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Cerebro

Cerebro (Spanish for "brain", from Latin cerebrum) is a fictional device appearing in American comic books published by Marvel Comics. The device is used by the X-Men (in particular, their leader, Professor Charles Xavier) to detect humans, specifically mutants. It was created by Professor X and Magneto, and was later enhanced by Dr. Hank McCoy.

Concept and creation
Cerebro first appeared in X-Men #7 (September 1964). Professor Jeffrey J. Kripal, in his 2011 book Mutants and Mystics: Science Fiction, Superhero Comics, and the Paranormal, calls Cerebro "a piece of psychotronics" and describes it as "a spiderlike, Kirby-esque system of machines and wires that transmitted extrasensory data into Professor Xavier's private desk in another room". Kripal notes that Cerebro made multiple subsequent central appearances, including Giant-Size X-Men #1 (1975), where Cerebro senses and locates a supermutant across the globe, resulting in the recreation of the X-Men team.

Use and function of the device
Cerebro amplifies the brainwaves of the user. In the case of telepaths, it enables the user to detect traces of others worldwide, also able to distinguish between humans and mutants. Depictions of its inherent strength have been inconsistent; at times in the storylines it could detect mutated aliens outside of the planet, when at others it could only scan for mutants' signatures in the United States. It is not clear whether it finds mutants by the power signature they send out when they use their powers or by the presence of the X-gene in their body; both methods have been used throughout the comics.

Using Cerebro can be extremely dangerous, and telepaths without well-trained, disciplined minds put themselves at great risk when attempting to use it. This is due to the psychic feedback that users experience when operating Cerebro. As the device greatly enhances natural psychic ability, users who are unprepared for the sheer enormity of this increased psychic input can be quickly and easily overwhelmed, resulting in insanity, coma, permanent brain damage or even death. The one exception has been Magneto, who has been said to have minor or latent telepathic abilities as well as experience amplifying his mental powers with mechanical devices of his own design.

The only characters to use Cerebro on a frequent basis are Professor X, Jean Grey, Emma Frost and the Stepford Cuckoos. However, Cable, Rachel Summers, Kitty Pryde, Danielle Moonstar, Psylocke and Ruth Aldine have also used it. After the device was upgraded to Cerebra, Cassandra Nova used it in order to exchange minds with Xavier. The Stepford Cuckoos once utilized the machine to amplify their combined ability, with only one of them directly connected to the machine, but all of them experiencing its interaction due to their psychic rapport.

Some mutants have learned to shield themselves from Cerebro, usually via their own telepathic ability. Magneto can shield himself from the device through use of minimal telepathic powers; in the film series, he does so with a specially constructed helmet.

It would soon become apparent as to just what and how Cerebro was really meant to be used; on top of tracking and locating mutants across the globe the tracking device's primary function was to act as a soul jar that could catalog the thought pattern self of any and every mutant ever pinpointed through it. X essentially utilized this function to resurrect the mutant strike team lost while battling Orchis by withholding their hard copied mind's, their anima, onto home grown clone bodies; which would effectively allow him to resurrect any and every mutant who has ever died or will die by imprinting a shell with their respective neuropsychic imprint.

History of the device
Originally, Cerebro was a device similar to a computer that was built into a desk in Xavier's office. This early version of Cerebro operated on punched cards, and did not require a user (telepathic or otherwise) to interface with it. A prototype version of Cerebro named Cyberno was used by Xavier to track down Cyclops in the "Origins of the X-Men" back-up story in X-Men #40. In the first published appearance of Cerebro, X-Men #7, Professor X left the X-Men on a secret mission (to find Lucifer) and left Cerebro to the new team leader, Cyclops, who used it to keep track of known evil mutants and to find new evil mutants. The device also warned the X-Men of the impending threat posed by the non-mutant Juggernaut prior to that character's first appearance. Later, the device was upgraded to the larger and more familiar telepathy-based technology with its interface helmet.

When the human-Sentinel gestalt Bastion stole Cerebro from the X-Mansion, Cerebro was hybridized with Bastion's programming via nanotechnology. The resulting entity, a self-aware form of Cerebro, created two minions, Cerebrites Alpha and Beta, through which it would act without exposing itself. It also used its Danger Room-derived records of the powers of the X-Men and the Brotherhood of Evil Mutants to create its own team of imposter "X-Men" whose members possessed the combined powers of specific members of each of the two teams. Cerebro's goal was to put human beings in stasis so that mutants could inherit the Earth, and to this end it hunted down a group of synthetic children called the Mannites who possessed vast psychic powers. It was destroyed by the X-Men, with the help of Professor X and the Mannite named Nina.

More recently, following the example set by the X-Men films, Cerebro has been replaced by Cerebra (referred to as Cerebro's big sister), a machine the size of a small room in the basement of Xavier's School For Higher Learning. Though designed to resemble the movie version of Cerebro, Cerebra is much smaller than the films' version. It resembles a pod filled with a sparkling fog that condenses into representations of mental images.

After it is discovered that Terrigen is toxic to mutants and Storm's X-Men move to Limbo, Forge programs Cerebra into the body of a Sentinel and uploads her with the capability to showcase human emotion. Cerebra accompanies the X-Men on many of their missions to help find mutants and bring them to X-Haven where they'll be safe from the Terrigen. Along with being able to detect mutants Cerebra can also fly and teleport, serving as a bridge between Earth and Limbo.

When the X-Men and Inhumans went to war to decide the fate of the remaining Terrigen cloud, Cerebra was destroyed after getting caught in the crossfire when Emma Frost unleashed an army of Sentinels programmed to kill Inhumans instead of mutants. While Storm's team of X-Men began returning refugees to their homes from X-Haven after Medusa destroyed the Terrigen cloud, Cerebra was found severely damaged in an abandoned barn surrounded by wild Sentinels. Once she was discovered and the X-Men saw that her current sentinel body was far beyond repair they uploaded her into a new body.

Later when a mutant nation was created on the Living Island Krakoa, Xavier reveals that when he approached Forge and asked him to expand the abilities of Cerebro, Forge was able to create a version of Cerebro that not only was capable of merely detecting mutant minds but also creating a copy of each mutants' mind. Forge was able to create this seventh version of the Cerebro as a portable unit able to be worn as a helmet by Xavier to focus his psionic talent at all times. Xavier first donned this Cerebro when he announced the existence of Krakoa to the world and invited all mutants to Krakoa. He then utilized its true functioning of stirring and transplanting persona & psyche while in conjunction with the technomorphically modified genus loci of Krakoa and the unified teamwork of the Five; a mutant conclave consisting of Joshua Foley, Hope Summers, Eva Bell, Kevin MacTaggert and Fabio Medina who gestate and accelerate the regrowth of fallen mutants by combining their powers. Xavier also had five working Cerebro Cradles: one main unit, three backup units, and one additional backup unit for unforeseen complications. These Cerebro Cradles are strategically located at multiple locations.

Not soon after, XENO mercenaries were able to infiltrate Krakoa's defenses and successfully assassinate Professor X, destroying Cerebro in the process. Before Professor X was resurrected, Magneto reshaped the broken shards of Cerebro into the Cerebro Sword to represent Xavier's dream, once broken, but now forged anew and refined. The sword retained the information stored in the other Cerebro Cradles, however, it is encrypted.

Later one of the backup Cerebro unit become sentient and rebranded itself under the name Cerebrax. Hunger for intelligence and power, the sentient machine begins killing mutants across the island and eventually takes control of Krakoa and begins unleashing a full-on attack. Answering the call to fight are Kid Omega, Omega Red, Wolverine, Domino and Phoebe Cuckoo. Kid Omega flies into Cerebrax and, with some help from Sage, unleashes a powerful explosion that ultimately destroys the Cerebro unit and himself. Given that Krakoa has the power to resurrect dead mutants, Wolverine tells Sage that they're going to have to do so for Kid Omega, however Sage reveals a problem, there's no trace of Kid Omega anywhere. He's wiped from all the Cerebro cradles.

Other versions
In Chris Claremont's X-Men: The End storyline, which takes place some 20 years ahead of standard X-Men continuity, Cerebro has been replaced in turn by the disembodied brain of Martha Johansson, a human psychic who was introduced during Grant Morrison's run on the X-Men.

In the video game X-Men Legends, Cerebro is identical to its appearance and usage in the X-Men film. Jean Grey and Emma Frost use the device at one point to attempt to return Professor X's mind to his body. In X-Men Legends II: Rise of Apocalypse, it was destroyed along with the rest of the mansion, but Forge mentioned plans on building Cerebra to replace it. He described Cerebra as Cerebro's big sister.

In the video game Marvel: Ultimate Alliance, while the team is staying in the Sanctum Sanctorum, Professor X used a device created by Beast allowing him to use Cerebro from long distance in order to find Nightcrawler, who had been kidnapped by Dr. Doom.

In the universe of Marvel Zombies, zombified versions of Beast and Mr. Fantastic reprogram Cerebro to help them and the other zombies track down the last remaining humans on Earth. Cerebro locates many in the European nation of Latveria, but all escape. In Marvel Zombies Return, the surviving zombies escape to another world where many of them restart the original infection, this time permanently fusing Professor X's partly zombiefied body with Cerebro so that he can find humans for them.

In the MC2 universe, the X-People carry "mini-cerebros", that can detect mutants just as well as the full-size version.

Generation X
In the 1996 Generation X telefilm on Fox, Cerebro was depicted as a desktop personal computer with a few custom peripherals.

