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You're the head engineer for an advanced civilization. Humanity has long since spanned the stars, as as vast as her civilization has become her need for power has increased exponentially. To feed this hunger the people of the Milky Way have set aside a few thousand stars of 'exhausted' systems (once inhabited, but drained of resources) to draw power from.

Assuming the following conditions, restrictions, and points of consideration:

  • You are seeking to draw power from the stars as effectively and quickly as possible
  • You do not care about being 'resource-efficient' or 'green.' Power throughput bests efficiency.
  • You must abide by the laws of physics (troublesome, ain't it?)
  • You have plentiful access to workers, materials, and have several decades of engineering and construction time to build the first functioning proof of concept.
  • You have access to Alloy X, an alloy with a melting point of 6,000 K, the hardness of tungsten, various strengths (yield, compression, tensile, and impact) of a tungsten/steel alloy, and possesses the trait that its hardness and strength remain consistent up until the substance begins to melt. The alloy conducts heat and electricity similar to copper.
  • After retrieving the energy you must also store it and transport it (you don't have to worry about end consumption, just packaging it up and sending it on the way)

...What solution would be the ideal proposition?

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  • $\begingroup$ Except for the part on energy storage, this sounds like Sunbeam may be relevant. $\endgroup$ – a CVn Aug 15 '16 at 11:30
  • $\begingroup$ Actually won't it be much more effective to just build shit-loads of nuclear reactors and have them charge super batteries that you can carry back home or smthing. Baked employees and any unfortunate accidents involving nuclear accidents are not covered under the companies insurance. $\endgroup$ – Skye Aug 15 '16 at 13:09
  • $\begingroup$ @Sky I feel like with a massive powersource waiting to be tapped into, building a new power source would be less efficient. Plus, since nuclear power generators are ultimately steam power generators, it seems like if nothing else we could make a 100km-away-sun-headed steam system. $\endgroup$ – Ranger Aug 15 '16 at 14:55
  • $\begingroup$ but drained of resources - specify which resources, it might be important for your question. $\endgroup$ – MolbOrg Aug 17 '16 at 23:17
  • $\begingroup$ @MolbOrg Any needed resource can be imported to the system/sun. They just no longer care about keeping the system around, so they're willing to sacrifice the star. $\endgroup$ – Ranger Aug 17 '16 at 23:25
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Since everyone's answering how to generate that much power, I have a solution for storing it: You don't. If you want to power this type 2 civilization, the best way to hold onto that energy would be to give it to them directly.

Let just say you decided to build a Dyson sphere around the star. Once the energy is collected, you can then use a huge array of high powered, high focus lasers to beam all of that energy towards giant relay stations positioned in other nearby systems. From there, the power can either be sent to nearby colonized systems (where it's picked up via a receiver station) or to other relays; creating an immense, galactic energy network that can be tapped into by any system that needs it.

It would also take decades for the laser light to reach other star systems. That means, even though it isn't stored, you would have decades worth of reserve power still traveling to its target system.

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  • $\begingroup$ But if all the lasers flicker off for a second there will be a second of power cut at the other end. There is no meaningful reserve. $\endgroup$ – Donald Hobson Aug 18 '16 at 23:11
  • $\begingroup$ That's the point of turning it into a network through the relays. If the power plant at one star suddenly malfunctions, there is plenty of reaction time for the relay to prepare for an interruption. When sudden stop in power does occur, the relay could simply compensate for it with power from other beams and relays (much like our modern day power grid). $\endgroup$ – Mattias Aug 18 '16 at 23:16
  • $\begingroup$ The storage should be at the destination not the source. I like the light idea; local power stations could always store the energy as kinetic energy in the spinning of generators (spinning reserve) just as they do today. A momentary interruption in the laser light would not need to stop all the local power grids. $\endgroup$ – jbord39 Aug 20 '16 at 4:12
  • $\begingroup$ awesome but honestly all i'm imagining is how much of a pain in the ass its going to be to target the recieving relay, as all systems moves at different speeds in different directs. This is going to be a pain to callibrate. Though as they're running on star power such a thing shouldn't be that hard, right? $\endgroup$ – Necessity Aug 20 '16 at 18:52
  • $\begingroup$ That just have me an awesome idea. What if the guidance system for the relays used quantum entanglement to position them directly at eachother. If one relay had to move, the other would copy that without any delay, no matter the distance. $\endgroup$ – Mattias Aug 20 '16 at 20:42
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You could use the powerof a blackhole to generate energy as has been observed. No problems with physics and with time dilation it might be even quicker... there may be some compensation scheme for employees who return after a few months to find all they loved dead and buried but that's just paperwork!

