Skip to main content
Engineering LibreTexts

9.5: Assignments

  • Page ID
  • Homework (Quiz)

    Watch the video on biodiesel production. It is in three parts, so watch all three parts. It will take less than 30 minutes and will give you a first-hand view of how biodiesel is made in a batch process.

    Part 1

    Biodiesel Production Demonstration

    Click here for a transcript of Biodiesel Production

    MARK HALL: Hello. I'm Mark Hall of the Auburn University Extension Renewable Energy Specialist. We're doing several of these things on energy options that you can do, several pieces that, each piece of the puzzle, that you can contribute to our energy independence by making ethanol, making biodiesel, being more energy efficient in how you operate your home.

    Today, we're going to talk about making biodiesel. And we have Lance Hall. Lance has been making biodiesel to run in his car. He bought a used Volkswagen off eBay and started making biodiesel. And he's liked it so much that he's bought a new diesel car. And he's been real successful doing this for a couple of years.

    Before we bring Lance in, I'd like to thank my friend and coworker Walter Harris, the county agent coordinator in Madison County, for filming us today. Lance, come in and show us what you've been doing. And congratulations. You've been successful doing this.

    I was talking to my daddy about my new job several years ago. And he said, well, Lance has been doing that for a long time. I said, what? I didn't know that. So Lance, show people how to make biodiesel.

    LANCE HALL: OK. A lot of people know about the biodiesel. They've read the stories. They've done some research. But, yet, they still don't have enough confidence in their ability to actually make a batch. So I'm going to show you today on how to make a batch of biodiesel, just small scale, but it's easy.

    OK. The first thing that we're going to do is start off with vegetable oil. Now, this will be 800 milliliters. And don't be confused between the milliliters and your normal units of measure. It's a simple conversion that anybody can do with a handheld calculator.

    So we've got 800 milliliters here. Well, first thing we want to do is heat it. Now, don't be concerned about this fancy piece of equipment, either. The main element of this is to heat it any way that you can safely.

    And these things here are magnetic stirrers. Again, don't be concerned with this. Just stir it while you're heating it to even things out. And we're going to heat this up to about 130 degrees Fahrenheit.

    MARK HALL: Lance, tell them about where you get this equipment.

    LANCE HALL: All of this equipment that I've got in my shop, all my lab stuff, eBay is a wonderful place to find a used lab supplies, lab glass. These are magnetic stirrer plates. These are really handy to have if you have the means to buy them. You don't have to have them, of course. But I like to use them.

    And this is also an electronic scale that comes in handy when you start weighing out your catalyst, doing anything that you want to measure a precise weight. That's worth the money there. And that's going to take a little while, so--

    MARK HALL: Lance, is there any other sites, internet sites that you would recommend for people that are interested in making biodiesel?

    LANCE HALL: There are several sites out there. One of the most informative on what biodiesel is, where it's being used, is That's the National Biodiesel Board website, lots of good information there. It won't really tell you as much how to make it, but hopefully, this will be one of the more informative sites that you'll actually be able to see somebody make one, make a batch.

    OK. As our oil is heating up, we have to mix up our methanol potassium hydroxide mixture. So safety is paramount with the use of methanol or the strong caustic lye potassium hydroxide. Methanol can cause blindness or death, and it can be absorbed through the skin. And the potassium hydroxide will burn your skin if it gets on you.

    So here's what we're going to do. We're going to take our methanol and we're going to pour this into a container. Face shields are good, too.

    We're going to use 175 milliliters of the methanol. That's roughly 20% of the 800 milliliters of oil. You usually want to use about a 20% methanol volume compared to the veggie oil volume.

    OK. Our next ingredient is our potassium hydroxide. That's our lye. Now, we have to do a quick calculation on how much of this we need to mix with our methanol in order for the reaction to take place.

    I've got a nice spreadsheet that I like to use. It's the Biodiesel-o-matic. You can usually find it online from different biodiesel websites. I'm going to pull that up.

