If you can make microscopic black holes then you can extract some energy (but nowhere close to a star). Otherwise the radiation is completely negligible. A black hole with 2 times the mass of the Sun (around the smallest black holes we know to exist) has a power of just 2*10^(-29) W.

To get a power of 1 MW you need a black hole with a mass of just ~10^10 tonnes (emissions would be gamma rays and electrons and positrons). These still live longer than the age of the universe so they might exist as primordial black holes but we have never found one.

A black hole with a luminosity similar to the Sun would evaporate in around a microsecond.

You can feed the black hole with matter and extract energy from the radiation emitted by the accretion disk. This is a very efficient process, better than fission or fusion, and you can use random waste as fuel.