In this very interesting discussion about the search for aliens, they describe some parameters and assumptions in terms of their potential use of energy:

If alien civilizations exist throughout the universe, many have had billions of years to develop technology, expand their population and energy supplies, and travel across their galaxies. Kardashev classified hypothetical advanced civilizations by the magnitude of their power supply, with Type II civilizations harnessing most of the energy output of their host star, and Type III civilizations using most of the power in their galaxy. As Dyson pointed out in 1960, the waste heat emitted by a such civilizations would easily overwhelm that of their host star or galaxy, distinguishing them from “normal” astrophysical sources. This approach to SETI makes few assumptions about the behavior of alien civilizations, primarily: conservation of energy, the laws of thermodynamics, and that given the age of the Universe aliens have had time to develop very large energy supplies.

Let’s find out what this could mean in the video on page 2

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