Time is commonly referred to in game by the unit: seconds.
The game operates in a tick based sequence, where an action is queued up to be executed in the next tick.
Each tick should equate to 0.2 seconds in real time, which implies that there are 5 ticks per second.
The tool-tip on the 
Miner specifies that it requires 15 units of energy, however, this is a visual conversion for the user interface and the game calculates energy consumption every tick which is a rate of -3.