Are Fuel Cells a Viable Alternative to Batteries Given Their Challenges?

[Oxygenne]

batteries or fuel cells?

hydrogen costs too much to be an effective fuel alternative?
the catalyst required for the electrochemical conversion reaction is pricey platinum?
Using hydrocarbons as a source for hydrogen we have more CO2 in the atmosphere?
and require a high temperature reactor under the car seats?

I just do not see if the fuel cells have a real future or ...

 

[Pythagorean]

batteries are most economic, currently. I'm looking forward to more R&D in all kinds of alternatives to fossil fuels though.

 

[Phrak]

What possible advantage is there in using hydrogen as an energy storage product, when it is derived from hydrocarbons? About none, I'd think. Even in the global-warming-carbon-footprint camps it shouldn't make too much sense.

It is used in places to replace the diesel fume spewing in mass transits, but what measure is this?

 

[Ivan Seeking]

What possible advantage is there in using hydrogen as an energy storage product, when it is derived from hydrocarbons?

Hydrogen is an energy storage medium that can be produced using excess energy. Energy storage has always been a problem for traditional and alternative energy technolgies. For example, Iceland has tremendous reserves of geothermal energy. They hope to use this to produce hydrogen, which could then be used or sold as a fuel. Likewise, it can be produced using wind, solar, hydro, nuclear, or any form of electrical power, and water or hydrocarbons. It may also be produced directly through biological processes. Right now there is a team at MIT working to produce hydrogen using algae.

Hydrogen is the ultimate clean fuel. Anyone who grew up in a city can appreciate the value of having nothing but water as exhaust fumes.

About none, I'd think. Even in the global-warming-carbon-footprint camps it shouldn't make too much sense.

Assuming that all practical aspects of hydrogen production and transportation are addressed, it makes exactly as much sense as the total of internal combustion emissions. You are effectively arguing that internal combustions play no significant role in CO2 emissions. But CO2 aside, it is the only completely clean fuel for combustion.

It is used in places to replace the diesel fume spewing in mass transits, but what measure is this?

See the cost of health care as a function of air pollution. It is huge! Things have improved some, but when I was a kid living in Los Angeles, it was found that other kids living in the most air-polluted areas of Los Angeles had the lungs of a pack-a-day smoker. Did you watch the olympics in China this summer? It was almost too dangerous to compete due to the levels of air pollution.

Hydrogen over fuel cells is the most efficient configuration for automotive applications if we have a source of hydrogen. But from where I sit, fuel cells are far too expensive to be practical for [standard] personal vehicles any time soon. I tend to favor hydrogen for internal combustion. While this is far less efficient than hydrogen/fuel cell/ electric, traditional internal combustion engines can easily be modified to burn hydrogen without any significant loss of performance. It could also play a role where electric motors are not an option, such as in heavy industry, aviation, and the shipping industry.

 

[Topher925]

My opinion may be somewhat biased as my research area is fuel cells, but I believe I is still well informed about both technologies.

hydrogen costs too much to be an effective fuel alternative?

False. Hydrogen's problem are in its method of storage, not the cost of the fuel itself.

the catalyst required for the electrochemical conversion reaction is pricey platinum?

Your average catalytic converter contains a lot more platinum that your fuel cell stack of equivalent power. Yes platinum is expensive, but compared to other chemicals such as lithium, the cost of it isn't an issue.

Using hydrocarbons as a source for hydrogen we have more CO2 in the atmosphere?

Not necessarily. One method of deriving H2 is by reforming hydrocarbons such as methanol. However, there are numerous ways to generate H2 with no CO2 generation in any part of the cycle. For example, solar thermolysis.

and require a high temperature reactor under the car seats?

Why would you have a reactor, let alone one under your seat? If a vehicle uses a liquid hydride it will have a reactor but it won't be located under the seat of the car. [/QUOTE]

I just do not see if the fuel cells have a real future or ...

PEM fuel cells are the slated to be the #1 technology to replace thermal engines and for good reason. Studies have shown the economics of fuel cell technology is cheaper than that of batteries, which is why all major auto manufacturers developing all fuel cell powered cars and not all electric cars. For example, the Honda FCX Clarity.

batteries are most economic, currently. I'm looking forward to more R&D in all kinds of alternatives to fossil fuels though.

Currently, yes. Although a hydrogen infrastructure does not currently exist so it can be difficult to compare.

What possible advantage is there in using hydrogen as an energy storage product, when it is derived from hydrocarbons? About none, I'd think. Even in the global-warming-carbon-footprint camps it shouldn't make too much sense.

There is some. Electrochemical engines are about twice as efficient as comparable thermomechanical engines and as a result can produce less CO2.

Fuel cells by their very nature offer features that batteries can not. The obvious one is no need for recharging, longer life span, and much less to none of an environmental impact when being disposed of. Other advantages are greater power to weight ratios and no self discharging.

 

[russ_watters]

What possible advantage is there in using hydrogen as an energy storage product, when it is derived from hydrocarbons? About none, I'd think. Even in the global-warming-carbon-footprint camps it shouldn't make too much sense.

It is used in places to replace the diesel fume spewing in mass transits, but what measure is this?

It would only be useful as a storage medium similar to batteries and derived from water. For that purpose, its main benefit is that is has a much higher energy density than a battery.

 

[Ivan Seeking]

False. Hydrogen's problem are in its method of storage, not the cost of the fuel itself.