X-Men
Professor Jeffrey J. Kripal, in his 2011 book Mutants and Mystics: Science Fiction, Superhero Comics, and the Paranormal, describes the Cerebro of the X-Men films as "a futuristic superroom into which Professor Xavier wheels over a bridge in order to don the helmet that would magnify his already extraordinary telepathic powers and project the results onto the skull-like internal walls of the room." In the films X-Men and X2: X-Men United, Cerebro is a device that fills a massive spherical room in the basement of Xavier's School. The helmet interface is similar to the version seen in the comics, although the bulk of Cerebro's machinery is contained in the surrounding walls. While in use, three-dimensional images of the humans whose minds are being scanned by the device appear around the interface bridge. Unlike the comics' version of Cerebro, the film version can detect both human and mutant minds with ease. The unique signature of mutant brainwaves is shown in the first film by the mental images of humans depicted in black and white, while those of mutants show up in red. When Xavier illustrates his connection with every human and mutant mind on Earth in the sequel, X2, mutants appear in red, and humans in white.

In the first film, Professor X mentions to Wolverine that Magneto helped him build it, and therefore knows how to construct helmets with circuitry to block its detection abilities. Cerebro is sabotaged by Mystique so that it injures Professor X, putting him into a coma. The only person seen using Cerebro effectively in the films is Xavier; Jean Grey successfully used the device to locate Magneto in the original film, but the input overwhelmed her nascent telepathic power and left her stunned. This has not been mentioned in the comics, although the Magneto of the comics can use Cerebro, and has designed similar devices.

X2: X-Men United
In X2: X-Men United, the device was copied and modified by William Stryker in his plot to have a brainwashed Xavier use his Cerebro-amplified powers to kill the world's mutants, although this plan was later 'hi-jacked' by Magneto—immune to the telepathic assault via his helmet—so that Xavier would be used to kill humans. According to X2, it is difficult to pinpoint the location of mutants who have the ability to teleport and are constantly in transit, such as Nightcrawler.

In both films, Magneto's helmet is capable of blocking the telepathic signals from Cerebro, as well as any telepathic mutants.

X-Men: First Class
In X-Men: First Class, an early version of Cerebro exists in an unnamed CIA science facility, built by the young Hank McCoy to amplify brainwaves. In a slight departure from the source material, its creation and design is attributed to Hank, instead of Charles Xavier. It is used by Xavier to find and recruit mutants for training in order to oppose Sebastian Shaw. It is later destroyed by Riptide as Shaw searches the facility for the young mutants.

In the film, Emma Frost comments on her perception of Xavier's increased telepathic range when using Cerebro, which she feels despite being some thousands of miles away.

X-Men: Days of Future Past
In X-Men: Days of Future Past, Cerebro appears in the future X-Jet as a built in extension to Xavier's hover-chair and is made up of three sensor-pads and a 3D holographic projector. In the past, it appears as it did in X-Men and X2, albeit dusty from long years of neglect due to the past Xavier's current inability to use his powers. As his abilities begin to return, the young Xavier initially attempts to use it to find Mystique after she escapes from their first confrontation, but has trouble concentrating enough to use it properly due to his current emotional turmoil. However, a conversation with his future self—using the time-displaced Wolverine as a 'bridge' to make contact with his other self in the future, who is close to Wolverine's currently-comatose body—helps him regain his old focus, allowing him to temporarily control others to speak to Raven before sending a psychic projection directly to her.

In the Rogue Cut version of the film, Cerebro is being used in the future as a prison for Rogue, who is being experimented on by the Sentinels' human agents in the hope of finding a way to duplicate her ability to take powers from others, with Cerebro being used as the room's interior is shielded from external telepathic probes. Also, in 1973, Mystique returns to the mansion to get treatment for her wound as a cover for her real agenda to smash Cerebro, preventing Xavier from finding her again.

X-Men: Apocalypse
Cerebro appears in X-Men: Apocalypse where Xavier uses Cerebro and sees Moira searching for Erik. Xavier tells Alex to destroy Cerebro after Apocalypse is able to use Xavier's search for him to take control of Xavier's powers through Cerebro, although Apocalypse still manages to use Xavier to make humanity sacrifice most of its nuclear weapons before Cerebro is lost.

Logan
In this alternate timeline of Logan, Cerebro has become a covering at Logan and Charles Xavier's home at an abandoned smelting mill in Mexico.

Deadpool 2
Cerebro appears when Deadpool 2 when a depressed Wade Wilson/Deadpool is trying to use the Cerebro at the X-Mansion to “look into the future.”

Dark Phoenix
Cerebro appears in Dark Phoenix When Xavier uses it to navigate Jean's mind and later to locate Jean, Magneto and Hank.

X-Men: The Animated Series
In the X-Men: The Animated Series Cerebro was heavily featured throughout the series' duration. It was primarily used by Professor Xavier and he was shown to use it in various ways, such as detecting mutants, increasing his powers, and even understanding Shi'ar technology, and so forth. There was no specified room where Cerebro was kept as in the other animated series but instead came out from the ceiling in most notably the War Room where the X-Men held their team meetings. Jean Grey was also noted to use Cerebro frequently and it would amplify her telepathic powers as it did for Professor X. Jean Grey in this animated series did not always join the X-Men on their field missions but rather monitored them telepathically using Cerebro's help. Even the White Queen of the Hellfire Club, Emma Frost, used Cerebro when she telepathically hacked into it to secretly "spy" on Xavier, the X-Men, and to learn more about Jean Grey and her transformation into the Phoenix. The X-Men's Blackbird jet was also equipped with its own Cerebro.

X-Men: Evolution
In the animated series X-Men: Evolution, Cerebro was featured numerous times. It was shown being used mainly by the Professor and eventually Jean Grey. In the beginning of the series Cerebro was a primitive version of what it would later become as the show progressed eventually taking an appearance identical to the Cerebro in the X-Men films. Cerebro originally appeared as a computer console with custom peripherals that came out of a hidden wall component in the mansion. Eventually, this Cerebro was destroyed by Professor X's evil step-brother the Juggernaut. When it was rebuilt the Cerebro was given its own room, instead of the hidden wall component as before, and looked identical to the designs of Cerebro in the films. Cerebro even came in a portable helmet form for travel and field missions. Jean Grey used this Cerebro to amplify her telepathic powers as she did in the comics and previous series. It even helped boost Jean's telepathic powers in order to battle a possessed Professor X in the series finale. During the fight, Cerebro was shown to unleash the Phoenix within Jean for a split second, eventually gaining the power to defeat the evil Xavier, and return him to normal. In the episode "Fun and Games", Arcade, a student version of one of the X-Men greatest villains, hacked into Cerebro and used it to control the mansion's security system to attack the X-Men believing the program to be a game. However, he made no use of its telepathy-enhancement technology, instead merely rewiring it to allow him access to the security systems.

Wolverine and the X-Men
In the 2008 series, Wolverine and the X-Men, Cerebro is extremely important to the overall series as it serves as a link to the past, present, and future. Originally Cerebro was damaged in an unexplained attack on Professor X in the present where he ends up in a coma only to awake twenty years into the future. In the future twenty years from now the X-Men have all been killed and the world is being controlled by the mutant-hunting robots named Sentinels. Xavier, with the surviving Cerebro components he finds, telepathically contacts the X-Men twenty years in the past (the present) and instructs them to stop those who would create the bleak future he awakes in twenty years later (his present). During the majority of the X-Men's present, as well as its first appearances in the future, it is similar to the version seen in the X-Men films, however, for the majority of the scenes in the future, Xavier uses a Portable version of Cerebro. With Warren Worthington's money and Forge's technical expertise, the X-Men were able to get the destroyed Cerebro at the mansion repaired. As Xavier is comatose in the present and Jean Grey missing, Emma Frost serves as the team's resident telepath and she primarily uses Cerebro.

Black Panther
In the 2010 series Black Panther, Storm uses Cerebro to locate Juggernaut in Wakanda.

Legion
An early version of Cerebro is seen in Legion used by Professor X in the third-season episode "Chapter 22."

M.O.D.O.K.

 * The Cerebro helmet appears in the second episode of M.O.D.O.K., where it was found by M.O.D.O.K. in a S.H.I.E.L.D. storage facility.

title: Cerebro


text: User talk:83.129.49.56

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: User talk:83.129.49.56


text:
Category:Scion vehicles

Automobiles sold by Toyota's Scion marque.

title: Category:Scion vehicles


text:
Wikipedia:Articles for deletion/Post-cyborgism

Post-cyborgism
IMHO, this is utter nonsense. Wearing a jacket with a cellphone in its pocket does not make me into a cyborg, and I do not go "offline" while getting undressed and taking a bath. --Jill St. Crux 14:33, 8 Oct 2004 (UTC)
 * personally, I have a waterproofed PDA-type thing so I can continue to contribute to Wikipedia from aqueous environments. I am also considering an implant which will project the Recent Changes page onto the inside of my retina. I will however use my finger lasers to support the deletion of what appears to be a neologism / original research.--Ianb 14:38, 8 Oct 2004 (UTC)
 * Delete. Crackpot sosiology. jni 14:41, 8 Oct 2004 (UTC)
 * Delete. I've changed my vote three times now - the term does have some currency, I think, but only amongst a small handful of academics at the moment, and is not really notable. And it's a load of effing nonsense, IMHO. Katherine Shaw 14:50, Oct 8, 2004 (UTC)
 * Reads like the ramblings of Kevin Warwick. Thats reason enough to delete in itself -- GWO 15:36, 8 Oct 2004 (UTC)
 * Steve Mann aka (possibly) User:Glogger, actually. And the etymology given for "portable" is exactly backwards - the French term for "to wear" almost certainly comes from the Latin term "to carry", portare, i.e., whereever you go, you carry the clothes you're wearing with you! I definately know it's that way with Gerere. Delete - RedWordSmith 17:31, 8 Oct 2004 (UTC)
 * Delete. EXTERMINATE! EXTERMINATE! this original research/nonsense. --Improv 18:47, 8 Oct 2004 (UTC)
 * Delete. Crackpot rant, neologism. Thanks for the laugh, Improv.   — Gwalla | Talk 22:10, 8 Oct 2004 (UTC)
 * Well, i think there is a small movement toward calling people who carry electronics on their person cyborgs, but this isn't the article to talk about that in.... delete. — siro  χ  o  22:49, Oct 8, 2004 (UTC)
 * Delete: idiosyncratic neologism, essay. At first I thought it was a parody: Bathing as a respite from cyborgism. Well. As for myself, I like to consider Bathing as a respite from being tired and dirty. Wile E. Heresiarch 00:59, 9 Oct 2004 (UTC)