Storage is another matter, you could use it to generate novel materials that can be fissioned down to drive nuclear engines. Or you could go the other way and use this to collect hydrogen to provide power to nuclear fusion engines.

With hydrogen being the most common element in the universe! Once you have a steady source (say a stellar nursery) you won't need an engine driving, more of a mining operation. And without the need of having to drag it out of a star's gravity well and operate in the temperature.

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  • $\begingroup$ Would storing the energy in micro black holes work? $\endgroup$ – PyRulez Aug 15 '16 at 12:00
  • $\begingroup$ @PyRulez I thought about it, but it just seems dangerous and messy, you could generate something called a torus blackhole but I think that if you lose containment you're then stuck in space without a way to get back home. I like hydrogen and nuclear as you have a store of power to fall back on with the proper knowledge so even if your engine dies in the void of space you can do something about it $\endgroup$ – Chris J Aug 15 '16 at 12:05
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Star Lifting might be the answer you are looking for, by creating a series of dyson spheres around the stars, you can then use the solar energy collected to extract hydrogen and helium directly from the star - storing the energy for transport.

Also, Laser cooling would be required which just sounds amazing.

You can then use the fuel generated to create a series of mini stars that can be used to power the rest of your civilization.

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Solve your storage problem first. No point drawing more power than you can store.
Assuming you're high-tech enough that you've got radiation collectors of over 50% efficiency in all frequencies:
once storage is ready, build a Dyson sphere with your radiation collectors on the inside, backed by thermal collectors. If you're drawing power fast enough, your collector appears as a black body. Thermodynamics alone will cause your sun to either:
a)expand and cool, or,
b)since there is now a convection process exerting a returning pressure, become hotter and denser, producing more power.

Either way, this would be the maximum sustainable output of the star, over however long it takes-- you have your own giant fusion reactor with steam (steam/superheated helium, same difference) converter.
The faster, but more suicidal, approach would be to drop a pipeline into the sun's mantle in order to pump out the hydrogen to use in your own fusion reactor. Think of the sun as a giant gas balloon, which you've just punctured, a giant, radioactive, hot, gas balloon.

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    $\begingroup$ some sources on this would be great :) $\endgroup$ – Chris J Aug 18 '16 at 15:06
  • $\begingroup$ @ChrisJ Which part exactly? The expansion and cooling is from red giant formation, the second option is based on the assumption that the Dyson sphere trapping the solar wind is simulating an increase in mass. Like a pressure cooker, the atoms within the star are subject to higher pressure, as though they are inside a bigger star. $\endgroup$ – nzaman Aug 18 '16 at 18:02
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A Dyson sphere is the standard answer, it will collect all of the energy radiated from the star.

If you however are concerned about speed you don't want to wait around for the star to slowly fuse all it's hydrogen and other light elements over several billion years. The quickest way to get all the power out nearly instantly would be to make the star go nova (or supernova) artificially. This is going to give you the maximum power (energy/time) possible, lots of energy in a really short time.

