Theorists assert that, as a civilization grows larger and becomes more advanced, its energy demands will increase rapidly due to its population growth and the energy requirements of its various machines. With this in mind, the Kardashev scale was developed as a way of measuring a civilization’s technological advancement based upon how much usable energy it has at its disposal.
Firstly, it is important to note that the human race is not even on this scale yet. Since we still sustain our energy needs from dead plants and animals, here on Earth, we are a lowly Type 0 civilization (and we have a LONG way to go before being promoted to a type I civilization). The famous physicist Michio Kaku believes we will reach Type I in 100 – 200 years time.