Why aren't hydrogen fuel cell cars more popular than conventional batteries?

[Greg Bernhardt]

Enuma's thread got me thinking why these isn't more buzz for the hydrogen cars like the Honda FCX, GM Sequel, Nissan Frontier, BMW 7...

 

[russ_watters]

Probably because they are nowhere close to production ready and the infrastructure to support them is years away as well. Plug-in hybrids just made some news. They are still a couple of years away and have a couple of hurdles to overcome (battery cost/life/weight), but at least they look like they might be viable. Fuel cell cars may not ever be viable. The enabling technologies to get over the remaining economic/engineering hurdles don't exist and don't appear to be close to happening.

They do get a little buzz, though. Some see them as the holy grail of auto technology.

 

[Ivan Seeking]

This is the worst of it.
http://www.fuelcellstore.com/en/pc/viewPrd.asp?idcategory=53&idproduct=889

Although not entirely representitive of the price for a car, here we can get a 1KW fuel cell for about $24,000. 1KW = 1.34 HP. At that price, a fuel cell capable of producing enough power to replace a lawn mower engine would cost $50,000.

I have found 1KW cells for half that price before, but when we consider that even a small car may produce 100 hp, the price for the same in fuel cell power becomes absurd - about a million bucks!

 

[russ_watters]

As I understand it, the reason for this is right now a fuel cell requires exotic materials like platinum and palladium.

 

[mheslep]

This is the worst of it.
http://www.fuelcellstore.com/en/pc/viewPrd.asp?idcategory=53&idproduct=889

Although not entirely representitive of the price for a car, here we can get a 1KW fuel cell for about $24,000. 1KW = 1.34 HP. At that price, a fuel cell capable of producing enough power to replace a lawn mower engine would cost $50,000.

I have found 1KW cells for half that price before, but when we consider that even a small car may produce 100 hp, the price for the same in fuel cell power becomes absurd - about a million bucks!

I got into this area for work last year. Fuel Cell Store appears to be mainly for do it yourself-ers but I spent some time there pricing a house backup system (for myself) . Just for the PEM stack, no fuel supply or reformulation, no inverter, I came in at about $2k per kw. YMMMV.
Fuel Cell store is mostly about traditional ~low temperature http://en.wikipedia.org/wiki/Proton_exchange_membrane_fuel_cell" which because of its high temperature (700-1000C) doesn't need the $$$ catalyst, and a vehicle sized platform can be hold the necessary thermal management bulk. Also, note that a vehicle fuel cell probably only has to provide average HP (3? 4? ) and peak HP (~100) can be provided by battery assist. I'd say the biggest problem now for fuel cell cars is the hydrogen delivery / infrastructure, not the cell technology anymore - Energy cost of liquefying H2, can't put H2 gas through the pipelines, etc, etc.

Edit: average HP is 10x too low as noted by Ivan. Should be >30HP.

 

[Ivan Seeking]

I don't see a car running on 3 or 4 HP; at least not one that anyone would buy. That is the same power that one finds in a small moped. And how do you get battery assist from a car that has no recharging system?

 

[mheslep]

Fuel cell charges the batteries. BTW, here's a gorgeous example of what battery power can do when you need that 'peak'. 248HP, 0-60 < 4secs, top speed 125mph.
http://www.teslamotors.com/design/gallery-body.php . Line for beta testing the next model forms behind me.

 

[Ivan Seeking]

I just did a quick calculation based on a car that gets 40mpg at 60 mph. Factoring in 40%efficiency for the engine, 90% efficiency for an electric car, and 125 kBTU per gallon of gasoline, I get a mininum of 24 KW; or 32 HP just to roll down the road.

 

[Ivan Seeking]

Fuel cell charges the batteries.

Then you need more fuel cells to provide the charging. There are no free lunches.

I think you also have to derate the batteries by about 50% to account for efficiency.

 

[chemisttree]

This is the worst of it.
http://www.fuelcellstore.com/en/pc/viewPrd.asp?idcategory=53&idproduct=889

Although not entirely representitive of the price for a car, here we can get a 1KW fuel cell for about $24,000. 1KW = 1.34 HP. At that price, a fuel cell capable of producing enough power to replace a lawn mower engine would cost $50,000.

