Kilo-Watt

OK, so what is electricity?
Everybody knows what electricity is, right? It's the shock you get from rubbing on the carpet and touching the door knob. It's in lightning. It's the switch on the wall that turns on a light. It's the big pole that has lots of wires on it.

Correct! All of these things have to do with electricity. But more precisely, electricity is the movement of tiny atomic particles called electrons, particles so small that you can't see them. As these particles move, they can give you the static shock from the carpet and the door knob, flash across the sky as lighting, flow to your light and make it glow, or travel across wires high atop poles.

Plant
Power Plants
Our company makes large amounts of electricity at power plants. Power plants typically heat water into steam. The steam expands like in a tea kettle. The force of the steam moves big fan blades (in a turbine) that connect to a shaft that then turns a device called a generator. The generator is what "generates" the electricity. It has magnets in it that spin around. The magnets make the electrons jump across coils of copper wire (electromotive force). "Electron jumping" is essentially what we call electricity. It takes a lot of jumping to make your air conditioner or refrigerator work so our generators have to be very big and spin very fast. We have hundreds of them to make sure everyone can get electricity when they want it. more on how plants work

Power Grid
The network of wires and power plants is called the power grid. Power companies like us are responsible for keeping the power grid charged with electricity. To do this we must push enough electricity into the wires to ensure it will reach every home, every factory, every light bulb connected to it. The amount of electricity in the lines must be kept at a constant level to give appliances and equipment enough power, but not too much of it. Either would damage devices connected to the grid. more on the power grid

Tower
Voltage
Electricity can't sit still. It always tries to get even, that is, it moves from where it is charged to where it is not. To move electricity to homes, we channel the electricity over transmission wires. We measure the electrical travel on the lines in a unit called a volt. Transmission wires operate at
Substation
high voltages—up to 500,000 volts—to go long distances. Since the electrical system in your home uses a pressure of 110 volts, the traveling electricity must be "stepped down" before it comes into your home. The process of stepping up electricity for travel, or down for use, is accomplished by devices called transformers. You may have seen some transformers in a substation near your neighborhood. Look for a place where the wires come together in a big fenced area that has lots of metal boxes with squiggly horns coming out of them.

Measuring electricity
Measuring electricity usage is more complicated than measuring the fuel used in things like cars. Cars consume (combust or burn) energy in easily measurable units — gallons of gas — which can be stored and sold by volume or weight. On the other hand, electricity actually passes through electrical appliances (and out of them) in a loop (or circuit). In many cases, comparatively little of the electricity is lost (or "used up") by the appliance and none of it is combusted like in an engine.

Metering electricity usage is like measuring the flow of water pushing a paddlewheel. You aren't using the water up; it is passing through the device as it performs work. In a paddle wheel, what water is lost is primarily lost to evaporation, a side effect. Like electricity, most of it is not consumed.

Now imagine that you could dam the river that drives the paddle wheel in order to turn the current on and off. This is much like the way electrical appliances work. Switch them on and you are opening the dam. Off and you are closing it. Thus, if you have no electrical devices switched on in your house, very little power passes through the circuit. As appliances and equipment are switched on, current must pass through the home to drive them.

This current running through the house is measured in kilowatt hours.

Kilowatt hours
A kilowatt hour is an amount of force (1,000 watts) passing through a gateway (your meter) over a period of time (an hour). A 100-watt light bulb turned on for 10 hours uses one kilowatt hour of electricity. Or, a 10-watt nightlight could be on for 100 hours before using a kilowatt hour of electricity. more on kilowatt hours

Like evaporation in the paddlewheel example, circuits and the devices on them lose electricity to resistance. Resistance can also be thought of as momentum lost to friction. Every wire and motor and burner on an electrical circuit resists the flow of electricity to some degree, and loses, or converts, electricity to heat, light, magnetism, pressure, or chemical action. In wires the resistance is unwanted and minimized as much as possible, but other devices on the circuit can use resistance to do important tasks.

Stove
Ways to use electricity
  • Stoves and heaters use the heat caused by resistance to current in a metal element, to provide warmth.
  • Light bulbs have filaments that glow when resisting current, providing light.
  • Appliances use resistance to charge magnets that can spin a shaft in a motor and power a variety of gears, wheels or blades.
  • Speakers use resistance to convert electric current into pressure that moves air and makes sound waves.
  • Batteries use chemical resistance to store electricity for later use.

Each device adds to the resistance against electrical current the way lots of paddlewheels would chop up and slow the flow of a river. The more things that are hooked up, the more electricity that has to be pushed into the circuit from the power plant.

Electrical demand
The energy made by power plants is for immediate use. Power plants cannot store or stockpile electricity—they must constantly make it. For this reason, electric demand must be well anticipated. Power companies are always watching weather conditions and typical usage patterns to make exactly enough power to serve everyone all of the time. more on electricity demand

If a bad storm topples transmission lines or interrupts power generation, some people will immediately be without electricity. Others will temporarily use stored power from batteries or they could generate power with their own small fuel-powered generators. But eventually alternative power sources run out and repairs must be made. Power companies have large crews of workers to restore power lines and generators quickly.