Welcome to the Energy Blog

  • The Energy Blog is where all topics relating to The Energy Revolution are presented. Increasingly, expensive oil, coal and global warming are causing an energy revolution by requiring fossil fuels to be supplemented by alternative energy sources and by requiring changes in lifestyle. Please contact me with your comments and questions. Further Information about me can be found HERE.



After Gutenberg

Clean Break

The Oil Drum


Blog powered by Typepad

« DOE to Fund Development of 10% Scale Cellulosic Biorefineries Using New Processes | Main | Energy and Water from Beer Waste »

May 02, 2007



I've always wanted to like Zn-Air fuel cells, but the problem I see is that there's only a finite amount of Zn metal in the world. What would happen when demand for it exceeds supply? I realise that it doesn't get destroyed as part of the cycle and that the oxide can be converted back into pure Zn but as there's only so much Zn metal in the world, there will only ever be able to be so much power we can generate from it.

Not a problem if the world realises growth can't be infinite on a planet of fixed size.


I doubt a zinc shortage is going to be a problem...it's the fourth-biggest industrial mineral, and the 23rd most abundant element. About one third of annual consumption is recycled.


I could see these being used for UPS systems.

But not for transportation.

The refueling network just wouldn't work.


It could be useful in bolstering a grid using plugins.

However I doubt it would be cost effective to do that.

Greg woulf

I'd love this thing for my Dad's cabin. It's off the grid, and using solar for everything but the stove and fridge, and those are propane. If this wasn't too expensive, he could use it for those two appliances and save a lot of money and hassle.

I wonder how much it costs per hour of use for the smallest version.


It would be great for emergency range extension for a pure EV. It could get you to a recharge.

But "gas" stations with liquid electrolyte recycling and zinc pellet dispensers? And a device to recycle the electrolyte back into zinc pellets? This is a huge investment in infrastructure.

Batteries, like the firefly design, are effective and inexpensive enough right now to provide a 60 mile range for an EV. And a backup generator that runs on fuel available at present gas stations can extend the range to provide the same utility as current iCE vehicles with an overall fuel consumption of 10% of present levels on average.

This is much more practical given the fact that GHG reduction needs to take place immediately to head off climate disaster.

Now if one could get a rechargeable zinc air fuel cell as one company claims to have developed, that would be different. It makes the electrolyte with the dissolved zinc oxide back into zinc when recharging right in the fuel cell device.

The problem is inefficiency, size, complication, and weight though. simple rechargeable batteries like the firefly design with backup generation powered by readily available liquid fuel is better.

Scarce research and development funds would be better spent at this time replacing the iCE backup generator with solid oxide (multi) fuel cell/microturbine generation.

Could a zinc/air breakthrough that allows recharging come along though? Absolutely. Keep trying Power Air. This technology is still a good emergency backup.

John Murch

Most fuel cells never see the production phase, I hope they are able to release them at a affordable price. Fuel cells have been around for over 40 years, I just hope someone can finally release one that is cost effective and ideal for various situations (Camping, cars, etc).

Stephen Boulet

Some comparisons

Power Air Zinc Air Fuel Cells
200 wh/kg

VRB Power Systems Vanadium Redox Battery
For large systems this is 100-150 Watts/kg and for the small systems about 80 Watts/kg

I guess the main difference is that, for the VRB flow battery, the electrolyte is recharged in place, whereas for the Power Air ZAFC the electrolyte is changed out like fuel, and someone else recharges it.

Maybe the ZAFC is less suitable for industrial power management, like providing power regulation to a wind farm, although perhaps the technology could be adapted for that.


Carl Hage

For transportation applications, infrastructure investment wouldn't be trivial, but it seems like it would be miniscule in comparison to that required for hydrogen.

A bus with range of >100mi was demonstrated

with energy (~200Wh/kg) comparable to lithium cells. In this system, the whole batteries were swapped out.

With the PowerAir system, you only need to swap out cassettes with zinc pellets and the spent liquid tank.

Zinc has good Wh/kg comparable to gasoline, and the metal is dense (Wh/l) so doesn't have the storage and transport problem of Hydrogen.

