Fuel Cells - A viable power source?

Shaun Barrett · 2002-06-09 19:02:36

With either fuel cells or closed-system reciprocating internal combustion engines using H2/O2, you still have to split the water first.
Where you get the energy to split the water is what it all comes down to, I suppose. Probably in the early days, a nice reliable little nuclear reactor will be the way to go. But, when we have janitors available to sweep the dust off the solar panels each morning, go with the photo-electric idea!!
Obviously, there will be times when power requirements are low and solar panels will be able to give us all we need. But for occasions when we need very high power outputs (especially for our vehicles), having stores of, say, H2/O2 will be essential to drive fuel cells and more conventional engines perhaps.

Shaun Barrett · 2002-06-09 19:09:56

Oops! I must have posted at the same time as Byron ... and we said pretty much the same thing.
Except Byron went further in suggesting geothermal energy sources would be a cool (sorry, hot) way to go!! I agree in principle but where you want to live may not be conveniently close to easily accessible geothermal heat.
But, if it proves to be a viable option later in the piece, I'm all for it!

Shaun Barrett · 2002-06-09 19:13:43

HELP!!! .... ADRIAN!!! There's something wrong with this topic!
I think the posts by Phobos and Byron have inexplicably vanished. Hope it wasn't something I did!!

Phobos · 2002-06-10 16:40:21

HELP!!! .... ADRIAN!!! There's something wrong with this topic!
I think the posts by Phobos and Byron have inexplicably vanished. Hope it wasn't something I did!!

This happens a lot when I start a thread for some reason. I hope those moles at NASA haven't attached some alien technology to my computer to keep the truth from getting out!

Mark S · 2002-06-17 10:02:13

I would definitely like to see fuel cells on Mars, and I believe that they will come of age as the automotive industy and the utility companies do more research.

Fuel cells are more efficient than internal combustion engines but they are much heavier than a combustion engine with the same power output. That's why companies like Ford and Volkswagen are working feverishly to reduce the size of the fuel cells. Chrysler was also working on a catalyst system that would extract hydrogen from normal petroleum. The power companies are going one step further, trying to build a catalyst that will take the hydrogen from natural gas on home fuel cells.

Assuming that we launch Mars Direct before 2020, that will give industry about ten years to make lightweight fuel cells that run on the methane produced in the Sabatier reactor. I would say that the odds are good for using fuel cells during the first exploration of Mars.

Mark S · 2002-06-18 09:51:57

Yes, fuel cells do run on hydrogen. The point I'm trying to make is that these fuel cells should be versatile. It would be preferrable if they ran on the hydrogen feedstock. But if that wasn't available, they could use a catalyst to break down the methane from the Sabatier reaction and use that hydrogen for fuel. This is the same technology the power companies are developing for home fuel cells.

C M Edwards · 2002-06-18 11:16:15

Don't fuel cells freeze solid and crack when they sit idle at Martian surface temperatures?

CME

Mark S · 2002-06-19 13:14:28

I've actually found a website describing fuel cells that run on methanol, with no need to break it down and extract the hydrogen. You can find it at http://fuelcells.sae.org/

C.COMMARMOND (FR) · 2002-08-28 05:01:33

Forget about H2/O2 and maybe about fuel cells in ground vehicles:

1) liquid hydrogen needs heavy tanks: i saw for cars 300kg of tank for 30 kg of H2.
2) To obtain H2 from H2O is very unefficient, it's not better than the best space batteries (30%/40%).

Nota: efficiency of a fuel cell is approx 40%, so, crack h2O to obtain H2 and O2, cool them, compress then, carry an heavy (and leeking) tank for H2... if probably not efficient.

I think the first thing is to know haw much energy you need. So if we talk of a 2 metric tons(vehicles for 4 people with sas, 1 week autonomy... , you need approx 40-50KW/h on Mars to drive at 50 Km/h, if you want a 500km autonomy, you will need 500KW of energy. So just find how to store this amount of energy in the minimum volume and weight!

1st idea: it is better to use fuel (carburant and comburant) liquid at standard (Marsians) temperatures (-30 ?C) with no need for pressure of big cooling and 'easy' to synthetise on Mars. H2 and O2 are the worst for this first idea. Methane (CH4) and H2O2 are possible choice.

2nd idea: don't use fuel... Pioneer 1 and 2 uses a small nuclear generator which give a few KW and works 20 years after. No mobile parts, but i don't know about radiation, but since the amount of plutonium they use is small, radiations should be small too. The biggest problem is politics and greens...

