|Watt||The basic unit of measure of electrical power. For example, a 60-watt light bulb uses 60 watts of electricity. Because a watt is a fairly small unit, electricity is typically measured in 1,000-watt units called kilowatts.|
|Kilowatt||A unit of electrical power equal to 1,000 watts. A kilowatt is the amount of electricity required to light 10 100-watt light bulbs.|
|Kilowatt-hour||A kilowatt-hour is the basic unit for measuring the generation and consumption of electrical energy.|
|Megawatt||A unit of electrical power equal to 1,000 kilowatts or 1 million watts.|
|Megawatt-hour (MWh)||A megawatt-hour of electricity is equal to 1,000 kilowatt-hours.|
|Gigawatt||A billion watts.|
|Gigawatt-hour||One billion watts of power over an hour. It is the standard unit for measuring electricity production on a national scale.|
|Joule||A unit of measure of energy. One joule is the equivalent energy of one watt of power radiated or dissipated for one second.|
|Gigajoule (GJ)||A gigajoule is one billion joules. It is the standard unit for bulk sales of natural gas. The amount of energy represented by one gigajoule is equivalent to about 30 litres of gasoline.|
|Petajoule (PJ)||One petajoule equals one quadrillion (1 x 1015) joules. It is the unit most often used to measure energy production and use on a national scale.
One petajoule contains energy equivalent to about 30 million litres of gasoline, enough to power Canada from all sources for a little more than an hour.
Natural Resources Canada
Oxford English Dictionary