how does a turbine generate electricity?

I teach ESL to adults. One of my students is a Japanese engineer.

I asked him how electricity is made. He struggled mightily with his limited English to explain it to me, but failed.

He told me that there are three kinds of energy: magnetic, kinetic, and electrical current. There is, apparently a law that states that, in order to creat one, you need the other two.

He said a generator has a cylinder with a wire coiled around it and a magnet inside (energy 1). The cylinder is then spun by one of several possible methods (energy 2), and voila! Energy 3: electrical current!

I must say I don’t get it…

RK

In simple terms, a changing magnetic field creates electrical current. By spinning the magnet you are rapidly changing the magnetic field, this produces the current. You can also create a magnetic field from electrical current. This is the essence of both power turbines which use motion to create electricity and also electric motors which use electricity to create motion.

How deeply do you want to get into this? It is an experimental fact that if you move a piece of wire across a magnetic field a voltage is generated in the wire. If the wire is part of a complete electrical circuit, a current will flow.

The effect is reciprocal. If you hold the wire still and wave the magnet past it, the same effect happens.

A turbine doesn’t generate electricity. The turbine spins a coil of wire in a stationary magnetic field and that is what generates the electricity. Or conversely, the tubine spins a magnet within a stationary coil of wire. Makes no difference.

An applied magnetic field and a moving electrical charge, like an electron, are coupled together because a moving electron generates a magnetic field and the applied field interacts with that.

Forget the bit about 3 kinds of energy. I think somebody garbled something.

The principal you are after is “electromagnetic induction”, discovered by Faraday in 1831. He figured out that if a conductor moves within a magnetic field, current is induced in the conductor. So you get a really BIG magnet, and move the conductor (or the magnet) really FAST …

Here’s a simple blurb, with an illustrative java animation:

http://www.wvic.com/how-gen-works.htm

You can find dozens more by googling about under things like “electromagnetic induction”.

The formulation of the law governing this is called, logically enough, “Faraday’s Law”, which you can also poke around for, if you are so inclined.

Since the word “electricity” has several contradictory meanings, there is no answer. Which “electricity” are you asking about? (Alternatively, we can say that there’s no single thing called “electricity,” so the original question has no meaning.)

Here are some sensible answers.

HOW ARE ELECTRONS MADE?
They’re not. All metals contain a ‘sea’ of movable electrons. In metals, the outer electrons of the metal atoms are orbiting among all the atoms as a whole. It’s as if copper wires are full of ‘electrical liquid.’

HOW IS ELECTRIC CURRENT MADE?
Electric current isn’t a stuff, it cannot be “made.” Remember that there’s a big difference between the water in a river and the current in a river. During an electric current, WHAT IS IT THAT MOVES? Current? No, current is the motion. Electric current is caused. What is the stuff that moves? Easy: all metals are full of movable electrons, so if you have a circle of wire, you have a sort of movable ‘conveyor belt’ inside that wire. The ‘belt’ is made of the metal’s movable electrons. (If electrons are particles of ‘electricity’, then we must admit that all metals are full of ‘electricity.’ But so is everything else.) If you can force that ‘conveyor belt’ within the circle of wire to start moving, then you’ve caused an electric current within the metal circle. If our belt of electrons stops moving, then the electric current has vanished. Current can appear and vanish as the metal’s electrons flow forwards or halt. But remember that the electrons are always there even when the current is zero. The movable “liquid” of electrons was always there in the metal even before it was mined and beaten into wires. If electrons in wires are like water in a pipe, then all wires come pre-filled with liquid, and no bubbles are allowed.

HOW IS ELECTROMAGNETIC ENERGY MADE?
Analogy: an electric generator is like a pulley. Your washing machine is like another distant pulley, and the electrons inside the long wires between the two form a circular “drive belt” which wraps around both pulleys. Turn the first pulley and the distant pulley turns too. By turning the first pulley we inject energy, and if the distant pulley turns, then energy must have moved from the first pulley to the second. It works this way with pulleys and rope, and it also works this way with motors and generators connected by wires. It LOOKS like two wires connect the generator to the distant washing machine. But really it’s just one long circular “conveyor belt”, a circle of wire. In other words, our entire civilization is run by greasy leather drive belts, just as it was with factory steam engines during the industrial revolution. It’s just that today the drive belts are silent, and they’re hidden inside very long narrow metal rods.

HOW DOES AN ELECTRIC GENERATOR WORK?
A generator is an electron pump. It sucks in electrons through the “inlet” wire, and it pumps them out through the “outlet” wire. All metals come pre-filled with movable electron-matter, so if you hook a wire between the generator’s “inlet” and its “outlet”, and if you crank the generator shaft, the electron-stuff within the wire will start moving like a drive belt.

HOW CAN A GENERATOR PUMP ELECTRONS?
If you wave a bar magnet near a metal ring, electrons in the ring will start flowing very slowly around the ring. It’s called “induction”; where the magnet’s invisible field “induces” an electron flow. The changing magnetic field “pumps” the metal’s movable electron-stuff into motion, and the motion inside the circle of metal is like the motion of a circular drive belt. Make a very long stretched-out metal ring, wave a magnet near one end, and all the electron-stuff inside the entire ring will move briefly along like a drive belt. Put another bar magnet near the far end of the ring and the moving electrons will create a magnetic field which causes that second magnet to move. You’ve just used a “generator” to drive a distant “motor!” Now put your two magnets on shafts so they can flip end over end. Flip one magnet, and the distant magnet starts flipping too. Stretch out the metal ring so it’s 100 miles long, and it still works. That’s the basic principle behind “motor”, “generator”, “electric circuit”, and “conductor.” Wasn’t too painful was it?