There is no discussion on the PowerAir recovery system. Perhaps the electrolyzer and pellet former machine could fit at a gas station to regenerate
using night-rate electricity.


For you Al Gorebels koolaid drinkers :

Reality Czech

The article text leaves a misleading impression.  The Power-Air ZAFC is refuelled by removal of the spent electrolyte and zinc sludge, and replacement with fresh electrolyte and metallic zinc particles.


So where is engineerpoet with some commentary on this? He delved pretty deeply into zinc-air on his weblog a couple of years ago. And whatever happened to the solzinc concept? I have been waiting to hear more on that one.


technofossil wrote:
There is no discussion on the PowerAir recovery system. Perhaps the electrolyzer and pellet former machine could fit at a gas station to regenerate using night-rate electricity.

Or how about a device in the garage where spent electrolyte and zinc sludge go in one end, and renewed electrolyte and zinc pellets come out the other end (plugged into the wall outlet, of course)? This would make even more sense for those with multiple vehicles.

With some extra storage, electric power consumption could even be moved way off-peak to the wee hours of the morning on the weekend.


"Better than Hydrogen" doesn't say much considering how bad hydrogen is to begin with.

Anything that isn't compatible with existing infrastructure is just a fish out of water.


Where am I?  I've got to work sometime, you know.

I've been waiting for these units to be available as more than OEM demos.  I wrote PowerFuel about them, offering to buy one so I could use it for demos; they weren't selling.  A pity.

The zinc could be regenerated by either electrolytic reduction or smelting.  My previous analysis from Electric Fuel's data found that the electrolytic method gave an end-to-end efficiency of about 50%.  If a zinc-fuel station bought off-peak power at 4¢/kWh and charged a markup of 5¢ per delivered kWh, the price to the customer would be 13¢/kWh.  Cost for a 30 mile commute at 200 Wh/mile would be a whole 78¢.

You could regenerate metallic zinc anywhere you can get or make electricity.  This is a system which could be rolled out almost immediately.


Question there being,

If it's just another way to carry electricity, how is it ever going to be any better at carrying electricity for vehicles than a battery?

kit p

E-P wrote, “You could regenerate metallic zinc anywhere you can get or make electricity. This is a system which could be rolled out almost immediately.”

Clearinghouse for Inventories & Emissions Factors: http://www.epa.gov/ttn/chief/ap42/

“Electric retorting with its greater thermal efficiency than externally heated furnaces, is the only
pyrometallurgical technique utilized by the U. S. primary zinc industry, now and in the future.
Product sinter and, possibly, secondary zinc materials are charged with coke to an electric retort
furnace. The charge moves downward from a rotary feeder in the furnace top into a refractory-lined
vertical cylinder. Paired graphite electrodes protrude from the top and bottom of this cylinder,
producing a current flow. The coke serves to provide electrical resistance, producing heat and
generating the carbon monoxide required for the reduction process. Temperatures of 1400°C (2600°F) are attained, immediately vaporizing zinc oxides according to the following reaction:

ZnO + CO = Zn (vapor) + CO2”

Also there is a two page list of emissions, the least significant being

“Global Warming Gases.
Pollutants such as methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O) have been
found to contribute to overall global warming.”

This is not 'zero emission energy' a Power Air claims.


Metal-air fuel cells are very promising for emergency backup power, but (depending on the design) they are difficult or impossible to recharge. Some questions: Are they messy to clean and refill? If the metal (zinc) is regenerated, what is the round-trip efficiency?
Are the fuel cells cheap to make?


Except the zinc regeneration need not be pyrometallurgical; Electric Fuel does it by electrowinning, at roughly 80% efficiency.  The ZAFC is about 62% efficient for roughly 50% end to end.

True to form, kit p is lying (this time by omission).


The A123 technology eclipses this completely. 40 miles on a charge beats the rest. Mass production would solve our oil problems and renewable energy feeding the batteries would go a long way towards stopping global climate disaster.

Zinc/air infrastructure would be way too expensive. similar to hydrogen or other alternative fuel delivery infrastructure.