 * Next will be post-cyborgasm. Delete neologism.  I used to be among the trade of people who made up stupid words for tenure.  I'm glad to be away from such.  Geogre 18:16, 9 Oct 2004 (UTC)
 * Delete. Utter rubbish. -- Necrothesp 11:55, 11 Oct 2004 (UTC)

 * Delete. If this is user Glogger, then especially Delete. Glogger doesn't seem to understand that he can't make up his own words for his personal beliefs and make encyclopedia articles out of them. func(talk) 18:11, 12 Oct 2004 (UTC)

 * Fucking hilarious but delete . --THE INTERNET OVERLORD 21:27, 13 Oct 2004 (UTC)


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Talk:Enzo Francescoli

Untitled
Accent on family name? Methinks not (being in Italian) elpincha 18:01, 24 September 2005 (UTC)
 * I deleted some accent marks on his name.--200.125.42.194 01:57, 15 November 2006 (UTC)

I've moved the following text here, in case someone wants to try to integrate it into the article:

First goal

in Argentine:

April 27, 1983

Ferrocarril Oeste 0 - River Plate 1

at 50th

Professional Career:

Year/Championship Team Played Goals 1980/82 Wanderers (Uruguay) 74 20 National '83 River Plate 7 2

Metro '83 River Plate 20 9

National '84 River Plate 14 5

Metro'84 River Plate 35 24

National '85 River Plate 5 3

1985/86 River Plate 32 25

1986/87 Racing de Paris (France) 35 14

1987/88 Racing de Paris (France) 28 8

1988/89 Racing de Paris (France) 26 10

1989/90 Olimpique Marseille (France) 28 11

1990/91 Cagliari (Italy) 33 4

1991/92 Cagliari (Italy) 33 6

1992/93 Cagliari (Italy) 32 7

1993/94 Torino (Italy) 24 3

Opening '94 River Plate 16 12

Closing '95 River Plate 11 5

Opening '95 River Plate 9 2

Closing '96 River Plate 11 8

Opening '96 River Plate 15 7

Closing '97 River Plate 16 12

Opening '97 River Plate 6 1

Total Argentina 197 115

Total Uruguay 74 20 Total France 117 43

Total Italy 122 20 Total 510 198

Factitious 14:29, Oct 8, 2004 (UTC)

Dubious Information
Caps and goal figures in the article likely contain European cup/Domestic cup data in addition to Domestic League data (this is very certain based on this user's previous edits containing similar information . Please correct this issue and leave a note here, http://en.wikipedia.org/wiki/User_talk:Alfmaster#Footballers.27_European_goals, to warn this person about putting improper information on Wikipedia. --Palffy 21:11, 25 June 2006 (UTC)

Francescoli a spanish name?
Uriarte is spanish, but Francescoli is an italian surname from italian given name Francesco, the spanish form is Francisco. In this italian article is clearly reported that Francescoli has italian origin. The article is from La Repubblica, as of 2006, the largest circulation Italian daily general-interest newspaper (from english Wikipedia). According to Wikipedia, in Uruguay there are 1,5 milion people of italian origin, see Demographics of Uruguay. --Larth_Rasnal (talk) 13:37, 23 November 2008 (UTC)

olympic titles with River Plate?
"Return to River Plate" section has this: The two Olympic titles in four days is still an Argentine football club record held by River Plate, and is a source of national pride.

The team won one national and one South American title. How exactly are those "Olympic titles"? 85.76.102.33 (talk) 08:04, 5 September 2016 (UTC)

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A Commons file used on this page has been nominated for deletion
The following Wikimedia Commons file used on this page has been nominated for deletion: Participate in the deletion discussion at the nomination page. —Community Tech bot (talk) 16:57, 16 September 2018 (UTC)
 * Francescoli river 85.jpg

title: Talk:Enzo Francescoli


text:
Phosphoric acid fuel cell

Phosphoric acid fuel cells (PAFC) are a type of fuel cell that uses liquid phosphoric acid as an electrolyte. They were the first fuel cells to be commercialized. Developed in the mid-1960s and field-tested since the 1970s, they have improved significantly in stability, performance, and cost. Such characteristics have made the PAFC a good candidate for early stationary applications.

Design
Electrolyte is highly concentrated or pure liquid phosphoric acid (H3PO4) saturated in a silicon carbide (SiC) matrix. Operating range is about 150 to 210 °C. The electrodes are made of carbon paper coated with a finely dispersed platinum catalyst.

Electrode reactions
Anode reaction: 2H2(g) → 4H+ + 4e

Cathode reaction: O2(g) + 4H+ + 4e‾ → 2H2O

Overall cell reaction: 2 H2 + O2 → 2H2O

Advantages and disadvantages
At an operating range of 150 to 200 °C, the expelled water can be converted to steam for air and water heating (combined heat and power). This potentially allows efficiency increases of up to 70%. PAFCs are CO2-tolerant and can tolerate a CO concentration of about 1.5%, which broadens the choice of fuels they can use. If gasoline is used, the sulfur must be removed. At lower temperatures phosphoric acid is a poor ionic conductor, and CO poisoning of the platinum electro-catalyst in the anode becomes severe. However, they are much less sensitive to CO than proton-exchange membrane fuel cells (PEMFC) and alkaline fuel cells (AFC).

Disadvantages include rather low power density and chemically aggressive electrolyte.

Applications
PAFC have been used for stationary power generators with output in the 100 kW to 400 kW range and are also finding application in large vehicles such as buses.

Major manufacturers of PAFC technology include Doosan Fuel Cell America Inc. (formerly ClearEdge Power & UTC Power ) and Fuji Electric.

India's DRDO has developed PAFC based air-independent propulsion for integration into their Kalvari-class submarines.

title: Phosphoric acid fuel cell


text:
Intercontinental Exchange Futures

The International Exchange, now ICE Futures (since 2005-04-7), based in London, was one of the world's largest energy futures and options exchanges. Its flagship commodity, Brent Crude was a world benchmark for oil prices, but the exchange also handled futures contracts and options on fuel oil, natural gas, electricity (baseload and peakload), coal contracts and, as of 22 April 2005, carbon emission allowances with the European Climate Exchange (ECX).

The IPE was acquired by the Intercontinental Exchange in 2001. The IPE was an open outcry exchange until 7 April 2005, when its name was changed to ICE Futures and all trading was shifted onto an electronic trading platform.

History
Until the 1970s, the price of oil was relatively stable with production largely controlled by the biggest oil companies. During that decade two oil price shocks led to continued price volatility in the market; short-term physical markets evolved, and the need to hedge emerged.

A group of energy and futures companies founded the IPE in 1980, and the first contract, for gas oil futures, was launched the following year. In June 1988, the IPE launched Brent Crude futures.

Since its inception, oil futures and latterly options have been traded in pits on the trading floor using the open outcry system. As business volumes have grown, the IPE has moved location several times to accommodate new pits and more traders.

The Exchange has experienced incremental growth, year-on-year for most of its history. Complexity, but also efficiency have increased as new trading instruments such as swaps, futures, and options have been developed.

Contracts
Since 1997, the ICE Futures has expanded its offerings from Brent Crude and Gas Oil to include Natural Gas (1997), Electricity (2004), and ECX carbon financial instruments (2005). These expansions have allowed ICE Futures to offer a wider range of energy products. More advanced transactions are also now possible, due to cross- and multi-product transactions, which eliminate the need to use multiple markets or an adviser.

title: Intercontinental Exchange Futures


text:
Welsford

Welsford may refer to:

 * Welsford is the name of a community in New Brunswick, Canada
 * Welsford is the name of two communities in Nova Scotia, Canada
 * Welsford is also a family name. e.g. Malcolm Welsford.

title: Welsford


text:
Damian Kratzenberg

Damian Kratzenberg (November 5, 1878 – October 11, 1946) was a highschool teacher who became head of the Volksdeutsche Bewegung (German-People's Movement), a pro-Nazi political group, in Luxembourg during World War II. He was executed after the war for collaboration with the Nazis.

Kratzenberg was the son of the administrator of the castle of Clervaux, a German immigrant. After receiving his baccalaureate at the Diekirch gymnasium, from 1898 to 1902 he studied literature in Luxembourg, Lille, Paris and Berlin. Following this, he taught Greek and German in Diekirch, Echternach, and from 1927 at the Athénée de Luxembourg.

From 1927 to 1936, Kratzenberg was a member of the liberal party. From the mid-1930s, he became a supporter of Nazi Germany. From 1935 to 1940, he was the president of GEDELIT, the Luxemburger Gesellschaft für deutsche Literatur und Kunst (Society for German Literature and Art). In 1936, he received the Goethe-Medaille für Kunst und Wissenschaft.

Kratzenberg became head of the regional branch of the Volksdeutsche Bewegung in 1940, and was appointed head of the Athénée de Luxembourg in 1941.

Kratzenberg fled to Weißenburg in Bayern a few days before the liberation of Luxembourg on 1 September 1944. A letter to his daughter after the end of the war however gave his location away and Kratzenberg was apprehended by American military police, moved to Luxembourg and stood trial. He was sentenced to death on August 1, with the sentence carried out on October 11, 1946, at the shooting range of the barracks of the Holy Ghost Plateau in Luxembourg City.

title: Damian Kratzenberg


text:
Solid oxide fuel cell

A solid oxide fuel cell (or SOFC) is an electrochemical conversion device that produces electricity directly from oxidizing a fuel. Fuel cells are characterized by their electrolyte material; the SOFC has a solid oxide or ceramic electrolyte.

