pic: Green Machine Competition - 10 Cell Fuel Cell Stack

[Conor Ryan]

loading photo ...

[Stuart]

so whats the risk of fire/explosion if one of the hydrogen tanks gets damaged

[lukevanoort]

Originally Posted by Stuart

so whats the risk of fire/explosion if one of the hydrogen tanks gets damaged

I imagine if a leak was formed it would be very, very high. Hydrogen burns very easily and with a very faint flame. Hopefully the tank is durable enough that a puncture is unlikely.

[Conor Ryan]

Originally Posted by Stuart

so whats the risk of fire/explosion if one of the hydrogen tanks gets damaged

I was waiting for someone to ask that question, it's no joke, hydrogen is best described as a Invisible Explosive. When we recieved out kit for the project at school, we weren't there to sign it, so when they saw this:

They freaked out.

We take every precaution neccessary (actually it's a rule of the game I think) when assembling the fuel cell (such as working on it in a lab environment). Right now, hydrogen isn't even allowed into venues of the competition (see original email blast). Phase 3 of the Green Machine Competition (released yesterday) is titled, "Design a Fuel Cell "Green Machine" Game and Hydrogen Safe Game Floor. They elaborate on it with one of the design parameters being,

Originally Posted by Green Machine Phase 3 Rules

No robot to robot contact, include a SAFETY FEATURE with 10 m.p.h. safety impact margin in case there is contact - no parts ejected or broken, robots retain motor function after collision, include rules for penalty points.

There is no such thing as a completely safe game, even games like Tag, have people that get hurt, so it's a touchy subject. I'd imagine an almost battle bots like venue with walls and everything.

[Arkorobotics]

Looks awesome! It would be nice if fuel cells were allowed in FIRST.

How much did that cost?

[MikeDubreuil]

Originally Posted by Arkorobotics

How much did that cost?

If you'd like you can buy a kit.

[ThomasP]

Buying a kit isn't nearly as fun as building one with stuff around a chemistry lab. We had a group project in AP Chemistry my senior year where we had to build something that produced electrical energy out of stuff we could find in the lab. My friend and I built a hydrogen fuel cell, it actually worked decent... after the first time we ran it we considered setting it up again to run something but never got the time to :-/.

[Stuart]

ok my next question is how much current can you suck out of one of those things?

and what happens if you suck too much?

[Peter Matteson]

Keeping a hydrogen leak from causing a fire is actually fairly simple, use proper ventilation to keep the maximum credible leak below the lower flamability limit of hydrogen. The basic way to figure this out should be clearly described in ANSI FC1 (Formerly ANSI Z21.83).
Pete

[chris31]

Originally Posted by MikeDubreuil

If you'd like you can buy a kit.

Im seeing them for $140. That seems low, am I missing something?

[Chuck Glick]

Originally Posted by chris31

Im seeing them for $140. That seems low, am I missing something?

What your seeing is for the 1 cell kit, the 10 cell they have retails at $399.99.

[ngreen]

Cool.

I think $140 sounds reasonable. I am on the Chemical Engineering Car team and the fuel cell car kits were prevalent at competition a couple of years ago. Since then they've made them illegal because they can be ran nearly unmodified, and make the competition unfair to those with completely team built cars. A few team still run fuel cell, but they manufacture them themselves (including the proton exchange membrane). The team that won nationals this year, Puerto Rico Mayaguez, built a fuel cell for their car.

To be dangerous, the hydrogen would need to be at proper concentration between the LFL and UFL, and require an ignition source. With proper precautions this shouldn't be a problem. I haven't seen problems with hydrogen at our competition, however, the green machine competition uses larger tanks and more hydrogen than the chemEcar.

On another safety note: Last year at nationals a car exploded during its run. It was using a chemical reaction to generate pressure and using PVC as a pressure containing device. Bad idea. Luckily, this year major rule changes required proper pressure containing devices, gauges, check valves, and proof your car won't blow up when you put it on the line.

edit: $140 is reasonable, albeit high, for the car type kits (experiment kits). For the fuel cells they are using it would be higher.

[Conor Ryan]

Originally Posted by Stuart

ok my next question is how much current can you suck out of one of those things?

and what happens if you suck too much?

Well the amount of current you get, is very much dependant on the flow of the fuel (hydrogen) through the unit. We have the capability in the kit to have a forced hydrogen flow, or more of an ambient flow. So there is no definitive answer I can get you right now, but once we run a test I'll post the results from the multimeter. In the mean time, you can look at some of the information on the TekStak page, they say 1.5amps, but we'll be testing a system 4 times the size they talk about, as well as a hybrid battery/fuel cell system.

Originally Posted by chris31

Im seeing them for $140. That seems low, am I missing something?

How big is that stack? In the kit we recieved 2 10-Cell TekStak kits, they are $399 retail each.

[John Gutmann]

I am a little confused, I don't see a PEM in the stack, and from looking at the picture of the plates, I don't see how the gasses flow through.

*I am new to fuel cells...I am only used to seeing PEM fuel cells

-john

[chris31]

Originally Posted by Conor Ryan

How big is that stack? In the kit we recieved 2 10-Cell TekStak kits, they are $399 retail each.

Oh. OK. I didnt think just one would be enough to power much.