Author Topic: Kinetic Batteries... In Space!  (Read 962 times)

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Online brilligtove

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Re: Kinetic Batteries... In Space!
« Reply #15 on: April 09, 2019, 04:35:48 PM »
This site has an estimate of about 13,000 tonnes launched into space as of the end of 2017. Let's grossly overestimate the amount of secret military launches or whatever and round it up to 100 million kg. Let's further imagine that it's all traveling at escape velocity instead of slow enough to orbit in approximately a circle.

This gross overestimate of the total kinetic energy ever sent into orbit comes out to 1.7 TWh.

That may seem like a lot, but it's less than 0.1% of the electrical energy the US uses each year.

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Online CarbShark

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Re: Kinetic Batteries... In Space!
« Reply #16 on: April 09, 2019, 05:34:25 PM »
This site has an estimate of about 13,000 tonnes launched into space as of the end of 2017. Let's grossly overestimate the amount of secret military launches or whatever and round it up to 100 million kg. Let's further imagine that it's all traveling at escape velocity instead of slow enough to orbit in approximately a circle.

This gross overestimate of the total kinetic energy ever sent into orbit comes out to 1.7 TWh.

That may seem like a lot, but it's less than 0.1% of the electrical energy the US uses each year.

Exactly. Plus, if you were able to collect it, you'd then how to figure out how to easily use it. But, you're also in an environment (space) where you have a virtually unlimited source of energy (the sun). A bigger challenge in orbit is protecting yourself from energy rather than being able to generate enough.
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Offline DanDanDan

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Re: Kinetic Batteries... In Space!
« Reply #17 on: April 09, 2019, 05:52:40 PM »
This site has an estimate of about 13,000 tonnes launched into space as of the end of 2017. Let's grossly overestimate the amount of secret military launches or whatever and round it up to 100 million kg. Let's further imagine that it's all traveling at escape velocity instead of slow enough to orbit in approximately a circle.

This gross overestimate of the total kinetic energy ever sent into orbit comes out to 1.7 TWh.

That may seem like a lot, but it's less than 0.1% of the electrical energy the US uses each year.
First off thanks! Good stuff, good times. I effin love thought experiments.

Second, what's the current cost of a human-generated watt in orbit, I'm now wondering.

The thing is, another and maybe better name for these could be gravity batteries, which are far more efficient than solar.

Lastly, given how clever scientists can be, I'm guessing that some would jump at the chance to do something other than chuck the stuff in the garbage.

Even trash has value, is my central point.

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Offline Alex Simmons

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Re: Kinetic Batteries... In Space!
« Reply #18 on: April 09, 2019, 07:19:04 PM »
Even trash has value, is my central point.

It's often a negative value.

Offline daniel1948

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Re: Kinetic Batteries... In Space!
« Reply #19 on: April 09, 2019, 08:07:32 PM »
BTW, all of this dovetails with the discussion on the pod about firing lasers or particle beams around black holes.

That is about as realistic as a sky hook to an orbiting satellite. It's a mathematical curiosity with no real application at all.

The thing is, another and maybe better name for these could be gravity batteries, which are far more efficient than solar.

No. There is no relation at all. Solar is a means of gathering energy. A battery is a means of storing energy. The relative efficiencies is totally irrelevant to any consideration. Further, the theoretical efficiency of a gravity battery tells you nothing about the cost of "mining" a resource that's so spread out that it will require more energy to obtain the debris than the energy contained in the debris. If it requires a thousand joules to gather one joule, your system is useless.

Clearing junk out of orbit is another issue, which is serious, and will be very expensive to do and will consume orders of magnitude more energy than could possibly be harvested from it. Note that to recover energy from a gravity battery, the weight has to operate some sort of generator as it falls. That means attaching it to a cable that is pulled by the weight. In the case of de-orbiting space junk, there's no generator to attach that cable to.
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Offline arthwollipot

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Re: Kinetic Batteries... In Space!
« Reply #20 on: April 09, 2019, 09:13:15 PM »
There's also the issue of ownership.  Space junk is actually owned by whomever put it into orbit. It would literally be illegal (in violation of treaties) to collect space junk.

Nudging it into the atmosphere is ok, though.

Isn't there something still on the books about maritime salvage? Perhaps some agreement based on that can still be made.
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Online CarbShark

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Re: Kinetic Batteries... In Space!
« Reply #21 on: April 09, 2019, 09:22:33 PM »
There's also the issue of ownership.  Space junk is actually owned by whomever put it into orbit. It would literally be illegal (in violation of treaties) to collect space junk.

Nudging it into the atmosphere is ok, though.

Isn't there something still on the books about maritime salvage? Perhaps some agreement based on that can still be made.

I don’t think they’ll renegotiate in order mine space junk for kinetic energy.

And I believe you are free to send derelict debris into the atmosphere if it poses a danger. 


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Offline DanDanDan

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Re: Kinetic Batteries... In Space!
« Reply #22 on: April 10, 2019, 12:46:32 AM »
That is about as realistic as a sky hook to an orbiting satellite. It's a mathematical curiosity with no real application at all.

Turns out that Texas A&M is already on this idea. As I thought, it's not new. https://www.space.com/20024-space-junk-removal-sling-sat.html

"The spacecraft would harness the momentum exchanged during both of these actions to cruise over to the next piece of space junk on its list, minimizing fuel use and extending its operational life to the point that such a mission might be practical."

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No. There is no relation at all. Solar is a means of gathering energy. A battery is a means of storing energy.