The A123 battery in an electric car with backup generator IS the answer. Agree with me now or agree with me later and pretend you new it all along. hehey. Either way you will eventually come around.


Way I see it, anything which requires new fueling infrastructure is pretty much dead on arrival.

And the only ones that survive that, that aren't electric are:
1. BioButanol
2. BioDiesel

And while algae gives them some potential,
No government is seriously doing Algae yet.
Without Algae, those are just porkbarrel.


A123?  Why not Altair, or Firefly?  And why can't ZAFC's be the backup generators?  If PHEV's are the way to add hours of storage to the electrical grid, ZAFC's have the potential to add days.

Unlike you, I'm not sure exactly what the future is going to look like.  All I know is that it is going to go electric in a very big way, and ZAFC can be electric from one end to the other.


True EP,
The trick being where people try to act like we should use it for mobile storage, rather than fixed infrastructure.

Now the real question here is how much better would this technology do as compared to flow batteries.

Kit P

E-P, I did not see in you link anywhere it said it was 'roughly 80%' efficient.

This is typical of the else where emission vehicle (EEV) omit all the sources of emissions and call anyone who brings them up a lier. I showed how the EPA is going to look at one step in the process.


The figures are derived from the SOLZINC press release and the associated diagram.

And I find it extremely ironic that you, of all people, would complain about others omitting sources.


Because A123 is proven in power tools, lighter, quickest charging, and now apparently racing into mass production. Could they falter now? Yes, but they look like the clear leader. independent testing would be nice too. Maybe NREL ought to step up?

Altairnano is going for pure electric, that might happen in the future. But until some quick recharging "gas" station infrastructure is built out, mass adoption remains problematic. Fleet vehicles only. And individual owners willing to accept the mileage limitations.

That was the problem with the EV-1, if GM had cut the battery pack in half and added a lightweight backup generator. The world would be different now. No need for oil war, GM would be gaining market share, renewable energy to feed these batteries would be on a fast track.

I like firefly, if it costs a quarter of what the A123 battetry does? I would see firefly pulling ahead at first, especially since overnight recharge is good enough for now. But as A123 comes down in cost with mass production? The car can be recharged at work, school, shopping centers in a few minutes. A short range charge is much quicker than a full 200 mile charge in an Altair vehicle. And available with lower wattage, standard plugin technology.

Whatever battery is used, if it beats the A123 performance and price, great! But this proves electric cars with backup generation can solve our oil energy problems.

Some chemical innovation is needed for zinc/air to become rechargeable in the vehicle. Doing it electrically and mechanically in the vehicle with today's technology is inefficient and impractical.

If a chemical catalyst and device could be invented that would easily produce zinc pellets out of dissolved zinc oxide inside the fuel cell with electric recharge? Great!!

But this continuing public/political debate at the expense of action has to stop. The voters need to send a clear message to the pols right now.

Convert government vehicle fleets to plugin using these batteries now and offer tax incentives to get others to do it. Build out renewable energy to charge the batteries in the government fleets and offer tax incentives for other to do that.

Tax dollars need to be used to get mass production and adoption of this real solution inexpensive enough for consumers to afford. 4 dollar gas will kill the few remaining good jobs left. This constitues an oil monopoly economic attack on our standard of living.

Do it now, run for office on that platform. No more lying and bribe taking from ethanol and other scammers. Which side of the gas pump are they on? The consumer's side where we are? Or the side of oil monopolists?

We need leadership that is on our side of the gas pump. That realize what 4, 5, 6 dollar gas (and climate disaster)does to US.

Kit P

Yes, E-P, it is ironic that your press release documents the technical paper I linked but neglected to discuss why it is butt ugly process. Again, I did not see in you link anywhere it said it was 'roughly 80%' efficient.


EP: True to form, kit p is lying (this time by omission).

And true to form, Engineer-Poet, a collaborator of the "peak oil" truther community, who are running headless now that oil output has actually increased by 6%, is engaging in ad hominem. For a person to lie, there must be an intent to deceive. Can you show how you arrived at the conclusion that there is intention to deceive?

