Fuel+cell

__**FUEL CELLS**__ __**TABLE OF CONTENT**__ //1. SUMMARY AND HISTORY 2. DESIGN/STRUCTURE 3. ELECTROLYTE// //4. DESIGN CHALLENGES 5. SOLID OXIDE FUEL CELLS 6. EFFECT ON GLOBAL WARMING 7. HYDROGEN ECONOMY 8. REFERENCES//

__**SUMMARY/HISTORY**__ The United States government in 2003 formed the Hydrogen Fuel initiative (HFI), which aimed at the development and research of hydrogen fuel cells that can be practically applied to everyday life, cost efficiently. This government funded program over the last five years expended over $1.2 billion ([|nice 1/]). Hoping to make fuel cell technology a commercial competitor with oil and natural gas. And in the long run, by 2020, replace oil and natural gas all together. The Fuel cell works on the basis of converting chemical energy into electrical. Taking hydrogen molecules and combining them with oxygen and in result producing water, heat, and energy. Another electrochemical device you might be familiar with is an average battery. The battery works on a lot of similar concepts as the fuel cell. The Fuel cell, or it’s base technology, has been around for a while now. In the 1960s NASA used an Alkline Fuel cell to power the craft that took man to the moon. It was a beneficial technology in those circumstances as its byproduct was clean water and heat, needed resources for the journey. This old fuel design quite efficient as 70% of energy produced becomes electricity ([|nice 1/]). Despite this, these fuel cells are very expensive as well as flawed. Currently, Polymer exchange membrane fuel cells or PEMFC, are the most looked as possible alternatives for natural gas in cars. The positive of using these cells is that they are able to work at lower operating temperatures. (60-80 degrees Celsius). Generating these temperatures is a lot more practical in a setting like a car. Other fuel cells like, s** olid oxide fuel cells, require temperatures between 700-1000 degrees Celsius. Fuel cells like SOFC are likely to be used in large stations to prodoce electricty for homes and buildings. We’ll look into the differences between each fuel cell later ([|nice 1/]). **  **media type="youtube" key="oy8dzOB-Ykg" height="344" width="425"

__DESIGN/STRUCTURE__** The basic design of all fuel cells is pretty much the same, the only real difference is what they are made out of, specificly the electrolyte. Their structure and the concept on which they work on is overall quite simple //([|nice 1]).// Just like a battery, the idea is to have electrons move from positive to negative and inbetween have some sort of resitor to use that energy in a mechincal fashion. The question is how do you extract these electrons from elements such as hydrogen and how do you have them move from postive to negative. A fuel cell consists of four parts, the anode is part which contains the hydrogen. The anode spreads the hydrogen over a catalyst -- through channels that are etched into it -- evenly. When the hydrogen comes in contact with the catalyst, in the case of a PEMFC it’s a platinum coated carbon paper plane, The Hydrogen molecules (H2 ) breaks down into hydrogen cations and electrons. The postively charged cations make there way through the electrolyte to the other side of the cell called the cathode. The reason they do this is because the the Proton Exchange membrane is a conductive material and thus provides a pathway along which protons can move. When they reach the other side two "waste products" (heat and H2 O) are created. The electrolyte is a material which only conducts other postive materials, so the electrons can’t go through. The electrons are repeled and in result forced to find another way to the postively charged cations which are moving (instantaneously) to the Cathode. The electrons take a detour through an external circuit which is attached to something that will hopefully use the electrical energy. In the Cathode the cations (H+) and electrons reattach with oxygen already in the Cathode to produce clean water (nice 2)//.// (note that in Alkalline, molten, and solid oxide fuel cells the negative ions move throught the electrolyte)  

 Anode: 2h2 => 4H+ + 4e-  © 2000 //How Stuff Works//
 * __Chemical Reactions__**
 * Cathode: O2 + 4H+ + 4e- => 2H2O **
 * Net reaction: 2H2+O =>2H2O **