What is the price of a Kg of hydrogen? Also, we don't have an energy competitive means of producing hydrogen. The well-to-wheels efficiency of a process is what ultimately matters.

 

[Ivan Seeking]

For general information:
http://www.hydrogenassociation.org/general/factSheets.asp
http://www.hydrogenassociation.org/general/index.asp

 

[russ_watters]

Hydrogen is an energy storage medium that can be produced using excess energy. Energy storage has always been a problem for traditional and alternative energy technolgies. For example, Iceland has tremendous reserves of geothermal energy. They hope to use this to produce hydrogen, which could then be used or sold as a fuel.

Iceland is a completely unique situation that provides no insight whatsoever into the issue anywhere else in the world. It is completely irrelvant here. In the rest of the world, there is no such thing as "excess energy" in the context you are using it. Ie:

Likewise, it can be produced using wind, solar, hydro, nuclear, or any form of electrical power, and water or hydrocarbons.

None of those are "excess energy" and will not be for the forseeable future. Not until they replace half of our current generating capacity.

It may also be produced directly through biological processes. Right now there is a team at MIT working to produce hydrogen using algae.

That's true, but it is a bit like fusion: it is 30 years away from being ready for commercialization and in 30 years, it probably still will be.

Hydrogen is the ultimate clean fuel.

Hydrogen is not a fuel, it is an energy storage medium.

Anyone who grew up in a city can appreciate the value of having nothing but water as exhaust fumes.

Since hydrogen isn't a fuel, that's just a misdirection hydrogen advocates throw around. In the world we live in today, hydrogen made by electrolysis exhausts carbon dioxide and lots of it.

Hydrogen over fuel cells is the most efficient configuration for automotive applications if we have a source of hydrogen.

Translation: if we ignore it's inefficiencies, hydrogen is efficient! That's just an absurd thing to say, Ivan. The reality of the issue is that hydrogen is not an efficient energy storage medium because producing it is a very inefficient process. Something like half the efficiency of batteries when used in a fuel cell.

But from where I sit, fuel cells are far too expensive to be practical for [standard] personal vehicles any time soon. I tend to favor hydrogen for internal combustion. While this is far less efficient than hydrogen/fuel cell/ electric, traditional internal combustion engines can easily be modified to burn hydrogen without any significant loss of performance.

That's a terrible idea. Starting with an energy storage medium that's half as efficient as batteries and ending with a usage that cuts the efficiency by an additional factor of 3. Now you have a car that operates at 1/6 the efficiency of a battery operated electric car. That's a big step backwards.

 

[russ_watters]

What possible advantage is there in using hydrogen as an energy storage product, when it is derived from hydrocarbons? About none, I'd think.

When derived from hydrocarbons, you can consider hydrogen a "fuel", not just an energy storage medium. The conversion is a refinement process not unlike how oil from an oil well is converted to gas in your car.

Traditionally, the refinement process simply releases the CO2 that burning the fuel for fuel would, so for now you are right - the pollution result is roughly the same. However, if carbon sequestering technology ever becomes a reality, then refining might be a viable option. I won't hold my breath for it any time in the near future, though.

 

[Phrak]

Fuel, a flywheel, a head of water, a battery are all energy storage mediums.

 

[russ_watters]

PEM fuel cells are the slated to be the #1 technology to replace thermal engines and for good reason. Studies have shown the economics of fuel cell technology is cheaper than that of batteries, which is why all major auto manufacturers developing all fuel cell powered cars and not electric cars. For example, the Honda FCX Clarity.

Currently, yes. Although a hydrogen infrastructure does not currently exist so it can be difficult to compare.

In light of the last sentence, I'd like to see some justification for the first. I'd like to see those studies. The last sentence implies to me that your statement is based on ignoring the cost of the infrastructure.

Also, the statement that electric cars are not being developed is just plain false. The worst that can be said about plug-in hybrids is that they are electric cars with an ICE backup. For people who would buy them, an extremely high fraction of their driving will be electric only, acting as a pure electric car.

Car companies are also, in fact, racing to develop production electric cars. Here's a statement of intent from VW: http://www.cleanedge.com/news/story.php?nID=5914
Mercedes says they will be on the road in 2011: http://www.usatoday.com/money/autos/environment/2008-03-23-mercedes-electric-car-battery_N.htm

Ford, too: http://blogs.cars.com/kickingtires/2009/01/ford-electric-car.html

Are any car companies actually planning on making production fuel cell cars, as opposed to technology demonstrators not ever meant to be sold? I don't think so. Here's what Ford says:

Ford researchers agree that much more work needs to be done before fuel cell vehicles can be commercialized. The biggest challenge according to Rob Riley, Ford fleet manager in California, is building a viable H2 infrastructure with fueling stations across the country.

http://www.autobloggreen.com/2008/08/19/ford-expands-fuel-cell-test-fleet-tests-by-two-years/
And that's even before you begin to address the commercial viability of the cars themselves:

Customer surveys suggest purchase consideration also will be dictated by affordability, reliability and useful life of the vehicle, as well as availability of fueling stations. In addition, parts availability and an adequate number of trained technicians will be essential to ensure convenient customer service of the vehicles.

 

[Ivan Seeking]

Fuel, a flywheel, a head of water, a battery are all energy storage mediums.