Advantages of this class of fuel cells include high combined heat and power efficiency, long-term stability, fuel flexibility, low emissions, and relatively low cost. The largest disadvantage is the high operating temperature which results in longer start-up times and mechanical and chemical compatibility issues.

Introduction
Solid oxide fuel cells are a class of fuel cells characterized by the use of a solid oxide material as the electrolyte. SOFCs use a solid oxide electrolyte to conduct negative oxygen ions from the cathode to the anode. The electrochemical oxidation of the hydrogen, carbon monoxide or other organic intermediates by oxygen ions thus occurs on the anode side. More recently, proton-conducting SOFCs (PC-SOFC) are being developed which transport protons instead of oxygen ions through the electrolyte with the advantage of being able to be run at lower temperatures than traditional SOFCs.

They operate at very high temperatures, typically between 600 and 1,000 °C. At these temperatures, SOFCs do not require expensive platinum group metals catalyst, as is currently necessary for lower temperature fuel cells such as PEMFCs, and are not vulnerable to carbon monoxide catalyst poisoning. However, vulnerability to sulfur poisoning has been widely observed and the sulfur must be removed before entering the cell. For fuels that are of lower quality, such as gasified biomass, coal, or biogas, the fuel processing becomes increasingly complex and, consequently, more expensive. The gasification process, which transforms the raw material into a gaseous state suitable for fuel cells, can generate significant quantities of aromatic compounds. These compounds include smaller molecules like methane and toluene, as well as larger polyaromatic and short-chain hydrocarbon compounds. These substances can lead to carbon buildup in SOFCs. Moreover, the expenses associated with reforming and desulfurization are comparable in magnitude to the cost of the fuel cell itself. These factors become especially critical for systems with lower power output or greater portability requirements.

Solid oxide fuel cells have a wide variety of applications, from use as auxiliary power units in vehicles to stationary power generation with outputs from 100 W to 2 MW. In 2009, Australian company, Ceramic Fuel Cells successfully achieved an efficiency of an SOFC device up to the previously theoretical mark of 60%. The higher operating temperature make SOFCs suitable candidates for application with heat engine energy recovery devices or combined heat and power, which further increases overall fuel efficiency.

Because of these high temperatures, light hydrocarbon fuels, such as methane, propane, and butane can be internally reformed within the anode. SOFCs can also be fueled by externally reforming heavier hydrocarbons, such as gasoline, diesel, jet fuel (JP-8) or biofuels. Such reformates are mixtures of hydrogen, carbon monoxide, carbon dioxide, steam and methane, formed by reacting the hydrocarbon fuels with air or steam in a device upstream of the SOFC anode. SOFC power systems can increase efficiency by using the heat given off by the exothermic electrochemical oxidation within the fuel cell for endothermic steam reforming process. Additionally, solid fuels such as coal and biomass may be gasified to form syngas which is suitable for fueling SOFCs in integrated gasification fuel cell power cycles.

Thermal expansion demands a uniform and well-regulated heating process at startup. SOFC stacks with planar geometry require on the order of an hour to be heated to operating temperature. Micro-tubular fuel cell design geometries promise much faster start up times, typically in the order of minutes.

Unlike most other types of fuel cells, SOFCs can have multiple geometries. The planar fuel cell design geometry is the typical sandwich type geometry employed by most types of fuel cells, where the electrolyte is sandwiched in between the electrodes. SOFCs can also be made in tubular geometries where either air or fuel is passed through the inside of the tube and the other gas is passed along the outside of the tube. The tubular design is advantageous because it is much easier to seal air from the fuel. The performance of the planar design is currently better than the performance of the tubular design, however, because the planar design has a lower resistance comparatively. Other geometries of SOFCs include modified planar fuel cell designs (MPC or MPSOFC), where a wave-like structure replaces the traditional flat configuration of the planar cell. Such designs are highly promising because they share the advantages of both planar cells (low resistance) and tubular cells.

Operation
A solid oxide fuel cell is made up of four layers, three of which are ceramics (hence the name). A single cell consisting of these four layers stacked together is typically only a few millimeters thick. Hundreds of these cells are then connected in series to form what most people refer to as an "SOFC stack". The ceramics used in SOFCs do not become electrically and ionically active until they reach very high temperature and as a consequence, the stacks have to run at temperatures ranging from 500 to 1,000 °C. Reduction of oxygen into oxygen ions occurs at the cathode. These ions can then diffuse through the solid oxide electrolyte to the anode where they can electrochemically oxidize the fuel. In this reaction, a water byproduct is given off as well as two electrons. These electrons then flow through an external circuit where they can do work. The cycle then repeats as those electrons enter the cathode material again.

Balance of plant
Most of the downtime of a SOFC stems from the mechanical balance of plant, the air preheater, prereformer, afterburner, water heat exchanger, anode tail gas oxidizer, and electrical balance of plant, power electronics, hydrogen sulfide sensor and fans. Internal reforming leads to a large decrease in the balance of plant costs in designing a full system.

Anode
The ceramic anode layer must be very porous to allow the fuel to flow towards the electrolyte. Consequently, granular matter is often selected for anode fabrication procedures. Like the cathode, it must conduct electrons, with ionic conductivity a definite asset. The anode is commonly the thickest and strongest layer in each individual cell, because it has the smallest polarization losses, and is often the layer that provides the mechanical support. Electrochemically speaking, the anode's job is to use the oxygen ions that diffuse through the electrolyte to oxidize the hydrogen fuel. The oxidation reaction between the oxygen ions and the hydrogen produces heat as well as water and electricity. If the fuel is a light hydrocarbon, for example, methane, another function of the anode is to act as a catalyst for steam reforming the fuel into hydrogen. This provides another operational benefit to the fuel cell stack because the reforming reaction is endothermic, which cools the stack internally. The most common material used is a cermet made up of nickel mixed with the ceramic material that is used for the electrolyte in that particular cell, typically YSZ (yttria stabilized zirconia). These nanomaterial-based catalysts, help stop the grain growth of nickel. Larger grains of nickel would reduce the contact area that ions can be conducted through, which would lower the cells efficiency. Perovskite materials (mixed ionic/electronic conducting ceramics) have been shown to produce a power density of 0.6 W/cm2 at 0.7 V at 800 °C which is possible because they have the ability to overcome a larger activation energy.

Chemical Reaction:

H2 +O2- ——> H2O+2e

However, there are a few disadvantages associated with YSZ as anode material. Ni coarsening, carbon deposition, reduction-oxidation instability, and sulfur poisoning are the main obstacles limiting the long-term stability of Ni-YSZ. Ni coarsening refers to the evolution of Ni particles in doped in YSZ grows larger in grain size, which decreases the surface area for the catalytic reaction. Carbon deposition occurs when carbon atoms, formed by hydrocarbon pyrolysis or CO disproportionation, deposit on the Ni catalytic surface. Carbon deposition becomes important especially when hydrocarbon fuels are used, i.e. methane, syngas. The high operating temperature of SOFC and the oxidizing environment facilitate the oxidation of Ni catalyst through reaction Ni + $1/2$ O2 = NiO. The oxidation reaction of Ni reduces the electrocatalytic activity and conductivity. Moreover, the density difference between Ni and NiO causes volume change on the anode surface, which could potentially lead to mechanical failure. Sulfur poisoning arises when fuel such as natural gas, gasoline, or diesel is used. Again, due to the high affinity between sulfur compounds (H2S, (CH3)2S) and the metal catalyst, even the smallest impurities of sulfur compounds in the feed stream could deactivate the Ni catalyst on the YSZ surface.

Current research is focused on reducing or replacing Ni content in the anode to improve long-term performance. The modified Ni-YSZ containing other materials including CeO2, Y2O3, La2O3, MgO, TiO2, Ru, Co, etc. are invented to resist sulfur poisoning, but the improvement is limited due to the rapid initial degradation. Copper-based cerement anode is considered as a solution to carbon deposition because it is inert to carbon and stable under typical SOFC oxygen partial pressures (pO2). Cu-Co bimetallic anodes in particular show a great resistivity of carbon deposition after the exposure to pure CH4 at 800C. And Cu-CeO2-YSZ exhibits a higher electrochemical oxidation rate over Ni-YSZ when running on CO and syngas, and can achieve even higher performance using CO than H2, after adding a cobalt co-catalyst. Oxide anodes including zirconia-based fluorite and perovskites are also used to replace Ni-ceramic anodes for carbon resistance. Chromite i.e. La0.8Sr0.2Cr0.5Mn0.5O3 (LSCM) is used as anodes and exhibited comparable performance against Ni–YSZ cermet anodes. LSCM is further improved by impregnating Cu and sputtering Pt as the current collector.

Electrolyte
The electrolyte is a dense layer of ceramic that conducts oxygen ions. Its electronic conductivity must be kept as low as possible to prevent losses from leakage currents. The high operating temperatures of SOFCs allow the kinetics of oxygen ion transport to be sufficient for good performance. However, as the operating temperature approaches the lower limit for SOFCs at around 600 °C, the electrolyte begins to have large ionic transport resistances and affect the performance. Popular electrolyte materials include yttria-stabilized zirconia (YSZ) (often the 8% form 8YSZ), scandia stabilized zirconia (ScSZ) (usually 9 mol% Sc2O3 – 9ScSZ) and gadolinium doped ceria (GDC). The electrolyte material has crucial influence on the cell performances. Detrimental reactions between YSZ electrolytes and modern cathodes such as lanthanum strontium cobalt ferrite (LSCF) have been found, and can be prevented by thin (<100 nm) ceria diffusion barriers.

If the conductivity for oxygen ions in SOFC can remain high even at lower temperatures (current target in research ~500 °C), material choices for SOFC will broaden and many existing problems can potentially be solved. Certain processing techniques such as thin film deposition can help solve this problem with existing materials by:

 * reducing the traveling distance of oxygen ions and electrolyte resistance as resistance is proportional to conductor length;
 * producing grain structures that are less resistive such as columnar grain structure;
 * controlling the microstructural nano-crystalline fine grains to achieve "fine-tuning" of electrical properties;
 * building composite possessing large interfacial areas as interfaces have been shown to have extraordinary electrical properties.

