How does a Van De Graaff Generator work?
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How it works\nThe Van de Graaff generator is powered by a high speed electric motor. It has a belt running on two pulleys. The lower pulley is made of an insulating material and the upper pulley is made of metal. There is a grounded comb close to the belt in front of the lower pulley, and another inside the terminal, close to the belt in front of the upper pulley, connected to the terminal.\n\nAdhesion between the belt and the lower pulley charges the pulley, and it attracts opposite charges to the outer surface of the belt from the grounded comb. The belt then transports these charges to the terminal, where they are collected by the upper comb and transferred to the terminal. The shielding provided by the terminal allows the continuation of the process even if the terminal is already strongly charged. The high speed of the belt, along with the large discharge electrode, allows the continuous buildup of charges and great voltages to be achieved.
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1. Energy cannot be created or destroyed only changed in form. 2. The total energy of any closed system is = 0\n\nA static generator does not create energy it only changes its form from mechanical to electrical.  Search on the web for perpetual motion for a more in depth explanation.\nalso search thermodynamics, first and second laws.
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Simply put, the generator voltage (volts), frequency (Hz) and power (watts) and phase (single/three) are called ratings. These are selected to suit the load that will be connected. and the environment in which it will be used
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Kilowatt\nCost depends on method of generation and location
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http://science.howstuffworks.com/vdg2.htm
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The generator consists mainly of a coil of wire wound over an iron core.This wire is connected to an external circuit where the current produced is either stored in capacitors or used to run a particular device. When the axle of the wire is rotated, magnetic flux linked with the wire changes and hence, according to Faraday's law, an electomotive force(emf) is induced in the wire as it is placed in between magnets having different polarities. Slip rings are present to allow the flow of the alternating current produced into an external circuit.
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You can't make a perpetual-motion machine, if that's what you're getting at. Whatever loop you make, you'll always end up losing energy until it stops, unless you are putting energy in (solar) but then what's the point?
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A voltmeter and an ammeter will provide the input power. You will need some form of dynamometer to measure output power.\n\nOutput power divided by input power yields efficiency.
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http://www.howstuffworks.com\nThey may have a link.\nThey did for building a wind powered generator.
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A generator is a machine that converts mechanical power to electrical power, by making a conductor cut across a magnetic field's lines of force.  This is done by moving either the conductor or the magnetic field.  Current flows in the conductor if its ends are connected to an electrical load thus producing electrical power.  Because an opposing magnetic field is created by the current in the conductor, it requires mechanical energy to maintain this motion.
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First of all the correct name of that machine is "Van De Graaff" Generator; named after the person who invented it.\nSecond, congratulations on your choice. I won a science fair by making one. I can assure you that the home-made ones are safe; the voltage gets high but not the amperage. Actually I play with it, sparkling by my fingers (I do not suggest doing so for a long time). The problem might be that, it terribly ionizes the air; not so good to breathe.\nAnd finally I have build mine base upon the article I have mentioned here as source.
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An induction motor will not work as a generator because there is no way you can create the magnetic field. You need some sort of magnetic field to make a generator work.\n\nIn order to induce a voltage you need three things:\n1. A conductor capable of carrying current\n2. A magnetic field\n3. Relative motion between the two.\n\nA generator either 3 phase or single phase, will have a rotating field. Power to this field is supplied via brushes and slip rings. See if you can find an old alternator from a car to take apart. Alternators are really 3 phase AC generators. The DC for the car is created using a set of diodes that you will find inside of the alternator. The diodes are often encased in plastic.\n\nA drill motor or other motor that has a commutator (a group of coppers bars that run parallel to the shaft) can be modified to be a generator, however it will produce a DC output.\n\n(Added 5/3)\nYou are correct that a voltage will be induced, however it is being induced in a place where you can't get it. An induction motor uses a squirrel cage rotor. When connected properly, the rotating magnetic field of the stator induces a voltage in the rotor. This voltage creates a magnetic field that causes the motor to rotate. However, since there are no slip rings or other connection to the rotor, there is no way for you to draw off the power generated. \n\nTo make a long story short, an induction motor can not be used as a generator. It simply does not have what you need to work.
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You need to know more information.  How many Poles does the Generator have?  How many windings per pole?  Is it synchronous or a-synchronous?  What is the reduction ratio between the turbine and the generator?  Does the generator utilize an armature, brushes, or slip rings?  is the generator self exciting?  At what frequency will the output be?
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The quick answer is no, if you could you'd have invented perpetual motion. \n\nIf the battery has a certain amount of stored energy, when it turns the motor some energy is lost (the motor will be about 80-90% efficient) with the same lost in the generator giving and approximate conversion of 60-80%.\n\nThe batteries themselves will also be inefficient in the charge discharge cycle, more so than the motor-generator combination although I haven't found a specific value. However, whenever you charge a battery it gets warm and this warmth is due to energy losses in the charge cycle. \n\nCoupled to all of these would be electrical losses in the wiring, but these would be minimal compared to the other losses.
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I think you are talking about a Peltier-effect thermoelectric generator, also called a thermocouple.\n\nIf you are using it as a generator and you reverse the hot and cold sides, the polarity of the output voltage is reversed. Similarly, if you are driving the Peltier module it produces heating on one side, cooling on the other. Reverse the current and you reverse the sides.\n\nThe latter effect is employed in the small 12V travel refrigerator/heaters that you can plug into a car's cigarette lighter socket. They have a switch to control whether the insulated box is heated or cooled. The switch reverses the current flow.
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generator.\n\nAn AC generator is turned by mechanical power like steam engine or a jet turbine. When its coils spin in a magnetic field, electricity is generated\n\n\nz
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A generator produces a current by moving a wire through a magnetic field.  If you had an infinitely large magnetic field, you could move in one direction forever and produce a dc current.  However, it isn't practical to do that.\n\nInstead, you put a ball of wire inside a much smaller magnetic field and you spin it.  The ends of the wire have to be touching something to complete the circuit so electrons can flow.  At one part of the circle, the wire is moving left to right across the magnetic field and causes electrons to flow in one direction in the wire, in another part of the circle, the wire is moving from right to left and the electrons flow in the opposite direction.  This is what causes the current to alternate.\n\nSo, when converting motive energy into electricity, ac current is the easiest to produce.  This is like what is produced by a car's alternator or a hydro-electric plant.