If PWAC a pink slip company had a viable product, then they would be more than happy to give out demonstration kits, and invite the press to show off their new technology. The metal oxide FC technology I gather has been around for quite a while. So what is keeping these folks from receiving the kind of attention A123 is getting?


Funny, the EIA says that world production is down from its 2006 peak.  It's actually worse than that, because the "all liquids" figure includes low-energy materials like natural-gas liquids and things like ethanol which are produced using a lot of petroleum/natural gas and are thus counted twice.

The graph of petroleum+condensate production which shows that world production peaked about a year ago was posted on The Oil Drum not long ago.  Unfortunately, I didn't bookmark it and it's buried in one of a pile of very long discussion threads which take forever to load.  Trust me, it's there.

I know kit p is lying because nobody picks so many perfect half-truths by accident.  An amateur would be a lot less polished.

PWAC's system requires a lot more supporting infrastructure than a Li-ion charger.  There's a certain minimum system size before it's practical.  But once a city decides to run its entire bus fleet on electricity and goes with ZAFC because of the low capital cost, the infrastructure becomes available to others as well.  This is not unlike the nucleation of an ice crystal in supercooled water.


"If it's just another way to carry electricity, how is it ever going to be any better at carrying electricity for vehicles than a battery?"

It's a good question and one that made me think. Zn won't lose it's 'charge' ever. Once the energy has been used to produce the Zn, you have it indefinitely without any special treatment. No need for storage tanks, no risk of electric shock if mishandled. Not even petroleum will last if you leave it lying around for a long time.

Kit P

As all good engineers know there are many good solutions to any problem. However, the EPA is going to require you to document the emissions from your process. One way to document emissions is to use EPA references.

There are many reasons for any good engineer to think that processing heavy metals will result in a vary ugly environmental problem. History lesson: Batteries = bad, bad, and more bad.

So it is no accident that I went to CHIEF to see if EPA has already had a reference.

CHIEF = Clearinghouse for Inventories & Emissions Factors

Yes indeed, there was a reference and the process is ugly.

So E-P tells me he is using different process that is clean and efficient. Since I have taken lots of really hard chemistry classes, I am skeptical about how efficient the process is. Checking E-P's link I see how he has been misled by a very clever press release.

E-P then provides two more links. His links then documents the more efficient process which is the one I identified. This a very dangerous process. You will need a full time chemical process engineer, industrial safety engineer, security, and training staff. While I believe that this is an efficient process, I am still very skeptical of what E-P said:

“You could regenerate metallic zinc anywhere you can get or make electricity. This is a system which could be rolled out almost immediately.”

Clearly some posters do not know the difference between facts, assumptions, predictions, and opinions. Here E-P is making an assumption and presenting it as a fact, “I know kit p is lying because nobody picks so many perfect half-truths by accident.”

Reality Czech

Except zinc isn't a heavy metal, it's an essential nutrient.

You wouldn't mind quoting the CHIEF page and posting links, would you?  You know, since you say you're so much more clued-in than everyone else here you should have no trouble proving it.

Kit P

See my May 02, 2007 at 10:24 PM post for the link.


Engineer-Poet: I know kit p is lying because nobody picks so many perfect half-truths by accident. An amateur would be a lot less polished.

I see. So any person who reads an article and selectively quotes from it, is engaged in a maliscious campaign to spread lies and deceive readers. There is another name for this. It is called bias, being ideological, or being selective. Like as if everyone is perfectly unbiased and is required by law to give a balanced opinion. Besides, you have so far not provided the statistical case to backup your ad hominem.

To label a person on this forum as a liar is a huge personal judgement that you are guilty of. So what is next? You and your Peak-Oil post-colonial apocalyptic buddies are going to empower the thought cops to go and pick Kit P up because he is deliberately deceiving society and is a danger to society or what? How is this different from what the left-fascists did in the Soviet Union?

There is no way you can prove intent. You may be able to show motive, but that is an empirical issue with solid due process of law behind that. Only the thought cops can "prove" intention.

The article I read, fresh out of a consulting firm, link of which was on TOD about 2 weeks ago, stated to the best of my memory that CRUDE PETROLEUM output, not derivatives, has increased by 6%.