Cathode
The cathode, or air electrode, is a thin porous layer on the electrolyte where oxygen reduction takes place. The overall reaction is written in Kröger-Vink Notation as follows:

 * $$ \frac{1}{2}\mathrm{O_2(g)} + 2\mathrm{e'} + {V}^{\bullet\bullet}_o \longrightarrow {O}^{\times}_o $$

Cathode materials must be, at a minimum, electrically conductive. Currently, lanthanum strontium manganite (LSM) is the cathode material of choice for commercial use because of its compatibility with doped zirconia electrolytes. Mechanically, it has a similar coefficient of thermal expansion to YSZ and thus limits stress buildup because of CTE mismatch. Also, LSM has low levels of chemical reactivity with YSZ which extends the lifetime of the materials. Unfortunately, LSM is a poor ionic conductor, and so the electrochemically active reaction is limited to the triple phase boundary (TPB) where the electrolyte, air and electrode meet. LSM works well as a cathode at high temperatures, but its performance quickly falls as the operating temperature is lowered below 800 °C. In order to increase the reaction zone beyond the TPB, a potential cathode material must be able to conduct both electrons and oxygen ions. Composite cathodes consisting of LSM YSZ have been used to increase this triple phase boundary length. Mixed ionic/electronic conducting (MIEC) ceramics, such as perovskite LSCF, are also being researched for use in intermediate temperature SOFCs as they are more active and can make up for the increase in the activation energy of the reaction.

Interconnect
The interconnect can be either a metallic or ceramic layer that sits between each individual cell. Its purpose is to connect each cell in series, so that the electricity each cell generates can be combined. Because the interconnect is exposed to both the oxidizing and reducing side of the cell at high temperatures, it must be extremely stable. For this reason, ceramics have been more successful in the long term than metals as interconnect materials. However, these ceramic interconnect materials are very expensive when compared to metals. Nickel- and steel-based alloys are becoming more promising as lower temperature (600–800 °C) SOFCs are developed. The material of choice for an interconnect in contact with Y8SZ is a metallic 95Cr-5Fe alloy. Ceramic-metal composites called "cermet" are also under consideration, as they have demonstrated thermal stability at high temperatures and excellent electrical conductivity.

Polarizations
Polarizations, or overpotentials, are losses in voltage due to imperfections in materials, microstructure, and design of the fuel cell. Polarizations result from ohmic resistance of oxygen ions conducting through the electrolyte (iRΩ), electrochemical activation barriers at the anode and cathode, and finally concentration polarizations due to inability of gases to diffuse at high rates through the porous anode and cathode (shown as ηA for the anode and ηC for cathode). The cell voltage can be calculated using the following equation:

 * $$ {V} = {E}_0 - {iR}_\omega - {\eta}_{cathode} - {\eta}_{anode} $$

where:
 * $${E}_0$$ = Nernst potential of the reactants
 * $$R$$ = Thévenin equivalent resistance value of the electrically conducting portions of the cell
 * $${\eta}_{cathode}$$ = polarization losses in the cathode
 * $${\eta}_{anode}$$ = polarization losses in the anode

In SOFCs, it is often important to focus on the ohmic and concentration polarizations since high operating temperatures experience little activation polarization. However, as the lower limit of SOFC operating temperature is approached (~600 °C), these polarizations do become important.

Above mentioned equation is used for determining the SOFC voltage (in fact for fuel cell voltage in general). This approach results in good agreement with particular experimental data (for which adequate factors were obtained) and poor agreement for other than original experimental working parameters. Moreover, most of the equations used require the addition of numerous factors which are difficult or impossible to determine. It makes very difficult any optimizing process of the SOFC working parameters as well as design architecture configuration selection. Because of those circumstances a few other equations were proposed:

 * $$E_{SOFC} = \frac{E_{max}-i_{max}\cdot\eta_f\cdot r_1}{\frac{r_1}{r_2}\cdot\left( 1-\eta_f \right) + 1}

$$

where:
 * $$E_{SOFC}$$ = cell voltage
 * $$E_{max}$$ = maximum voltage given by the Nernst equation
 * $$i_{max}$$ = maximum current density (for given fuel flow)
 * $$\eta_f$$ = fuel utilization factor
 * $$r_1$$ = ionic specific resistance of the electrolyte
 * $$r_2$$ = electric specific resistance of the electrolyte.

This method was validated and found to be suitable for optimization and sensitivity studies in plant-level modelling of various systems with solid oxide fuel cells. With this mathematical description it is possible to account for different properties of the SOFC. There are many parameters which impact cell working conditions, e.g. electrolyte material, electrolyte thickness, cell temperature, inlet and outlet gas compositions at anode and cathode, and electrode porosity, just to name some. The flow in these systems is often calculated using the Navier–Stokes equations.

Ohmic polarization
Ohmic losses in an SOFC result from ionic conductivity through the electrolyte and electrical resistance offered to the flow of electrons in the external electrical circuit. This is inherently a materials property of the crystal structure and atoms involved. However, to maximize the ionic conductivity, several methods can be done. Firstly, operating at higher temperatures can significantly decrease these ohmic losses. Substitutional doping methods to further refine the crystal structure and control defect concentrations can also play a significant role in increasing the conductivity. Another way to decrease ohmic resistance is to decrease the thickness of the electrolyte layer.

Ionic conductivity
An ionic specific resistance of the electrolyte as a function of temperature can be described by the following relationship:

 * $$r_1 = \frac{\delta}{\sigma}$$

where: $$\delta$$ – electrolyte thickness, and $$\sigma$$ – ionic conductivity.

The ionic conductivity of the solid oxide is defined as follows:

 * $$\sigma = \sigma_0\cdot e^\frac{-E}{R\cdot T}$$

where: $$\sigma_0$$ and $$E$$ – factors depended on electrolyte materials, $$T$$ – electrolyte temperature, and $$R$$ – ideal gas constant.

Concentration polarization
The concentration polarization is the result of practical limitations on mass transport within the cell and represents the voltage loss due to spatial variations in reactant concentration at the chemically active sites. This situation can be caused when the reactants are consumed by the electrochemical reaction faster than they can diffuse into the porous electrode, and can also be caused by variation in bulk flow composition. The latter is due to the fact that the consumption of reacting species in the reactant flows causes a drop in reactant concentration as it travels along the cell, which causes a drop in the local potential near the tail end of the cell.

The concentration polarization occurs in both the anode and cathode. The anode can be particularly problematic, as the oxidation of the hydrogen produces steam, which further dilutes the fuel stream as it travels along the length of the cell. This polarization can be mitigated by reducing the reactant utilization fraction or increasing the electrode porosity, but these approaches each have significant design trade-offs.

Activation polarization
The activation polarization is the result of the kinetics involved with the electrochemical reactions. Each reaction has a certain activation barrier that must be overcome in order to proceed and this barrier leads to the polarization. The activation barrier is the result of many complex electrochemical reaction steps where typically the rate limiting step is responsible for the polarization. The polarization equation shown below is found by solving the Butler–Volmer equation in the high current density regime (where the cell typically operates), and can be used to estimate the activation polarization:

 * $$ {\eta}_{act} = \frac {RT} {{\beta}zF} \times ln \left(\frac {i} {{i}_0} \right) $$

where:
 * $$R$$ = gas constant
 * $${T}_0$$ = operating temperature
 * $${\beta}$$ = electron transfer coefficient
 * $$z$$ = electrons associated with the electrochemical reaction
 * $$F$$ = Faraday's constant
 * $$i$$ = operating current
 * $$i_0$$ = exchange current density

The polarization can be modified by microstructural optimization. The Triple Phase Boundary (TPB) length, which is the length where porous, ionic and electronically conducting pathways all meet, directly relates to the electrochemically active length in the cell. The larger the length, the more reactions can occur and thus the less the activation polarization. Optimization of TPB length can be done by processing conditions to affect microstructure or by materials selection to use a mixed ionic/electronic conductor to further increase TPB length.

Mechanical Properties
Current SOFC research focuses heavily on optimizing cell performance while maintaining acceptable mechanical properties because optimized performance often compromises mechanical properties. Nevertheless, mechanical failure represents a significant problem to SOFC operation. The presence of various kinds of load and Thermal stress during operation requires high mechanical strength. Additional stresses associated with changes in gas atmosphere, leading to reduction or oxidation also cannot be avoided in prolonged operation. When electrode layers delaminate or crack, conduction pathways are lost, leading to a redistribution of current density and local changes in temperature. These local temperature deviations, in turn, lead to increased thermal strains, which propagate cracks and Delamination. Additionally, when electrolytes crack, separation of fuel and air is no longer guaranteed, which further endangers the continuous operation of the cell.

Since SOFCs require materials with high oxygen conductivity, thermal stresses provide a significant problem. The Coefficient of thermal expansion in mixed ionic-electronic perovskites can be directly related to oxygen vacancy concentration, which is also related to ionic conductivity. Thus, thermal stresses increase in direct correlation with improved cell performance. Additionally, however, the temperature dependence of oxygen vacancy concentration means that the CTE is not a linear property, which further complicates measurements and predictions.

