The kilowatt-hour explained

Two centuries ago, in 1800, an average human was estimated to use just over 16 kWh per day. A century ago this had increased to just over 24 kWh per day. Today, the average person uses around 60 kWh per day. But what is this kWh-thing exactly? Well, the technical description would be this: If we take a device that draws 1000 Watts of power (1 kiloWatt), say a decent toaster/grill, 1 kiloWatt-hour (kW·h or kWh) is the amount of energy that it will consume in one hour. So kWh is a measure of energy, and a fair amount of energy at that. For people who like standard units: 1 kWh is qual to 3.6 MJ (megaJoules). Let’s look at a few examples.

1 kWh of energy will keep my small 2000 W electrical space heater running for half an hour. It will keep an old-fashioned 40 W lightbulb burning for roughly 24 hours, and it’s enough energy to boil a bucket of water.¹ However, an average (gasoline) car will only drive around 1 to 1.5 km on 1 kWh of energy.² Being derived from crude oil, a litre of gasoline contains almost 9 kWh of energy (or 33 kWh per gallon). And a cubic metre of natural gas contains around 11 kWh (or 0.3 kWh per cubic foot).³
Worldwide, an average electrified household uses around 10 kWh of electricity per day inside their home, although in Australia and France it’s almost double this amount, and in the US and Canada it’s easily three time this figure.⁴

There is also the terawatt-hour (TWh), which is used for really really large amounts of energy, such as the energy requirement of countries. 1 TWh is 1 billion kWh. We humans currently use over 430 billion kWh of energy per day. That’s a lot of energy.