    OK. We want to use 7 grams of potassium hydroxide per each liter of veggie oil. So you take 7 divided by 0.8. And that gives you 6.4 grams.

    Double bag this stuff, or it will absorb moisture. And that will kill your process.

    So we're going to use our scale. We're going to zero the container. And then we're going to put 6.4 grams into it. Make sure you have your gloves on.

    OK. That's our 6.4 grams. Close this immediately. Keep it double bagged. OK. Now, you're going to take your 6.4 grams of potassium hydroxide and put that into your 175 milliliters of methanol.

    Again, you want to stir this. It's not necessary to heat it, though. Just stir. And stir this until at least the potassium hydroxide is completely dissolved into the methanol. You don't want to see any chunks of white potassium hydroxide flakes.

    All right. Our potassium hydroxide is fully mixed into our methanol. We want to remove the stir bar. And then we're just going to slowly pour this into our oil as it's being stirred.

    Again, you don't have to have fancy equipment. Just pour it in as you're stirring it manually. But the key is to do it slowly.

    Credit: Alabama, A&M, & Auburn Universities Extension

    Part 2

    Biodiesel Production Demonstration

    Click here for a transcript of Biodiesel Production

    PRESENTER: You always want to start with a much bigger container than for the amount of oil that you're going to make because you have to add another 20% to that with your methanol. This is a 1,000 milliliter container. So if I would've made a 1,000 milliliters, I would have overflowed it when I put in an extra 200 milliliters of the methanol. OK, we've added about half of our methanol. Let it stir. Then I'm going to add. Add some more.

    You can tell when you need to add more. Once the color change goes from an opaque to a translucent. And then when we come back, it will be-- we'll show you how it separates.

    OK. We're done with the first batch of bio-diesel. We're making bio-diesel with regular, unused oil. And as you watch this will eventually go down. And it will be clear. And you'll have the separated layers.

    So while we're waiting on that to separate out, most people that want to make bio-diesel want to make it out of recycled veggie oil from restaurants or cafes or whatever it may be. There's a few things we need to do before we start making that though. The most important thing you need when you're using with recycled veggie oil is the titrant solution. This is going to determine-- this is going to help us determine how much extra catalyst we need to neutralize the free fatty acids that are in the vegetable oil that are made during the cooking process.

    So we're going to start on our scale over here in at least a one liter jar. I'm going to zero that out. We need one gram of our potassium hydroxide. Now we want to add 1,000 grams of water, which is extremely close to one liter, or 1,000 milliliters. So we're going to add that to our current jar. Oh, maybe. OK, there's our one liter of titrant solution. OK.

    So we've made our solution. We're going to heat our 800 milliliters again because we're only using 1,000 milliliter bakers to 140 degrees like we did earlier. I'm going to wait while that heats up. Bio-diesel is messy. Be prepared to have all kinds of paper towels and soap and everything else to clean up. OK, while that's heating up, we're going to do the titration to determine how much we need to add.

    So we're going to use this. This is a titration Burette. These can be found on eBay for really cheap, and they're really precise. So I recommend getting at least getting this. OK, we're going to take a small container. And then what we want to do is we want to measure out 10 milliliters of isopropyl alcohol. Also known as ISO-HEET. The regular HEET version is not isopropyl. We're going to get 10 milliliters. We've get milliliters of our isopropyl alcohol. Now we need one milliliter of the oil that we're about to make into bio-diesel.

    And this is-- you can find these just about anywhere. These are turkey flavor injectors from any grocery store. Don't use them as turkey injectors once you make bio-diesel with them. Get the air out. And these are graduated in 1 milliliter so we want to move from one line to the next line. OK. Put the rest back. So we've got 10 milliliters of isopropyl alcohol and we've got 1 milliliter of our veggie oil in it. Now we need an indicator solution to know when the pH has changed to the appropriate level. So we'll put about four drops of a phenol saline solution. This can be purchased off of eBay. A couple little bottles go a long way.