Are you saying that you couldn't cut your grass with a self-propelled lawn mower that had a 1.34 HP motor? From my calculations, you need about half of that fuel cell's output to power an electric mower (24V at 12 amps).

I have found 1KW cells for half that price before, but when we consider that even a small car may produce 100 hp, the price for the same in fuel cell power becomes absurd - about a million bucks!

The price per kilowatt of the most employed fuel cell currently used is between $3,000 and $4,500 per kilowatt. And... you cannot scale horsepower to electric power as you have done. Can you imagine a car running on a 100 HP electric motor? That would truly be a funny sight! A 30 to 50 kW electric motor is perfectly acceptable to power a Honda-sized vehicle. Price for that (if it were available) would be closer to $120,000. If the DOE's program to lower the cost to about $400 to $500 per kW is achieved, the price is cut to a (reasonable?) $12,000! Still pretty high but not out of the range for an fuel cell/battery hybrid vehicle which could use much smaller fuel cells.

 

[mheslep]

I just did a quick calculation based on a car that gets 40mpg at 60 mph. Factoring in 40%efficiency for the engine, 90% efficiency for an electric car, and 125 kBTU per gallon of gasoline, I get a mininum of 24 KW; or 32 HP just to roll down the road.

Yes you beat me to it; I guessed low for the average, nice work, That agrees w/ this http://mb-soft.com/public/headlite.html" . Add another HP or two to charge the batteries in the background. So a practical target cost then is perhaps $1k/10kw for a solid oxide cell. Edit: since there's no $$ catalyst, I expect that is doable.

 

[mheslep]

Can you imagine a car running on a 100 HP electric motor? That would truly be a funny sight!

Yes, and http://www.teslamotors.com/performance/perf_specs.php"

3-phase, 4-pole electric motor, 248hp peak (185kW), redline 13,000 rpm, regenerative "engine braking"

Click http://www.teslamotors.com/design/under_the_skin.php" here for a picture.

 

[chemisttree]

I just did a quick calculation based on a car that gets 40mpg at 60 mph. Factoring in 40%efficiency for the engine, 90% efficiency for an electric car, and 125 kBTU per gallon of gasoline, I get a mininum of 24 KW; or 32 HP just to roll down the road.

But here is what is actually being done...

http://www.metricmind.com/ac_honda/main2.htm

That approximately 30 kW is about what is used on average for acceleration and rolling down the road. The inverter used limits the maximum power to 80kW for brief periods of acceleration but you can just about estimate that roughly 10 to 15 kW is used to maintain speed at 100 km/hr. The http://www.metricmind.com/line_art/us06_us.gif"

 

[chemisttree]

Yes, and http://www.teslamotors.com/performance/perf_specs.php"



Click http://www.teslamotors.com/design/under_the_skin.php" here for a picture.

That's a little more than a small 100 hp comparison there... 0 to 60 in under 4 seconds! Yeah! Sign me up as well!

 

[mheslep]

The inverter used limits the maximum power to 80kW for brief periods of acceleration but you can just about estimate that roughly 10 to 15 kW is used to maintain speed at 100 km/hr.

Yes the power conversion electronics, not the motor, are probably the technically most challenging part of the electric drive train. They licensed the charging electronics integration into the inverter from http://www.acpropulsion.com/"

 

[Ivan Seeking]

I must say, this new technology is very exciting!

...But among the various challenges to developing the technology, manufacturing cost has been a potential deal breaker. Now, researchers at GE have demonstrated a manufacturing method that assembles layers of ceramic and electrolyte materials cheaply so that the final product can be built for about $800 a kilowatt, which starts to approach the $500-to-$550-per-kilowatt cost of building a conventional gas-fired power plant.

GE's six-kilowatt prototype achieves 49 percent efficiency in converting fuel into electricity, which compares favorably with the 35 percent efficiency of conventional coal-burning power plants. [continued]

http://www.technologyreview.com/Energy/17644/

That is a vast improvement!