3rd idea: don't use fuel again,
Store a non burnable energy:
- compress some gas in a bottle and just use it to run the vehicle just look ther http://www.mdi.lu/acceuilgb.htm for a workable vehicle which be sell in France very soon. The problem with this is you need a source of heat to obtain a better efficiency.
- Store movment:
Uses a flywheel to store energy (look at http://rhlx01.rz.fht-esslingen.de/project....el.html or better to http://www.upei.ca/~physics/p261/projec … eel1.htm). I saw some time ago a company which made very efficient ones for car propulsion...

This is just to open new paths, please think about it and answer...

CC

RobS · 2002-08-28 11:46:27

The Mars Direct book advocates liquid oxygen and liquid methane storage for the rover, and burning them in a fairly standard internal combustion engine. You would condense the water vapor for drinking and reuse to make more methane at the base.

Probably the best combination would be the vehicle described above, with a nuclear power cart following at a discrete distance behind, where its radioactivity is not a problem. Every morning you could dock the two together for five minutes and, using a remote manipulating arm, hook a few hoses together to transfer methane and oxygen to the rover and water to the reactor cart. The latter would make new methane and oxygen for you for the next day's fillup. If the reactor cart had obstacle avoidance software, it could follow in the rover's tracks automatically, especially if the rover had a bulldozer blade in front to clear away obstacles as it went (which would also make a return trip home safer and faster). Such a combination would allow two or three pressurized rovers to travel together for several months, covering thousands of kilometers, before returning home. One could start clearing a regular system of dirt roads this way!

-- RobS

turbo · 2002-08-28 12:52:01

Hi Everyone!
I humbly submit that my final term paper was on hydrogen power. The fuel cells look like a good idea, and absolutely does liquid hydrogen need a lot of storage space. The biggest stumbling block I've yet seen is the membranes for the fuel cells. So many of the designs call for platinum!

Sandia national labs is working on hydrogen in a couple of different ways. try: http://www.ca.sandia.gov and look at the projects they have going.

turbo

C.COMMARMOND (FR) · 2002-09-03 14:58:47

Hi Robs,

if you take a Nuclear Power with you (my #2 suggestion) , why don't you use electricity to run your car ? It is more efficient by a factor of 2 or 3.

Or maybe you take a small one which needs 24 hours work to give only some hours autonomy ?

CC

umrover · 2002-09-25 18:16:37

We have a paper discussing power on our website http://www.umrover.org/reports/ . Basically current fuel cell technology is a little big, but in 10 years it should be fine. The problem is heat disapation. The rover is too hot on mars! We also have a thermo report discussing this. Its very important and fascinating finding.

RobS · 2002-09-26 00:50:37

Regarding a nuclear-powered rover, it probably would work also if a heavy radiation shield was added. I was assuming it was easier to keep a lightly shielded reactor 100 meters behind you that a shielded one 1 meter away from you, under the hood of the rover.

-- RobS

Phobos · 2002-09-26 18:00:12

Hidden messages show thyself! (place holder post)

SpaceNut · 2004-11-16 09:11:54

Well this has been a real dead thread since it was started so long ago but it is the right one to post this reference within.

This may or may not be a first for
NASA Buys Hydrogenics Light Weight Fuel Cell Stack To Test For Uses In Space.
Granted it is a light weight 5kW hydrogen/oxygen Proton Exchange Membrane (PEM) fuel cell. But in a pinch when power is of need it may do.

The technology of fuel cells has been matching forward to make them smaller and of course with that more effecient as well. Maybe someday they will replace batteries and then again maybe not.

Dook · 2004-11-16 18:03:29

Hmm, same old arguments. Fuel cells vs nuclear vs combustion engines.

Combustion engines are extremely inefficient for use on mars. You need a giant LOX tank just to supply a very small ICE.

Nuclear is too heavy.

Fuel cells supplying a very efficient drivetrain are the way to go. You don't need liquid either, gas cylinders will work. And the water they create can then be used by the crew.

It's all there in the Simple Mars Vehicle post.

GCNRevenger · 2004-11-16 20:54:38

I'm still a fan of using alcohols and LOX for fuel cell operation, heavier yes but much easier to handle.

One blurb that popped up on an old early NASA DRM study was to use dynamic RTGs to power a rover. They would have a much higher efficency then the thermocouple ones in use.

Dook · 2004-11-19 20:09:49

LOX supplying fuel cells could certainly work. One problem is if you can't keep it at -298 degrees F it boils off but you should have enough to complete the mission. I haven't looked at the math on it though. Another problem is that LOX would be heavier than gas. Also it could be used in a simple vehicle internal cooling system.

