I found this old article by Steven Frautschi [1](https://www.science.org/doi/10.1126/science.217.4560.593) which talks about avoiding heat death by a hypothetical advanced civilization able to group Black Holes in clusters. He writes that in this way, the civilization could endure forever by consuming the energy from the Black Hole (for example, taking the emitted Hawking radiation)

However, wouldn't there be an end to this source? Wouldn't all black holes evaporate evetually, leaving the civilization with no energy sources left?

And if this mechanism would not work, could anything avoid heat death somehow? Perhaps, the expansion of the universe itself could avoid it in some way?