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  • Inside It: Fuel Cells

    raj87verma88

    Member

    Updated: Oct 26, 2024
    Views: 2.7K
    This is an article I completed yesterday. It is to be published in a magazine. Thought I would share with all of you and add it to the "Inside It" series list. Hope people like it.
    ​
    Fuel Cells​
    (Sources: Principles of Fuel Cells by Xiango Li, Fuel Cell Projects for the Evil Genius by Gavin D.J. Harper)
    ​
    Fuel Cells are environmental friendly devices for energy conversion and zero emission power generation. In fact they have been described as the energy technology of the future. It is a slight misnomer though, due to the fact, that the basic principle of fuel cell was discovered in 1838 by German scientist Christian Friedrich Schonbein and the first fuel cell was demonstrated in 1839 by Welsh scientist Sir William Robert Grove. The development of fuel cell technology slowed down due to the more reliance on heat engines (steam engines, internal combustion engines) and fossil fuels, which were at that time readily available.
    The extensive and exclusive use of fossil fuels has left a deep mark on our environment and this will continue to deepen unless and until we do something to stop it. Air pollution due to pollutant emissions like SOx, NOx, CO and particulates is a series threat. Moreover, global warming is threatening our very existence on earth. In addition to all this the fossil fuels we use are not unlimited in supply. They are depleting at an exponential rate and we need to look at better, environment friendly and more economic substitutes.
    Fuel Cell technology has been recognized as a promising future technology for this purpose and it meets all our energy requirements.
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  • raj87verma88

    Member • Jul 23, 2009

    What are Fuel Cells and how do they work?
    They are electrochemical devices that directly convert chemical energy from reactions to electrical energy. It produces electricity when fuel (which basically contains Hydrogen) on the anode side and an Oxidant on the cathode side react in the presence of an electrolyte which is sandwiched in between. The residual products of this reaction are electricity, water and heat.

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    Fuel Cell is only an energy conversion device i.e. it converts energy from one form to another subject to constraint that the reactants are supplied continuously. The reactants (fuel and oxidant) are stored outside fuel cell and the products of the electrochemical reaction are rejected from the fuel cell.
    A fuel cell can produce electricity as long as the reactants are supplied. Because reactants are stored externally, the amount of useful energy derivable from a fuel cell is inexhaustible as long as the reactants are available.
    The life of a fuel cell is unlimited in theory as long as the reactants are supplied and products are expelled out. But, this is only good in theory because in practical application due to degradation of parts with time the fuel cell like all appliances has an operational life after which it has to be replaced.
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  • raj87verma88

    Member • Jul 23, 2009

    Why Fuel Cell?
    Now, the question arises why fuel cells, when we can tap into more vast resources like wind, hydro, solar, bio energy etc. Moreover, these various alternate forms of energy are being used worldwide for power generation. They are easy to use and generate electricity for utility application, but are subject to seasonal and irregular fluctuation with respect to the amount of energy available and are limited in the quantity of harvestable energy. Further more, they are more suited for power generation and their use is virtually impossible with respect to direct utilization of power as in transportation application, which is a significant source of environment pollution.
    It has been proposed that the most promising option is to use hydrogen as an energy carrier, produced from renewable energy sources, and to adopt fuel cells as a clean and effective means for energy conversion and power generation for mobile applications.
    They also poses many advantageous characteristics like high conversion efficiencies, are environment friendly and might help to eliminate our dependence on fossil fuels. Furthermore, they are flexible and can fit into a variety of applications such as on site, distributed and dispersed generation as well as co-generation, without the need of a long distance power transmission network. And, they are compatible with renewable energy sources and carriers for future energy security, economic growth and sustainable development.
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  • raj87verma88

    Member • Jul 23, 2009

    Applications of Fuel Cells
    As we know fuel cells produce power on demand and can be used to supplement power or in a diverse situation where other methods of power generation are unable o meet the specific requirements.
    The majority applications may include:-

