This question is a different version of other questions that I have found here discussing a similar but different problem.

The problem I'm facing here is about the excess or waste heat that an advanced civilization will have to find a solution for. To illustrate, the Earth receives $10^{17}$ Watts from the Sun (ignoring the Earth albedo), and since we capture almost none of this energy, the Earth atmosphere heats to its current habitable temperature. Now, whenever we get to the Type I level, we will be using all those $10^{17}$ Watts from the Sun and since energy can't be created nor destroyed, all this energy will in one way or another end up as heat, but this is not a problem for a Type I since it's what we have always been heating the Earth with in the first place. It starts to make the Earth uninhabitable if we use any more energy than this.

The problem with Type II now is that we will have $10^{26}$ Watts available to us. That is $10^{9}$ times more available energy than before. Now let's imagine a solar system of 10 rocky planets that we want to colonize. Keeping in mind that we are limited by $10^{17}$ W for every planet or else it becomes too hot to live on, how would any of these 10 Type II planets be any different to the previous Type I planet if they are using the exact same $10^{17}$ W?

Also note that in this Type II scenario we only used $10^{18}$ W of the available $10^{26}$ W. So are there any possible ways to dissipate the heat at a faster rate so can use more energy while still making the planets habitable?

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    $\begingroup$ You are assuming that the energy use is all taking place on the planet AND ending up as heat, ignoring space and modify the orbit of the planet. $\endgroup$
    – jmoreno
    May 18 '19 at 15:24
  • $\begingroup$ It also neglects binding up the energy in other forms, such as useful chemicals and materials. Some heat will be lost in all cases, but definitely not all of it. $\endgroup$ May 18 '19 at 15:44
  • $\begingroup$ (also, simple answer: the tech level and societal organisations are probably about a thousand years more advanced on the type II world[s], so the differences are going to be enormous independent of energy use) $\endgroup$ May 18 '19 at 15:46
  • $\begingroup$ I don't know what physics and engineering they have at their disposal in a Kardashev Type I or Type II civilization... The development of said physics and engineering is what makes an advanced civilization. $\endgroup$
    – AlexP
    May 18 '19 at 18:37

I think you may be experiencing a cart-before-the-horse moment here, so I’m going to issue a bit of a frame-challenge.

Civilisations shouldn’t develop to KS-II and then look around nonplussed, wondering what to do with all the energy. They should first develop the need to use that much energy (with its attendant mechanisms for dealing with waste), and then eventually look back and say ‘huh, we’re using a whole starsworth of energy there’

With that in mind: I expect the planets would look pretty much identical, as no civilisation in their right mind would ram that much energy through a place they expected to live.

There may be more or brighter stars in the sky as you can look up and see the space-borne megastructures that use all that energy, or maybe not. Could be that your major energy user is built into the moon. Who knows.

You may also see more structures dedicated to energy transmission and storage. Presumably some of your colonies are a long way away from the star and will need regular shipments of batteries/more wireless power receivers, but they shouldn’t really outweigh the power generators/capturing facilities on your initial world in terms of societal impact.

Point is: no KS-II civilisation would have reached that point if they were spending all their energy at home!


The Kardashev Scale is absolute claptrap. It relies on a Soviet era dogma that assumed that alien civilisations would develop like the USSR did, by corralling ever more resources into more and more production, generating ever more energy, without really thinking where that energy and the produced materials would be consumed. It's this fallacious thinking that led in the USSR to the endemic over-production of some resources, and under-production of others.

In reality, energy is produced in keeping with demand, and demand is moderated by people constantly seeking more energy efficient ways of performing tasks. An advanced civilisation is the one that can meet all of its citizens' needs with the lowest possible energy footprint. Yes, over time that will likely tend upwards, but I see absolutely no reason to believe that that upward trend will be permanent, or ever need to get to the stage where any civilisation ever gets near even the Type 1 level on the Kardashev Scale.

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    $\begingroup$ "An advanced civilisation is the one that can meet all of its citizens' needs with the lowest possible energy footprint": actually, in anything other that Mao's Red China, that should of course be "needs and aspirations". Since the needs and aspirations of mankind are unbounded, it follows that the energy demand is also unbounded. And as for not seeing any reason for a permanent increase in energy consumption, you may want to check your imaginative function; the starships which unite the interstellar economy will most likely require quite a lot of energy... $\endgroup$
    – AlexP
    May 18 '19 at 18:35
  • $\begingroup$ There are two big reasons to assume it will rise, populations grow, and doing things take energy, Civilizations create new needs when old ones are met. consider things like the internet, high speed travel, and entertainment. There is no reason to expect energy usage of a civilization to decrease unless their is a population collapse. $\endgroup$
    – John
    May 19 '19 at 3:39

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