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PEM Fuel Cells and Thier Cost.

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Patrick

Sat May 28 2016, 04:11AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

I have the following quote for a 12 volt, 500 watt H2 PEM fuel cell. 1.2kg. it does look like the Aerotek 500 is a horizon made product but resold by this company. o ive put in for a direct quote too.

Spec page.

Qoute for alot of $

]electrolyzer_hardware_stacks_- _fuel_cell_store.pdf[/file]

So, some questions...

what makes an electrolyzer so expensive? Do they just have a low volume sales problem in a infant market? or is there labor or what? special metal that justifies almost 4k$ ?

I realize PEM's have platinum in them but it still seems like a lot of $. i knew fuel cells were expensive, but this and the other related products are ridiculous.

given these limitations and the research ive done, its pretty obvious why the market hasnt opened up to this tech, despite all the propaganda from the companies who make them. I remember 21 years ago in science class hearing this stuff was right around the corner.

Carbon_Rod

Sat May 28 2016, 08:52AM

Registered Member #65 Joined: Thu Feb 09 2006, 06:43AM
Location:
Posts: 1155

Most current polymer based cells are based on an accidental discovery from the 90's.
The largest manufacturer was gutted for the patents, and driven into bankrupted obscurity.

So today, you can buy an expensive PEM based cell that will slowly get poisoned by trace CO, and eventually stop working well.

The DoE has done extensive feasibility studies on variants of both low and high temperature catalyst based fuel cells.
Some new research seems to think they can solve the storage issues with high concentration, room temperature, and low pressure liquid peroxides. However, I seem to recall a generation of rocket scientists that failed to make it safe enough for general use.

Primarily, Hydrogen gas is problematic to handle even if corrosion issues are solved:

Best of luck,

Patrick

Sat May 28 2016, 07:01PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

what about mitigating hydrogen embrittlement using fiberglass or carbon ? could that be effective ?

and Horizon seems to be a large player in this market. i keep running into them. i keep running into them.

and, what lifecycle do the PEM's have before the CO poisoning really effects performance ? just an order of magnitude, like 10, 100 or more hours to decrease by 10%. or is there some formal way the industry describes this reduction in useful life.

My purpose is for small ground and under water bots. so 2 or 3 hours at a time. maybe 1000 hours total life of the stack.

Carbon_Rod

Sun May 29 2016, 12:32AM

Registered Member #65 Joined: Thu Feb 09 2006, 06:43AM
Location:
Posts: 1155

"what about mitigating hydrogen embrittlement using fiberglass or carbon ? could that be effective ?"
The prototype H2 vehicles from the local facility generally use carbon-fiber composite wrapped storage tanks.
At the time, I didn't ask about the metal alloy they used for the pressure vessel.

"and Horizon seems to be a large player in this market. i keep running into them. "
Indeed, they seem to be one of the few groups still trying to make it practical for consumer use.
A few years back...I seem to recall thinking their $2k 200W kit was outrageously overpriced...

"and, what lifecycle do the PEM's have before the CO poisoning really effects performance ?"
I was told it was a trace contamination problem, but can't recall much of the research on the chemistry.
We were more interested it the support hardware at the time:

"My purpose is for small ground and under water bots. so 2 or 3 hours at a time. maybe 1000 hours total life of the stack"
Having built on both platforms, I can assure you that there are quite a few design differences in these systems.

Mass and energy density are important for "ground" vehicle range:
A 24v 20ah LiFePO4 e-bike power pack already comes with a charger system, and you could buy over 100/pcs for the price you were quoted.

The range estimate is "1 mile per amp" for e-bike users, but I seem to recall around 2Ah/km of flat terrain for autonomous robots.

"under water bots" mean the Buoyant Mass == Ballast (energy density is less important for surface craft):
There are now full sized craft using LiFe power systems, but in water these things have an endless list of trade-offs.
Note, automotive style lead acid industrial marine batteries have well over 200 Ah, and for the unit price one gets 4x the run-time for much less hassle. Note, Pb cells don't state they need venting, but precautions should be taken seriously.

1000 hours is a long run-time unless the units are in standby, and you may need to start thinking about generation/sail options.
The Li cells will last 2k+ charge cycles, as long as you don't deep cycle discharge over 20% of the labelled capacity.

Good luck,

Bored Chemist

Sun May 29 2016, 09:40AM

Registered Member #193 Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022

Carbon_Rod wrote ...

So today, you can buy an expensive PEM based cell that will slowly get poisoned by trace CO, and eventually stop working well.

Then don't put CO in them.

Patrick

Mon May 30 2016, 02:17AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Bored Chemist wrote ...

Then don't put CO in them.

It slowly appears.

ANd on a seperate note:

How do methanol fuel cells age? is it similar to one of the above graphs ?

Bored Chemist

Mon May 30 2016, 12:00PM

Registered Member #193 Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022

Patrick wrote ...

Bored Chemist wrote ...

Then don't put CO in them.

It slowly appears.

How?
Where does the carbon come from?

klugesmith

Tue May 31 2016, 06:50AM

Registered Member #2099 Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1714

Bored Chemist wrote ...

Patrick wrote ...
It slowly appears.

How?
Where does the carbon come from?

This thread is the first time I heard of CO poisoning of hydrogen fuel cells.

Many people, apparently including Elon Musk, think that the "hydrogen economy" is supposed to use hydrogen made by electrolysis of water. Pretty darn inefficient way to store electricity.

Ask a big user of hydrogen (e.g. for making ammonia or refining petroleum, not little stuff like space shuttle fuel tanks) where it comes from. They'll say "the vast majority is prepared by steam reforming of natural gas".

So hydrogen is primarily a low-density fossil fuel product, noteworthy for low carbon emission at the time & place of consumption as fuel.

Here is a small format self-powered reforming system, using methanol, that produces enough H2 to run 2.5 to 7.5 kW of fuel cells.

I would not be surprised if told that its output includes measurable traces of CO.

johnf

Tue May 31 2016, 06:51AM

Registered Member #230 Joined: Tue Feb 21 2006, 08:01PM
Location: Gracefield lower Hutt
Posts: 284

Because you are stripping ions in the PEM you get active ions looking for mates with enough energy to break up a happy couple. For air 300ppm co2. "O" ion with energy looking for mate has the chance to steal an "O" from co2 to form CO and O2.
Even worse for the methanol based cells as there are much more carbons to play with M2CentsW

Patrick

Tue May 31 2016, 05:30PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

klugesmith wrote ...

Many people, apparently including Elon Musk, think that the "hydrogen economy" is supposed to use hydrogen made by electrolysis of water. Pretty darn inefficient way to store electricity.

Yes, here in California, without enormous government subsidies fuel cells and solar cells wouldn't last at all in the market place. Solyndra in my home town of Fremont CA, comes to mind. We have a political class here that just has to cram this tech into the market place. We have endless commercials on our radio and TV wanting to install wind or solar, at almost no cost, theres a lot of fine print though on those contracts.

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