Question about the Penrose process

[pbjsandwich]

Can anyone tell me how energy created via the Penrose process can be extracted and converted into useable energy? What kind of infrastructure would we need on Earth, in space, etc.?

Many articles talk about how energy can be created through the Penrose / Blandford–Znajek process, but none describe how these energies are captured... at least not in a simple enough way that my feeble mind can understand :) Any input is welcome!

 

[timthereaper]

IMHO, we really don't know. The Penrose process basically says if an object breaks apart a the ergosphere of the black hole, part of the object would pass the event horizon and part of the object will be ejected away with more energy than it entered with. We know how much energy we can get, but we don't know how to capture it into something usable. A similar thing is how the Blandford-Znajek process works. This basically involves black holes with a magnetic field radiating outward and an accretion disk around it. If matter gets trapped along the field lines, electrons can be accelerated away from the hole, travel at relativistic speeds around the field line, and radiate gamma rays. How and why that happens is a mystery to me, but we know how much energy the electrons can get theoretically. Sci-fi basically handwaves away the part about how we don't know how to practically harness the energy by saying "humans will eventually figure it out". Basically I don't think anyone's done any practical thinking about it since we're SO far away from even getting to a black hole.

EDIT: This is an interesting article on black hole power extraction:
http://large.stanford.edu/courses/2011/ph240/nagasawa2/

 

[stevebd1]

Can anyone tell me how energy created via the Penrose process can be extracted and converted into useable energy? What kind of infrastructure would we need on Earth, in space, etc.?

Many articles talk about how energy can be created through the Penrose / Blandford–Znajek process, but none describe how these energies are captured... at least not in a simple enough way that my feeble mind can understand :) Any input is welcome!

Here's a paper that looks at spinning black hole energetics-
http://web.mit.edu/dvp/www/Work/8.224/dvp-8.224-paper.pdf

Also in Gravitation by Misner, Thorne, Wheeler (MTW) is a proposed city that uses the Penrose process for power, this is discussed in the following blog-
http://cr4.globalspec.com/blogentry/1564/GIGO-Garbage-In-Gigawatts-Out
and subsequent thread-
http://sciencechatforum.com/viewtopic.php?p=265016

There's a bit more detail in this field study, page 10-
http://www.fieldstudy.com/Classes/AstroReadings/BlackHolesErin.pdf