I Harnessing Energy from Black Holes: Possibility or Fantasy?

[luke m]

Whether it be through Hawking radiation, miniature black holes, or even white holes, is it possible that one day energy could be harnessed from black holes and used on earth?

 

[Ibix]

Hawking radiation I doubt. For a stellar mass black hole you'd actually get more heat coming from the blackest part of the night sky. Larger holes emit less radiation (so are net absorbers of energy, until the CMB cools below their Hawking temperature) and we aren't yet aware of a process that would create small black holes.

Roger Penrose developed the Penrose process, which is a method of dropping stuff into a spinning black hole, slowing its spin, and extracting energy from that. It's basically using the hole as a gigantic flywheel. However, you'd have to build your civilisation around a black hole. Transferring energy across interstellar distances to use on Earth would be problematic.

 

[Ibix]

For a stellar mass black hole you'd actually get more heat coming from the blackest part of the night sky.

...which means you could use the CMB and a black hole as the high and low temperature reservoirs of a classical heat engine, I suppose.

A damn silly way to boil a kettle (of liquid helium), as someone (almost) said of nuclear reactors.

 

[SiennaTheGr8]

However, you'd have to build your civilisation around a black hole. Transferring energy across interstellar distances to use on Earth would be problematic .

would be awesome

 

[phinds]

would be awesome

So would unicorns but don't hold your breath.

 

[Ibix]

unicorns

We could use them to pull carts full of batteries!

 

[luke m]

Thank you for your replies. I am new to this, but could there be any application from the recent detections of gravitational waves at LIGO to harnessing energy? For example, could gravitational waves from black holes be used as an energy source? If you know of any related scientific papers, I would love to see them.

 

[luke m]

Also, you mentioned that in the Penrose process it is difficult to transfer energy across interstellar distances. I know that there is current technology being developed to beam energy from space down through Earth’s atmosphere using lasers. Could the energy from the Penrose process be carried by a laser through space, and then brought down to Earth’s surface using this technology?

 

[Ibix]

could there be any application from the recent detections of gravitational waves at LIGO to harnessing energy?

Gravitational waves do carry energy and the LIGO detectors do extract energy - but it is just barely on the edge of detectability. It's not a practical energy source.

Could the energy from the Penrose process be carried by a laser through space, and then brought down to Earth’s surface using this technology?

Laser beams spread out. Not very much across a room, but over interstellar distances they spread a lot. So most of the energy doesn't reach Earth - the beam spreads and it misses its target. That's a really wasteful way of transmitting energy. Also, a laser that carries significant power can be used as a weapon. That's a fairly major issue for orbit-to-surface beams. Interstellar beamed power would need a devastatingly powerful laser.