The main difference between every kind of fuel cell is its the electrolyte; a crucial and deceive part of the fuel cell. In a PEMFC, the electrolyte consists of a Polymer, thus the name Polymer Exchange Membrane Fuel Cell. To really understand why the PEMFC is so favored over other fuel cells (when used in cars and appliances) it's important to understand the chemical and physical properties of the electrolyte. The electrolyte in PEMFCs consists of a //polymer that is modified by// //substituting fluorine for the hydrogen ([|Larminie 102])//. This process is called perflourination and it’s used to form stronger bonds among compounds. The resulting polymer after perflourination is called polytetrafluorethylene or more commonly known as teflon. Due to teflon's strong bonds it's very durable and tough. As well important is the fact that it’s a hydrophobic material. This means that when the hydrogen cations, electrons and oxygen unite, the resulting water won’t flood the cell; it "pushs" the water from the cathode and keeps any excess water out of the electrolyte. To complete the Electrolyte, a SO3 - molecule is added to the molecular chain of the teflon. A significant feature of SO<span style="font-weight: normal; font-size: 12pt; color: black; font-family: 'Times New Roman'; mso-ansi-language: EN; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;">3 - is that it's a hydrophyllic structure meaning that it attracts water. the effect of a hydrophillic material in a mostly hydrophobic enviroment is that it absorbs any excess water that might have gotten into the electrolyte. It maks the H<span style="font-weight: normal; font-size: 12pt; color: black; font-family: 'Times New Roman'; mso-ansi-language: EN; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;">2 O molecules clump near the SO<span style="font-weight: normal; font-size: 12pt; color: black; font-family: 'Times New Roman'; mso-ansi-language: EN; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;">3 - ion. Even though the hydrogen cations have an attraction to the SO<span style="font-weight: normal; font-size: 12pt; color: black; font-family: 'Times New Roman'; mso-ansi-language: EN; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;">3 - they rarely form bonds since the region around the SO<span style="font-weight: normal; font-size: 12pt; color: black; font-family: 'Times New Roman'; mso-ansi-language: EN; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;">3 - is ussually hydrated (surounded by water), due to it's hydrophillic properties. The water, is a requirement for the electrolyte, because it works as a conductor and helps move the cations through the electrolyte. These regions in the electrolyte become over time dry and the level of conductivity decreases. A Fuel cell therefore must stay hydrated however, there must not be so much water that the electrolyte floods. A //balance is needed, which takes care to achieve (//[|//Larminie 104//]//).// <span style="font-size: 160%; font-family: 'Arial Black', Gadget, sans-serif;"><span style="font-size: 12pt; font-family: 'Times New Roman', Times, serif;">__DESIGN CHALLENGES__ There are many challanges that engineer face when constructing full cells. One major problem is how to keep the Electrolyte hydrated. If you remember the Hydrogen cations are attracted to the SO<span style="font-weight: normal; font-size: 12pt; color: black; font-family: 'Times New Roman'; mso-ansi-language: EN; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;">3 - molecules, since they have opposite charge. The cations while passing through the electrolyte tend to //pull water molecules with them. This process is called 'electro-osmatic drag' ([|Larminie 104]).// another thing to remember is that fuel cells require a high temperature to operate (due to various thermochemical reasons). Though as you proubably know, as you approach high temperatures, specifically 100 C, water in the fuel cell evaporates. Another thing that is important to relieze is that fuel cells aren't cheap, they are composed of precious materials and their overall difficult to make and up keep. //For PEMFC systems, proton exchange membranes, precious metal catalysts (usually platinum), gas diffusion layers, and bipolar plates make up 70 percent of a system's cost [Source:// [|//Basic Research Needs for a Hydrogen Economy//]//].([|Nice 6).]//These plates consist of platinum, the same platinum you might find in a medal to contest or competion. The job of the plates is to seperate the electron from the hydrogen cation in the Anode. To keep hydrogen in the tank is just as complicated and expensive. Hydrogen beinging the smallest element can pretty much leak out of anything, for that reason it has to pressurized. You don't want to park your car and then come back to it with the tank empty. If Fuel cells become standard, car designers will have to come up with new car designs as the fuel cells changes the interior mechanics of a car and the general placement of various parts. <span style="font-family: Cambria; mso-ascii-theme-font: minor-latin; mso-hansi-theme-font: minor-latin; msoasciithemefont: minor-latin; msohansithemefont: minor-latin;"><span style="font-size: 12pt; font-family: 'Times New Roman', Times, serif;"> Solid oxide fuel cells are used in large scale heating of buildings. These fuel cells generate enormous amounts of energy of up to 2 megawatts but operate at extremely high temperatures; between 500 and 1,000 degrees Celsius. There are several reasons why the study of fuel cells in going in the direction of solid oxide fuel cells. One advantage to the creation of Solid Oxide fuel cells is that they use readily available solid oxide as opposed to the more restricted amounts of hydrogen available on the earth. The second advantage is that they operate with very high efficiency; of around 40-60% unassisted but that number can get up to 70% if you harness the energy of the output gas with a turbine ([|De Guire]). This gas would be in the form of steam, which could be used for hot water or to harness more energy.
 * __ELECTROLYTE__**
 * __ SOLID OXIDE FUEL CELLS __**