Just as thermal stresses increase as cell performance improves through improved ionic conductivity, the fracture toughness of the material also decreases as cell performance increases. This is because, to increase reaction sites, porous ceramics are preferable. However, as shown in the equation below, fracture toughness decreases as porosity increases.

$$ K_{IC} = K_{IC,0}\exp{(-b_{k}p')} $$

Where:

$$K_{IC}$$ = fracture toughness

$$K_{IC,0}$$ = fracture toughness of the non-porous structure

$$b_k$$ = experimentally determined constant

$$p' $$ = porosity

Thus, porosity must be carefully engineered to maximize reaction kinetics while maintaining an acceptable fracture toughness. Since fracture toughness represents the ability of pre-existing cracks or pores to propagate, a potentially more useful metric is the failure stress of a material, as this depends on sample dimensions instead of crack diameter. Failure stresses in SOFCs can also be evaluated using a ring-on ring biaxial stress test. This type of test is generally preferred, as sample edge quality does not significantly impact measurements. The determination of the sample's failure stress is shown in the equation below.

$$ \sigma_{cr}= \frac{3F_{cr}}{2\pi h_{s}^{2}}+ \Biggl((1-\nu)\frac{D_{sup}^{2}-D_{load}^{2}}{2D_{s}^{2}}+(1+\nu)\ln\left ( \frac{D_{sup}}{D_{load}} \right )\Biggr) $$

Where:

$$ \sigma_{cr} $$ = failure stress of the small deformation

$$ F_{cr} $$ = critical applied force

$$ h_s $$ = height of the sample

$$ \nu $$ = Poisson's ratio

$$ D $$ = diameter (sup = support ring, load = loading ring, s = sample)

However, this equation is not valid for deflections exceeding 1/2h, making it less applicable for thin samples, which are of great interest in SOFCs. Therefore, while this method does not require knowledge of crack or pore size, it must be used with great caution and is more applicable to support layers in SOFCs than active layers. In addition to failure stresses and fracture toughness, modern fuel cell designs that favor mixed ionic electronic conductors (MIECs), Creep (deformation) pose another great problem, as MIEC electrodes often operate at temperatures exceeding half of the melting temperature. As a result, diffusion creep must also be considered.

$$ \dot{\epsilon}_{eq}^{creep}=\frac{\tilde{k}_0D}{T}\frac{\sigma_{eq}^{m}}{d_{grain}^{n}} $$

Where:

$$ \dot{\epsilon}_{eq}^{creep} $$ = equivalent creep strain

$$ D $$ = Diffusion coefficient

$$ T $$ = temperature

$$ \tilde{k}_0 $$ = kinetic constant

$$ \sigma_{eq} $$ = equivalent stress (e.g. von Mises)

$$ m $$ = creep stress exponential factor

$$ n $$ = particle size exponent (2 for Nabarro–Herring creep, 3 for Coble creep)

To properly model creep strain rates, knowledge of Microstructure is therefore of significant importance. Due to the difficulty in mechanically testing SOFCs at high temperatures, and due to the microstructural evolution of SOFCs over the lifetime of operation resulting from Grain growth and coarsening, the actual creep behavior of SOFCs is currently not completely understood

Target
DOE target requirements are 40,000 hours of service for stationary fuel cell applications and greater than 5,000 hours for transportation systems (fuel cell vehicles) at a factory cost of $40/kW for a 10 kW coal-based system without additional requirements. Lifetime effects (phase stability, thermal expansion compatibility, element migration, conductivity and aging) must be addressed. The Solid State Energy Conversion Alliance 2008 (interim) target for overall degradation per 1,000 hours is 4.0%.

Research
Research is going now in the direction of lower-temperature SOFCs (600 °C). Low temperature systems can reduce costs by reducing insulation, materials, start-up and degradation-related costs. With higher operating temperatures, the temperature gradient increases the severity of thermal stresses, which affects materials cost and life of the system. An intermediate temperature system (650-800 °C) would enable the use of cheaper metallic materials with better mechanical properties and thermal conductivity. New developments in nano-scale electrolyte structures have been shown to bring down operating temperatures to around 350 °C, which would enable the use of even cheaper steel and elastomeric/polymeric components.

Lowering operating temperatures has the added benefit of increased efficiency. Theoretical fuel cell efficiency increases with decreasing temperature. For example, the efficiency of a SOFC using CO as fuel increases from 63% to 81% when decreasing the system temperature from 900 °C to 350 °C.

Research is also under way to improve the fuel flexibility of SOFCs. While stable operation has been achieved on a variety of hydrocarbon fuels, these cells typically rely on external fuel processing. In the case of natural gas, the fuel is either externally or internally reformed and the sulfur compounds are removed. These processes add to the cost and complexity of SOFC systems. Work is under way at a number of institutions to improve the stability of anode materials for hydrocarbon oxidation and, therefore, relax the requirements for fuel processing and decrease SOFC balance of plant costs.

Research is also going on in reducing start-up time to be able to implement SOFCs in mobile applications. This can be partially achieved by lowering operating temperatures, which is the case for proton-exchange membrane fuel cell (PEMFCs). Due to their fuel flexibility, they may run on partially reformed diesel, and this makes SOFCs interesting as auxiliary power units (APU) in refrigerated trucks.

Specifically, Delphi Automotive Systems are developing an SOFC that will power auxiliary units in automobiles and tractor-trailers, while BMW has recently stopped a similar project. A high-temperature SOFC will generate all of the needed electricity to allow the engine to be smaller and more efficient. The SOFC would run on the same gasoline or diesel as the engine and would keep the air conditioning unit and other necessary electrical systems running while the engine shuts off when not needed (e.g., at a stop light or truck stop).

Rolls-Royce is developing solid-oxide fuel cells produced by screen printing onto inexpensive ceramic materials. Rolls-Royce Fuel Cell Systems Ltd is developing an SOFC gas turbine hybrid system fueled by natural gas for power generation applications in the order of a megawatt (e.g. Futuregen).

3D printing is being explored as a possible manufacturing technique that could be used to make SOFC manufacturing easier by the Shah Lab at Northwestern University. This manufacturing technique would allow SOFC cell structure to be more flexible, which could lead to more efficient designs. This process could work in the production of any part of the cell. The 3D printing process works by combining about 80% ceramic particles with 20% binders and solvents, and then converting that slurry into an ink that can be fed into a 3D printer. Some of the solvent is very volatile, so the ceramic ink solidifies almost immediately. Not all of the solvent evaporates, so the ink maintains some flexibility before it is fired at high temperature to densify it. This flexibility allows the cells to be fired in a circular shape that would increase the surface area over which electrochemical reactions can occur, which increases the efficiency of the cell. Also, the 3D printing technique allows the cell layers to be printed on top of each other instead of having to go through separate manufacturing and stacking steps. The thickness is easy to control, and layers can be made in the exact size and shape that is needed, so waste is minimized.

Ceres Power Ltd. has developed a low cost and low temperature (500–600 degrees) SOFC stack using cerium gadolinium oxide (CGO) in place of current industry standard ceramic, yttria stabilized zirconia (YSZ), which allows the use of stainless steel to support the ceramic.

Solid Cell Inc. has developed a unique, low-cost cell architecture that combines properties of planar and tubular designs, along with a Cr-free cermet interconnect.

The high temperature electrochemistry center (HITEC) at the University of Florida, Gainesville is focused on studying ionic transport, electrocatalytic phenomena and microstructural characterization of ion conducting materials.

SiEnergy Systems, a Harvard spin-off company, has demonstrated the first macro-scale thin-film solid-oxide fuel cell that can operate at 500 degrees.

SOEC
A solid oxide electrolyser cell (SOEC) is a solid oxide fuel cell set in regenerative mode for the electrolysis of water with a solid oxide, or ceramic, electrolyte to produce oxygen and hydrogen gas.

SOECs can also be used to do electrolysis of CO2 to produce CO and oxygen or even co-electrolysis of water and CO2 to produce syngas and oxygen.

ITSOFC
SOFCs that operate in an intermediate temperature (IT) range, meaning between 600 and 800 °C, are named ITSOFCs. Because of the high degradation rates and materials costs incurred at temperatures in excess of 900 °C, it is economically more favorable to operate SOFCs at lower temperatures. The push for high-performance ITSOFCs is currently the topic of much research and development. One area of focus is the cathode material. It is thought that the oxygen reduction reaction is responsible for much of the loss in performance so the catalytic activity of the cathode is being studied and enhanced through various techniques, including catalyst impregnation. The research on NdCrO3 proves it to be a potential cathode material for the cathode of ITSOFC since it is thermochemically stable within the temperature range.

Another area of focus is electrolyte materials. To make SOFCs competitive in the market, ITSOFCs are pushing towards lower operational temperature by use of alternative new materials. However, efficiency and stability of the materials limit their feasibility. One choice for the electrolyte new materials is the ceria-salt ceramic composites (CSCs). The two-phase CSC electrolytes GDC (gadolinium-doped ceria) and SDC (samaria-doped ceria)-MCO3 (M=Li, Na, K, single or mixture of carbonates) can reach the power density of 300-800 mW*cm−2.

LT-SOFC
Low-temperature solid oxide fuel cells (LT-SOFCs), operating lower than 650 °C, are of great interest for future research because the high operating temperature is currently what restricts the development and deployment of SOFCs. A low-temperature SOFC is more reliable due to smaller thermal mismatch and easier sealing. Additionally, a lower temperature requires less insulation and therefore has a lower cost. Cost is further lowered due to wider material choices for interconnects and compressive nonglass/ceramic seals. Perhaps most importantly, at a lower temperature, SOFCs can be started more rapidly and with less energy, which lends itself to uses in portable and transportable applications.

As temperature decreases, the maximum theoretical fuel cell efficiency increases, in contrast to the Carnot cycle. For example, the maximum theoretical efficiency of an SOFC using CO as a fuel increases from 63% at 900 °C to 81% at 350 °C.

This is a materials issue, particularly for the electrolyte in the SOFC. YSZ is the most commonly used electrolyte because of its superior stability, despite not having the highest conductivity. Currently, the thickness of YSZ electrolytes is a minimum of ~10 μm due to deposition methods, and this requires a temperature above 700 °C. Therefore, low-temperature SOFCs are only possible with higher conductivity electrolytes. Various alternatives that could be successful at low temperature include gadolinium-doped ceria (GDC) and erbia-cation-stabilized bismuth (ERB). They have superior ionic conductivity at lower temperatures, but this comes at the expense of lower thermodynamic stability. CeO2 electrolytes become electronically conductive and Bi2O3 electrolytes decompose to metallic Bi under the reducing fuel environment.