    • Residences. A fuel cell of size range around 1-5 kW is available for residential houses in cities. It operates on natural gas. The unit will be inside the house and connected to the electric grid. When a household needs extra power for a short time, it can tap into the grid. Moreover, the waste heat can be used for various purposes like room heating, water boiling etc. The house owners could even sell the unused power.
    • Commercial power plants made of fuel cells in the size range of 200 kW to 1 MW.
    • Transportation. Buses and commercial vehicles running on fuel cells have been demonstrated successfully. Boats and ships can also be run by fuel cells.
    • Space Exploration. Fuel Cells have been used in this field since 1964
    • Defense. Submarines running on Fuel Cells would be less noisy and easy to hide because of the low thermal signatures.
    • Small fuel cells for running cell phones, laptops etc.
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  • raj87verma88

    Member • Jul 23, 2009

    Summary
    We see that the fuel cells have a tremendous scope and can be considered as serious contenders in our search for better energy sources to power our daily lives. A lot of research has been done, a lot is being done and lot will be done. R&D is being done to make them even more cost effective and efficient. There are different varieties of fuel cells in existence and each has its pros and cons and is suitable for use in different applications. The fuel cells could be the answer for our search for clean energy.


    Conclusion
    Fuel Cell technology was discovered a long while ago but was allowed to stagnate. During those times environmental pollution had not been recognized. Times have drastically changed. Now, environmental pollution is accepted as one of the greatest hazards to human survival. All out efforts must be made to exploit and utilize fuel cell technology for commercial purposes and for every day use.
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  • gohm

    Member • Jul 23, 2009

    Nice one Patty, great job!
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  • durga ch

    Member • Jul 23, 2009

    Raj, may be this sounds lame, but current batteries what we use are also kind of chemical -electrical energy conversants right? i am talking about lithiom ion batteries. So is it like the basic reactants are different with the end result being same?
    one more thing: though it is inexaustable. you have specified the clause stating as long as we have reactants.. so its not actaully in exhaustable right? I am refering in context of solar or wind energy which in my view are inexhaustable. infact even they get exhausted i think, and one more thing, is is replenishable ? can the by products be re used as reactants?
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  • raj87verma88

    Member • Jul 23, 2009

    Thank You Gohm.
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  • raj87verma88

    Member • Jul 23, 2009

    Answers to Durga's Questions

    Ans1 Fuel Cell and Batteries are similar in a lot of ways. Both are electrochemical devices and produce electricity directly from electrochemical reactions. The components like electrodes and electrolytes are common to both. But this is where the similarity ends.

    A battery is an energy storage device. The maximum amount of useful energy depends on the amount of reactants stored in the battery. Even in theory the lifetime of a battery is limited and depends on the amount of reactants stored. Since both fuel and oxidant are stored inside together, a very slow reaction takes place which corrodes battery parts. This leakage of useful energy under no-load conditions further reduces the operational life of a battery. Also the electrode of a battery is not stable during energy conversion and is consumed and has to be changed after some time.

    On the other hand, reactants are stored outside in a fuel cell and the products of reaction are expelled out. It produces energy as long as the reactants are available. Because they are stored externally, the amount of useful energy producible is virtually infinite as long as the reactants are available. And in theory the life of a fuel cell is unlimited but as you know everything degrade with time and so do fuel cell parts. But the total life of a fuel cell is much longer than a battery. Since there is no leakage in a fuel cell therefore he parts do not corrode. Also the electrode of a fuel cell is stable and is not consumed in the reaction and need not be changed.
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  • vivekk

    Member • Aug 22, 2009

    Re:Fuel Cells vehicles

    What is a fuel cell ?
    A fuel cell harnesses the chemical energy of hydrogen and oxygen to generate electricity without combustion or pollution. The only by products are pure water and useful heat.

    q Working of fuel cell:

    A fuel cell produces electricity directly from the electrochemical reaction between hydrogen from a hydrogen-containing fuel and oxygen from the air. Like an internal combustion engine, it turns fuel into power by doing something to the fuel to make it release energy. The electrochemical reaction is the reverse of what occurs when electricity is used to produce hydrogen and oxygen. In a conventional car engine, what happens is combustion: the fuel burns in tiny explosions that push the pistons up and down. When a fuel burns, it is being oxidized. That is, the fuel combines with oxygen and, as a result, produces energy. In a regular car (internal combustion) engine, this energy takes the form of heat and kinetic energy (the mechanical motion). In a fuel cell, the fuel is also oxidized, but the resulting energy takes the form of electricity (plus a little heat). A fuel cell power system has many components, but its heart is the fuel cell stack. This stack is actually made of many thin, flat cells layered together. (The term. fuel cell. is often used to refer to the entire stack, but, strictly speaking, it refers only to the individual cells.) Each cell produces electricity, and the output of all the cells is combined to power the vehicle. Each cell contains several layers of different materials. Some layers help start the reactions that produce electricity; these are called catalysts. Each cell is supplied with hydrogen (from the fuel) and oxygen (from the outside air). The hydrogen moves through the cell and encounters the first of two catalyst layers. The catalyst causes the hydrogen molecules to release electrons and protons, creating the electrical current that powers the car. The protons migrate through the electrolyte to the second catalyst layer where they react with oxygen to form water. Most of the water is collected and reused within the system, but a small amount is released in the exhaust as water vapor. Other layers of materials called bipolar plates are designed to help draw fuel and air into the cell, and to conduct electrical current through the cell.







    q Advantages of fuel cell vehicles:

    Compared to internal combustion engine vehicles are

    · Direct energy conversion (no combustion).​


    · No moving parts in the energy converter, quiet, and fuel flexibility.



    · The fuel cell vehicles can dramatically lower energy use, lower air ​

    pollution, and increase the use of alternative fuels.

    · The fuel cell efficiency does not decrease sharply as the size of the
    system is decreased.

    · The fuel cell efficiency does not appreciably change if the fuel cell
    operates at part load. Under comparable road load conditions, the
    fuel cell efficiency is significantly greater than the efficiency of
    internal combustion engines, especially at part load. At a nominal
    driving speed of 30 mph, the efficiency of fuel cell electric drive
    using Hydrogen from natural gas is about two times higher than that
    of a conventional engine.

    · Replacement of ICE with fuel cell system could save 60% of the
    primary energy consumption, the CO2 emission can be reduced by
    about 75%, and release of toxic substances could be largely reduced
    q Disadvantages of hybrid vehicle:

    · The system can be very heavy and bulky (especially batteries) and very costly and require a complex control system.

    · The series hybrid driven systems overall efficiency remains low in spite of the ability to run the ICE at constant speed because of the series losses inherent in the design. However recent advances in lower cost electronic controllers and some battery storage advancements have made the prospects for hybrid driven vehicles more plausible.
    · The relative magnitude of added weight is much greater for passenger car than a truck, or city bus, although some of this penalty may be offset by downsizing (e.g. engine battery, fuel tank) some of the components used in conventional vehicle.

    · Other disadvantages may include noisier operation (than conventional vehicle), safety implications of the energy storage system, size and packaging constraints and the requirement for additional maintenance.
    Above mentioned shortcomings are being overcome by new technologies day by day and “Environmentally friendly cars will soon cease to be an option, they will become a necessity.”

    Ä REFERENCES

    v www.exxonmobil.com

    v SAE Technical paper (2000-01-0369)
    Propulsion technologies for fuel cell vehicles.

    v www.ott.doe.gov

    v www.state.hi.us\dbedt\ert\cc\
    Vehicle fact sheet
    v Alternative engines for road vehicles
    -M.L.Poulten.
    -Computational Mechanics Publications
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