<span style="font-size: 12pt; font-family: 'Times New Roman', Times, serif;"><span style="font-size: 12pt; font-family: 'Times New Roman', Times, serif; msoasciithemefont: minor-latinmso-hansi-theme-font;">The amount of energy and efficiency of the SOFC’s is incomparable by the other large-scale fuel cells available today. The incredible amount of efficiency and the close to nothing emissions would, if implemented in all large buildings, would cut our greenhouse gas emissions severely. These greenhouse gases are what is causing the global warming because of their ability to let heat through the atmosphere, but not allow it out. The U.S. Environmental Protection Agency estimated that the U.S. carbon dioxide levels have raised 20% between 1990 and 2004 ([|Birnbaum]). This carbon dioxide comes from the burning of gases for heat and energy. A German paper by U. Birnbaum says that the maximum amount of carbon dioxide avoided by implementing residential fuel cells is around 54 million tones and a minimum of around 12 million tones by 2050 ([|Birnbaum]).

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<span style="font-size: 12pt; font-family: 'Times New Roman', Times, serif;">[|SOFC's are fairly simple in how they work.]They are constructed of two electrodes on either side of an electrolyte. Then air flows over the cathodes, causing a reaction between the oxygen molecules and the cathode where four electrons are transfered from the oxygen molecule to the cathode. These electrons then go to the other side of the cell and go over the anode. This is where the important reaction occurs. The oxygen reacts with the anode and produces the electrons among other results. The electrons are then harnessed by an external circuit and are put to use. [|(De Guire, 1)]

The technology involved with SOFC's is advancing at a very quick pace. There are designs being created for tubular SOFC's which will be more efficient in storage and in harnessing heat and electrons. One company that is currently developing this technology is [|Siemens Westinghouse]. They have been experimenting with this tubular technology since the late 1970's and are just now harnessing its full potential. The operational system remains relatively similar to the flat SOFC's except for that there is a mix of oxygen and steam passing through the center of the tubes. The result when all of the tubes are connected is that there will be almost no lost oxygen in the system; it will all be used.

__**EFFECT ON GLOBAL WARMING**__ The future of the fuel cell industry is to get as many engines as possible to run off of fuel cells. The hope is that all home energy sources will become fuel cells to get away from the dependancy on oil for power in our country and the rest of the world. According to SECA, there will be a doubling in the amount electricity worldwide in the next 20 years. The best thing for us to do is decrease our reliance on oil and to increase our production of energy through fuel cells. There are also plans for the fuel cells to become easily transportable for trucks and cars. The plan for trucks is to get smaller SOFC's to run the air conditioning and interior electronics. With more than 600 million cars in the world (a number which is still going up) there is huge incentive for automobile companies to put out a car that has little to no emissions. Finally the military would benefit largely because of the introduction of personal SOFC's. The military could use them for power in practically every location, they have little pollution, and generate no noise. Finally it is reported that 70% of the militaries moving cost comes from the need for them to move fuels to remote locations.

