By Lauren Sheldon and Marissa Boyer
Chemistry A, Period A

Biodiesel is a type of clean burning diesel fuel that is either vegetable oil or animal fat-based. There is no petroleum in biodiesel, however, it can be mix with petroleum to fuel large vehicles such as boats. This type of fuel is rapidly increasing in use.
Pure Biodiesel
Pure Biodiesel

Biodiesel made from sunflowers
Biodiesel made from sunflowers

Rudolph Diesel
Rudolph Diesel

The use of alternative fuels dates back to the early 1900s, starting with Rudolph Diesel, the inventor of diesel fuel. Diesel wanteed to fuel vegatable oils for fuel use and in 1900, at the World Exhibition in Paris, France, he demonstrated the first use of this type of fuel by running an engine using peanut oil. Henry ford also wanted to use ethanol, a corn-based fuel, for his Model-T. However, when petroleum was dscovered to be cheaper and more readily available, the biofuels were disregarded. But in 1970, when the Clean Air Act was passed in United States, researchers began to look into biofuels once more[1] . And as fears of a limited petroleum supply grew, biodiesels were developed for new and alternative fuels. Now as global climate changes are increasing, biodeisel is regarded as a new and efficeint was to help threverse the effects of global warming[2] .

The Chemistry

Biodiesel is most commonly a monoester, or fat bonded to alcohol, of methanol. However, other alcohols can be use to make the fuel. So, essentially, biodiesel is a single chain of fats bonded to an alcohol molecule.
In the composition of biodiesel, triglycerides are used. Triglycerides can be explained as three acids bonded to an alcohol. In biodiesel's, it is three fatty acids (make of hydrocarbon chains) bonded to a glycerin:
external image triglyceride.gif
During transesterification, the biodiesel reaction, a basic catalyst, generally Sodium Hydroxide (NaOH) or Potassium Hydroxide (KOH), separates the fatty acids from the glycerin, one by one. If a methanol contacts a fatty acid they will bond and form biodiesel. The hydroxyl group from the catalyst stabilizes the glycerin[3] .
Transesterification Equation
Transesterification Equation

After the glycerin molecules stabilize, the more dense molecules fall to the bottom of the container in which the biodiesel is being made, while the pure biodiesel stays at the top[4] .

Production of Biodiesel

Biodiesel is made through a process that converts fats and oils of natural origins into fatty acid methyl esters. This process of converting oil into bioldiesel is called transesterification. A fat or oil is combined with an alcohol, usually methanol is reacted together usually in the presence of a catalyst (usually sodium or potassium hydroxide). Then, glycerine and esters (in this case biodiesel) is produced. The methanol has a higher charge and can quickly convert and be recovered so that it can be reused.
This process is done witht he base catalyzed reaction because it uses a low temperature (around 150 F) and pressure (20 psi). There is also a high converstion rate (98%) and it has minimal side reactions and has a low reaction time. There are also no middle steps in this process. This makes the process of converting vegetable oil into biodiesel very economic.[5]

external image flowchart_biodiesel_prod.gif

Biodiesel is biodegradable and has a lower toxicity than petroleum diesel fuel. It is also safer to handle and has reduced exhaust emissions than petroleum diesel fuel.[6] Bioddiesel can also be blended with a petroleum diesel fuel. It is a renewable resource and can be beneficial to the economy as well as the environment. There are also many different sources that biodiesel can come from. This makes it versitile and a good source of renewable energy because there are many sources that you can get it from. The graph below shows how much biodiesel a source can yeild per liter under optimal conditions.

external image resources_biodiesel.jpg


Biodiesel advocates argue that biodiesel has several important advantages, the first and foremost of which being environmental consciousness. Biodiesel in environmentally friendly because it has fewer emissions to the environment, and it is both a renewable and biodegradable source of fuel. Emissions control is an argument that is very key, especially in legislative matters. Biodiesel can reduce the amount of harmful chemicals that are emitted into the air because of conventional fuel sources. To see an estimate of the reduction rates of several emissions look at the EPA Emissions Reduction Table. Biofuel is also biodegradable, so it decomposes because of natural processes. The EPA reports that biodiesel decomposes at a rate of four times faster than conventional diesel fuel. So, if there were to be an oil spill, the cleanup would be easier and the effects of the spill would not be as drastic.
In addition to being environmentally friendly, biodiesel fuel also has several other advantages. The fuel could ultimately lower the United States' dependence on foreign oil. Most US-made biodiesel is made from soybean oil, which is also a major domestic crop in this country. Because of the decreasing supply of petroleum, a renewable fuel source such as biodiesel, could decrease some of the country's energy demand. Biodiesel can also help increase the length of an engine's life. THe fuel acts as a solvent which dissolves the deposits that have formed on the inside of the engine. THis would reduce the possibility of a clog. Biodiesel doesn't leave any residue behind, therefore increasing engine life. The U.S. DOE Office of Transportation Technology estimates that even a fuel that is 1% biodiesel could increase a fuel lubricity, or it's ease of motion, by up to 65%. Biodiesel can be used in a car with little or even no engine modification. There is no need to chance the enginge of a car for the use of this type of fuel, and as a result it can be used with ease. It is also safer than conventional diesel fuel. It is non-toxic and it has a higher flashpoint, or temperature at which it burns. Because the fuel burns at a higher temperature, there is less chance of an accidental combustion [7] .


