Nuts and Volts - June 2010

Figure 10. Stylized

Example of a Fuel Cell Stack.

cell phone directly or, at least, supply power to charge your cell phone’s battery. MBI Micro has one that may be something you’re after (Figure 12). The company’s Mobion, 100% methanol fed, passive DMFC technology has been demonstrated in fully-functional prototypes and concept models in three primary product directions: external cord-free rechargeable power packs; attached fuel cell power sources; and embedded micro fuel cell designs. They (correctly) claim that your lithium-ion battery loses its charge capacity after a few years, so why not replace it with a fuel cell instead. However, who keeps their cell phone much over two years these days, and who wants to carry around a bottle of methanol to recharge your cell phone? (Try getting it past the TSA at the airport and see what happens.) Nevertheless, it looks like it can be done and it’s a neat concept.

For mobile fuel cell stacks, Honda has one for its FCX Clarity car that is as functional and sleek as the car itself

Figure 11. Bloom Box Fuel Cell Installation (photo credit Bloomenergy).

(Figure 13). For mobile applications, fuel cell stacks and the fuel itself must be designed for both performance and safety in mind, and Honda has done both very well. Honda has been the pioneer for many emerging technologies like robotics (Azimo), hybrid cars (the Insight), and now fuel cell powered vehicles. Hopefully, the Hydrogen Highway initiatives will occur to make the FCX a reality.

important differences relative to the fuel cell’s unique physical geometry and fueling requirements. Depending on the fuel cell type (Part 10) and power requirements, each stack is different but the idea is still the same: Take something that generates about 0.5 volts at various currents (depending mainly on physical size) and scale it up to produce useful voltage, current, and power — just like a battery pack or solar module. Again, the similarities between fuel cells and batteries are amazingly close and, I guess, we can throw in solar cells, as well.

Fuel cell stacks are used for stationary, portable, and mobile applications. As of this writing, the most hyped of the stationary fuel cells is the Bloom Box (Figure 11). The Bloom Box is a solid oxide fuel cell stack that purports to be the solution for independent power for small homes to large buildings and everything else in between; it uses anything from natural gas to bio gas for a fuel source. Right now, it’s very expensive and big and is only capable of powering large facilities like the Google headquarters and similar installations. If it can be scaled down to a smaller size, it may be able to power homes, but this is yet to be realized even in operational prototype form.

On the other end of the size and power spectrum of fuel cell stacks, you’ll find a few that can power your

Summary

This time, you learned more about the essentials of how a fuel cell works and what can be done with them in terms of fuel cell stacks. You’ll need this background information for our next fuel cell article. In it, I’ll put our fuel cell powered Hydrocar through the paces to see how we can apply most of what we’ve learned about fuel cell technology to a neat mobile fuel cell project. So until next time, conserve energy and stay green. NV