How much power do the dynamic RTG's put out and more importantly how much to they weigh?

mboeller · 2004-11-20 06:10:21

Well,

at first I was not sure if fuel-cells are an good idea or not, but after reading the following PDF's I'm sure that fuel cells are not the way to go. They waste far too much energy (3/4) to be useful.

Links:

http://www.evworld.com/library/carbdeto … detour.pdf
http://www.ilea.org/downloads/MazzaHamm … schlag.pdf
http://www.modenergy.com/BEVs%20vs%20FC … 120603.pdf

MarsDog · 2004-11-20 08:10:03

http://www.keveney.com/Wankel.html]Wankel

or

http://quasiturbine.promci.qc.ca/QTInde … asiturbine

Lightweight, just run generator to power everything.

Dook · 2004-11-20 08:38:41

http://www.keveney.com/Wankel.html]Wankel
or
http://quasiturbine.promci.qc.ca/QTInde … asiturbine
Lightweight, just run generator to power everything.

Where are you going to get the oxygen to provide combustion in your wankel engine from? Do a little math, take into account the volume of air/fuel used per revolution and multiply that by the rpm. How are you going to provide all that oxygen?

Dook · 2004-11-20 08:44:34

Well,
at first I was not sure if fuel-cells are an good idea or not, but after reading the following PDF's I'm sure that fuel cells are not the way to go. They waste far too much energy (3/4) to be useful.

Fuel cells don't waste any energy. What you call 'waste' is pure water that can be used to supply the crew and heat that would be necessary to keep the inside of the vehicle warm. Remember mars temperatures are routinely -70 F. With one or two outside excursions a day this heat will be useful byproduct.

Also when you consider the other options fuel cells are still the best choice. RTG's have a lot of wasted weight in sheilding and internal combustion engines are even less efficient than fuel cells.

MarsDog · 2004-11-20 10:50:35

Fuel cells don't waste any energy

The fuel cell busses were similar efficiency as diesel busses.
The energy losses were through different processes, but ended up as heat, before reaching the wheels..

Where are you going to get the oxygen to provide combustion in your wankel engine from? Do a little math, take into account the volume of air/fuel used per revolution and multiply that by the rpm. How are you going to provide all that oxygen?

Instead of wasting Oxygen, in place of the non reactive Nitrogen, simply feed some of the exhaust back in.

-------------------------------------------------------

Quasiturbine provides 5 KW per kilogram,
while fuel cell only 10 Watts

http://www.google.com/url?sa=U&start=1& … e=9872]See chart in pdf

For brute power in a small package, forget the fuel cell.

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#1 2002-06-09 19:02:36

Re: Fuel Cells - A viable power source?

#2 2002-06-09 19:09:56

Re: Fuel Cells - A viable power source?

#3 2002-06-09 19:13:43

Re: Fuel Cells - A viable power source?

#4 2002-06-10 16:40:21

Re: Fuel Cells - A viable power source?

#5 2002-06-17 10:02:13

Re: Fuel Cells - A viable power source?

#6 2002-06-18 09:51:57

Re: Fuel Cells - A viable power source?

#7 2002-06-18 11:16:15

Re: Fuel Cells - A viable power source?

#8 2002-06-19 13:14:28

Re: Fuel Cells - A viable power source?

#9 2002-08-28 05:01:33

Re: Fuel Cells - A viable power source?

#10 2002-08-28 11:46:27

Re: Fuel Cells - A viable power source?

#11 2002-08-28 12:52:01

Re: Fuel Cells - A viable power source?

#12 2002-09-03 14:58:47

Re: Fuel Cells - A viable power source?

#13 2002-09-25 18:16:37

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#14 2002-09-26 00:50:37

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#15 2002-09-26 18:00:12

Re: Fuel Cells - A viable power source?

#16 2004-11-16 09:11:54

Re: Fuel Cells - A viable power source?

#17 2004-11-16 18:03:29

Re: Fuel Cells - A viable power source?

#18 2004-11-16 20:54:38

Re: Fuel Cells - A viable power source?

#19 2004-11-19 20:09:49

Re: Fuel Cells - A viable power source?

#20 2004-11-20 06:10:21

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#21 2004-11-20 08:10:03

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#22 2004-11-20 08:38:41

Re: Fuel Cells - A viable power source?

#23 2004-11-20 08:44:34

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#24 2004-11-20 10:50:35

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