# Fuel cells versus batteries

1. Feb 10, 2010

### gloo

From what i understand, the only thing that makes using fuel cells in cars versus lithium batties less desirable, is the cost of hydrogen.

If hydrogen can be produced extremely cheaply, assuming the same standards for compressing and transporting and storage of hydrogen, would it be better to invest in the fuel cell industry, or in the car battery industries.

The assumption that it is made really cheaply, abundantly and has NO CARBON EMISSIONS in the process.

2. Feb 10, 2010

### Staff: Mentor

No, it isn't just the cost of the hydrogen, it is also the cost of the fuel cell itself as well as the storage density of hydrogen. Hydrogen is made from water using electrolysis and that makes it a storage medium conceptually similar to batteries. Albeit a much less efficient one (that would be where the cost of the hydrogen comes in). Fuel cells are made using exotic metals and that makes them expensive. And since hydrogen isn't stored as a liquid, the storage density is much lower than gasoline.

3. Feb 10, 2010

### mgb_phys

And that a fuel cell is primary power source (fuel in -> power out) unlike a battery you can't (easily) refill the fuel cell when braking - so a fuel cell vehicle would probably need batteries as well.

Fuel cells are a bit more practical for bikes, they are much lighter than a battery and because you lose most of the power to wind drag on a bike there isn't as much scope for regenerative braking.

4. Feb 10, 2010

### gloo

so doesn't that mean the fuel cell industry is doomed in terms of it's use for cars?
I don't know what metals are in fuel cells, but lithium is only abundantly found in a few places on earth isn't it? I thought car batteries were really expensive as well and would pose problems when it needs to be replaced.

So the answer is that batteries are better economically even in light of cheap cheap hydrogen? What about just a pure hydrogen powered car then? I know the tank has to be bigger, but isn't that still a good tradeoff over the cost of replacing batteries and the future environmental problems of that?

5. Feb 10, 2010

### mgb_phys

Lithium is currently only mined commercially in a few places but it isn't that rare, as demand goes up new sources will be worth extracting.
Most current fuel cells use rather more exotic materials, Platinum, Silver, Palladium etc - these aren't going to get cheaper. There are fuel cell technologies that use cheap polymers being developed.

Current lithium-ion batteries are expensive, they will get cheaper as production ramps up but they will always be fairly large, heavy and expensive.

The main problem with hydrogen (other than you can't fit much in a tank) is where do you get the hydrogen? Main sources at the moment are either from natural gas - in a rather nasty process that involves carbon dioxide and high temperature/pressure. Or by splitting water which requires a huge amount of energy.

If you have nuclear reactors then making hydrogen from water migth be practical. Another source is countries with an abundance of cheap power, (solar/geothermal/wind) which might make H2 locally and ship it the customers.

Last edited: Feb 10, 2010
6. Feb 10, 2010

### gloo

Yes, i understand the ramifications of our current technology to extract hydrogen, that was why i tried to take that out of the equation by assuming that away. Russ, says that the elements to make fuel cells are really expensive so I buttled that with the cost of replacing a lithium battery and the environmental cost of dead battery storage. From what I understand, fuel cells don't have limited life spans that batteries do, so, with the assumed world of cheap cheap, easily made, carbon less production of hydrogen, is the fuel cell a clear winner over lithium batteries, or even yet, a pure hydrogen combustion car?

7. Feb 10, 2010

### Q_Goest

I think it is. If we look at the market today, we see batteries being replaced by fuel cells in the material handling market (ie: forklifts). Warehouse operations commonly employ dozens or even hundreds of battery operated fork lifts.
Ref: http://blog.wholefoodsmarket.com/2009/11/hydrogen-fuel-cell-powered-forklifts/ [Broken]

Recharging a 5000 psi hydrogen cylinder on the other hand, only takes a few minutes. There are a number of fuel cell companies now making drop in replacement systems for batteries used in fork lifts. These replacement systems consist of a fuel cell, a cylinder for the hydrogen, and of course controls. They also include weight because they're much lighter than the battery and the fork lift needs the weight to operate properly.

It's this material handling market which may eventually give birth to fuel cell vehicles as described here: http://www.nuvera.com/blog/?p=203
I would agree with all this. Note that hydrogen may be made primarily from natural gas today, but what about electricity? For the most part, it's made from coal and other fossil fuels too. Hydrogen is only an energy carrier, not a fuel source. There are many efforts today that are focused on how to make hydrogen in the 'greenest' way possible. The accusation that it is dirty doesn't make sense.

