While shopping for batteries that can run a CPAP machine for a couple nights, I was wondering why not a fuel cell. A few years ago I think I saw an article about how they’d become widely available for purposes like running a laptop for many hours, with a photo of somebody doing what looked like using a butane refiller on a gray plastic brick.
I’m not making much progress online. For sales, it turns out car racing enthusiasts call gas tanks “fuel cells” so I’m mostly turning up hot rod ads, and it seems like all the articles are about vehicle power.
I’m thinking of energy of 2000 to 10000 watt hours.
I suspect that what you are referencing is the direct methanol fuel cell (DMFC) which was supposed to be the next big thing in portable electronics about ten years or so ago because you could refuel it with a small canister of methanol and essentially run indefinitely without having to carry a DC ‘brick’ or find a place to plug in. This wasn’t some Steorn-type bullshit hype; DMFCs exist and do work, but the catalyst is made from platinum and ruthenium which are expensive and rare, so the price of doing this on a consumer scale is prohibitive. You mostly see DMFCs used in applications where the emissions of gasoline and natural gas engines are unacceptable and the duration of lead-acid and NiMH battery-powered vehicles are insufficient, so clean room manufacturing areas.
I haven’t really followed DMFCs recently but my impression is that they’ve become less used as LiPo and LiFeO4 batteries have become much cheaper and dominated the market offering a substantial increase in the period between charges over older batteries. There were a few people claiming that DMFCs would be a good technology for automotive versus battery electric but the specific power output just isn’t there for a roadworthy car, and the real advantage of methanol is that it could be used in many gasoline engine designs or converted to dimethyl ether (DME) to be used in diesel and turbine applications with essentially no fundamental changes other than adding a lubricity agent, and could be distributed using the existing hydrocarbon fuel infrastructure.
For running a CPAP machine overnight you are better off looking at lithium battery power stations (sometimes referred to as AC battery “generators” even though they don’t actually generate electricity); there are some with adequate amp-hours to run a CPAP for tens of hours (I assume without knowing the specific power requirements of a CPAP device; I have a compact station I keep in my truck that can run a high efficiency refrigerator for >20 hours) but you can’t take them on an airplane or ship them after the battery has been activated due to FAA safety regulations.
A liquid fueled portable solid state power generator would be very cool but until we get much cheaper catalysts it just isn’t a practical reality.
This one (also there in the previous link) uses propane; at 100W it seems to use about 50 g/hr (I’m wildly guessing what a CPAP machine takes), so you should be able to run it for 9 hours on a 1 lb propane cylinder; 48 hours would be like a gallon of propane. That isn’t cheap but I guess it’s OK for emergency backup, but then we are back to what @Stranger_On_A_Train said about Lithium batteries being much cheaper at the moment; a 2000 Wh power bank should be not more than $1600 (but maybe the fuel cells are more cost-effective if you need 10000 Wh; I really haven’t even tried to do lifetime cost comparisons)
It doesn’t look good. The one you linked to only has a 600 hour runtime. That means it only produces 210 kWh total over its entire life. There’s no price listed, but based on other units at the fuelcellstore.com site, I’d guess it’s at least $8k, so $38/kWh equivalent. A lithium ion battery pack with controller, etc. is about $600/kWh. You only have to recharge 16 times before the battery comes out ahead, and that’s not even counting fuel.
Where but the Dope? Thank you for several great answers. Overall it’s not promising, and batteries turn out to be more plausible than I guessed. I’m happy there’s an accessible answer, even though it’s clearly not fuel cells.
There was at least one that looked possible and competitive with batteries for the weight and volume, but only if I ignore the fuel, which would be in a massive pressure vessel!
It does look like fuel cells are currently a pretty viable option for something like a cabin or trailer without access to utilities or solar charging. They’re not as cheap as engine driven generators, but they’re certainly quieter and apparently lower maintenance.
I wonder if something will shift the market to more mass production and drive the price down for small ones?
They can be noisy. We have a 3,000 W Honda, and it’s fairly quiet… though I do put a padded chaise longe on its side to help attenuate the noise. With the back doors shut (with the extension lead coming in under one) it’s quiet in the house. Some generators are quieter than others. I would expect a smaller one to be less noisy than a larger one.
We had some severe weather this past Winter, and a lot of people were without power for a long time. In those cases, a portable generator is invaluable. Better for the neighbours to have a little noise, than to die for want of a CPAP (or refrigerator for insulin, or whatever).