Along with the advantages of using biodiesel, there are also a few disadvantages. One of the problems with the fuel is that it increases the amount of nitrogen oxide emissions in the air. This increase in nitrogen oxide levels contributes to the formation of smog. However, some of the levels can be decreased by adjusting the engine, but that does not always work. There is now new technology being developed to try to produce biodiesel that has less nitrogen oxide levels[8] . Also, biodiesel is not suitable for cold weather, which makes it difficult for people living in states that have a winter season. It tends to gel when the temperature gets low. However, the temperature at which the fuel gels depends on the primary component. For example, biodiesel made from canola oil gels at around -10 degrees Celsius and biodiesel made from tallow will gel at around 16 degrees Celsius. Another more important disadvantage of biodiesel is the amount and availability. Biodiesel is currently not made in all 50 states so it really is only available in some. It is also more expensive to make biodiesel than it is conventional diesel or conventional fuel. Switching completely to biodiesel would be hard because of the difference in price.
Biodiesel, in some engines, can create a reduction of power. On average, there is about a 10% difference in the number of miles capable from one gallons of biodiesel and one gallon of conventional diesel. This requires more biodiesel to be consumed to create the same amount of power[9] . Finally, a major issue that has come up with the use of biodiesel is the debate of whether the crops used for the fuel should be used for food. While developed countries are using food crops, such as corn and soybeans, for the use of biodiesel, underdeveloped countries are being stripped of the crops. There is much debate of whether those crops should be used to feed the underdeveloped countries or for use of fuel[10] .

Future of Biodiesel

Biodiesel is becoming one of the fastest growing alterntative fuels in the world. The process of making biodiesel is very economic and therefore the cost of biodiesel is comparative to the cost of petroleum diesel. [11] However, the future for biodiesel relies on the ability to produce the renewable oils and fats such as vegetable oils. If the availabilty of these goes down then the cost of biodiesel will rise. However, biodiesel enthusists do not want to take talnd that is necessary for food production or destroy natural ecosystems.
Producing biodiesel will give a clean, renewable, and cost effective fuel that will help the world tremendously. This will also help by having another source of energy to avoid the already increasing shortages of petroleum. However, not all biofuels are green and sustainable. One company, Pacific Biodiesel shows that the community-based biodiesel model works the best. [12] It maximizes the advantages of smaller scale plants and it reduces the long distance shipping of the feedstock (oils used to make biodiesel). They are working to help farmers who produce the vegetable oil and to keep the cost of the biodiesel comparative to the price of petroleum diesel. They have 'multiple feedstock technology' which creates a high quality, stable fuel suppy and enables farmers to utilize more of their locally available resources. This flexibility means that farmers land will not be ruined due to the production of the feedstock. Using local feedstock also reduces the need for imported feedstock which comes from deforested land and even rainforests. When community-based production of biodiesel is used it can help the farmers as well as the marketers and the people who use biodiesel. Community-based production can produce a renewable fuel that not only has a positive enviornmental and economic impact but is also good for the people and the farmers.
Bus that runs on soybean biodiesel
Bus that runs on soybean biodiesel

Biodiese-Powered car
Biodiese-Powered car

Other References

This video describes how to make home-made biodiesel, using vegetable oil. However, the process can be very dangerous so be careful and be sure to wear goggles and gloves.

"More, better biodiesel"
"Biodiesel from Sewage"
"Biodiesel farming looks to be an environmental disaster"
  1. ^ "HowStuffWorks "History of Biofuels"" Howstuffworks "Auto" 1998-2010. Web. <>.
  2. ^ "Pacific Biofuel: History of Biodiesel." The Green Station Santa Cruz Bio Diesel And Zenn Electric Cars. Web. <>.
  3. ^ Type your rNational Center for Appropriate Technology. Basic Chemistry of Biodiesel: A Curriculum for Agricultural Producers. USDA Risk Management Agency. Web. <>.eference here.
  4. ^
    Belser, Evan M. Biodiesel Chemistry. Powerpoint Presentation. Web. <>.
  5. ^ "Production of Biodiesel"
  6. ^ "What is biodiesel?"
  7. ^ "HowStuffWorks "Emissions Control and Other Biodiesel Pros"" Howstuffworks "Auto" Web. <>.
  8. ^ "HowStuffWorks "Biodiesel Cons"" Howstuffworks "Auto" Web. <>.
  9. ^ "Problems with & Disadvantages of Biodiesel - Problems with." - Biodiesel WWW Encyclopedia - Bio-diesel, Bio-fuels Reference, Biofuel, Links, Directory, WWW Resources. 2006. Web. <>.
  10. ^ Hayhurst, Chris. Biofuel Power of the Future: New Ways of Turning Organic Matter into Energy. New York: Rosen Pub. Group, 2003. Print.
  11. ^ "Biodiesel Overview"
  12. ^ "Biodiesel sustainability"