Nuclear fusion,solar fuels, floating offshore nuclear plants, and microwave beaming. These are some of the esoteric and rather outrageous renewable energy ideas that scientists have proposed to help break our over-reliance on fossil fuels. Some like nuclear fusion are much further ahead than others after scientists last year kicked off the five-year assembly phase of the massive International Thermonuclear Experimental Reactor (ITER), the world's largest fusion reactor, in Saint-Paul-les-Durance, France.
And now you can add harvesting energy from black holes to that list as we kick-start missions to colonize Mars and other planets.
Fifty years ago, British mathematical physicist, Roger Penrose, proposed a seemingly absurd idea of how an alien society (or future humans) could harvest energy from a rotating black hole by dropping an object just outside its sphere of influence, also known as the ergosphere, where it could gain negative energy. Since then, nobody was able to verify the viability of this seemingly bizarre idea--that is, until last year when the University of Glasgow's School of Physics and Astronomy provided a nice proof of concept that demonstrates how the idea just might work.
Stephen Hawking proposed that black holes could release energy through quantum mechanical emission, while Roger Blandford and Roman Znajek proposed electromagnetic torque as the main agent of energy extraction.
And now a new Columbia study has come up with yet another interesting idea to harvest black holes: Reconnection of magnetic field lines.
According to Einstein's theory of general relativity, rotating black holes possess enormous amounts of energy that might be available to be tapped.
Magnetic reconnection
Black holes have captured the imagination of astrophysicists ever since the first one was discovered in 1971--and for good reason. After all, they are some of the strangest and most fascinating objects in outer space.
Black holes represent the end-stage of the lifecycle of stars so massive that, once it's gone supernova, the core can no longer withstand its own gravity and collapses totally into a singularity--a single one-dimensional point of infinite density. This singularity sits inside a region called the event horizon--the point at which the gravity around the black hole is so strong, not even light-speed is sufficient to achieve escape velocity. Related: U.S. Shale Is Gaining Influence Over Oil Markets
Physicists Luca Comisso from Columbia University and Felipe Asenjo from Universidad Adolfo Ibáñez in Chile say they have discovered a new way to harvest black holes by breaking and rejoining magnetic field lines near the event horizon. The scientists say that their theory shows that disconnecting and reconnecting magnetic field lines in just the right way can accelerate plasma particles surrounding the black hole to negative energies, thus allowing large amounts of energy to be extracted from the black hole.
Why it might work
Comisso and Asenjo's magnetic reconnection theory is built on the premise that reconnecting magnetic fields accelerates plasma particles in two different directions. The plasma flow that is pushed against the black hole's spin can escape the clutches of its super-powerful gravitational pull and release energy if the plasma particles swallowed by the black hole have negative energy.
Comisso has likened the process to a person losing weight by eating candy with negative calories, pointing out that black holes lose energy when they feast on negative-energy particles. The scientists say this can happen in a black hole's ergosphere, a region where the spacetime continuum is rotating so fast that every object spins in the same direction as the black hole. Magnetic reconnection in the ergosphere is so extreme that plasma particles are accelerated to velocities approaching the speed of light.
Asenjo, professor of physics at the Universidad Adolfo Ibáñez, has explained that the high relative velocity between the captured and escaping plasma streams could allow massive amounts of energy to be extracted from the black hole.
Indeed, the researchers say that the process of plasma energization can reach an efficiency of 150%, with the efficiency exceeding 100% because black holes leak energy, which can be picked up for free by the plasma escaping from the black hole.
Holy grail of endless energy?
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While this might sound like the stuff of science fiction, the process of harvesting energy from black holes as envisioned by Comisso and Asenjo is an ongoing process in a large number of black holes and is actually responsible for black hole flares--energy bursts powerful enough that the radiation can frequently be detected from Earth.
However, the scientists have conceded that it could be thousands or even millions of years before humans could figure out how to survive in the vicinity of black holes without needing to rely on energy from a nearby star.
Which is just as well, considering that our sun is about to make our planet a literal living hell 1-2 billion years from now.
By Alex Kimani for Oilprice.com
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