Hands-On Science

making biodesel

The biodiesel crew demonstrate how they make biofuel (Michael Friedman).

EG: Can you explain the process that you and the kids have developed to make biodiesel?

MF: The processor is a water heater. It heats the oil to 130° F. Then we add methanol and potassium hydroxide or sodium hydroxide. A pipe system comes out of the bottom of the processor and goes back in through the top. When we turn on the processor, it heats the oil and mixes it with the chemicals. The sodium hydroxide or potassium hydroxide acts as a catalyst, breaking the vegetable oil into its component parts: glycerin and three fatty acids. Then one methanol molecule attaches to each of the fatty acids, producing three biodiesel molecules. The glycerin settles to the bottom of the tank, and we pump it out. Because the proportions are never exactly right, there is always some catalyst, methanol, and other schmutz left in the biodiesel. To get rid of that, we pump it into a 50-gallon wash tank and use a garden hose to mist water over it. The water attaches to any impurities and causes them to sink. Most of the water can be drained from the bottom of the tank, but some of it dissolves in the biodiesel. We put an aquarium bubbler in the fuel to remove the last of the water.

EG: How much fuel are you able to produce?

MF: Last year we didn’t do that much because we were busy outfitting our space to conform to license and inspection standards. After months of working we realized that we simply did not have the finances to renovate the space. So we were left thinking, “What do we do now?” We had built the processor but couldn’t use it because we don’t have the right ventilation system and other safety features in the space. We decided to buy rolling carts so we can roll our processor outside.

I didn’t anticipate how long it would take to make one batch of biodiesel. I meet with the students for an hour and a half each week, and we do some measurements, mix chemicals, put them in the processor, and turn it on. Then we wash the fuel from the previous batch, and that takes hours—which, for us, is multiple weeks. And the next batch just sits in the processor until we finish washing. We make five gallons at a time, maybe a little more. We don’t make that much, but we’re always busy.

EG: What decisions have the kids made about the project?

MF: The kids have extended the scope of the project beyond the making of biodiesel and are very active in getting the word out. They traveled to Washington, D.C., and presented at the National Sustainable Design Expo. We have also exhibited our work at GreenFest and at the Schuylkill Center, both in Philadelphia. Not all of the kids are excited about brewing the stuff; some are more interested in the environmental reasons for making biodiesel and are more inclined to create PowerPoint presentations about the experience. They all have their roles: one is an expert on the chemistry; another helps manage the mechanical equipment; another built the stand for one of our exhibits.

EG: What’s the future of the project?

MF: A lot of the decision making this year has centered on how we will recruit and train new kids to carry on the project after this class graduates. We’ve come up with a model for training new students that is similar to a residency program: each new student will learn about all the facets of the project and then choose a specialty. The future of the project depends on what the next group of kids wants to do. One possibility is to start getting oil from our own kitchens (as opposed to the restaurant that has been supplying us) and make this more of a community effort. We already give the fuel to an organization within our community: each eighth-grade class goes on an Outward Bound trip and is driven in vans that are fueled in part by our biodiesel. At the same time, I would like to expand the reach of the program by developing a workshop for teachers. Ideally, I would collaborate with other teachers—in math, social studies, etc.—to design an interdisciplinary curriculum for the workshop.