leonard.kiely.energy.water.spring.2010

= Hydrogen Fuel Cells = = =

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By: Sean Kiely + Richard Leonard

Introduction
In our world today, scientists are constantly trying to find alternative forms of energy. Fossil fuel supplies are becoming more scarce, therefore, a major focus of scientists is to find a way to power cars and other mechanisms without the use of these limited supplies. SInce fossil fuels encouraged global warming as well as pollution (acid rain), inevitably harming us for the long run, scientists want to find an abundant and clean alternative fuel source. Recently, the use of hydrogen fuel cells have become the focus of scientists in their attempts to find this "alternative fuel source." Hydrogen fuel cells is practically an unlimited form of alternative energy that is not harmful or toxic to the envorionment and beneficial to our world.

What is the problem at hand?
The problem with fossil fuels is that this form of energy is becoming more and more scarce. Fossil fuel is a non-renewable energy that pullutes our envoronment and increases global warming. Scientists must fund an alternative source of energy that does not have so many cons and one that will be beneficial for the long run. As the years progress the cost of fossil fuels and other forms of non-renewable forms or energy will only increase, so it is time to find a solution now. Hydrogen fuel cells seem to be the key to our success as an energy craving popullation. Hydrogen is an energy carrier that is very versatille that can be used for all different types of energy. A fuel cell is an energy conversion device that can take holf of hydrogen and use it for powering purposes. Hydrogen fuel cells are what should be looking at in order to solve the problems at hand surrounding the outdated forms of non-renewable energy.

Why fuel cells and how do they work?
Fuel cells can power just about anything that typically uses batteries. The most important device they have the abilitiy to power are cars, trucks, and our many other forms of transportation. Our human society depends on tranportaiton on a day to dat basis, and with fuel cells we can keep this tradition. Fuel cells are the little guys that extract the energy from the hydrogen. They do this by converting the chemical energy of hydrogen into electricity. The resulting by-products; H2O and Heat!...Basically, the use of hydrogen fuel cells would be harmless to our environment. Not only are they good for our planet, but they are 2 to 3 times more efficient than fossil fuels and coal. Not only do fuel cells do all this, but they also operate very very quietly. This is how they work... A single fuel cell is an elecrolyte which is situated between two electrodes....an anode and a cathode. Hydrogen gas flows through channels to the anode, where a catalyst seperates the hydrogen molecules into protons and electrons. The membrane allows for only the protons to pass through. While the protons go through, the negativie electrons follow an external circuit to the cathode. This flow of electons is electricity which therefore, can be used to do work. A picture says a thousand words......



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You may notice Oxygen serving a role in the use of this reaction. Well, on the other side of the cell, O2 (usually drawn from the surrounding atmosphere) flows through channels to the cathode. When the electrons finish doing their work, they react with O and H protons which have also moved through the cathode to form H2O. This is all an exothermic reaction (out heat) which generates heat that can be uses outside the fuel cell.

The majority of hydrogen is locked with water or hydrocarbon fuels. As a result, there is ongoing research into the most effective way of obtaining pure hydrogen. Several current production methods include: Steam reforming: Steam reforming involves burning natural gas in order to obtain hydrogen. CH4(g) + H2O(g) → CO(g) + 3H2(g) + energy Carbon Monoxide (Water Shift Gas Reaction): In this process, oxygen from a water molecule is stripped and bonded to carbon monoxide, freeing up hydrogen. CO(g) + H2O(g) → CO2(g) + H2 + energy Electrolysis: Hydrogen can be made via the electrolysis of water. However, because the electricity consumed during this process tends to be more valuable than hydrogen, very little hydrogen is produced using this method. About 4% of hydrogen is produced from electrolysis. 2H2O(aq) → 2H2(g) + O2(g)

How much power is produced by hydrogen fuel cells?
The amount of power produced depends on several different factors which include; fuel cell type, size, temperature at which it operates, and the pressures of the gasses that are supplied in the process. One fuel cell produces about 1 volt or less. This is not enough to power anything...So these fuel cells are combined in a "stack" or like an assembly line. When scientists use the term "fuel cell" they are usually refering to the entire stack since a single fuel cell does barely anything. When they are ocmbined in stacks of up to hundreds of fuel cells, then they have the ability to power computers, cars, and all sorts of appliances.

Different Types of Fuel Cells:
All fuel cells are made up of an electrolyte and 2 electrodes but there are different types determined by the type of electrolyte used in the process. This difference determines the different chemical reactions that will inevitably take place with in the cell.