We do use uphill pumping for water energy storage, but that is only practical in some cases. It also tends to waste a lot of water through evaporation and seepage. Water shortages are an issue in many areas of the US other countries.

We can't make other fuels as easily as we can H2.

Batteries have always been impractical in terms of energy storage, but people are working hard to solve that problem. However, at this time we have no reason to believe that batteries will ever be practical for anything except [short distance] commuter vehicles.

Flywheel technology has been around a long time and enjoys a very limited market. In fact I investigated flywheel energy storage for a real application recently [for my job] and found it to be far too limited and too expensive to be useful. For one, the flywheel units cannot tolerate vibrations.

 

[Ivan Seeking]

Iceland is a completely unique situation that provides no insight whatsoever into the issue anywhere else in the world. It is completely irrelvant here. In the rest of the world, there is no such thing as "excess energy" in the context you are using it. Ie: None of those are "excess energy" and will not be for the forseeable future. Not until they replace half of our current generating capacity.

Iceland is unique. However, the point was that H2 can be used as a storage medium.

That's true, but it is a bit like fusion: it is 30 years away from being ready for commercialization and in 30 years, it probably still will be.

Did you get that from your psychic? How much time have you spend studying the subject; none?

Hydrogen is not a fuel, it is an energy storage medium.

When derived from hydrocarbons, you can consider hydrogen a "fuel", not just an energy storage medium

If is a fuel, but unless taken from existing HC, it is not a source of energy.

Since hydrogen isn't a fuel [it is a fuel] that's just a misdirection hydrogen advocates throw around. In the world we live in today, hydrogen made by electrolysis exhausts carbon dioxide and lots of it.

Hydrogen does not exhaust CO2. That is a blatently false statement and you know it. And obviously the point would be to produce the hydrogen using clean technologies. No one said it is a viable option today.

Translation: if we ignore it's inefficiencies, hydrogen is efficient! That's just an absurd thing to say, Ivan. The reality of the issue is that hydrogen is not an efficient energy storage medium because producing it is a very inefficient process.

Get a grip. I said that earlier myself. I limited my statement in this case to the assumption that we already have the hydrogen. Now try to pay attention.

Something like half the efficiency of batteries when used in a fuel cell. That's a terrible idea. Starting with an energy storage medium that's half as efficient as batteries and ending with a usage that cuts the efficiency by an additional factor of 3. Now you have a car that operates at 1/6 the efficiency of a battery operated electric car. That's a big step backwards.

If we consider lifetime efficiency of the car [and all required technology], it may make sense if we have a good source of hydrogen. What's more, electric is not always an option, such as for trucks. Also, the grid could not sustain a nation of electric vehicles and may not be able to for many decades to come.

 

[Topher925]

What is the price of a Kg of hydrogen?

I don't know what the bottom dollar price is but we pay about $1.95 per kg of H2 for our FC testing lab at school.

Hydrogen is not a fuel, it is an energy storage medium.

Incorrect. Hydrogen is a fuel, hence the name "Fuel Cell". Definition of a fuel: "an energy source for engines, power plants, or reactors". Hydrogen is as much a fuel as gasoline and diesel, the only difference is that we are breaking and recombining the chemical bonds and not nature.

That's true, but it is a bit like fusion: it is 30 years away from being ready for commercialization and in 30 years, it probably still will be.

How do you know? Are you a biochemist at MIT who does research in biofuels? Fusion is an entirely different ball game and is no where near as simple as breaking down organic matter with a H2 byproduct.

In light of the last sentence, I'd like to see some justification for the first.

I did have a good study done on this from an 08 fuel cell convention but I think its on my PC at school. In the mean time there are plenty of good articles on line such as this one: http://www.autobloggreen.com/2009/0...n-proponent-sandy-thomas-says-fuel-cells-bea/

Are any car companies actually planning on making production fuel cell cars, as opposed to technology demonstrators not ever meant to be sold? I don't think so. Here's what Ford says:

First of all, who cares what Ford says they haven't done anything in terms of fuel cell development. Second, what do you think the purpose of the FCX Clarity is? Honda isn't going to spend millions of dollars and lease out hundreds of FC cars for nothing. Both Honda, Toyota, and GM are performing major research in the area of PEM fuel cells as they are expecting it to be the future power plant of transportation.

Also, the statement that electric cars are not being developed is just plain false.

What major auto manufacturers are developing all electric vehicles that are planned to compete with gasoline powered vehicles and not a glorified gokart for city driving? The ICE in series hybrids are not a "back up" at all. They are there to actually power the vehicle past its very short 40 mile battery capacity.

Hydrogen does not exhaust CO2. That is a blatantly false statement and you know it.

Hell yeah it is. As a matter of fact methods of hydrogen production have greatly advanced in the past few years becoming more efficient, less expensive, and in most cases generate no pollution for the generation process itself.

 

[Phrak]

We do use uphill pumping for water energy storage, but that is only practical in some cases. It also tends to waste a lot of water through evaporation and seepage. Water shortages are an issue in many areas of the US other countries.

I surely must be speaking a foreign language if I can say one thing and it's heard as another.

 

[signerror]

What possible advantage is there in using hydrogen as an energy storage product, when it is derived from hydrocarbons?

It is presently derived from natural gas, and the demand (for hydrocarbon cracking) is low enough that this is viable. There is no technical reason why this is necessary - it can be made from splitting water, for instance. I strongly doubt that natural-gas derived hydrogen would be used for fuel on a large scale - that would be obviously inferior to powering cars directly from CNG, cutting out the transformations in the middle.