Last edited by a moderator: May 4, 2017
8. Feb 10, 2010

### cepheus

Fuel cells are more expensive than batteries, hydrogen is more expensive than electricity, hydrogen is more expensive to transport than electricity.

The only economic way of producing hydrogen is via steam reforming from natural gas so unless you sequester the CO2 it doesn't even reduce greenhouse gases. At least electricity can be sourced from nuclear and renewables for all their problems. So what's the point?

To me the hydrogen fuel cell has been a diversion, I am almost tempted to say a conspiracy to convince the public that an environmentally acceptable fossil fuel replacement solution exists.

This is the finest critique of Hydrogen

http://www.oilcrisis.com/hydrogen/crea.htm

If your interested in real world tests of fuel cells v Diesel read this

http://www.dpi.wa.gov.au/mediaFiles/alt_CUTEreport.pdf [Broken]

See Fig 4.12, greenhouse gases are about 3 times greater than diesel when using steam reforming using latest bus design! And these buses cost a milllion quid each!

Last edited by a moderator: May 4, 2017
9. Feb 17, 2010

### mheslep

Lithium batteries are not classified as hazzardous waste. They can go in the so called universal waste stream. They won't though, they'll be recycled.

Fuel cells do have limited life spans in relation to vehicle life. The membranes degrade over time. Google 'fuel cell stack poisoning'.

10. Feb 17, 2010

### mheslep

I'm not persuaded. These links refer to one-off pilot projects or blogs, not any major move in the material handling market. (The other similar area is airport ground equipment). Batteries http://www.youtube.com/watch?v=5b0T5NUHyxs" be switched in 2-3 minutes, even if this particular facility's equipment is slower. And 2000 lbs of lead acid can be replaced with 400 lbs of lithium ion these days. How many labor hours are required to handle the receiving and storage and removal of H2 bottles for such an operation? There are no H2 pipelines. What's the life cycle cost of those fuel cells?

Last edited by a moderator: May 4, 2017
11. Feb 17, 2010

### Topher925

No it isn't. Electrolysis is a very common process, and while more expensive than steam reforming, it is still very economical. It is also extremely likely that future nuclear power plants will abandon the rankin cycle and operate using thermochemical cycles which produce hydrogen directly. Future technologies such as photochemical and photovoltaic electrolysis are good candidates for hydrogen generation as well.

On another note, no way does a diesel powered bus produce less pollutants than one that is H2 powered. That article may state that, but I've read half a dozen more that state the opposite. I'll try and find some of them later.

Membrane degradation is really no longer an issue with FCs. There's a variety of flavors of Nafion that easily exceed DOE targets. Poisoning isn't a real big issue anymore either assuming the hydrogen is relatively pure. The only real poisons that need to be considered are sulfur based compounds commonly generated by diesel engines, i.e. H2S. Right now, the most dominant PEMFC degradation mechanism is the cathode catalyst layer which suffers from Pt particle agglomeration and dissolution.

I don't understand? Why would you ever remove a H2 tank from a vehicle unless its being serviced? It only takes a few minutes to fill a 4kg H2 tank from empty to full in a FC vehicle (I've witnessed it first hand).

Back to the OP question,
It's actually much more than this. The #1 advantage of using PEM fuel cells for vehicles is it allows for a completely closed chemical cycle. There is no other technology that can do that although some bio-diesel schemes aren't to far away from it. The other distinct advantage over batteries is that FCs are engines, not energy storage devices. Transportation requires an energy scheme which allows a vehicle to be able to travel from point A to point B with little to no downtime, aka charging a battery. You can however just swap a battery out and replace it with a charged one but then you create a logistics nightmare which would most likely come with severe cost penalties. Another aspect is that hydrogen is an incredibly versatile fuel. It can be made efficiently in a variety of ways and on any scale. Theres no reason you can't economically generate H2 from solar panels at home and still be able to fill up at fuel station if your taking a road trip.

So now for the real question, why aren't we driving FC vehicles today? In a nutshell its because of the scarcity of platinum which is the primary material used for the anode and cathode catalyst of PEMFCs. If Pt was cheap and plentiful, we would all be driving fuel cell powered cars today. About 75% of the cost of a FC stack (batch production) comes from the price of Pt, and its only getting more expensive. In order to solve this problem there is an enormous scientific effort to discover new catalyst materials in order to reduce costs and at the same time increase durability. A lot of scientists are looking at materials that are N or Fe based complexes to replace Pt, but so far most materials provide to low of an activity. But the prospects are looking pretty good and its very likely better catalyst materials will be discovered in the next few upcoming years. Toyota, Honda, GM, and I believe Nissan are all planning on releasing FCVs for commercial sale before 2015. Germany, Japan, and Iceland are already developing hydrogen infrastructures to support this new technology.

