Units

Factorio and this wiki are using the following units:

[J] Joules (Power)

the unit for work. Please don't mix work with energy! Work is in coal, oil, hot water and must be converted into energy before usage.

This is most important, because this conversion takes time; it's a big difference if I convert one item of coal in 1 second or in one minute.

Dependend on this conversion-rate is the resulting/needed power; in Factorio most entities describe their needed power per Tick.

A real-life example: Work for 1 liter gasoline is about 44 megajoules (Motorbenzin), if you convert that with liquid oxygen into energy, you can drive a rocket with it (Very, very hot! :) ). If you convert that within 1-10 Minutes it is good for driving a car. If you convert that within 1-2 hours it's just enough to warm a house.

More reasons:

http://answers.yahoo.com/question/index?qid=20061001142636AADb40G, http://www.differencebetween.net/science/difference-between-work-and-energy/ or just https://www.google.de/search?q=difference+between+energy+and+work

[chunk] (Area, Lenght)

a Chunk is an area of 32x32 tiles, an area of 1024 tiles, or a length of 32 tiles. See also Tile.

[s] Second (Time)

a Game-second.

[tile] (Area, Length)

a tile is the smallest piece of map. See Tile.

[W] Watt (Energy)

the unit for power. If something uses power, it means, that it will do work (see Joules above), as long as it is used.

Work is power multiplied by time. For difference between work and energy see also Joules above.