I'm working on the hydrogen from algae problem as fast as I can! It may help that the folks at MIT are as well.

 

[Ivan Seeking]

Are you saying that you couldn't cut your grass with a self-propelled lawn mower that had a 1.34 HP motor? From my calculations, you need about half of that fuel cell's output to power an electric mower (24V at 12 amps).

Yes. My lawnmower is 5HP and barely has the power needed in spring. Of course I live in Oregon.

The price per kilowatt of the most employed fuel cell currently used is between $3,000 and $4,500 per kilowatt.

Source?

And... you cannot scale horsepower to electric power as you have done.

It is called conservation of energy.

Can you imagine a car running on a 100 HP electric motor?

That is part of the point.

That would truly be a funny sight! A 30 to 50 kW electric motor is perfectly acceptable to power a Honda-sized vehicle.

That has yet to be determined. It is a consumer driven market.

 

[Ivan Seeking]

Of course, if you are driving a biodiesel powered car, all of this goes away. You still get 100+ hp for the same price as a gasoline engine, and you pay about $3 a gallon for fuel. No infrastructure problem, no price problem, no power problem.

Later we can go to algae produce hydrogen - internal combustion. No need to drive go-carts.

 

[mheslep]

I must say, this new technology is very exciting!


http://www.technologyreview.com/Energy/17644/

That is a vast improvement!

Thanks for the link. I couldn't tell from the description of that So-Ox rack shown there how much of the volume and cost is allocated to reforming the hydrocarbon fuel down H2. I think the reforming bulk would have to go for a vehicle size unit.

I'm working on the hydrogen from algae problem as fast as I can! It may help that the folks at MIT are as well.

Best of luck. Please post up how its going from time to time.

 

[mheslep]

Best article I've found on the Tesla.

Newsweek, October '07
"http://www.newsweek.com/id/55405/page/1" "

Guess who's helping to hold up the electric car now? The government.

That "if and when" is proving problematic. This green machine was originally due to hit the road this month. But that tricky transmission and other mundane issues for major automakers—like crash-testing the cars—are taking longer than the neophyte auto moguls expected. It now looks like customers won't get their cars until early next year. "I had a friend cancel his order because he didn't want to wait," says Chris Paine, the director of "Who Killed the Electric Car?" who still has his deposit down

Insurance co.'s could test the car much more economically, or assess it as is and issue riders.

They go on to say that they plan to go from being a niche sports car to a mass market model, which I believe is foolish w/ a Li ion battery powered car. They'll never build a model that will go on long trips. Can't fill 'er up. Got to have fuel cells and hydrogen/hydrocarbon fuels to make the pure electric play work.

 

[russ_watters]

Fuel cell charges the batteries.

Why would you do that? The fuel cell is the battery.

 

[Argentum Vulpes]

They'll never build a model that will go on long trips. Can't fill 'er up. Got to have fuel cells and hydrogen/hydrocarbon fuels to make the pure electric play work.

With a range of 220 miles between charges I'd say the Tesla roadster has some decant lags on it. Granted in some parts of the country that is not enough to get to the next major city.

Or another approach is that of the Chevy Volt. It is setup like the big diesel trains running today. Electric motors provide the power for driving, a diesel motor spins a generator to provide electricity. The Volt's drive train is similar except the car has a battery pack to provide some gas free miles. When the battery pack runs down, an engine hooked up to a generator provides power to the electrical system to keep the car moving.

The next evolution step in battery systems is replacing the Li-ion pack or some other exotic and/or new battery pack with an ultra capacitor system. Basically it is just what it sounds like, a large bank of capacitors. When the charge runs down pull into a charging station, plug it in and bam you are ready to go again.

And before anyone says that this technology is a pipe dream with no possible future. http://www.colemanflashcellscrewdriver.com/" has introduced on the market a cordless screwdriver that runs off an ultra capacitor pack.

 

[mheslep]

Why would you do that? The fuel cell is the battery.