Last edited: Feb 17, 2010
12. Feb 18, 2010

### cepheus

At what cost?

I would like to see some evidence of this, do you mean economical for producing hydrogen? I recall seeing actual figures during the CUTE bus project I linked, which used local electroysis stations and the economics both in terms of energy and money was appalling!

13. Feb 18, 2010

### Q_Goest

Hi mheslep,
As Topher also mentions, the hydrogen cylinders are refueled not replaced. The refueling station looks a lot like a conventional gas station, with an interface display on the dispencer just like at a gas station, and a hose that connects to your vehicle. The dispencer purges the connection with helium automatically and pressurizes the cylinder in a few minutes. It even has safety features built in that detect leakage, fire, tow away, etc...

Regarding supply, stations are presently being supplied in a variety of ways depending on customer requirements. The most common means of supply are:
- Electrolysis
- Gasseous delivery
- Liquid delivery
- Portable refueling stations

Regarding cost, like anything - costs are dictated by technology, quantities and infrastructure. Right now, hydrogen is only manufactured in large quantities at a few locations around the US, so shipping costs are relatively high. It isn't unusual to see hydrogen being shipped over a thousand miles for a demonstration project. There's probably a few hundred miles of pipeline but they're mostly around the gulf coast and used by refineries.

Also, the technology for producing hydrogen from renewables hasn't gotten off the ground yet; but that doesn't mean it won't. Comparing the cost of hydrogen to fossil fuels right now means nothing. It's like comparing the cost of a transistor radio to the cost of a vacuum tube radio in 1961. Making those kinds of comparisons simply shows a misunderstanding and lack of foresight for the technology.

14. Feb 18, 2010

### cepheus

Well true, but there are just so many inefficiencies along the route to producing power, even before transport, storage then use in the fuel cell:

I recall assessing a proposal for a hydrogen powered fuel cell tram! why not just use the electricity directly?

15. Feb 18, 2010

### Staff: Mentor

Strange. That means 17 minutes per change. I have seen large batteries changed in much shorter time, thery were just rolled out, rolled in. 2 minutes max, including cigarette break.

I am not stating batteries are better than fuel cells, I just don't like numbers presented.

16. Feb 18, 2010

### Topher925

http://www.popularmechanics.com/science/research/4212844.html [Broken]

Right now you can buy H2 at 5kpsi for about $3.25 a kilogram depending on where you live. This is the typical cost when you get it by reforming a hydrocarbon on an industrial scale. The link I posted to above is an electrolyzer that GE developed which claims that they can make H2 for about$3 at pressure. I've personally never seen real numbers this low but I have seen H2 at 5kpsi for about $5 a kg generated by electrolysis. I concur, you can't make direct comparisons, but I would like to add that as far as the cost of fuel is concerned, it is cheaper to drive a fuel cell powered car 250 miles than a similar ICE powered car. For example (using local prices near me), Honda FCX Clarity - 250 miles - 60mpkg - 4.2 kg of H2 @$3.25/kg - Total Cost $13.65 Honda Civic - 250 miles - 35mpg - 7.14gllns of gas @$2.75/glln - Total Cost \$19.635

Last edited by a moderator: May 4, 2017
17. Feb 18, 2010

### cepheus

I suggest that power units should be standardised with respect to the fixture points, and module based (battery pack or hybrid). The position of the module is defined relative to the wheels and ramp so the module replacement can be largely automatic and shouldn't take longer than normal refuelling. Of course the advantage of a module is that you can effectively swap your battery for a IC engine generator for the occasions you travel long distances.

http://www.entrans.co.uk/entransmainreport2/index38.html

18. Feb 18, 2010

### mheslep

Agreed. I provided a 90sec switch film link above, 250kg, 25kWh battery

19. Feb 18, 2010

### mheslep

I wasn't referring to switching H2 in the fork lifts. The blog link was adding up man hours for everything in the process. I was referring to fact that the H2 has arrive at the warehouse somehow. In most of the cases today for a warehouse this will be done periodically via pressurized H2 bottles brought by truck: receiving, storing, and shipping out H2 bottles at the warehouse takes time and space. There's no such overhead with electricity - it comes in over the wire.

Last edited: Feb 18, 2010
20. Feb 18, 2010

### pantaz

Are there any figures available for comparing lifetime costs? I know many people with well over 100,000 miles on their Honda Civics and Accords, with quite reasonable maintenance costs. How long does a H2 fuel cell actually last? Are they recyclable?