Most grade school textbooks get this stuff wrong, and the problem never is fixed in higher grades, and even many science teachers have heads full of misconceptions about this stuff. (After all, they were educated by the erroneous books.)

In truth, it’s very easy to explain “electricity.” All you have to do is first to understand it yourself. But if the books are full of misconceptions, how can anyone get a clear understanding? The answer: just act like a scientist. Ignore the books, distrust your teachers, and go find things out on your own. Buy a bunch of parts from Radio Shack and spend a few years futzing with them and figuring out your own explanations. In science, the combined authority of a thousand experts is nothing when it’s compared to a simple experiment. In some situations “amateur science” is just wasting time covering well-trod paths. But where beginners’ electricity is concerned, “amateur science” is the only way to learn the subject without aquiring a mass of twisted concepts that you’ll probably never be able to loose yourself from.

See:

Electricity articles
http://amasci.com/ele-edu.html

Misconceptions taught by grade school textbooks
http://amasci.com/miscon/miscon.html

Amateur Science
http://amasci.com/amasci.html

Fascinating!

Thank you all very much for your answers.

Whats the deal with alternating current? My student explained to me that electrons flow in two direction simultaneously. He also mentioned “three phrase” AC, which is the same but its in three directions simultaneously.

I didnt get that at all.

Sniff Sniff
bbeaty, that was beutiful man. I spent 7 months of the Air Force’s time and money learning that stuff and I still learned things reading your one post. Good job.

AC:
the “drive belt” wiggles back and forth. Doing it this way allows those very long wires to easily be “geared down” into slow current at high pressure, then “geared back up” at the far end. It keeps the long power lines from getting hot and wasting energy. (Think of a high-power drive belt that moves at less than 1mph, but is under thousands of pounds of tension.) The step-up and step-down devices are called “electric transformers” and they need vibrating current in order to work. Those trash-can shaped thingies on the telephone poles are step-down transformers.

DC:
the “drive belt” rotates continously. Batteries use DC, i.e. they’re something like water pumps which produce constant pressure and can create a smooth flow. Nearly all electronics uses DC internally.
3-phase AC:
Invented by the bizarre mind of Nikola Tesla, in 3phase there are three loops of “drive belt” electrons wiggling back and forth with a wave-like pattern. When connected to 3 electromagnets in a triangle, this creates a magnetic vortex. Put a copper block in the magnetic vortex and a magnetic drag effect starts it spinning. Most large motors in factories are Tesla Vortex Motors (better known by their non-weird name: 3-phase induction motors.)

Common question: if during AC the charges wiggle back and forth, then why does an AC motor spin constantly rather than just vibrating? Answer: Tesla’s magnetic vortex! Two or more waves of current going in sequence around a bundle of wires can create a rotating magnetic field. The idea appeared to Tesla as he was walking in a park with a friend while reciting Goethe poetry about the sun “going down” in the evening yet actually going on to illuminate some other distant land. The USA experiences waves of day and night with phase-lag when compared to the day and night they experience in Europe. One moment of insight, and within a few decades the entire world is covered with towers strung with 3-phase power lines.

No, electrons don’t flow in two directions simultaneously. As an example; we have two wires with a voltage difference between them. Assume at the start wire A is positive with respect to wire B. A short time later wire B is positive with respect to wire A and this voltage polarity reverses back an forth on a regular basis. This is alternating voltage. If the circuit is complete the current will flow in one direction for a while and then reverse and flow in the other direction for a while and then recycle this sequence over and over.

“phases” are a lot more involved and you really need to check a trigonometry book on how a sinewave is generated out of a library somewhere. Or have someone who understands trigonometry draw some illustrations.

Ok, let’s assume you are the power company. You need to string out thousands and thousands of miles of wire all over the country side. These are all AC power systems, so if you graph the voltage and current with respect to time it makes a sine wave. Now, what would happen if we took half of our system and delayed it by half of the sine wave cycle? As the first sine wave goes up, the second sine wave goes down. When the first sine wave goes back down, the second sine wave goes up. You have two opposite sine waves, and if you add them together you get zero.

Ok, you’re thinking someone is just having some fun with math, but what does it really mean? What it means is that if you add the returns together from both power systems, they add up to zero, which means there is no current in the return. If there’s no current then you might as well not bother having the wire there, so instead of having two power wires out and two returns, you have two power wires out an no return. You just cut the amount of wire you need in half.

3 sine waves that are each 1/3 of a cycle apart also add up to zero, although it is a little harder to picture than 2 opposite sine waves. So, you run three circuits out, tie all of their nuetrals together, and you don’t need any return wires.

Now in practical applications, not all residences use the exact same amount of electricity, so your three phases won’t exactly balance out and there will be some small amount of current. This means that you can’t completely eliminate the nuetrals, but since the current is fairly small, you can use a much smaller wire. Whenever you look at power wires, this is what you will usually see, three thick wires on the bottom, and one small wire on the top (the nuetral is grounded for protection against lightning and such, which is why it is always on top).

Just a nitpick: A turbine does not generate electricity. A turbine generates rotating mechanical power which, in turn is used to turn a generator which is what does generate electrical power. A generator transforms mechanical power into electrical power. The mechanical power can come from a turbine from the belt in your car’s engine or, as in the case of this board, from hamsters spinning wheels.

Fascinating!

Thank you all very much for your answers.

Whats the deal with alternating current? My student explained to me that electrons flow in two direction simultaneously. He also mentioned “three phrase” AC, which is the same but its in three directions simultaneously.

I didnt get that at all.