Electrode
An electrode is a conductor used to make contact with a nonmetallic part of a circuit (e.g.
a semiconductor, an electrolyte or a vacuum). The word was coined by the scientist
Michael Faraday from the Greek words elektron (meaning amber, whence the word
electricity is derived) and hodos, a way [1].
Anode vs. cathode in electrochemical cells
An electrode in an electrochemical cell is referred to as either an anode or a cathode,
words that were also coined by Faraday. The anode is defined as the electrode at which
oxidation occurs, and the cathode is defined as the electrode at which reduction occurs.
Each electrode may become either the anode or the cathode depending on the type of
reaction occurring in the cell.
A primary cell is a special type of electrochemical cell in which the reaction cannot be
reversed, and the identities of the anode and cathode are therefore fixed. It can be
discharged but not recharged.
A secondary cell, for example a rechargeable battery, is one in which the reaction is
reversible. When the cell is being charged, the anode becomes the positive (+) electrode
and the cathode the negative (-). This is also the case in an electrolytic cell. When the cell
is being discharged, it behaves like a primary or voltaic cell, with the anode as the
negative electrode and the cathode as the positive.
Other uses of anode and cathode
In a vacuum tube or a semiconductor having polarity (diodes, electrolytic capacitors) the
anode is the positive (+) electrode and the cathode the negative (-).
In arc welding an electrode is used to conduct current through a workpiece to fuse two
pieces together. Depending upon the process, the electrode is either consumable, in the
case of gas metal arc welding or shielded metal arc welding, or non-consumable, such as
in gas tungsten arc welding.
Anode
Diagram of a zinc anode
An anode (from the Greek άνοδος = 'going up') is the positive electrode in an electrolytic
system or circuit. Literally, the path through which the electrons ascend out of an
electrolyte solution.
In electrochemistry, the anode is where oxidation occurs and is also the negative
discharge plate in an electrochemical cell. In charge mode the flow reverses and this plate
becomes the cathode. In electronic circuits such as a cathode ray tube or a diode, the
anode is the positive plate.
In solution negatively charged particles -Anions, flow to the anode. In tubes or circuits
electrons flow to the anode.
cathode
Diagram of a copper cathode
In chemistry a cathode is the electrode of an electrochemical cell at which reduction
occurs. It comes (from the Greek word κάθοδος = 'going down'). In an electrolytic cell
the cathode is negatively charged and in a galvanic cell the cathode is positively charged.
The oppositely charged electrode in that same cell is referred to as the anode.
In physics a cathode is an electrode in a vacuum tube or other vacuum system which
produces electrons. Electrons are extracted from metal electrodes either by heating the
electrode, causing thermionic emission, or by applying a strong electric field and causing
field emission.
Cathodes used for field emission are called cold cathodes. Heated electrodes, frequently
called filaments, are much more common. They form the source of the electron beam in
cathode ray tubes and the electrodes for fluorescent lamps.
About Fuel Cells:
http://en.wikipedia.org/wiki/Fuel_cell
Reserves:
http://www.umich.edu/~gs265/society/fossilfuels.htm
Source of Fossil Fuels
http://www.energyquest.ca.gov/story/chapter08.html
A Learning page for Fossil Fuels
http://www.schoolscience.co.uk/content/4/chemistry/fossils/
Fuel Cells Working with a clear picture
http://www.ucsusa.org/clean_vehicles/cars_pickups_suvs/how-a-fuel-cell-works.html