Some of you who are mostly trained in biology will see the Lab 3-6 (Fuel Cell Dynamics) and get turned off before you even purchase the lab manual. For the record, my doctorate is in zoology, and the title of my dissertation is “The Hormonal Control of Vitellogenesis in Decapod Crustacea” (are your eyes glazing over?). I teach classes peripherally related to my specialty because my post-doc did not take me anywhere (mostly my fault). In fact, I never heard of environmental science until I started teaching it seven years ago and only wrote the manual because six years ago the College Board mandated at least one hour of lab per week to qualify for AP designation.

The activity I published in the manual is based on a modified version of this activity developed by Simon Quellen Field, who kindly allowed me to use it:

http://scitoys.com/scitoys/scitoys/echem/fuel_cell/fuel_cell.html 

This simple and incredibly clever model teaches students that fuel cells work by means of a catalyst that speeds up the process of “reverse electrolysis”. Unless your students are going to study engineering, this is the only principle they need to understand. The other exercise involves using a watt meter to measure the energy consumed by a small fuel cell as it runs a toy car motor. The students do not need to learn about how the proton exchange membranes works (but it does not hurt for you to learn about it in case they ask). This activity also serves to estimate first-hand how much electricity you get back after charging the fuel cell by means of electrolysis. According to our data, lead-acid batteries have a much better charging efficiency than these small fuel cells (and this does not even take into account the energy needed to compress the hydrogen).

Even though the “hydrogen economy” is not practical for now, I think that the principle can be applied to develop affordable fuel cells that run on more practical fuels like methane or methanol. Here is an interesting article on the current state of fuel cell technology:

http://www.techradar.com/us/news/world-of-tech/when-will-fuel-cells-power-the-world-1098488


And here is another article about a fuel cell that runs on ….hydrazine:

 http://www.greencarcongress.com/2007/09/daihatsu-develo.html

For those of you who do not also teach chemistry, hydrazine (N2H4) is a toxic, energy-dense liquid that is often used as rocket fuel. I got a whiff of it when I deliberately mixed bleach and ammonia together in order to collect the gas (mostly hydrazine vapor) from this highly exothermic reaction. Even though I was only 14 I knew enough to do it outside. The fact that I got away with it doesn't mean you should try it too!

For everyday transportation, hydrazine is probably even less practical than hydrogen because it cannot be produced efficiently. However, this technology is noteworthy because this fuel cell does not require any precious metals and (for the tech savvy among you) it replaces the proton exchange membrane with an anion exchange membrane. Now that’s what I call thinking out of the box!

Even if you are not interested in learning about hydrazine fuel cells, this article has a nicely simplified diagram showing how proton exchange membranes work (much better than the illustration in the textbook I used in my class).