Back when gas prices peaked many people began to talk about the possibility of using biodiesel as a form of fuel. At the COP15 conference there has been many mentions of biodiesel as a part of the renewable energy solution for the 21st century. Being interested in biology and chemistry the idea of powering some of our cars using a carbon neutral source that we can grow every year really appeals to me. I have only been a few side events where the specifics behind biodiesel have been mentioned. This has spurred me to do a little bit of internet research and see what I can find. I can tell you that this is an exciting technology that is currently under-utilized in the world. But before I get in to that let me first give some background on biodiesel.

The word “Biodiesel” has been associated with many different products over the past three years. Broadly speaking biodiesel is any fuel that can be produced from vegetable oils (such as soybeans) or animal fats. It is renewable and it is clean burning. It can be used in 2000 onwards diesel engines without any problems. The most common form of biodiesel is B20. That is 20% of biodiesel mixed with 80% normal gasoline. Biodiesel has become more common in the US since 1998 when the Department of Energy (DOE) published its report talking about the benefits of using biodiesel. Biodiesel is much more environmentally friendly than traditional fuel. It is also relatively simple to create.

At the most basic level the reagents one uses when making biodiesel are simply triglycerides (fats like most of us can find around our mid sections) or vegetable oil. For the purpose of this post I am going to use an example of making biodiesel from vegetable oil. Please keep in mind that I don’t state a specific amount of any of the ingredients that one would need to do this process. Also, I would not recommend that anyone tries to produce their own biodiesel unless they have some experience with chemistry. In other words, I am NOT responsible if you hurt yourself, your property, or others by attempting this.

1. Start by cleaning out any impurities from the oil. This can include dirt, food residue, or water.
2. Next you titrate a sample of your oil to determine the free fatty acids. This is done by measuring out a specific volume of oil. From there you add an phenolphthalein (an indicator) then you proceed to slowly add your base (usually sodium hydroxide) until the solution turns very pale pink. You then measure how much base you added to the solution. After that you use the equation Molarity = Moles/Volume (L) solving for moles. You then divide the number of moles by the volume of sample you added. That number is your acid concentration.
3. Once the acid concentration as been established you can then add your vegetable oil to a mixture of 3 times methanol (CH3OH) and sodium hydroxide (NaOH). Run the reaction at about 60C and 20 PSI. Let the reaction run for 15 to 20 minutes.
4. The product is a mixture of soap, glycerin, alcohol, and water. The glycerin is denser then the biodiesel. So the first course of action is to separate the two layers. This is most easily down by pipetting out and then discarding the lower layer of the product from the previous reaction.
5. Next remove the excess water by using a technique called counter-flow washing. Place a funnel with your biodiesel over a separation funnel with water. From there slowly run the biodiesel through the water.
6. When the wash is complete separate the bottom aqueous layer from the top layer. Then check the pH of the bottom layer. If it is basic repeat the wash.
7. Once you have the product with the correct pH add about 5g of sodium sulfide to the biodiesel then shake and let it stand for 15 to 20 minutes.
8. Now distill out the methanol from the product.
9. The resulting product is your biodiesel.

Obviously, there are specific steps that one must take to produce biodiesel on a larger scale. However the chemistry remains about the same. The ease of this reaction makes one wonder why we have not seen a larger increase in biodiesel production. The answer to that question is very complicated. One reason it would require a massive amount of land or freshwater to grow enough plants to produce enough biodiesel to power all the vehicles in the US. One has to take in consideration that this space must be used for other things such as food production and industry. Also, history has shown us that “putting all our eggs in one basket” is not a very good idea. Even with all the logistical problems ignored biodiesel faces tough completion from energy lobbyists who do not want the US to move away from using oil.

The biggest concern with moving towards the widespread adoption of biodiesel is the risk of not producing enough food because those crops have been converted to plants that can produce biodiesel. That is where 2nd generation biodiesel comes in. 2nd generation biodiesel works much the same way as normal biodiesel only it uses the cellulose rich parts of the plants that we generally do not eat and cannot digest. It works by pre-treating the plants with enzymes or steam to break about the bonds in cellulose and lignin. After that the reaction takes place much like traditional biodiesel synthesis. This biodiesel is just as environmentally friendly as the previous generation and it is much less stressful on the food supplies.

So how much should we rely on biodiesel in our energy portfolio? Personally I think that we could to biodiesel to power at least 25% of our cars in the near future. As more people begin to embrace the idea of biodiesel production will increase and prices will come down. Biodiesel also has the advantage of not being subject to the price fluctuations that traditional gasoline has to go through. I apologize for my long post. However, this is something I feel very strongly about and I feel that I should share this information with everyone else. If you take nothing else away from this post I would hope that you take away the idea that biodiesel is already here. We just need to begin to utilize it.

Written by BEN ROBERTS.

One thought on “Biodiesel

  1. Peter

    Biofuels would appear to be an attractive supplement for petroleum products. But ………

    Generally, it takes about as much energy to produce a unit of biofuel as the energy which you get from that unit of biofuel.

    And then, of course, there are other issues; some of which the author of this blog has taken note of.

    For some excellent discussions and articles on this issue, Google:

    Kevin Libin Biofuels.



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