Monday, October 29, 2012


So, I left off with the freshly-made biodiesel suspended upside-down so the glycerol and actual biodiesel could separate. This is what it should look like after 24-48 hours:

Separated mixture of biodiesel and glycerol

As you can see, there are two distinct layers. The top is our product- biodiesel. The bottom layer is our glycerol, which we can dispose of. Glycerol is soluble in water, and harmless. We can drain the bottom layer out by unscrewing the cap slightly and applying pressure to the bottle- squeezing a little biodiesel out as well (now you understand why I stored it upside-down- I'm not crazy!). What we will need to do now is something called "washing" the biodiesel. This doesn't mean using Dawn detergent to clean it up- but on the same track. Even though we got most of the glycerol out, there still may be some impurities. This could include tiny amounts of glycerol, bits of dust from the pot and pouring apparatus we used, or even un-reacted lye (NaOH). Basically, anything that's not an organic molecule needs to come out (OK, glycerol technically is an organic alcohol, but it is water soluble, and we need to get rid of it, so it fits our description). This is done by simply pouring about 500 mL (you don't need to be exact, this is to get rid of impurities, so the the amount you put in doesn't really matter- I've found that this technique throws off lots of budding organic chemists in lab settings) or so of water. Then, mix it up, and let it separate (sit overnight- upside-down again!). After the product is settled, we can do the same procedure to remove the water- drain it out through the cap. If you feel so bold, and want to follow proper lab technique, you can repeat this washing process two more times. Since I'm not planning on actually using this biodiesel as a fuel source (I don't have a diesel-powered vehicle or engine), one washing is good enough. However, I strongly suggest that you wash yours two to three times if you plan on using it for fuel. When all is said and done, we have a low-grade, pure biofuel. Pretty awesome. 
Homemade biodiesel. To quote Bill Nye- "Science rules"

So, to recap, we took vegetable oil, drain cleaner, and Heet fuel additive, and turned it into a drop-in biofuel know as biodiesel. There was some chemistry fun along the way, and we learned some basic organic lab techniques. I always like to reflect on anything scientific that I learn or do by asking myself the following question:
So now what?
Naturally this raises other questions such as, can I eliminate making gas station stops? Can this be scaled up? Is this process economically viable? Will this help USA fuel independence? 
Part of this blog and project is for addressing some of these questions, and doing some math to answer them. That will have to wait until tomorrow, but if you're following along in real-time, see if you can find some answers! In the meantime, I need to crunch some numbers, and we'll talk in my next post about costs of biodiesel fuel, practical concerns, and we can see if this is really a viable option to help solve the renewable energy debate.

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