Macroscopic black holes seem like a good source of energy mid-term. But if you consider the very long term (tens of billions of years and beyond), this seems li

Macroscopic black holes seem like a good source of energy mid-term. But if you consider the very long term (tens of billions of years and beyond), this seems like a waste of matter. You're sending lots of precious baryonic stuff literally down the cosmic drain. Microscopic black holes seem more efficient. They are one of the very few ways to achieve total mass conversion (complete conversion of mass into energy).