<span style="font-size: 12pt; font-family: 'Times New Roman', Times, serif;">This graph represents the levels of CO2 in the atmosphere by the red line (parts per million) and the average temperature on the up and down bar. From the year 1000 to 1900 there looks to be no sever difference in the temperature of levels of CO2. But, when the industrial age comes in the early 1900, there is a huge spike in both CO2 levels and temperature change. This is due to the enormous levels of CO2 being put into the air through thousands of factories worldwide. The worst part of this situation is that the global warming and raising levels of CO2 won't be stopping any time soon. It was predicted by the International Panel on Climate Change in 2007 that the rising CO2 levels will cause global warming, which will cause fo the sea levels to rise anywhere from 0.59 feet to 2.0 feet. This number needs to be kept as low as possible and with the number of factories and cars increasing in our nation and worlds daily, there is need for a dramatic change in the way that we are getting energy. One possible solution is to make rapid use of Fuel Cells technology. These Fuel Cells will hopefully eliminate much of the alarming levels of CO2 being put into the atmosphere through factories and cars. (//more specifics on the greenhouse effect)//

__HYDROGEN ECONOMY__ A hydrogen economy is the distrubition of energy through hydrogen (Russell 135). To make the change from a fossil fuel economy, currently in place, into a hydrogen economy will take some adjusting and revaluating. The current economic and politcal infustructure of the world makes it very difficult to make a sudden change from one to the other. The desired end result is to create a system of stations, some maybe even in our homes, that generate relatively pure hydrogen that could be applied to our cars and appliances. Currently the two most widely used techniques in extracting hydrogen are electrolysis of water and reformation of fossil fuels, the latter is more common; both have their share of problems. Reformation of fossil fuel is overall quite the backwards step becuase it goes opposite of the intended goal. Oil and natural gas contain hydrocarbons or molecules containing hydrogen and carbon. Using a reformer these hydrocarbons are split into hydrogen and carbon, hydrogen is kept for later use but the leftover carbon is released into the atmosphere as carbon dioxide, the final result is just furthur contribution to global warming ([|Brain 5]). A possible solution is the use of carbon capture technology that will work coefficently with the reformer. A sort of carbon scrubber that absorbs the CO2 before it is exausted. This would improve the enviormental cleanliness of fuel cells so that there would be almost no harmful environmental impact. The other option is the use of electrolysis. Again though you have to ask where will the electricty for the process comes from. Today most electricity is produced through coal and natural gas. Electricity CAN be produced in other ways specificly through renewable resources like wind, solar, geothermal, and water powered turbines, which is how electricity needs to be made if a totally non-pollutant system was to be achieved.

Brain, Marshall. "How the Hydrogen Economy Works." __Howstuffworks "Auto Channel"__ Howstuffworks inc. 04 Apr. 2009 <http://auto.howstuffworks.com/hydrogen-economy4.htm>.
 * __REFERENCES__**

"Distributed Energy Resources Guide: equipment - Fuel Cells." __California Energy Commission Home Page__. 19 Aug. 2003. California Energy Commission. 04 Apr. 2009 <http://www.energy.ca.gov/distgen/equipment/fuel_cells/fuel_cells.html>.

<span style="font-family: Cambria; mso-bidi-font-size: 13.0pt; mso-ascii-theme-font: minor-latin; mso-hansi-theme-font: minor-latin;">De Guire, Eileen J. "Solid Oxide Fuel Cells." __CSA__. Apr. 2003. 17 Jan. 2009 <http://www.csa.com/discoveryguides/fuecel/overview.php?SID=mtmlpcnc6nv486e5mh9i65gne7>.

Birnbaum, U. "REDUCTION OF GREENHOUSE GAS EMISSIONS THROUGH." __Fuel Cells__. 19 June 2008. 17 Jan. 2009 <http://www.fuelcells.org/info/residentialsavings.pdf>. Nice, Karim, and Jonathan Strickland. "How Fuel Cells Work." 18 September 2000. HowStuffWorks.com. <http://auto.howstuffworks.com/fuel-cell.htm> 21 January 2009.

<span style="font-size: 12pt; font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;">Larminie, James, and John Lowry. __Electric Vehicle Technology Explained__. New York: John Wiley & Sons Australia, Limited, 2003. Jones, Russell H. __Materials for the Hydrogen Economy__. Null: CRC, 2007.

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