 

[signerror]

Not necessarily. One method of deriving H2 is by reforming hydrocarbons such as methanol.

Methane, you mean.

However, there are numerous ways to generate H2 with no CO2 generation in any part of the cycle. For example, solar thermolysis.

That's a bit restrictive. ANY energy source can be used to split water - every clean energy source, from hydropower to nuclear. And thermolysis is only particular method (a bit extreme, isn't it?); alternate approaches are electrolysis (redox reactions driven by an applied voltage) and thermochemistry (chemical transformations running off of an applied temperature difference - basically chemical heat engines). An example of the latter is

http://en.wikipedia.org/wiki/Sulfur-iodine_cycle

I think the temperatures involved (~800 °C) are much more manageable than direct thermolysis of steam.

 

[signerror]

What is the price of a Kg of hydrogen?

I don't think it is meaningful, because there is no hydrogen fuel economy, so current prices do not reflect what commercial fuel would cost.

Also, we don't have an energy competitive means of producing hydrogen. The well-to-wheels efficiency of a process is what ultimately matters.

I disagree; it's the total cost which matters. Given very cheap energy sources, a highly wasteful hydrogen economy (say liquid hydrogen combusted in a pure oxygen environment (very clean)) could be superior to, say, efficient EVs with extremely expensive batteries. This of course is assuming a hydrogen combustion engine, which would be very cheap, rather than a fuel cell stack.

But with expensive energy, the advantages would be reversed.

 

[Phrak]

Hydrogen is not an energy source. Hydrogen is a way to store energy that comes at a hefty premium. Dynamite is a way to store energy, and probably a bit safer. Where is the 'dynamite as fuel' advocacy thread?

 

[Phrak]

Hydrogen from electrolysis runs at a dismal 40% efficiency. Stored in liquid from it evaportes to keep the rest below boiling point. There is unrecoverable energy spent in compressing it.
How does this make more sense than powering a car with water?


With dwindling supplied of crude, the first consideration is the source of energy, not it's storage medium.

 

[Zdenka]

An advanced civilization would be laughing their heads off that our society is still running on the fats of dead beasts from long ago.

 

[Topher925]

Methane, you mean.

No, I meant methanol. http://en.wikipedia.org/wiki/Methanol_reformer

That's a bit restrictive. ANY energy source can be used to split water - every clean energy source, from hydropower to nuclear. And thermolysis is only particular method (a bit extreme, isn't it?);

Yes, thermolysis is a rather extreme example but it offers a great benefit that other methods of H2 generation can not. Thermolysis has the capability of directly creating H2 from sun light extremely efficiently. Although current thermolysis reactors only operate at ~2% efficiency the technology is promising.

Hydrogen is not an energy source. Hydrogen is a way to store energy that comes at a hefty premium.

Technically, neither is gasoline. What's your point? I wouldn't call the premium's "hefty". There are more ways of storing hydrogen then compressing it and freezing it to liquid form.

Hydrogen from electrolysis runs at a dismal 40% efficiency.

If it was 1975, you might be right. Most modern electrolysis setups are around 65%, some at 80%. And let's not forget about the recent work by MIT.
https://www.physicsforums.com/showthread.php?t=248265
http://www.qsinano.com/white_papers/2006_09_15.pdf

How does this make more sense than powering a car with water?

How do you power a car with water?

 

[Phrak]

No, I meant methanol. http://en.wikipedia.org/wiki/Methanol_reformer

If it was 1975, you might be right. Most modern electrolysis setups are around 65%, some at 80%. And let's not forget about the recent work by MIT.
https://www.physicsforums.com/showthread.php?t=248265
http://www.qsinano.com/white_papers/2006_09_15.pdf

How do you power a car with water?

The supplied links hardly make your point. Where does the electrical power come from. Are you going to burn Hydrogen to get it? There is something of the practicle missing.

 

[mheslep]

Hydrogen is not an energy source. Hydrogen is a way to store energy that comes at a hefty premium. Dynamite is a way to store energy, and probably a bit safer.

Hydrogen, like gasoline, requires safety measures but it is not an explosive boogey man.

https://www.physicsforums.com/showpost.php?p=1789430&postcount=97

 

[Phrak]

Hydrogen, like gasoline, requires safety measures but it is not an explosive boogey man.

https://www.physicsforums.com/showpost.php?p=1789430&postcount=97

ok... I doubt storing hydrogen in a big bag under atmospheric pressure in the trunk is a viable means in the use hydrogen as a transportation fuel. The alternatives are pressurization+cooling or pressurization+evaporation cooling or stored as a hydride. I don't recall gasoline requiring this added attention.

If hydrogen as transportation fuel is more than yet another empty promise, I'm sure the advocates are aware of the production and supply chain economics, the means of generation, storage, and distribution, the comparison of costs to gasoline, diesel, and electric vehicle power, and the BTU per dollar comparison. I'm all ears.

 

[Topher925]

The supplied links hardly make your point.

I'm sorry, but how does five different methods of electrolysis with production efficiencies greater than 40% not prove my point? Did you even read the links?

Where does the electrical power come from.

Any electrical source you want. Solar, wind, hydro, nuclear, take your pick.

Are you going to burn Hydrogen to get it?

Why would you burn hydrogen to generate hydrogen? You're not making any sense.