Actually collecting or using that energy would be difficult, but if you have the technology to make a star artificially nova (I would guess some form of gravity manipulation), you could conceivably also have the means to use the massive energy released to do some interesting things: direct the energy of the explosion to designated energy use locations, generate stellar mass quantities of exotic matter or antimatter (and send it to a destination at near the speed of light), seriously distort space-time (manufacturing black holes or wormholes), with the quantities of energy we're talking about pretty much anything would be possible.

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Using Alloy X, you create a large box. In the center of 1 face of the box is a magnification lens, focused on a mirror on the inside of the box, opposite face. The mirror is angled slightly to hit a redirect mirror, sending it to the first of 8 corner mirrors. Each corner mirror sends the light to the next corner, creating a box of light that can enter, but not escape. When the box has reached it's full potential, a cover slides over the magnification lens and the box shoots off across the galaxy to a pre-programmed location.

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    $\begingroup$ light reflects in a reversible manner. This meand that at no point can two different beams of light be reflected in and merged into one beam. $\endgroup$ – Donald Hobson Aug 18 '16 at 23:09
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I wouldn't touch the current solar power harvesting techniques...who wants to get bombarded by all these photons?

Lets go magnetic induction instead. I get some creative room here as it's pretty speculative that it could be done...but harvest the heliosphere https://en.wikipedia.org/wiki/Heliosphere using the concepts found here https://en.wikipedia.org/wiki/Geomagnetically_induced_current with inducing currents through magnetism.

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As others have mentioned, solve the storage problem first. If you don't want to necessarily store the energy and there are multiple stars in question, since my reading comprehension is impaired a la sickness, Steven Hawking has speculated, albeit in a simplified manner and through a television program, that should a civilization be able to harness the entire power of a star, they could possibly open wormholes (which if I'm not mistaken, pop in and out of existence at the quantum level).

Assuming these wormholes could be captured and stabilized, it might be a convenient mode of transportation. As to collection, others have mentioned Dyson Spheres, but you definitely don't want it to be contiguous. A large array of satellites (perhaps self-replicating to cut down on work required) with very efficient solar panels can possibly form a network. Since they're so close to the star, perhaps the beams will be bent via gravity. Regardless, they can dump the energy to a collection point, and there should probably be six collection points for all the directions. "Up", "down", "left", "right", "front" and "back", all relative to the center of the star.

Assuming I didn't misunderstand your question and what Hawking said in that TV program (which is Into The Universe With Steven Hawking, the Aliens episode), and if that was him and not some writer's imagination, the wormhole can allow for a quick transit of energy. So if a smaller division of those already allocated stars can generate wormholes, they can create wormholes to link all the other purely energy "generating" stars, and then that can be redirected by changing the wormhole exit (somehow) to planets that need it in the form of a beam. The aiming has to be correct cause then it goes from power supply to doomsday weapon. This is pretty speculative, but not more than any of the other answers here.

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Long term energy storage in this sense is over time sea;es that make geological eras seem like a standard work week.

For truly long term energy storage in a Type II or Type III Civilization, the energy will have to be stored in black holes. The simple solution is spinning up black holes and then after the Stelliferous Era (when all the stars have gone out, trillions of years in the future) gradually tapping the black holes to release the energy stored in the spin. Other mechanisms like tapping the Hawking Radiation are also plausible, but for very large black holes, the rate of energy release via Hawking Radiation is quite slow. An even more improbable idea of dipping a "box" lowered on a rope into the environment close to the rotating event horizon has also been postulated

As a bonus, it is apparently possible to store information on the event horizon of rotating black holes, which would make it the largest hard drive ever created and allow the storage of vast sums of information into deep time.

enter image description here

Charging up the black hole can be done in numerous ways, including dropping matter into the hole, or beaming energy into it. Since many of the other answers suggest using massive assemblies of Dyson spheres to harvest the energy of the suns, using arrays of lasers to beam energy at target black holes doesn't seem to be an issue at all.

So for the long term storage of energy, capturing and "farming" black holes to charge them with energy and information is the way to go.

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