Again, there are major useful applications for a PWAC's battery. For example, the difference in price between intermittent peak-shaved power and peak-load on demand power can be as high as 15 cents a KWh or more. This would be a perfect application for ZAFC and it is not a mobile application either. So where are the power companies or independents clamoring to cash in on this opportunity?

The "nucleation" theory that some government entity (city busses) must invest in this technology before the rest see the light of day is not credible. The market does not work like that. This sounds more socialistic "all technologies are equal and should be equally supported by society" to me.

Kit P.

For what it is worth, the reason to post an short excerpt and a link is so others can can get the information without bias.

Reality Czech

Just one problem with your 10:25 link, Kit: the text you quote from it does not refer to the process EP was talking about.  Of the processes listed in it, electrolysis has the lowest emissions of all (see Table 12.7-1 on page 5) and it's not obvious how the electrolysis of zinc oxide and potassium zincate would have any emissions.

Even if there are, the stuff is safe enough to use as sunscreen.  I suppose that a NIMBY who gets the vapors about PABA-free sunscreen might object, but who else would?

Kit P.

Good job RC, you have opened the link and demonstrated reading skills. This will allow us to have a civil discuss.

Please go back and read carefully. E-P has discussed two processes for reducing ZnO. While he did specify he efficiency, he did not provide a reference.

It is the old trade off between efficiency and emissions. The less efficient electrolysis process has more emissions at the coal plant.


My goodness, if you just checked my blog you'd find exactly where all the efficiency stuff comes from.

For those who refuse to click throught the link, it references some work at the University of Zürich into solar-chemical reduction of zinc using carbon (presumably electric resistance heat from surplus wind power could substitute for the solar furnace).  The byproduct is carbon monoxide (not CO2) which contains a large amount of energy suitable for other purposes.  If the carbon is supplied from charcoal there is no coal plant involved, nor (fossil) coal of any kind.

Kit P.

I have wasted time over at E-P's blog (again) and do not recommend it for anyone who wants to learn about energy.

Going to E-P's blog is just a circular argument.

“It appears likely that a solar-mediated zinc reduction process using coal could power 3.5 times as many vehicle-miles as a conversion of coal to liquid fuel.”

Solar-mediated?? My BS alarm just went off. That way not circular that is convoluted.

Starting over with my original question about claims of 80% efficiency. If you are going to use something as a storage for electricity, how much electricity do you put in and how much do you get out? When a press release does not address the basic information, my BS alarm goes off.

Does E-P answer my question, no he toggles back and forth. Rather than answer my question he switches to a different process. Well of course, to get the required efficiency for a zinc battery to practical, we have to use a high temperature chemical process exactly like the one I linked. Here is what E-P calls impressive:

“The researchers claim 30% conversion efficiency in the pilot plant, with full-scale plants expected to hit 50%-60%.”

I call it DOA.

E-P then creates a fantastic Rube Goldberg machine that combines concentrating solar, high temperature chemical process, biomass processing, with a CCGT to achieve:

“You could regenerate metallic zinc anywhere you can get or make electricity. This is a system which could be rolled out almost immediately.”


EP: surplus wind power could be used to reduce ZnO - except that wind currently supplies about 2% of N.A. energy needs. There is no such thing as surplus wind power yet. And the wind industry is being subsidized by about 4 cents a KWh (or about 30% of the cost of electricity), where I am in Canada. Wind is not yet cost effective, as compared to coal, nuclear, or even hydro. If you could produce wind energy so easily, then you are better off retiring coal and gas plants than to reduce zinc oxide, if your intention is to reduce the environmental impact at any cost.

EP: if the carbon is supplied from charcoal, it will be carbon-neutral - heh, if you could get charcoal so easily, then you could replace the coal and gas firing plants. Fact is that biomass combustion to produce power is not cost effective yet, and cannot compete with coal or gas.

Such argumentation that "this process is environmentally benign, because I can preceed it with another totally unrelated benign process, so now my process is even more benign" is a rational fallacy which is not empirically correct. You have to investigate each and every process in isolation, to arrive at its benefits independently. There usually are other applications for a (benign) process that would be more suitable than the pet project.