There is something of the practicle missing.

Your understanding of what electrolysis actually is?

I don't recall gasoline requiring this added attention.

I don't recall gasoline being pollution free and having the greatest energy density than any other chemical fuel.

If hydrogen as transportation fuel is more than yet another empty promise, I'm sure the advocates are aware of the production and supply chain economics, the means of generation, storage, and distribution, the comparison of costs to gasoline, diesel, and electric vehicle power, and the BTU per dollar comparison.

Are you aware of these things? The cost to fuel the Honda FCX (~70mpkg of H2) is about the same it takes to fuel my Honda Civic (~34mpg) assuming you buy your H2 in California ($5/kg) and with current gas prices in MI of $2 a gallon. If you want to compare numbers from 6 months ago when gas was $4+ a gallon, its pretty obvious that H2 is a hell of a lot cheaper.

H2 in most other states such as Illinois, it is actually much cheaper and can be found around $3.50 per kg. In Dearborn, MI near where I used to work, I believe you could buy a gallon of H2 for your FC car for around $3.70/kg.

http://www.hydrogencarsnow.com/blog2/index.php/hydrogen-distribution/illinois-opens-first-hydrogen-fueling-station-today/

And all of this is WITHOUT a hydrogen infrastructure!


Global Hydrogen Link Removed. I'll repost it later if I can confirm it is legit.

 

[mheslep]

You also have companies such as Global Hydrogen which can produce H2 for even cheaper than that, around $2.60/kg

http://www.newswiretoday.com/news/37455/

And all of this is WITHOUT a hydrogen infrastructure!

I'm skeptical that the GH price accounts for any infrastructure at all. That is, I suspect their price accounts only for the energy cost of making the H2, not the annualized capital cost of installing the electrical infrastructure (4-5MW), nor the water supply infrastructure (2000gal/day), not to mention the cost of the onsite H2 storage and electrolysis equipment itself, that a comparable vehicle H2 refueling station would require.

 

[Phrak]

I'm will await for the worldly responses that are more than empty promises based on a laboratory demonstration and the like. In the real world, dreams don't come true because it's way cool. You need to put in more than 10%.

Just for starters, 1) How do I store 12 gallons of liquid hydrogen in a vehicle? (Liquid hydrogen has about 1/2 the BTU content of gasoline.)

 

[signerror]

How do I store 12 gallons of liquid hydrogen in a vehicle?

Like this.

http://www.wired.com/news/images/full/hydrogenbmw2_f.jpg

One major challenge is how to keep the hydrogen cooled to minus 253 degrees Celsius (minus 423 degrees Fahrenheit) so it remains in liquid form without boiling off. Despite the double-walled, stainless-steel tank [a Dewar flask] that stores the liquid in high-vacuum conditions with aluminum reflective foil [which reflects infrared, to slow the rate of radiative heat transfer][/color], the liquid hydrogen in the 8-kilogram fuel tank begins to boil after 17 hours if the car remains parked. The tank empties completely after 10 to 12 days.

During the test drive, I pulled over to a Total hydrogen filling station to tank up.

The BMW Hydrogen 7 holds approximately 8 kilograms of liquid hydrogen. The car consumes about 15 miles per kilogram for a total cruising range of 120 miles, BMW says. In gas mode, the car's 74-liter (19.5-gallon) gasoline tank offers a range of about 300 miles.

http://www.wired.com/cars/energy/news/2006/11/72100?currentPage=all

 

[signerror]

http://img301.imageshack.us/img301/857/800pxwasserstoffeinfc3b.jpg

 

[mgb_phys]

Also from the same company as the BMW system.
Uses H2 fuel cells instead of batteries and regenerates H2/O2 at sea from diesels .

 

[mheslep]

Also see previous threads
https://www.physicsforums.com/showthread.php?t=276757&referrerid=70823"
https://www.physicsforums.com/showthread.php?t=204457&referrerid=70823"
and
http://www.rsc.org/images/NEWS-p14-395_tcm18-99997.jpg

 

[mheslep]

(Liquid hydrogen has about 1/2 the BTU content of gasoline.)

Yes and no. Liquid H2 has a 3x greater energy density by weight (143MJ/kg) than gasoline (47MJ/kg), but a 1/3 lower volumetric density (10 MJ/L vs 34MJ/L). Typically the addition of an impact resistant cryogenic tank eats away the weight advantage. Of course if a spacecraft is the goal, where a weight is mostly the only concern then one can't beat liquid H2 for a fuel / energy carrier / whatever.

 

[Phrak]

Take out the back seat, and install a tank good for a 120 mile range. That's 1% of a compromise dsolution.

That tank wouldn't fit in the 'skateboard' chassis so excitedly promoted on the Planet Green channel. Why is that? But, then again, they were talking about perpetual motion automobiles last Sunday.

 

[mgb_phys]

Take out the back seat, and install a tank good for a 120 mile range. That's 1% of a compromise dsolution.

They are covering their backs in case someone somewhere demands a mandatory % of ZEV in your lineup. BMW are feeling nervous as a maker of large high performance cars.

BMW are also partnering with Fiat to produce a range of small electric cars (BMW make the new 'mini' - which isn't very mini and Fiat make the new Fiat 500 which is a 1300)

 

[mheslep]

This H vs Batteries efficiency chart ought to be at the top of all threads like this, a sticky perhaps.

http://www.physorg.com/news85074285.html

 

[Topher925]

Take out the back seat, and install a tank good for a 120 mile range. That's 1% of a compromise dsolution.

