Energy Storage category at Future Energies, on-line magazine. Covers fuel cells, hydrogen, and batteries.
Hydrogen as a Secondary Fuel Large color photograph of the Hindenberg burning, with lecture notes on Hydrogen for Fuel Cells. Large Print, with an e-mail contact
Wikipedia Links
Fuel Cell A fuel cell is an electrochemical device similar to a battery, but differing from the latter in that it is designed for continuous replenishment of the reactants consumed; i.e. it produces electricity from an external fuel supply as opposed to the limited internal energy storage capacity of a battery.
Biological Fuel Cell A Biological fuel cell is a type of fuel cell that uses bacteria to reform glucose into hydrogen, or directly extract energy from the glucose.
See also:
* Microbial fuel cell
Microbial Fuel Cell A microbial fuel cell exploits electrical currents generated by bacteria.
See also:
* Biological fuel cell
Electro-Galvanic Fuel Cell An electro-galvanic fuel cell is an electrical device used to measure the concentration of oxygen gas in SCUBA diving and medical equipment.
A chemical reaction occurs in the fuel cell when the potassium hydroxide in the cell comes into contact with oxygen. This creates an electric current between the lead anode and the gold-plated cathode through a load resistance. The voltage produced is proportional to the concentration of oxygen present.
By doing hydrolysis "backwards" the reversible fuel cell works as a hydrogen generator. In other words, hydrogen is produced within the cell itself. The only reactants required to perform this reaction are water and, in some cases, a slight acidic medium. This is a very new technology and is still considered by many to be too inefficient and expensive for mass production and personal use.
Several steps that outline the process:
Water Fuel Cell The water fuel cell is an electrolysis device which is claimed to break water into hydrogen and oxygen gas using less energy than the energy present in the bond itself. The Water Fuel Cell was claimed to produce several times more energy than it consumed. Since this violates the current theories of conservation of energy, it is most likely a hoax. Stanley Meyer invented it and was granted patents in 1989 & 1990. (Note that a patent merely gives the inventor exclusive rights to his/her idea. It does not imply that the idea actually works.)
Fuel Cell (Disambiguation) Fuel cells can mean several things: * Electrochemical fuel cell * A fuel storage device, typically the gas tank on a vehicle
Proton-Exchange Fuel Cell Proton-exchange fuel cells, also known as Polymer Electrolyte (Membrane) Fuel Cells ("PEM" or "PEMFC") are low temperature fuel cells which are being developed for transport applications as well as for stationary applications. In this fuel cell, hydrogen is split at the anode (which in practice is a thin layer of catalyst on the polymer membrane's surface) into protons, that travel across the membrane to the cathode (similar or identical to the anode layer) where they combine with oxygen and electrons (which have travelled to the cathode from the anode via an external "load" circuit) to create water, the cell's only product when using pure hydrogen. To function the membrane must conduct hydrogen ions (protons) but not water molecules or electrons as this would in effect "short circuit" the fuel cell. The oldest and most commonly used membrane is Nafion by Dupont.
Direct-Methanol Fuel Cell A subcategory of Proton-exchange fuel cells is the DMFC, or direct-methanol fuel cell; here, the methanol is not reformed, but fed directly to the fuel cell. One does not need complicated catalytic reforming, and storage of methanol is much easier than that of hydrogen because it does not need to be done at high pressures. The energy density of methanol (the amount of hydrogen in a given volume) is orders of magnitude greater than even highly compressed hydrogen. However, efficiency is low, due to the high permeation of methanol through the membrane, and the dynamic behaviour is sluggish. Methanol is also extremely poisonous.
Phosphoric-Acid Fuel Cells Phosphoric-acid fuel cells (PAFC) are a type of fuel cell that uses a sponge soaked in phosporic aicid as an electrolyte. They are not affected by carbon monoxide impurities in the hydrogen stream. They require platinum catalysts, which drives up the price. Unfortunately, the phosphoric acid solidifies under 40ºC, making startup very difficult. They have been used for stationary applications with an efficiency of about 40%, and many believe they do not offer much potential for further development.