See above. Fuel cells, even Solid-Ox, are too expensive and too large at the 200HP scale to fit into a car, even an exotic car >$100k. However, a ~30HP cell is doable both economically and technically, and ~30 HP is all you need to maintain average road speed. Then, since 30HP doesn't give you much giddy up, add traditional batteries to raise the hybrid's peak power up to common car ICE peak power. The reason for this hybrid approach is the relatively low http://en.wikipedia.org/wiki/Energy_density" of battery technology vs hydrocarbon fuel. HC fuel gives you 10 to 143 Mj/Kg, where as the best batteries are ~1Mj/Kg, ie 100:1. Then for power output in KW per dollar, batteries out perform fuel cells by a similar multiple. Thus the hybrid fuel cell + battery approach.

With a range of 220 miles between charges I'd say the Tesla roadster has some decant legs on it. Granted in some parts of the country that is not enough to get to the next major city.

In the US 220 mi (and that's with new batteries) won't do it. No, that range is for commuters (and the tech is too expensive for that) or out and back trips. The problem is you can't 'fill er up' anywhere with stopping ~over night. See above. A 20 L tank of gasoline is 680mega joules. Recharging that amount of equivalent electrical energy in 5 mins as is common now with gas would require a 680Mj/300s = 2.2MW electrical charge capability per pump. Thus a regular filling station would have to be a 20MW generating plant. Not going to happen.

Or another approach is that of the Chevy Volt. It is setup like the big diesel trains running today. Electric motors provide the power for driving, a diesel motor spins a generator to provide electricity. The Volt's drive train is similar except the car has a battery pack to provide some gas free miles. When the battery pack runs down, an engine hooked up to a generator provides power to the electrical system to keep the car moving.

Yes agree hybrid is the right approach, just not ICE + battery hybrid as you're still wed to oil.

The next evolution step in battery systems is replacing the Li-ion pack or some other exotic and/or new battery pack with an ultra capacitor system. Basically it is just what it sounds like, a large bank of capacitors.

Except the tech. doesn't exist, at least not in any 'evolutionary' better than present tech form.

When the charge runs down pull into a charging station, plug it in and bam you are ready to go again.

No, as per above that will never happen, at least not with a 'bam'. Maybe with a 'zzzzzzzz'.

And before anyone says that this technology is a pipe dream with no possible future. http://www.colemanflashcellscrewdriver.com/". Can't get there from here. Most promising battery tech appears to be Li ion w/ nanowires - 6Mj/Kg

 

[chemisttree]

Without the battery, can a fuel cell react to throttle inputs quickly and with low energy waste? I don't think so.

 

[mheslep]

Without the battery, can a fuel cell react to throttle inputs quickly and with low energy waste? I don't think so.

Good question. The fuel cell related latency would be in the hydrogen transport time across the membrane, i.e. the answer would come from some kind of diffusion analysis. The search for designs w/ higher power per volume and weight often concentrates on improving the power vs diffusion rate; I'm guessing that has the side effect of also reducing the transport time. Also, because I don't see mass H2 distribution occurring, we must also consider lag in the onboard HC reformulation. To stop that from adding to throttle to power lag we'd want more hydrogen storage, etc = more $.

Yes forget fuel cell only. Got to have those batteries.

 

[chroot]

You do not ever want to use a fuel cell to directly power a vehicle. It'd have to be enormous, and thus less efficient when not run at nominal power. The reason hybrids are so efficient is that they always run the ICE at its most efficient operating point -- the same must be done with a hydrogen fuel cell.

Another major problem with using a fuel cell for direct drive is not the fuel cell's membrane -- it's all the air compressors and fuel delivery mechanisms that would need to spool up in order to deliver more power. If you stomp on the pedal and get power three seconds later, it'll never attract a single buyer.

You can avoid batteries with other kinds of energy storage. Flywheels and compressed air are two kinds of non-electrical storage technologies that could be mated to a fuel cell to provide an energy buffer.

- Warren

 

[mheslep]

...Another major problem with using a fuel cell for direct drive is not the fuel cell's membrane -- it's all the air compressors and fuel delivery mechanisms that would need to spool up in order to deliver more power. If you stomp on the pedal and get power three seconds later, it'll never attract a single buyer.