You need to stop using asinine and completely obsolete facts to support your arguments. I don't think anyone believes BMW's concepts to go anywhere, not even them. As I already stated the Honda Clarity gets 280 miles for 4 kg of H2 and has a normally size back seat. As already mentioned H2 does require larger volumes of space but has about 3 times the energy density which is what really matters for most fuels.

This H vs Batteries efficiency chart ought to be at the top of all threads like this, a sticky perhaps.

Nice chart but we all know that batteries have a more efficient operation process than fuel cells. And where does the 80% for trasport/transfer come from? I'm calling shenanigans on that. That graph is also missing a discharge efficiency for the battery as well.

The advantages of fuel cells aren't that they are more efficient, its that they have the possibility to be more economic, environmentally friendly, and allow vehicles to be refueled and not recharged.

 

[mheslep]

...Nice chart but we all know that batteries have a more efficient operation process than fuel cells. And where does the 80% for trasport/transfer come from? I'm calling shenanigans on that

The answer is straightforward. How do you expect to get the H2 -compressed or liquified - to Topher's H2 refueling station? The answer is you will burn up, on average, 20% of the equivalent energy of the fuel payload in transportation energy. It requires on the order of a dozen tanker loads of H2 to bring the energy contained in one tanker load of gasoline. Details are in Bossel's paper as alluded to in the link.

That graph is also missing a discharge efficiency for the battery as well.

That's small and covered in the 90% EV block.

The advantages of fuel cells aren't that they are more efficient, its that they have the possibility to be more economic, environmentally friendly, and allow vehicles to be refueled and not recharged.

Efficiency largely equates to economics, especially when the topic is energy. Emissions is a wash with either fuel cell or batteries. Refueling vs charging time and vehicle range are the advantages of the fuel cell, and they're important, maybe critical. It is certainly not economics, even looking solely at the vehicle. If one assumes a centralized H2 infrastructure the economic comparison is no longer in the same ball park (distributed, i.e. localized H2 production might work).

 

[Topher925]

The answer is straightforward. How do you expect to get the H2 -compressed or liquified - to Topher's H2 refueling station? The answer is you will burn up, on average, 20% of the equivalent energy of the fuel payload in transportation energy. It requires on the order of a dozen tanker loads of H2 to bring the energy contained in one tanker load of gasoline. Details are in Bossel's paper as alluded to in the link.

Your answer is miss guided. Many hydrogen refueling stations manufacture H2 on sight or refilled by near by sources and produce it in accordance with demand. H2 isn't dug up out in Saudi Arabia and shipped over to refueling stations like gasoline. There is no reason why you couldn't have your FCV produce H2 at home either.
http://www.fuelcells.org/info/charts/h2fuelingstations.pdf

That's small and covered in the 90% EV block.

No it isn't. Discharge efficiencies are not small, that's why battery arrays in BEVs have such elaborate cooling systems. Cooling is actually one of the major road blocks for the development of the Chevy Volt and I believe is still a problem for the Tesla roadster (which keep in mind ended up being a failure). Bossol's statement about 80% cycle efficiency is true if you are operating a battery under ideal conditions. With the discharge rates that cars demand (even NiMH hybrids) I think you would be rather hard pressed to find a cycle that efficient. This isn't even including self discharging. I believe there were some very good rebuttals to that IEEE paper as well, I'll try to dig them up.

Efficiency largely equates to economics, especially when the topic is energy.

Is this why gasoline cars are so much cheaper than electric ones?

Emissions is a wash with either fuel cell or batteries.

Not necessarily. An electric cars battery needs to be replaced and recycled several times (with current tech) during the cars life cycle. As I am sure everyone knows, lithium chemistry based batteries aren't cheap to recycle and can do some serious damage if just disposed of in the environment. Electric cars may be 0 emission in the long run but it comes with a big price tag. The #1 ingredient for fuel cells however is plain old carbon, and contains no toxic chemicals.

It is certainly not economics, even looking solely at the vehicle. If one assumes a centralized H2 infrastructure the economic comparison is no longer in the same ball park (distributed, i.e. localized H2 production might work).

And how would you know this? I refer you to an article I previously posted up above. Even a highly educated guess about economics at this point is still almost fantasy.

 

[mheslep]

Your answer is miss guided. Many hydrogen refueling stations manufacture H2 on sight or refilled by near by sources and produce it in accordance with demand. H2 isn't dug up out in Saudi Arabia and shipped over to refueling stations like gasoline.

Actually, that's exactly how the vast majority of H2 is currently produced (95%) - by reforming natural gas. Electrolysis doesn't compete with reforming NG. Those stations are demos, they are not practical.
http://www1.eere.energy.gov/hydrogenandfuelcells/production/natural_gas.html

There is no reason why you couldn't have your FCV produce H2 at home either.

Practically a home setup would have to be quite elaborate: electrolysis gear, a heavy home power hookup (~40kw for 5kg H2 in 5 hours), 5kpsi compressor and on site storage for compressed H2.

http://www.fuelcells.org/info/charts/h2fuelingstations.pdf

12kg H2 storage? 10 cars per day and so on? A 'big' 20 car/d station is using an internal combustion engine generator to to make the electrolysis power. I've seen the list, they are all demos. Bossel shows a real, 1000 car/day station would need a 30MW electrical service and 110M^3 water per day.

