HALO DRIVE: Could We Use Black Holes for Space Travel?

[Rynn]

If it takes too long to get to a natural black hole, you'll just have to whip up a local Kugelblitz.

You could indeed, but unfortunately there is no such thing as a free lunch. The energy the laser beam gains from going round the black hole comes from its angular momentum, which came ultimately from the energy used to make the black hole. You could just use that energy to propel space craft directly. But like Todd I’m not dismissing the idea some systems might choose to pump gigantic amounts of energy into a black hole so that future travellers can easily use it for transport.