-10% depending on the age of the vehicle and the tuning of the engine

Reduction of soot emissions by 40-60%

Reduction of carbon monoxide (CO) emissions by 10-50%

Reduction of hydrocarbon (HC) emissions by 10-50%

Reduction of all polycyclic aromatic hydrocarbons (PAHs)

Biodiesel replaces the exhaust odor typical of petroleum diesel with the pleasant smell of french fries or donuts

Problems with Biodiesel

There may be a slight increase in NOx emissions, however this problem can be eliminated through the use of a catalytic converter which reduces all emissions or by a simple engine upgrade.

Biodiesel experiences dificulties in cold weather, this can be solved through the use of winterizing agents used in ordinary diesel vehicles or through the addition of heating devices

How to make Biodiesel
Making biodiesel is a very simple process. To power our vehicles, we need to reduce the viscosity of the vegetable oil. Basically the vegetable oil needs to be mixed, given time to settle, then drained. There are literally millions of different ways this can be done.

Vegetable oil is a tri-glyceride, that’s three vegetable molecules, or esters, attached to one molecule of glycerin. Glycerin is what makes vegetable oil thick and sticky. To make biodiesel, we want to remove the glycerin and replace it with an alcohol. This is the process of transestrification. The alcohol we use is methanol.

To initiate the biodiesel reaction, we need a catalyst. Vegetable oil is an acid, so to ‘break’ the vegetable oil molecule, we add a strong base. For this we use Sodium Hydroxide (NaOH) also known as lye. The amount of lye is constant when using new vegetable oil, but used cooking oil varies due to the amount of Free Fatty Acids (FFAs) from heating the oil. To determine the amount of FFAs, we perform a titration.

Use Extreme Caution:
Methanol is Flammable and Dissolves Rubber
Lye can Damage Skin, Eyes, and Lungs
Both Can Be Fatal if Swallowed

The Titration
When using virgin oil of any type, the amount of lye used in a biodiesel reaction equals about 1.0% of the weight of vegetable oil. This amounts to 3.5 grams per liter of vegetable oil. Used cooking oil, however, is more acidic than new vegetable oil, as heating vegetable oil creates free fatty acids. Free fatty acids clog your arteries as well as your fuel lines and need to be neutralized in the biodiesel process. These acids float freely amongst the triglycerides and attach themselves to anything that is basic, such as lye. So, a titration is performed in order to determine the total amount of catalyst to be added.

Isopropyl alcohol is used in the titration, rather than methanol, as it will not react with the vegetable oil. The isopropyl alcohol keeps the vegetable oil in solution.

Careful: it is easy to make a mistake
To avoid errors, perform three titrations, this will help you when making larger batches.
Don’t be stuck with 50 gallons of wasted fuel!

1. Dissolve 1 gram of lye into 1 liter of distilled water
2. Dissolve 1 milliliter of vegetable oil into 10 milliliters of isopropyl alcohol
3. Drop the lye solution into the dilluted vegetable oil while measuring the pH one milliliter at a time
4. When the pH rises to 8 or 9, the free fatty acids have been neutralized

The number of milliliters added to the vegetable oil equals the number of grams of lye per liter of vegetable oil that need to be added in the biodiesel reaction. This needs to be added to the 3.5 grams per liter required for the reaction. If you added 1.5 milliliters of lye/water solution to your oil/alcohol in the titration, it would require 5 grams of lye per liter of vegetable used. The amount will generally vary in between 4.5 to 6.5 grams depending on your source of feedstock.

Making Biodiesel
Biodiesel can be made in a blender, a soda bottle, or a 1,000 gallon mixing tank. The only difference is the size of the containers and the amount of feedstock used. This section contains the details on how to make a small batch of biodiesel. When making larger amounts, just use the same proportions, mixing them in larger containers.

Making biodiesel requires vegetable oil, alcohol and a catalyst. The alcohol can be either ethanol or methanol; the catalyst can be lye (NaOH) or potassium hydroxide (KOH). When using different alcohol or catalysts, different proportions need to be added. For simplicity, this section only contains the amounts for the most commonly available materials: methanol and lye. Mixing methanol and lye creates sodium methoxide, which is then mixed with the vegetable oil to create biodiesel and glycerin.

How to make 1 liter of biodiesel
1. Perform a titration to determine the amount of lye needed
2. Dissolve the lye into 200 milliliters of methanol
3. Mix the sodium methoxide with 1 liter of vegetable oil for 20 minutes
4. Allow the glycerin to settle for at least 8 hours. Most of the separation occurs after the first hour, so you will see immediate progress.
5. Separate the biodiesel from the glycerin
6. Drive!

We hope that you stay involved in the future development of sustainable technology. Please consider becoming a member of Boulder Biodiesel and join our discussion forum. We often have vehicles for sale, can help you with vehicle conversions, fuel making, and presentations. Help us convert every diesel vehicle to Biodiesel!