No it isn't. Discharge efficiencies are not small, that's why battery arrays in BEVs have such elaborate cooling systems. Cooling is actually one of the major road blocks for the development of the Chevy Volt and I believe is still a problem for the Tesla roadster (which keep in mind ended up being a failure)

Yes the batteries generate heat, relative to the load, about 10%. That is not the primary reason for the cooling system. BEVs need cooling systems to extend cycle life by keeping the battery temperature as constant as possible despite fluctuations in environmental temperatures. The Tesla a high-end exotic toy, selling as a high-end exotic toy. Technically it performs largely as promised: ~200mi range, blazing speed off the line, hours to charge.

Is this why gasoline cars are so much cheaper than electric ones?

From an energy use stand point obviously the EV is cheaper than gasoline, even at today's price. Batteries aside, the EV overall is cheaper - no ICE, no transmission, no differential, no lube system, no gas tank, no large ICE radiator, etc, etc. But then this thread is about batteries vs FCs.

Not necessarily. An electric cars battery needs to be replaced and recycled several times (with current tech) during the cars life cycle.

Well current tech is Li-ion, so no; the Li batteries for the Volt should go 5000 cycles, 10 years, enabled by temperature stability and discharge limits.

As I am sure everyone knows, lithium chemistry based batteries aren't cheap to recycle and can do some serious damage if just disposed of in the environment

They're not cheap ($1k/kw-hr), so far. Lithium is not a heavy metal and is thus not a major environmental threat. The batteries need to be recycled just like the rest of the car.

Electric cars may be 0 emission in the long run but it comes with a big price tag. The #1 ingredient for fuel cells however is plain old carbon, and contains no toxic chemicals.

Last I looked the FCEV's being produced were costing Honda et al 6 to 7 figures a vehicle. FC's also have reliability problems (stack poisoning) over vehicle lifetimes and low temperature challenges (water exhaust -> ice).

And how would you know this? I refer you to an article I previously posted up above. Even a highly educated guess about economics at this point is still almost fantasy.

Hardly. DoE has done a lot of work on an H2 economy and found the problems extremely challenging. They've published studies costing out all the components - H2 production, storage, transportation, etc.
This link contains all of the DoE H2 2007 reports on the state of the art.
http://www.hydrogen.energy.gov/annual_progress07_storage.html#e

The Sanders slides in AutoGreen ... are based on an Ethanol infrastructure not Hydrogen per say, and certainly not H2 from electrolysis. So that's an entirely different conversation, viability of biofuels, etc. I tend to agree Ethanol->H2->FC is a plausible road ahead.

www.physorg.com/pdf85074285.pdf
http://spectrum.ieee.org/jan07/4848
http://www.batteryuniversity.com/parttwo-34.htm
http://www.rsc.org/chemistryworld/Issues/2007/October/HydrogenStorageTargetsOutOfReach.asp

 

[signerror]

I think it is likely that the disadvantages of battery EVs will completely negate their efficiency advantage. Chemical batteries just aren't a very good energy storage, as they exist now.

Particularly, take the example of a Tesla Roadster, the failed $100k sports car. I think it's the only fair comparison, because it's the only EV with storage capacity (244 miles) comparable to a petroleum car. You could argue that is unfair, that a 40-mile range EV like the Chevy Volt is perfectly 'suitable' for ascetics who don't drive - but that defeats the point of this discussion, which is to highlight its disadvantages, not gloss over them.

First, there's the low energy density, even compared to hydrogen. In the Tesla, the batteries take up the entire back seat and half the trunk:

http://img104.imageshack.us/img104/3696/80882634vb004tesla.jpg

And even with that, it only seats two, and it needs heavy use of carbon composites to get the full (ordinary) mileage.

Wikipedia has a graphical comparison of energy densities - even on a volumetric measurement, liquid H2 is a full 10x more energetic than Li batteries. And only about 40% less than methanol, which (IIRC) is used in car racing.

Then, look at the charging time: 3 1/2 hours maximum, and that's at 70A @ 240V - far beyond the capability of a residential circuit (20A @ 120V I think?)

http://en.wikipedia.org/wiki/Tesla_Roadster#Battery_system

Even with a dedicated, high-power charging station, it takes a full afternoon to refuel. Replacing the whole battery pack doesn't seem sensible either, as it weighs 992 lbs. (You might as well replace the entire car - e.g., zip cars.)

It's not physically impossible, but for practice it seems far inferior to hydrogen power.

 

[signerror]

This H vs Batteries efficiency chart ought to be at the top of all threads like this, a sticky perhaps.

http://www.physorg.com/news85074285.html

Why does it say 'renewable electricity'? Is nuclear power not suitable?

I think it is a flaw to start with electricity at the top - heat sources like nuclear power (fossil fuel combustion, solar thermal, geothermal...) do not directly produce electricity. With thermochemical hydrogen cycles, water is split using heat as the only input - which replaces two steps, the (i) electricity generation (which your chart omits) and (ii) the DC electrolysis. I think this is a glaring omission. The chart depicts the intermediate conversion electricity -> hydrogen -> electricity, which is motivated by pragmatic issues (storage density). But it hides the conversion heat -> electricity -> hydrogen, where electricity is an unnecessary intermediate - and this is case is completely unnecessary.