Fast fuel delivery is an issue dealt with now in ICE cars. The fuel system design requires attention but tenths of second are common there (to deliver the fuel, spinning up the ICE moments is another issue). In any case, agreed, the hybrid fuel cell + low cost electrical energy buffer obviates all those problems.

You can avoid batteries with other kinds of energy storage. Flywheels and compressed air are two kinds of non-electrical storage technologies that could be mated to a fuel cell to provide an energy buffer.- Warren

Have the old problems ever been worked out of flywheels? There were the bus experiments that never went very far. Some of initial promise was that the exorbitant weight problems (3T bus required a 3T flywheel) would be solved by high rpms w/ high tensile strength disks but those could never be made safe enough without a high strength enclosure and we're back to exorbitant weight again. Then there was the effect of angular mo. on handling. I'd heard of the compressed air car in India but know nothing about it. The keys for a transient high power source to well complement a f. cell are good KW/Kg and KW/$ ratios

 

[mheslep]

The next evolution step in battery systems is replacing the Li-ion pack or some other exotic and/or new battery pack with an ultra capacitor system. Basically it is just what it sounds like, a large bank of capacitors. When the charge runs down pull into a charging station, plug it in and bam you are ready to go again.

And before anyone says that this technology is a pipe dream with no possible future. http://www.colemanflashcellscrewdriver.com/", we get 25MJoules and you could keep your foot to the floor for ~3mins. The commonly available ultracaps from Maxwell Tech are rated at 0.01 Mjoules/Kg - if that's all that can be done economically ultracaps are out.

The ultracap's has some other advantages over batteries: short charge time (batteries 10:1 charge:discharge), temperature insensitive.

 

[RonL]

Looking thru the thread, i see a lot of good comments, and a few links that provide a lot of information for study.
One point of view that i don't see, is that of how we use our vechicles. An average of around 30 miles per day, and around 2 or 3 hours of actual use, the rest of the time they are parked and motionless.
I believe batteries (lead acid) can be designed to be serviceable, and less expensive.
Out of 24 hours, if only 2 or 3 are being used for travel, then a small, well engineered diesel engine, of small horsepower, can drive a generator at a steady speed recharging and maintaining the battery state of charge. It would run continually (24 hours a day) with charge rate being controlled as is common practice today. My thoughts are that it would be much like the refrigerator in a home, cycles would be longer and speeds would be governed by charge demand. For auto's that are not used every day the engine might even be shut down completely.
A separate auto might be needed for more extensive use, but for a serious reduction in energy demands, the mindset of the majority needs to reshaped.

 

[mheslep]

Turns out fuel cell + ultra cap is already in use at the vehicle scale:
http://electronicdesign.com/files/29/17465/Figure_05.jpg", General Hydrogen
Edit: appears they designed a 3:1 ultracap:fuel cell peak power ratio, so our 125KW:30KW ratio may be a little optimistic.

Edit: Elecrtonic Design http://electronicdesign.com/Articles/Index.cfm?ArticleID=17465&pg=2" detailing numerous ultracap uses. One factor driving use is that they don't need service as batteries do. Ultracaps withstand millions of charge cycles.

 

[mheslep]

Out of 24 hours, if only 2 or 3 are being used for travel, then a small, well engineered diesel engine, of small horsepower, can drive a generator at a steady speed recharging and maintaining the battery state of charge. It would run continually (24 hours a day) with charge rate being controlled as is common practice today. My thoughts are that it would be much like the refrigerator in a home, cycles would be longer and speeds would be governed by charge demand. For auto's that are not used every day the engine might even be shut down completely.
A separate auto might be needed for more extensive use, but for a serious reduction in energy demands, the mindset of the majority needs to reshaped.

The round trip commute you suggest is all you'd be able to do. You couldn't go on any long trips without stopping every three hours to recharge for five, at least w/ batteries. Ultracaps may help that. Anyway, the thread topic is fuel cells, ostensibly because a) everyone likes the fact that they move all the HC pollution back to a central power plant and b) they're more efficient than any heat cycle engine.

