Energy Glossary

Alternating current (AC)

An electric current that continually reverses its direction at regular intervals (usually 60x per second).

Ampere (amps)

The basic unit of measurement to measure the rate of flow of an electric current through a conductor.


The smallest particle of any element. Everything is made up of atoms. Atoms are atom considered a source of vast potential energy.


A group of electric cells that provide electric current. A battery is an example of direct current.


A period when lights are off as a result of an electrical power failure.


A temporary reduction in the use or availability of electricity. Brownouts usually cause the lights to dim.


A device that stores electricity for future use.


A container filled with a chemical substance (electrodes and electrolytes) that produces an electric current by chemical action.


Electricity produced by a surplus (positive) or shortage (negative) of electrons in an object. A positive charge will cause the object to push, while a negative charge will pull the object. If there is no charge, it is called a neutral charge.


The complete path electricity follows from a source through a connection to an output device. For example: A circuit can be made from a battery (source) through a copper wire (connection) to a light bulb (output device) and back to the battery.


A material or object that permits an electric current to flow easily. Common examples of good conductors are metal, salt, water and wool.


The physical connection (e.g. transmission lines, transformers, switch gear, etc.) between two electric systems that allows the transfer of electric energy in one or both directions.


The basic unit of measurement of an electric charge. It is equal to the quantity of electricity transferred by a current of one ampere in one second.


A steady flow of electric charges through matter.


The rate at which electric energy is delivered to or by a system, either at a given instant or averaged over a designated period of time.

Direct current (DC)

An electric current that flows in only one direction (e.g. battery).

Distribution system

The portion of an electric system dedicated to delivering electric energy to an end user (homes, businesses, etc.)


A form of energy found in nature but can also be artificially produced by rubbing together two unlike things (particles with opposite charges (+/-) attract each other).

Electric system

Physically connected generation, transmission and distribution facilities operating as a unit to provide electricity to customers.


The production of chemical energy by passing an electric current through a liquid called an electrolyte.


A coil of wire wrapped around a soft iron core that is magnetized when electric current flows through it.


A negatively charged particle that rotates around the nucleus of an atom.


The ability to do work and produce power. Two types of energy are kinetic and potential energy.

Energy source

The primary source providing the power be converted to electricity through chemical, mechanical, or other means. Common energy sources include coal, petroleum, gas, water, uranium, wind, sunlight, geothermal, etc.

Fossil fuel

Any naturally occurring fuel (formed in the earth from plant or animal remains), such as petroleum, coal and natural gas.


Any substance that can be burned to produce heat or materials that can be fissioned in a chain reaction to produce heat.

Fuel cell

A device that combines a fuel, such as hydrogen gas, with oxygen to produce electricity, water and heat.


A safety device with a metal wire or strip that melts when the current gets too strong and cuts off the flow of electricity.


A machine that produces electric current by spinning a magnet inside a coil of wire.

Geothermal energy

The heat energy that is naturally stored below the earth’s surface.


A connection from an electrical circuit to the earth. Electricity is always looking for the easiest path to the ground.


The power network for electricity. This includes high-voltage transmission lines and substations.


The conversion of energy produced from running water into electricity.


An object or material that does not allow electricity to pass through. Common examples of good insulators are dry air, glass, plastic and rubber.

Kilowatt (kW)

A unit for measuring electrical energy. 1,000 watts = 1 kW

Kilowatt Hour (kWh)

The use of 1,000 watts of electricity for one full hour.

1 kWh = ten 100 watt bulbs all burning at the same time for one hour.

10 bulbs x 100 watts each x 1 hour = 1 kWh

Kinetic energy

The conversion of potential energy into motion.


A flash of light produced by the static electrical discharge between two clouds or between a cloud and the earth.


The power output of a generator or power plant.


An object surrounded by a magnetic field that has the ability to attract iron or steel.

Magnetic field

A detected force that exists around a magnet.

Mechanical energy

The energy of motion used to perform work.


An instrument that records or regulates the amount of electricity passing through it. Power companies read meters to determine how much electricity each customer used.

Nuclear power

The energy produced by splitting atoms in a nuclear reactor.


The unit of measurement of an object’s resistance to the flow of electricity.


The period during which a generating unit, transmission line, or other facility is out of service.

Potential energy

The capability of something to do work or go into motion. E.g. A stopped car has potential energy, but it begins moving it converts to kinetic energy.


The force or energy used to do work (measured in watts).


A tiny particle in the nucleus (center) of an atom. Protons have a positive charge.


The sending or receiving of sound through electromagnetic waves through the air without a connecting wire.


The opposition of a object or material to electricity passing through it (measured in Ohms).

Scheduled outage

The shutdown of an electrical facility, for inspection or maintenance, which is scheduled in advance.

Solar energy

Energy produced by the Sun’s light and heat.

Static electricity

The buildup and imbalance of like charges.


Facility equipment on an electric system that switches, changes or regulates electric voltage.


A device that opens or closes a circuit. This prevents or allows an electric current to flow.


A device that raises or lowers the voltage or force of AC electricity.


The movement or transfer of electric energy over an electric system between the point it is supplied and the point it is delivered to customers.


The force or pressure that moves electric current through a conductor (measured in volts).


A unit for measuring the force used to produce an electric current.


A unit for measuring electric power.

1 kW = 1,000 watts

1 Megawatt (MW) = 1,000,000 watts