This one, featured on Wikipedia (is it a real or a spam article??)
doesn’t sound like it is for home use (though there is a 10-year-old link there mentioning plans for one…), but they claim a 10-year lifetime and a break-even cost point after 8 years, and a capital cost of $7–8 per watt. There are photos there of a bank of them at Yahoo, Google, eBay, etc so evidently some organizations bought some.
A lithium battery is worth shite unless you can recharge it … and in a power outage, potentially not possible, however one can get a 150# of propane and do the power cell for oodles of time [I think the longest power outage at the farm would either be that hurricane that hit the New England coastal area back in the 90s, or the kerfluffle with blizzards about a decade ago, both were roughly 3-4 weeks of no grid.
We have a small gas powered generator, when we hear that heavy weather is incoming, we top off the 4 propane cylinders and the 5 5 gallon blue gas totes. The propane tends to last us about 2 weeks in blizzard conditions, and the 25 gallons of gas something like a week [summer less because we run it longer to hold refrigeration, I use a small solar rig to recharge my phone, from BioLite, the Solar Home 620, it has a base station with a radio, USB port, a spot for an SD card and a set of 3 lights to string out and a solar panel.] [our barn heat is not dependent upon electricity, it is all pilot light, since each unit only heats an open space, it doesn’t need the fan that is electric dependent.]
The o.p. asked about “…batteries that can run a CPAP machine for a couple nights, …” presumably either for travel or the occasional incidence of an short duration power outage. A gas or diesel generator is invaluable if you need to run multiple appliances indefinitely without access to electricity or solar power to recharge a battery but comes at the cost of having to maintain a small engine and clean fuel, which is a real burden for intermittent use once or twice a year. I long ago gave away my small gas generator because it wasn’t worth the maintenance (and switched to a battery powered chainsaw for my very occasional use in clearing trail roads and cutting up deadfall for camp firewood) because it just wasn’t worth the trouble and effort to maintain them.
You can certainly buy small LiPo stations and batteries with pure sine AC ‘generation’ capable of 1800 W total output a >3000 Wh capacity (with multiple batteries), or a LiFeO4 system capable of running an entire set of household appliances for multiple days without recharging, and for just powering a single appliance like a CPAP device a smaller battery power supply is pretty much ideal even if you have a generator because it allows you to run the device continuously without having a gas generator running.
More about why I asked the OP question in the first place: I use CPAP, and have friends who go hiking and camping. I’ve been part of the hiking, but thought of the CPAP as a reason I might not be able to do the camping. Now, there were two different scenarios – backpacking, and campground camping next to the car. Even if it took a huge battery like a marine deep cycle battery for trolling motors, camping next to the car could be just fine. But I was afraid I’d have to have 20 lbs of battery just for the CPAP (as well as the machine itself) which would kind of knock out the backpacking option.
Now I’m thinking CPAP doesn’t have to stop me. And what my friends almost always do is camping next to the car, which makes that even more apparent.
All the same, I have had passing interest in fuel cells for many years, so it’s still a fascinating discussion! Thanks to you all!
I remember there used to be a briefcase fuel system setupp used to let teachers do classes on fuel cells - one of my proffs had one. Let me hit google and see if there is still some mention about it.
Here is the hydrogen one mentioned - If one paired it up with a water cracker one could [if one had a source of water] go without having to dick around with peopleing. Fuel Cell Store has a whole bunch of very interesting info - stuff has gotten more available since I did a class in alternate energy 15 years ago =) [rather obviously!]
Though as I said, I am rather fond of solar with charging and battery backup setups.
In the early 2000s Coleman sold a unit for camping. It was about 50 pounds. I think it was in their Powermate line. We had a rack of them at work to test. I can’t find anything about them, however.
That may be good enough, but note that the specifications on that link is a capacity of 95 Wh, not 2000–10000 as in the original post. It says it is a Lithium-Ion battery, product weight 1.3 lbs.
You can also get 95 Wh (depends on what batteries they put in) mobile charger/power banks like that with USB outputs that you can use as a DC power supply at various voltages. They are supposed to be more or less pocket-sized.
I think Linus Tech Tips did a few YouTube videos about fuel cells, and at least in a laptop computer application, they were a problem because they have to dissipate steam. Not something you really want around an expensive electronic device, and it could be a concern in a camping situation too.
When we were camping (back last century) we pitched next to someone who had a small steam-powered generator that ran his TV and charged his battery. It was almost silent and ran on methylated spirits. It was home made so I doubt you could buy one.