To combat this, researchers created a functionally graded ceria/bismuth-oxide bilayered electrolyte where the GDC layer on the anode side protects the ESB layer from decomposing while the ESB on the cathode side blocks the leakage current through the GDC layer. This leads to near-theoretical open-circuit potential (OPC) with two highly conductive electrolytes, that by themselves would not have been sufficiently stable for the application. This bilayer proved to be stable for 1400 hours of testing at 500 °C and showed no indication of interfacial phase formation or thermal mismatch. While this makes strides towards lowering the operating temperature of SOFCs, it also opens doors for future research to try and understand this mechanism.

Researchers at the Georgia Institute of Technology dealt with the instability of BaCeO3 differently. They replaced a desired fraction of Ce in BaCeO3 with Zr to form a solid solution that exhibits proton conductivity, but also chemical and thermal stability over the range of conditions relevant to fuel cell operation. A new specific composition, Ba(Zr0.1Ce0.7Y0.2)O3-δ (BZCY7) that displays the highest ionic conductivity of all known electrolyte materials for SOFC applications. This electrolyte was fabricated by dry-pressing powders, which allowed for the production of crack free films thinner than 15 μm. The implementation of this simple and cost-effective fabrication method may enable significant cost reductions in SOFC fabrication. However, this electrolyte operates at higher temperatures than the bilayered electrolyte model, closer to 600 °C rather than 500 °C.

Currently, given the state of the field for LT-SOFCs, progress in the electrolyte would reap the most benefits, but research into potential anode and cathode materials would also lead to useful results, and has started to be discussed more frequently in literature.

SOFC-GT
An SOFC-GT system is one which comprises a solid oxide fuel cell combined with a gas turbine. Such systems have been evaluated by Siemens Westinghouse and Rolls-Royce as a means to achieve higher operating efficiencies by running the SOFC under pressure. SOFC-GT systems typically include anodic and/or cathodic atmosphere recirculation, thus increasing efficiency.

Theoretically, the combination of the SOFC and gas turbine can give result in high overall (electrical and thermal) efficiency. Further combination of the SOFC-GT in a combined cooling, heat and power (or trigeneration) configuration (via HVAC) also has the potential to yield even higher thermal efficiencies in some cases.

Another feature of the introduced hybrid system is on the gain of 100% CO2 capturing at comparable high energy efficiency. These features like zero CO2 emission and high energy efficiency make the power plant performance noteworthy.

DCFC
For the direct use of solid coal fuel without additional gasification and reforming processes, a direct carbon fuel cell (DCFC) has been developed as a promising novel concept of a high-temperature energy conversion system. The underlying progress in the development of a coal-based DCFC has been categorized mainly according to the electrolyte materials used, such as solid oxide, molten carbonate, and molten hydroxide, as well as hybrid systems consisting of solid oxide and molten carbonate binary electrolyte or of liquid anode (Fe, Ag, In, Sn, Sb, Pb, Bi, and its alloying and its metal/metal oxide) solid oxide electrolyte. People's research on DCFC with GDC-Li/Na2CO3 as the electrolyte, Sm0.5Sr0.5CoO3 as cathode shows good performance. The highest power density of 48 mW*cm−2 can be reached at 500 °C with O2 and CO2 as oxidant and the whole system is stable within the temperature range of 500 °C to 600 °C.

SOFC operated on landfill gas

Every household produces waste/garbage on a daily basis. In 2009, Americans produced about 243 million tons of municipal solid waste, which is 4.3 pounds of waste per person per day. All that waste is sent to landfill sites. Landfill gas which is produced from the decomposition of waste that gets accumulated at the landfills has the potential to be a valuable source of energy since methane is a major constituent. Currently, the majority of the landfills either burn away their gas in flares or combust it in mechanical engines to produce electricity. The issue with mechanical engines is that incomplete combustion of gasses can lead to pollution of the atmosphere and is also highly inefficient.

The issue with using landfill gas to fuel an SOFC system is that landfill gas contains hydrogen sulfide. Any landfill accepting biological waste will contain about 50-60 ppm of hydrogen sulfide and around 1-2 ppm mercaptans. However, construction materials containing reducible sulfur species, principally sulfates found in gypsum-based wallboard, can cause considerably higher levels of sulfides in the hundreds of ppm. At operating temperatures of 750 °C hydrogen sulfide concentrations of around 0.05 ppm begin to affect the performance of the SOFCs.

Ni + H2S → NiS + H2

The above reaction controls the effect of sulfur on the anode.

This can be prevented by having background hydrogen which is calculated below.

At 453 K the equilibrium constant is 7.39 x 10−5

ΔG calculated at 453 K was 35.833 kJ/mol

Using the standard heat of formation and entropy ΔG at room temperature (298 K) came out to be 45.904 kJ/mol

On extrapolation to 1023 K, ΔG is -1.229 kJ/mol

On substitution, Keq at 1023 K is 1.44 x 10−4. Hence theoretically we need 3.4% hydrogen to prevent the formation of NiS at 5 ppm H2S.

title: Solid oxide fuel cell


text:
Molten carbonate fuel cell

Molten-carbonate fuel cells (MCFCs) are high-temperature fuel cells that operate at temperatures of 600 °C and above.

Molten carbonate fuel cells (MCFCs) were developed for natural gas, biogas (produced as a result of anaerobic digestion or biomass gasification), and coal-based power plants for electrical utility, industrial, and military applications. MCFCs are high-temperature fuel cells that use an electrolyte composed of a molten carbonate salt mixture suspended in a porous, chemically inert ceramic matrix of beta-alumina solid electrolyte (BASE). Since they operate at extremely high temperatures of 650 °C (roughly 1,200 °F) and above, non-precious metals can be used as catalysts at the anode and cathode, reducing costs.

Improved efficiency is another reason MCFCs offer significant cost reductions over phosphoric acid fuel cells (PAFCs). Molten carbonate fuel cells can reach efficiencies approaching 60%, considerably higher than the 37–42% efficiencies of a phosphoric acid fuel cell plant. When the waste heat is captured and used, overall fuel efficiencies can be as high as 85%.

Unlike alkaline, phosphoric acid, and polymer electrolyte membrane fuel cells, MCFCs don't require an external reformer to convert more energy-dense fuels to hydrogen. Due to the high temperatures at which MCFCs operate, these fuels are converted to hydrogen within the fuel cell itself by a process called internal reforming, which also reduces cost.

Molten carbonate fuel cells are not prone to poisoning by carbon monoxide or carbon dioxide — they can even use carbon oxides as fuel — making them more attractive for fueling with gases made from coal. Because they are more resistant to impurities than other fuel cell types, scientists believe that they could even be capable of internal reforming of coal, assuming they can be made resistant to impurities such as sulfur and particulates that result from converting coal, a dirtier fossil fuel source than many others, into hydrogen. Alternatively, because MCFCs require CO2 be delivered to the cathode along with the oxidizer, they can be used to electrochemically separate carbon dioxide from the flue gas of other fossil fuel power plants for sequestration.

The primary disadvantage of current MCFC technology is durability. The high temperatures at which these cells operate and the corrosive electrolyte used accelerate component breakdown and corrosion, decreasing cell life. Scientists are currently exploring corrosion-resistant materials for components as well as fuel cell designs that increase cell life without decreasing performance.

Background
Molten carbonate FCs are a recently developed type of fuel cell that targets small and large energy distribution/generation systems since their power production is in the 0.3-3 MW range. The operating pressure is between 1-8 atm while the temperatures are between 600 and 700 °C. Due to the production of CO2 during reforming of the fossil fuel (methane, natural gas), MCFCs are not a completely green technology, but are promising due to their reliability and efficiency (sufficient heat for co-generation with electricity). Current MCFC efficiencies range from 60 to 70%.

=== Reactions === Internal Reformer (methane example):

$$CH_4 + H_2O = 3H_2 + CO$$

Anode (hydrogen example):

$$H_2 + CO_3^{2-} = H_2O + CO_2 + 2e^-$$

Cathode:

$$\frac{1}{2}O_2 + CO_2 +2e^- = CO_3^{2-}$$

Cell:

$$H_2 + \frac{1}{2}O_2 = H_2O$$

Nernst Equation:

$$E = E^o + \frac{RT}{2F}log\frac{P_{H_2}P_{O_2}^{\frac{1}{2}}}{P_{H_2O}}+\frac{RT}{2F}log\frac{P_{CO_2,cathode}}{P_{CO_2,anode}}$$

Materials
Due to the high operating temperatures of MCFC's, the materials need to be very carefully selected to survive the conditions present within the cell. The following sections cover the various materials present in the fuel cell and recent developments in research.

Anode
The anode material typically consists of a porous (3-6 μm, 45-70% material porosity) Ni based alloy. Ni is alloyed with either Chromium or Aluminum in the 2-10% range. These alloying elements allow for formation of LiCrO2/LiAlO2 at the grain boundaries, which increases the materials' creep resistance and prevents sintering of the anode at the high operating temperatures of the fuel cell. Recent research has looked at using nano Ni and other Ni alloys to increase the performance and decrease the operating temperature of the fuel cell. A reduction in operating temperature would extend the lifetime of the fuel cell (i.e. decrease corrosion rate) and allow for use of cheaper component materials. At the same time, a decrease in temperature would decrease ionic conductivity of the electrolyte and thus, the anode materials need to compensate for this performance decline (e.g. by increasing power density). Other researchers have looked into enhancing creep resistance by using a Ni3Al alloy anode to reduce mass transport of Ni in the anode when in operation.