Here's a talk from General Atomics.

http://gcep.stanford.edu/pdfs/hydrogen_workshop/Schultz.pdf

They estimate 50% direct efficiency (at 900° C - high-temperature helium-cooled nuclear reactors, or solar thermal plants), which completely alters the chart you brought up. Take a high-temperature thermal power plant, with two paths: a 50% efficient Brayton cycle, and a 50% efficient sulfur-iodine hydrogen plant. Then the end-point of "electroylsis" on your graph would be identified with the start point of "AC via grid transmission" - both start at 50%.

 

[mheslep]

I don't know what the bottom dollar price is but we pay about $1.95 per kg of H2 for our FC testing lab at school.

Then that is a subsidized price. As of a couple years ago, a standard cylinder containing 0.6kg H2 out of the phone book costs you $100/kg PLUS the cylinder rental.
Mass production, H2 economy costs:
http://www.nap.edu/openbook.php?record_id=10922&page=51

 

[mheslep]

...
Wikipedia has a graphical comparison of energy densities - even on a volumetric measurement, liquid H2 is a full 10x more energetic than Li batteries. And only about 40% less than methanol, which (IIRC) is used in car racing.

...]

See the other efficiency chart. H2 gives away its advantage in liquification, transportation, storage, and finally the fuel cell is much less efficient than the battery discharge - motor combination.

Then, look at the charging time: 3 1/2 hours maximum, and that's at 70A @ 240V - far beyond the capability of a residential circuit (20A @ 120V I think?)

http://en.wikipedia.org/wiki/Tesla_Roadster#Battery_system

Even with a dedicated, high-power charging station, it takes a full afternoon to refuel. Replacing the whole battery pack doesn't seem sensible either, as it weighs 992 lbs. (You might as well replace the entire car - e.g., zip cars.)

It's not physically impossible, but for practice it seems far inferior to hydrogen power.

Yes, recharge time is and will likely remain a major limitation for pure EVs for some time, hence the move to PHEVs such as the Volt. That 40 mi range covers a large chunk of daily US driving, and the Volt is a 4-5 seat vehicle.

 

[signerror]

See the other efficiency chart. H2 gives away its advantage in liquification, transportation, storage, and finally the fuel cell is much less efficient than the battery discharge - motor combination/

Even with 50% fuel cell loss, it remains five times denser (energy/volume) than Li batteries. That is not trivial.

Yes, recharge time is and will likely remain a major limitation for pure EVs for some time, hence the move to PHEVs such as the Volt. That 40 mi range covers a large chunk of daily US driving, and the Volt is a 4-5 seat vehicle.

Which is just a huge, intrinsic advantage of chemical-fuel vehicles like hydrogen, methanol, ethanol - and fossil fuels, petroleum, natural gas.

 

[Phrak]

It's meaningless to compare energy density without including the containment flask, which too me appears at least 5 times the volume of the contained hydrogen for small quantities in the 10-20 gallon range.

How much does a fuel cell cost capable of putting out 100 HP? Not tomorrow's price. Today's.

How much space and energy overhead does the particulate and dehumidifier cost?

Leakage of cryogenic fluids such as hydrogen can cause the accumulation oxidizers to dangerous levels. How?

 

[signerror]

It's meaningless to compare energy density without including the containment flask, which too me appears at least 5 times the volume of the contained hydrogen for small quantities in the 10-20 gallon range.

That's absurd. The LH2 tank I showed earlier stores 8 kg LH2 = 30 gallons; and visually its seems much closer to 30 gallons volume than 150 gallons. (I think of fish tanks as visual references). 150 gallons would be 20 cubic feet, which is 4ft * 3ft * 1'8", which would be the whole trunk. Or slightly bigger: looking it up, BMW 7-series have 18 cubic foot trunks.

http://auto.howstuffworks.com/auto-parts/towing/towing-capacity/vehicle/cargo-carrying-capacity4.htm

(Deep apologies for these units, they are not my choice. In metric: 8 kg hydrogen = 113 liters, and five times that would be half a cubic meter.)

http://www.wired.com/news/images/full/hydrogenbmw2_f.jpg

Another source says the BMW Hydrogen 7 LH2 tank is about 1 inch thick (2.5cm).

http://www.cars.com/go/features/aut...7hydrogen&make=BMW&model=Hydrogen+7+Prototype

How much does a fuel cell cost capable of putting out 100 HP? Not tomorrow's price. Today's.

Like Ivan in this thread, I think hydrogen combustion engines make much more sense. These are far cheaper than fuel cells. The BMW has 256 HP on hydrogen.

http://en.wikipedia.org/wiki/BMW_Hydrogen_7#Specifications

Leakage of cryogenic fluids such as hydrogen can cause the accumulation oxidizers to dangerous levels. How?

I understand these cars have external vents. You are referring to liquefaction of atmospheric oxygen on a cold surface, right? There is no such cold surface, nor any pools of leaking liquid hydrogen, so this should not be an issue.

 

[Phrak]

I'll stop kicking the sod, and get to the main issue. What's the price of a fuel cell? Without a answer to this, the rest is window dressing.

 

[Phrak]

Hydrogen produced on site, in the US means that nominally, 40 percent is from burning coal, with a site delivery efficiency of about 36%. But coal is bountiful and cheap. It costs only 100 bucks a ton. It's the reason we can sit a a desk and argue about hydrogen and wring our hands over global warming.