Without getting into the energy efficiency merits of ZAFC, which Kit P. is already doing a marvelous job of de-mystifying - let me ask Engineer-Poet if by any chance he has made a business analysis of ZAFC? What is the cost of capital for this process? What is the depreciation factor? What are the costs for environmental and social permitting? Or are we just speaking out of worthless idealism here?

Can you show me your economic analysis for ZAFC, and provide us the 40-year NPV with a 10% WACC? How about the sensitiviey to risk analysis? Without cost of capital, I guess the sky is the limit. How can you even recommend this process without an economic analysis? Or do you think society is obligated to subsidize this process because a bunch of planners, who do not have to put their own money where their mouth is, think this is the best thing since sliced bread?

Kit P.

Beek, you are too generous. Wind in the US supplies less than 0.5% of US electricity and becoming less important every year.

As Beek's economic analysis suggests, basing a high capital cost project on an intermittent energy supply will not pass the banker test.

One of the more interesting aspects of windpower is the need for new transmission lines to bring all the renewable energy to market. It is just a coincidence that they lines also pass near new coal plants.

Paul Dietz

Except zinc isn't a heavy metal, it's an essential nutrient.

A few years ago, the EPA put up for comment some proposed regulations for zinc release.

Someone pointed out that, according to the proposed regulations, zinc dietary supplements would be classified as hazardous waste. You could eat them, but it would be illegal to throw them in the trash.

The proposed regulations were withdrawn.

G. R. L. Cowan, boron combustion fan

It is true that no reference yet given has substantiated the claim of 80 percent electricity-to-zinc efficiency.

Zinc is a heavy metal. It is a mineral essential to animal life. These are not mutually exclusive.

Air-breathing zinc fuel cells are a technology with which few people have experience. Perhaps bizarre quantum entanglement effects can occur between zinc in a fuel cell that is being used as backup power for a roomful of computer equipment and zinc in the bodies of technicians. Could this result in the technicians' being found dead at the feet of the equipment racks, unmarked and with no apparent toxins in their blood?

This worry or a similar one may be why the company isn't selling them to just anyone just yet.

Paul Dietz

Metals used in primary batteries (with air as the oxidant) might be interesting for propelling electric ships. How about sodium? It can be melted and pumped at a not-too-high temperature. Sodium-air batteries (if they could be built) would produce sodium oxide or hydroxide, which could be released into the ocean as it is produced, helping the ocean absorb more CO2.

Making the sodium would involve electrolyzing molten salt, so you'd need a way to dispose of the chlorine. Maybe reaction with minerals containing reduced iron?


I am very ignorant about cells, batteries, fuel cells etc, so my question is probably very easy. Here it goes: If the anode is a bunch of pellets, how is the is the circuit closed and current collected? Thanks for all replies.


One problem that A123/Altairnano fans (which I used to be part of till recently) is that from a study published this spring the total known Hearth reserves of practically extractable Lithium would allow to build no more than 8m Volt-like vehicles before they fully dry off. Means a small fraction of the number of cars on the planet. So that can't be the long term way. Hence the interest of that Fuel Cell techno based on most available metals. No ?

Dr. T K Chongdar

Respected sir,

You are requested to Participate & Circulate the following information among the concerned and encourage them to participate:

International Symposium and Exhibition on
‘Fuel Cell Technologies: FUCETECH 2009’
at Mumbai (BOMBAY), India during 11-13, Nov. 2009

Please visit the website for details


Dr. T K Chongdar, Convener


Brilliant thoughts gets me boiling up!


Photo Bio reactor uses to produce bio diesel from algae. There are many research and development in using Photo bio reactor to produce bio diesel from algae. Phycotech’s mission is to provide its customers with leading edge photo bioreactor technology.

Tours of the Vatican

So excited about this one! I love that it can recycle the zinc that it uses. One step closer to sell sustaining energy/batteries.

Online Furniture Stores

I would love to see the zinc energy system replace those phone towers. What are the changes of it shorting out?

The comments to this entry are closed.

. .

Batteries/Hybrid Vehicles