Cathode
On the other side of the cell, the cathode material is composed of either Lithium metatitanate or of a porous Ni that is converted to a lithiated nickel oxide (lithium is intercalated within the NiO crystal structure). The pore size within the cathode is in the range of 7-15 μm with 60-70% of the material being porous. The primary issue with the cathode material is dissolution of NiO since it reacts with CO2 when the cathode is in contact with the carbonate electrolyte. This dissolution leads to precipitation of Ni metal in the electrolyte and since it is electrically conductive, the fuel cell can get short circuited. Therefore, current studies have looked into the addition of MgO to the NiO cathode to limit this dissolution. Magnesium oxide serves to reduce the solubility of Ni2+ in the cathode and decreases precipitation in the electrolyte. Alternatively, replacement of the conventional cathode material with a LiFeO2-LiCoO2-NiO alloy has shown promising performance results and almost completely avoids the problem of Ni dissolution of the cathode.

Electrolyte
MCFC's use a liquid electrolyte (molten carbonate) which consists of a sodium(Na) and potassium(K) carbonate. This electrolyte is supported by a ceramic (LiAlO2) matrix to contain the liquid between the electrodes. The high temperatures of the fuel cell is required to produce sufficient ionic conductivity of carbonate through this electrolyte. Common MCFC electrolytes contain 62% Li2CO3 and 38% K2CO3. A greater fraction of Li carbonate is used due to its higher ionic conductivity but is limited to 62% due to its lower gas solubility and ionic diffusivity of oxygen. In addition, Li2CO3 is a very corrosive electrolyte and this ratio of carbonates provides the lowest corrosion rate. Due to these issues, recent studies have delved into replacing the potassium carbonate with a sodium carbonate. A Li/Na electrolyte has shown to have better performance (higher conductivity) and improves the stability of the cathode when compared to a Li/K electrolyte (Li/K is more basic). In addition, scientists have also looked into modifying the matrix of the electrolyte to prevent issues such as phase changes (γ-LiAlO2 to α-LiAlO2) in the material during cell operation. The phase change accompanies a volume decrease in the electrolyte which leads to lower ionic conductivity. Through various studies, it has been found that an alumina doped α-LiAlO2 matrix would improve the phase stability while maintaining the fuel cell's performance.

MTU fuel cell
The German company MTU Friedrichshafen presented an MCFC at the Hannover Fair in 2006. The unit weighs 2 tonnes and can produce 240 kW of electric power from various gaseous fuels, including biogas. If fueled by fuels that contain carbon such as natural gas, the exhaust will contain CO2 but will be reduced by up to 50% compared to diesel engines running on marine bunker fuel. The exhaust temperature is 400 °C, hot enough to be used for many industrial processes. Another possibility is to make more electric power via a steam turbine. Depending on feed gas type, the electric efficiency is between 12% and 19%. A steam turbine can increase the efficiency by up to 24%. The unit can be used for cogeneration.

title: Molten carbonate fuel cell


text:
Alkaline fuel cell

[[Image:alkalinecell.svg|thumb|270px|Diagram of an Alkaline Fuel Cell:

1. Hydrogen

2. Electron flow

3. Load

4. Oxygen

5. Cathode

6. Electrolyte

7. Anode

8. Water

9. Hydroxide Ions]]

The alkaline fuel cell (AFC), also known as the Bacon fuel cell after its British inventor, Francis Thomas Bacon, is one of the most developed fuel cell technologies. Alkaline fuel cells consume hydrogen and pure oxygen, to produce potable water, heat, and electricity. They are among the most efficient fuel cells, having the potential to reach 70%.

NASA has used alkaline fuel cells since the mid-1960s, in the Apollo-series missions and on the Space Shuttle.

Half Reactions
The fuel cell produces power through a redox reaction between hydrogen and oxygen. At the anode, hydrogen is oxidized according to the reaction:

$$\mathrm{H}_2 + \mathrm{2OH}^- \longrightarrow \mathrm{2H}_2\mathrm{O} + \mathrm{2e}^-$$

producing water and releasing electrons. The electrons flow through an external circuit and return to the cathode, reducing oxygen in the reaction:

$$\mathrm{O}_2 + \mathrm{2H}_2\mathrm{O} + \mathrm{4e}^- \longrightarrow \mathrm{4OH}^-$$

producing hydroxide ions. The net reaction consumes one oxygen molecule and two hydrogen molecules in the production of two water molecules. Electricity and heat are formed as by-products of this reaction.

Electrolyte
The two electrodes are separated by a porous matrix saturated with an aqueous alkaline solution, such as potassium hydroxide (KOH). Aqueous alkaline solutions do not reject carbon dioxide (CO2) so the fuel cell can become "poisoned" through the conversion of KOH to potassium carbonate (K2CO3). Because of this, alkaline fuel cells typically operate on pure oxygen, or at least purified air and would incorporate a 'scrubber' into the design to clean out as much of the carbon dioxide as is possible. Because the generation and storage requirements of oxygen make pure-oxygen AFCs expensive, there are few companies engaged in active development of the technology. There is, however, some debate in the research community over whether the poisoning is permanent or reversible. The main mechanisms of poisoning are blocking of the pores in the cathode with K2CO3, which is not reversible, and reduction in the ionic conductivity of the electrolyte, which may be reversible by returning the KOH to its original concentration. An alternate method involves simply replacing the KOH which returns the cell back to its original output.

When carbon dioxide reacts with the electrolyte carbonates are formed. The carbonates could precipitate on the pores of electrodes that eventually block them. It has been found that AFCs operating at higher temperature do not show a reduction in performance, whereas at around room temperature, a significant drop in performance has been shown. The carbonate poisoning at ambient temperature is thought to be a result of the low solubility of K2CO3 around room temperature, which leads to precipitation of K2CO3 that blocks the electrode pores. Also, these precipitants gradually decrease the hydrophobicity of the electrode backing layer leading to structural degradation and electrode flooding.

$$\mathrm{CO}_2 + \mathrm{2KOH}\longrightarrow \mathrm{K}_2\mathrm{CO}_3 + \mathrm{H}_2\mathrm{O}$$

On the other hand, the charge-carrying hydroxide ions in the electrolyte can react with carbon dioxide from organic fuel oxidation (i.e. methanol, formic acid) or air to form carbonate species.

$$\mathrm{2OH}^- + \mathrm{CO}_2\longrightarrow \mathrm{CO}_3^{2-} + \mathrm{H}_2\mathrm{O}$$

Carbonate formation depletes hydroxide ions from the electrolyte, which reduces electrolyte conductivity and consequently cell performance. As well as these bulk effects, the effect on water management due to a change in vapor pressure and/or a change in electrolyte volume can be detrimental as well.

Basic designs
Because of this poisoning effect, two main variants of AFCs exist: static electrolyte and flowing electrolyte. Static, or immobilized, electrolyte cells of the type used in the Apollo space craft and the Space Shuttle typically use an asbestos separator saturated in potassium hydroxide. Water production is controlled by evaporation from the anode, which produces pure water that may be reclaimed for other uses. These fuel cells typically use platinum catalysts to achieve maximum volumetric and specific efficiencies.

Flowing electrolyte designs use a more open matrix that allows the electrolyte to flow either between the electrodes (parallel to the electrodes) or through the electrodes in a transverse direction (the ASK-type or EloFlux fuel cell). In parallel-flow electrolyte designs, the water produced is retained in the electrolyte, and old electrolyte may be exchanged for fresh, in a manner analogous to an oil change in a car. More space is required between electrodes to enable this flow, and this translates into an increase in cell resistance, decreasing power output compared to immobilized electrolyte designs. A further challenge for the technology is how severe the problem of permanent blocking of the cathode is by K2CO3; some published reports have indicated thousands of hours of operation on air. These designs have used both platinum and non-noble metal catalysts, resulting in increased efficiencies and increased cost.

The EloFlux design, with its transverse flow of electrolyte, has the advantage of low-cost construction and replaceable electrolyte but so far has only been demonstrated using oxygen.

The electrodes consist of a double layer structure: an active electrocatalyst layer and a hydrophobic layer. The active layer consists of an organic mixture which is ground and then rolled at room temperature to form a crosslinked self-supporting sheet. The hydrophobic structure prevents the electrolyte from leaking into the reactant gas flow channels and ensures diffusion of the gases to the reaction site. The two layers are then pressed onto a conducting metal mesh, and sintering completes the process.

Further variations on the alkaline fuel cell include the metal hydride fuel cell and the direct borohydride fuel cell.

Advantages over acidic fuel cells
Alkaline fuel cells operate between ambient temperature and 90 °C with an electrical efficiency higher than fuel cells with acidic electrolyte, such as proton-exchange membrane fuel cells (PEMFC), solid oxide fuel cells, and phosphoric acid fuel cells. Because of the alkaline chemistry, oxygen reduction reaction (ORR) kinetics at the cathode are much more facile than in acidic cells, allowing use of non-noble metals, such as iron, cobalt, nickel, manganese, or carbon-based nanomaterial at the anode (where fuel is oxidized); and cheaper catalysts such as silver at the cathode, due to the low overpotentials associated with electrochemical reactions at high pH.

An alkaline medium also accelerates oxidation of fuels like methanol, making them more attractive. This results in less pollution compared to acidic fuel cells.

Commercial prospects
AFCs are the cheapest of fuel cells to manufacture. The catalyst required for the electrodes can be any of a number of different chemicals that are inexpensive compared to those required for other types of fuel cells.

The commercial prospects for AFCs lie largely with the recently developed bi-polar plate version of this technology, considerably superior in performance to earlier mono-plate versions.

The world's first fuel-cell ship, the Hydra, used an AFC system with 5 kW net output.

Another recent development is the solid-state alkaline fuel cell, utilizing a solid anion-exchange membrane instead of a liquid electrolyte. This resolves the problem of poisoning and allows the development of alkaline fuel cells capable of running on safer hydrogen-rich carriers such as liquid urea solutions or metal amine complexes.

title: Alkaline fuel cell


text:
User:Andre Wong

Andre Wong 01:17, 18 Nov 2004 (UTC)

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title: User:Andre Wong