 

[RonL]

Anyway, the thread topic is fuel cells, ostensibly because a) everyone likes the fact that they move all the HC pollution back to a central power plant and b) they're more efficient than any heat cycle engine.

Sorry if i went off-thread with the diesel engine, but the point of my post is how we use the vehicle. A much smaller fuel cell than we need for full power, can be used in the same manor as the ICE mentioned.
The mindset of how we use transportation for local work related travel, needs to change, i know there are reasons that this would not work for everyone, but if the majority in the work force are doing the same things, then this type of adjustment would make a very large reduction in both, fuel, and pollution.

 

[mheslep]

SOFC Text

Just noticed this text by Singhal and Kendal
https://www.amazon.com/dp/1856173879/?tag=pfamazon01-20
but the list price, $245, ouch. Anyone care to suggest another reference?

 

[mheslep]

Looking thru the thread, i see a lot of good comments, and a few links that provide a lot of information for study.
One point of view that i don't see, is that of how we use our vechicles. ...

Chemistree posted this graph up thread on driving http://www.metricmind.com/line_art/us06_us.gif" .

 

[shotgun]

the one thing that may save fuel cells (for hybrid power systems of course) is that they can really last a lot longer than batteries. In this way the batteries can focus chemistry more on high rate and power and less on energy density. I think that when you try to get a lot of power out of a high energy density battery, it's never good. So if the fuel cell can provide the bulk of the energy, and the batteries the power then I think the life of the power system will be improved. At some point, the aux. fuel cell cost can be justified even if it doesn't meet the DOE targets.

 

[mheslep]

US DOE has an extensive, in depth, resource on http://www1.eere.energy.gov/vehiclesandfuels/" .

Each report multi MB pdf.

http://www1.eere.energy.gov/vehiclesandfuels/pdfs/program/2007_avtae_report.pdf"

http://www1.eere.energy.gov/vehiclesandfuels/pdfs/program/2007_hvso_report.pdf"

http://www1.eere.energy.gov/vehiclesandfuels/pdfs/program/2007_apeem_report.pdf" 9MB

http://www1.eere.energy.gov/vehiclesandfuels/pdfs/program/2007_energy_storage.pdf" - everything A-Z on batteries. Ultracap section.

http://www.eere.energy.gov/vehiclesandfuels/pdfs/program/2005_ace_merit_review.pdf" - mainly just improved efficiency of traditional ICE but also includes hydrogen based ICE

 

[taylaron]

organic fuel cells -fixing the nano-scale problem

Hey, I know this is a bit of a stretch from the traditional way of thinking about fuel cells (and I am certainly no expert) but what is the likelihood of genetically designing a fuel cell? couldn't you use stem cell technology to start the growth of a fuel cell that uses its cells as the building blocks of a incredibly intricate cell. wouldn't that increase the efficiency of fuel cells because we currently don't have a reliable way of making a fuel cell of the complexity and practical size (thus cost) that consumers require. (to my understanding)
I don't know where we are in the bio-engineering stage right now but I certainly think it should be further looked into. heck, we've had some success in growing human organs from stem cells.

this is more of a question than a statement. my entire understanding of this technology could be far off.


see: Growing New Organs http://www.popularmechanics.com/science/research/4212851.html"


thanks,
Taylaron

 

[mheslep]

Taylaron: do a little introductory reading on fuel cells, as what you are suggesting is not relevant to the current technology. The limitations are not from complexity or size (see up thread, some very large fuel cells have been built). One limitation of PEM fuel cells is the cost of the catalyst material required, platinum.

 

[thatotherguy]

Maybe y'all can help out automakers in figuring out a way to make them fuel cells practical for automotive application. I understand that the BMW 7 is already a "production" car which means that it is ready for the road but not yet available in the market because of course of its price. By the way, would using a fuel cell displace the use of some http://www.autopartsdeal.com/"?

 

[mheslep]

By the way, would using a fuel cell displace the use of some http://www.autopartsdeal.com/"?