__Polymer Exchange Membrane Fuel Cell (PEMFC)__ The Department of Energy is focusing on the Polymer Exchange Membrane Fuel Cell as the most likely candidate for the transportation. The PEMFC has high power output and a relitively low operation temperature between 140 to 176 degrees farenheit. The low operating temperature means that it doesn't take very long for the fuel cell to warm up and begin generating electricity. We?ll take a closer look at the PEMFC in the next section.

__Solid oxide fuel cell (SOFC)__ These fuel cells are best suited for large-scale stationary power generators that could provide electricity for factories or towns. This type of fuel cell operates at very high temperatures (between 700 and 1,000 degrees Celsius). This high temperature makes reliability a problem, because parts of the fuel cell can break down after cycling on and off repeatedly. However, solid oxide fuel cells are very stable when in continuous use. In fact, the SOFC has demonstrated the longest operating life of any fuel cell under certain operating conditions. The high temperature also has an advantage: the steam produced by the fuel cell can be channeled into turbines to generate more electricity. This process is called co-generation of heat and power (CHP) and it improves the overall efficiency of the system.

__Molten-carbonate fuel cell (MCFC)__ Like the SOFC, these fuel cells are also best suited for large stationary power generators. They operate at 600 degrees Celsius, so they can generate steam that can be used to generate more power. They have a lower operating temperature than solid oxide fuel cells, which means they don't need such exotic materials. This makes the design a little less expensive.

__Phosphoric-acid fuel cell (PAFC)__ The phosphoric-acid fuel cell has potential for use in small stationary power-generation systems. It operates at a higher temperature than polymer exchange membrane fuel cells, so it has a longer warm-up time. This makes it unsuitable for use in cars.



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Hydrogen Fuel Initiative (HFI)
The HFI is a program that gained backing from President Bush in 2003. It was supported by the Energy Policy Act of 2005 and the Advanced Energy Initiative of 2006 which attempted to solve problems surrounding non-renewable energies. The HFI focuses on the development of hydrogen as well as the improvement of fuel cell technologies in order to make fuel cell vehicles "cost-effective" by the year 2020. So far, the U.S. government has put in over 1 billion dollars into increased fuel cell research.

"Tonight I am proposing $1.2 billion in research funding so that America can lead the world in developing clean, hydrogen-powered automobiles." "A simple chemical reaction between hydrogen and oxygen generates energy, which can be used to power a car producing only water, not exhaust fumes. With a new national commitment, our scientists and engineers will overcome obstacles to taking these cars from laboratory to showroom so that the first car driven by a child born today could be powered by hydrogen, and pollution-free. Join me in this important innovation to make our air significantly cleaner, and our country much less dependent on foreign sources of energy." -President Bush, State of the Union Address, January 28, 2003.

What is slowing the process of the development of fuel cells???
We are gradually making it happen but money is everything in our society. People are going to buy the item they get the most out of for the amount of money they spend. As it stands now, it is cheaper to buy a car or an appliance that uses non-renewable energy. Another factor is the lack of durability of hydrogen fuel cell systems. They are simply not built to withstand long term strains but future research will hopefully solve this issue at hand. Between these two factors, it is going to take a while for hydrogen fuel cells to be the most common form of energy used but it is definitely in store for us in the future. We will see its popularity increase tenfold in our lifetime and hopefully continued research will go into making it the commonly used form of energy. It's popularity has been steadily growing and will continue to grow in years to come.



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__Pros:__

 * Eco-friendly and do not pose any threat to the environment.
 * Fossil Fuels are non-renewable but hydrogen is plentiful and we will never run out
 * 90-95 % of the energy generated by the fuel cells is transformed into electrical energy...therefore, the cars are very energy efficient
 * Toxic gases are not released into the atmosphere. Only water and heat are released.

__Cons:__

 * $$$$...platinum is involved in the process of fuel cells which is a very expensive element to use.
 * If fuel cells are damaged, the cost to make repairs is very expensive.
 * Hydrogen cars, if they get into a collision, a huge explosion can result. Hydrogen must be stored properly to prevent these massive explosions from even the slightest collision.
 * Temperature restrictions- the water can freeze causing the process to stop working.

"The FCX concept is Honda's latest take on fuel cells. It features a compact, Honda-developed fuel-cell stack in the middle of the car with two hydrogen tanks in the rear. The stack is actually much smaller than is now technologically feasible."
 * Honda FCX Concept....The Future**

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Works Cited:
1. "Emerging Environmental Issues - October 2005." //Joint Service Pollution Prevention and Sustainability Technical Library//. Oct. 2005. Web. 03 June 2010. [].

2. "HowStuffWorks "Hydrogen Fuel Cell Challenges"" //Howstuffworks "Auto"// Oct. 2008. Web. 03 June 2010. [].

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