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EEYORE

Mon Aug 14 2006, 07:23AM

Registered Member #99 Joined: Thu Feb 09 2006, 06:10PM
Location: florida, usa
Posts: 637

Hello all,
I have decided I would like to build a fuel cell. I would like to either build a hydrogen fuel cell, or a methanol fuel cell. I am not sure how to bypass spending $$$$$$ though. I have thourally checked out ebay and google and just see "kits" rather than materials. What is the membrane made of?Seems this is the one most costly part of the fuel cell. Which would be easier?Methanol, or hydrogen?
I have seen platinum wire glow in the presence of methanol. I wonder how hot?Perhaps a thermocouple heated by the glowing platinum creating some current?I am not looking to power my car, just looking to demonstrate the technology, perhaps lighting an LED at most...

Any tips?Has anyone made a good reliable one?I am really more interested in hearing ideas, or experience, rather than having others go research it online for me, unless they too would like to build one...(Hate doing others HW!)

Thanks!
Matt

Marko

Mon Aug 14 2006, 02:06PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

PE membrane is usually some kind of proton-porous polymer doped with tiny particles of platinum (hardly something you can come by).

Except membrane I don't think there's anything unacessable for you. Those 'kits' are usually consisting simply of two pieces of acrylic, two electrodes and PEM pressed between.
FUel cells are usually capable of giving lots of power out and have very high energy/weight ratio when compared to standard batteries.

Usually these stacks are paralelled to get high output voltage (putting this just because of nice picture)

If you are unable to get a carpet roll of PEM or large amounts of exotic platinated metals I doubt you can come to building somethigng (but guys who produce 'kits' got their membranes from somewhere..?)

Bjørn

Mon Aug 14 2006, 05:06PM

Registered Member #27 Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058

You can demonstrate a primitive fuel cell without membranes, there are a few websites that describe how. The power output is extremely low.

Platinum wire glowing in metanol and a peltier element could give 5-20W. The peltier element has an efficiency of up to 10% but it is difficult to regulate the temperature.

If you want to run a car you should look into steam engines, a modern steam engine has a higher efficiency and lower weight than an internal combustion engine.

Marko

Mon Aug 14 2006, 07:03PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Some available membranes and prices

EEYORE

Mon Aug 14 2006, 07:29PM

Registered Member #99 Joined: Thu Feb 09 2006, 06:10PM
Location: florida, usa
Posts: 637

Firkragg wrote ...

Some available membranes and prices

That site seems a bit overpriced. 22$ for a small plate of graphite'?Come on...

So the methanol heating platinum wire inturn heating a peltier sounds feasible?I dont need more than maybe say 50mW.(around 2 volts)

What about pumping Hydrogen and Oxygen gas over two platinum wire coils?One coil gets hydrogen, the other gets oxygen?Are there ANY other materials that are cheaper than platinum that can be used as the catalyst?The only source of platinum i have is of like 44awg wire, 12inches for 5$. That is gosh darn THIN!

Matt

Marko

Mon Aug 14 2006, 07:47PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Yep, such things get a bit expensive if you want soem really useful power.
I didn't find much places where you could get that membrane for cheaper.

Heating a peltier with platinum wire dipped in methanol wouldn't really be an electrochemical reaction and it would be unfair to call that a fuel cell.

Produced voltage and power is also going to be very low, after pouring liquid nitrogen on a side e of a peltier tesladownunder got some 150mA at 350mV (you'l have to stack a lot of these to light a led)

EEYORE

Mon Aug 14 2006, 08:12PM

Registered Member #99 Joined: Thu Feb 09 2006, 06:10PM
Location: florida, usa
Posts: 637

There goes the methanol idea...

Well, i bought the guy out on ebay. I figure 3 strands of 43 awg wire twisted together should be much more manageable. Its is 92%platinum, 8%tungsten.

What I want to do now is coil them into two coils. Place them into a container filled with distilled water. Each coil will have a glass tube to direct hydrogen and oxygen gas over. This should allow the two gasses to recombine to form water, and thus produce a current, no?
Comments?
Matt

Electroholic

Mon Aug 14 2006, 08:43PM

Registered Member #191 Joined: Fri Feb 17 2006, 02:01AM
Location: Esbjerg Denmark
Posts: 720

you might need some electrolyte in the water.
say koh or something like that.
turnign the thin wires into coils is actually a very good idea.
good luck. and keep us posted.

EEYORE

Mon Aug 14 2006, 09:01PM

Registered Member #99 Joined: Thu Feb 09 2006, 06:10PM
Location: florida, usa
Posts: 637

Electroholic wrote ...

you might need some electrolyte in the water.
say koh or something like that.
turnign the thin wires into coils is actually a very good idea.
good luck. and keep us posted.

How about NaOH?I can get that as RedDevil Lye in the store here...Im wondering how the direct methanol cells work. Seems it would be much easier to poor methanol into the cell than to pump H2 and O in there...The fuel cell store sells a methanol kit for 30$ which must be able to be built for like 5$ considering THEIR markups.

That looks QUITE simple and something tells me I wouldnt need to spend 30$ to get the results...So how might that thing work?What is converting methanol into electricity?Platinum?
Also, just how pure does the platinum need to be?My wire is 92% platinum...Might a platinum coated wire of much great thickness work better?
I plan to make a small dc-dc converter for this.

EDIT:
After some more googling, a methonal fuel cell needs just two electrodes ( could be graphite/stainless stell mesh ect, ) an electrolyte (KOH, maybe NaOH?) and fuel(methanol). So, what kinda methanol should i buy?I see it listed as plane methyl alcohol, and also as ANAHYDROUS?I guess it means, dry?Like, i mix it myself?In that case, I could make a strong molar solution and boost the cell?

Matt

...

Mon Aug 14 2006, 11:36PM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

Seems like for making the H2/O2 you would be best off using a little bit of metal dipped in a pool of water, with a little bit of salt in there to get the current flowing... As long as you only use a little voltage (3v) you should get mostly O2 and H2 out. Then let the bubbles rise up onto the electrodes and life would be good

As to their prices, I didn't see a $22 piece of pure carbon, but some pieces of carbon that had been machined with small channels in them ($$$) or pieces that had been doped with platinum ($$$$)... Their prices for the pem membrane seems decent for the quantities they are selling...

As to the % methanol; I would assume you would just mix a little pure methanol into the KOH solution. You could use something weaker, but add more of it to compensate. A page linked by yours states that 1-4M KOH should be used, so it is mostly water anyway.

Also, about the platinum... I think that instead of using wire you would get much more bag for the buck with Pt plated wire or foil. Seems like a 300u layer is pretty cheap... I calculate 15mg/in^2 (double for double sided) so at $38/g that is only $1/in^2 of platinum

But since we can't get foil with a 300u Pt plating for anywhere near what it costs in the platinum I think we should stick with a 2mg/in^2 Pt doped carbon for $20/in^2 as sold by the fuelcellstore

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