Absolutely. Take a look at this "[URL car
[/URL]. Its a pure electric battery play, no fuel cell, but you can get the idea by imagining a fuel cell in place of some of the battery load. The transmission and its losses are gone, as is all of those pumps usually seen running off belts on a normal combustion system: alternator, the whole combustion engine oil lubrication system is gone, etc, etc.

 

[thatotherguy]

cool. that means the auto industry has to cope up with that change too right? hopefully, not too many employees working on factories manufacturing these displaced parts would be, well, displaced.

 

[mheslep]

The Tesla recently, finally, went into production. Leno did a piece on it.
http://www.jaylenosgarage.com/video/video_player.shtml?vid=229378\

So did Motortrend
http://www.motortrend.com/roadtests/alternative/112_0803_2008_tesla_roadster

 

[bassplayer142]

Wouldn't it be smarter to just have plants where the hydrogen cells are turned into electricity. Then you charge your car. I don't see why there is a need for the car to be the source in the first place. All you need is a good battery.

 

[russ_watters]

That would be redundant, bassplayer. The hydrogen plant would be sitting next to a regular power plant.

The point of fuel cell cars is to use the fuel cell instead of a battery.

 

[bassplayer142]

I just don't see how it is more economical to use the fuel cell in a car instead of at some plant instead.

 

[chroot]

Conventional batteries weigh a ton, take time to recharge, have limited lifespans, and most pollute the environment with heavy metals.

Hydrogen fuel cells are a type of battery, since, just like any other battery, they convert chemical energy into electrical energy. Fuel cells just happen to be a much better kind of battery for automotive applications because they don't weigh much, can be recharged essentially "instantly," and do not use large quantities of toxic metals.

- Warren

 

[mheslep]

That would be redundant, bassplayer. The hydrogen plant would be sitting next to a regular power plant.

The point of fuel cell cars is to use the fuel cell instead of a battery.

As discussed up thread in https://www.physicsforums.com/showpost.php?p=1585492&postcount=23" and by chroot in #26 its advantageous to use both. Fuel cell to provide average power and traditional batteries or utracaps to provide peak power. Edit: The FC is far too expensive per kw to stand alone.

 

[mheslep]

Conventional batteries weigh a ton, take time to recharge, have limited lifespans, and most pollute the environment with heavy metals.

Hydrogen fuel cells are a type of battery, since, just like any other battery, they convert chemical energy into electrical energy. Fuel cells just happen to be a much better kind of battery for automotive applications because they don't weigh much, can be recharged essentially "instantly," and do not use large quantities of toxic metals.

- Warren

Perhaps you are referring to future performance for fuel cells? Of the metrics listed here, I believe only time-to-recharge (refuel) is an advantage of todays fuel cells over todays batteries. I'd also add range extension, if the fuel is methane or methanol, since an all electric vehicle can really only take round trips without a long stop over.

Weight:
A fair comparison to batteries/ultra caps must include storage tank which, because of the volume required for H2, is inevitably massive. Thus fuel cell kg + tank kg + plumbing kg + fuel kg, I doubt there's much of a weight advantage over Li ion cells. Replace H2 fuel with methane or methanol and then you must add the weight of the reformer. For comparison the http://www.teslamotors.com/performance/perf_specs.php" , ~3400lbs curb weight, 100kw fuel cell is 220lbs/ ~200mi, can't dig up the tank or plumbing weight. The FCX

Life Cycle:
- Time
Fuel cells are subject to stack poisoning from any practical H source. Imperfect water management and disposal over the temp. range of vehicles also reportedly harms FC life. Though the DOE goals are 40,000 hrs, practically I read ~3000 hrs is the current reality. LiIon, at least per the Tesla, is 100,000 mi/10 yrs or again perhaps 3000hrs.
- Disposal
Li Ion batteries are not classified as hazardous waste in the US and can go to the dump unlike lead acid. Dump disposal is not desirable, but then PEM fuel cells (ala the Honda) contain heavy metal catalysts and shouldn't be tossed down in the storm drain either.