    And as with everything else, I have stir bar for this. And a bug. So we'll let the oil dissolve into the isopropyl alcohol. OK. Now we're going to use this. These are graduated in 0.1 milliliter increments. So it's very precise. So I'm going to run just briefly some distilled water though it just to wash out any contaminants. And then we're going to pour in our titrant solution, our 0.1 potassium hydroxide titrant solution. And we want to do this a couple of times to make sure that the water that may be left in this does not affect our readings.

    OK. We've washed our titration duray with our titrant solution. Now what we're going to do is slowly add the titrant solution to our isopropyl alcohol and veggie oil mixture down here. The indicator solution that we put in at the phenol saline will turn a bright pink when we reach a certain pH, which is the pH that we want. So as soon as it turns pink and stays pink, that's when we stop.

    Credit: Alabama, A&M, & Auburn Universities Extension

    Part 3

    Biodiesel Production Demonstration

    Click here for a transcript of Biodiesel Production

    LANCE HALL: OK you can see it's remaining pink, now. So that gives us about 4 milliliters of our solution went in to change this from a dull yellow to a pink.

    So we're going to put this in our spreadsheet.

    I'm using the spreadsheet. You can also make a worksheet that you just write your numbers down. And you use a standard calculator for.

    So as we did before, we're going to use same jar. This time, we're going to put 9 grams of our potassium hydroxide.

    OK, we've gout our 9 grams. Now, we're going to add 175 milliliters of methanol.

    OK, we're going to stir that up again.

    All right, so we've got our methanol and potassium hydroxide mixture. And then, we're going to do the same thing, just add it slowly to our waste veggie oil, recycled veggie oil, however you want to say it. And you'll be able to know when you need add more by the color change.

    I don't know if the camera can see it or not, but while you're looking right at through the top, you can tell when it turns translucent. And see how it lightened it up. It's not quite as clear.

    All right, can tell how it's lightened up there, from adding some to it. That will turn to a darker translucent as it gets mixed in. OK, we're going to let that mix for a few minutes. And then, when we come back, we'll show you how it separated.

    Just as a demonstration, this is a batch that I made, a larger batch, that I made a couple of weeks ago. And you can see how clear it actually gets after a little bit of time of settling. This is almost, if not just as, clear and the same color as the virgin veggie oil. So once you get your process down, you should be able to make just as high quality stuff with the waste veggie oil as you do with the virgin.

    OK once you feel comfortable with your biodiesel-making technique, it's time to step up for a reactor. I've got five tanks in my system. This is a oil processing tank. When I first get my waste veggie oil, I pour it through a large strainer to catch all the big bits of French fries, and tater tots, and chicken nuggets, and everything else.

    And I heat it up. So I can put it into my storage tank. I have to heat it because it's got another filter on the inside of this tank to filter even the smaller bits out. And it has to be heated up to go through that filter. So once we're done with it in storage, and we're ready to make a batch, it comes to this 60 gallon full drain inductor tank.

    It's got a large lid on it. So I put my veggie oil in here. This tank is the methanol lye mixture tank. Only methanol and lye's ever in this tank. Once I figured out how much lye and methanol I need for my batch of oil, I mix it up in here. And then it's mixed in the pump and also heated. And it reacts in this tank.

    And once it's done reacting, I will drain the glycerine off of the bottom using these series of valves. And then I'll do whatever means necessary to get the methanol and other nasties out of it. And once it's done, and I'm happy with it, it comes to this storage tank. And once it's in the storage tank, I can then put it in my tractor, car, whatever.

    MARK HALL: Walter, Lance, thank you so much for showing us how to make biodiesel today. Wherever you live, you can make a difference in our nation's energy crisis. Please look and do what you can to lessen our dependence on foreign oil. Look at our website, and you'll see more opportunities to save renewable energy. For the Alabama Cooperative Extension system, this is Mark Hall.

    Credit: Alabama, A&M, & Auburn Universities Extension

    • Was this article helpful?