On that point, you're correct. I completely botched what I was trying to say. I meant that converting solar energy is far less efficient than converting kinetic energy. Gravity batteries are currently being built that are charged with solar.

As for what I was also trying to suggest, intentionally putting some kind of object or system of objects in orbit to later be used as a fuel saving conveyance, like a conveyor belt, I'm optimistic. Comparing it to the Halo Drive would be ore accurate if a gravity assist is part of the equation.

On whether or not objects in orbit can withstand debris strikes, here's this. https://en.wikipedia.org/wiki/Whipple_shield
« Last Edit: April 10, 2019, 01:52:47 AM by DanDanDan »
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Offline gmalivuk

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Re: Kinetic Batteries... In Space!
« Reply #23 on: April 10, 2019, 08:18:54 AM »
Launching an object to orbit in order to harvest its energy later is a horrifically inefficient way of doing things, even if you could magically obtain 100% of its kinetic and potential energy after that.

All of the energy spent to lift propellant that's ejected later, and all the energy spent to get through air resistance, and all the energy spent just fighting gravity, are gone forever. The final payload accounts for only a tiny fraction of the energy cost to send it to space in the first place.

Using it to conserve fuel in a craft already in space is one thing. After all there definitely is some energy there and any of that you could harvest would translate into energy savings for whatever harvested it. But comparing it to a battery shows just how many orders of magnitude you're missing here.
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Offline daniel1948

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Re: Kinetic Batteries... In Space!
« Reply #24 on: April 10, 2019, 08:30:06 AM »
... I meant that converting solar energy is far less efficient than converting kinetic energy. Gravity batteries are currently being built that are charged with solar.

As for what I was also trying to suggest, intentionally putting some kind of object or system of objects in orbit to later be used as a fuel saving conveyance, like a conveyor belt, I'm optimistic. ...

But a "gravity battery" has physical connection to the weight to allow it to be raised when you have power, and lowered when you need power. There's no need to go extremely high, and the higher you try to go, the more expensive the mechanism becomes. Rather than looking at theoretical efficiency, you have to look at cost per kWh of energy obtained or stored. Gravity is practical when you have sloping terrain. Otherwise it is cost prohibitive. A "conveyor belt" to space, if it were even possible to build, which it's not, would be astronomically expensive (pun intended).

If you had solar panels that were only 5% efficient but cost $1/kWh obtained, and a gravity "battery" that was 99% efficient but cost $1,000 per kWh stored, the solar panels would be the only possible choice. (Except of course that production of energy and storage of energy are entirely different things. You cannot compare solar panels to gravity batteries. You need to compare your gravity battery to chemical batteries or other energy storage methods. For example, your space battery to a conventional Earth-based gravity battery, which would be much cheaper.) Physical efficiency is only relevant as it affects cost. Cost is the bottom line.
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Offline DanDanDan

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Re: Kinetic Batteries... In Space!
« Reply #25 on: April 10, 2019, 08:51:07 AM »


But comparing it to a battery shows just how many orders of magnitude you're missing here.

Could you be more specific? Not being snarky, I just get the feeling that I'm doing a horrible job of explaining the picture I'm trying to paint with words.

I'm using the battery comparison only, and I do mean only, because it's hypothetically possible to harness energy from virtually anything with potential energy. That's the name of the game with thought experiments: hypothesis.

When I was talking about putting things in orbit, I was picturing the use of garbage which we are already putting up and will continue to put up. Otherwise, the source of such materials would have to be the moon, meteors, asteroids, etc, given how strong the gravity on Earth is.

Isn't that the whole point of setting up a moon base before going to Mars? Shipping stuff around  in space is vastly more cost effective when that stuff is sourced in low or micro gravity.

This isn't the solar freaking highways situation. I'm proposing we produce research now, and hopefully a product later. I am not not not saying that we're ready for construction.

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Offline DanDanDan

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Re: Kinetic Batteries... In Space!
« Reply #26 on: April 10, 2019, 10:02:26 AM »
But a "gravity battery" has physical connection to the weight
No, the battery is the weight itself. The suspended, moving mass "contains" the potential energy is the battery. Anything locked to the part that goes up and down is also part of the battery. Anything that stays stationary relative to the source of gravity, which is the closest thing to being a true source, is something else. For example, if the weight is connected to an electrical generator, which is on the ground, the electrical generator is not part of the battery. That I think we agree on.

BTW, don't forget that, technically, there is no such thing as an original source of energy. The first law of thermodynamics states that the total amount of energy in a closed system cannot be created nor destroyed (though it can be changed from one form to another). Source: http://www.physicscentral.com/experiment/askaphysicist/physics-answer.cfm?uid=20120221015143

Even the Big Bang was a conversion of something to something. There are hypotheses out there that something can come from nothing and not immediately disappear, but we haven't thrown out the first law of thermodynamics yet .

Thermodynamics specifies that all energy in a closed system is recycled energy. That's what I'm saying can, is, and will be done. Recycling through conversion.
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Gravity is practical when you have sloping terrain. Otherwise it is cost prohibitive.
Incorrect. In fact, that exact type of battery that you are saying doesn't work was discussed on the show. Steve himself once pointed out that, paraphrasing here, simply raising stuff straight up is a phenomenal way to store energy.

Perhaps the confusion here comes from the idea that we should use masses sourced on Earth. Unless we're talking about stuff that is going to be raised up and thrown away anyway, you're correct, it's cost prohibitive. We will use stuff already in space, such as materials from asteroids and moons.
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You cannot compare solar panels to gravity batteries.
Yes I can, and I'll do it again to demonstrate where I'm coming from. And keep in mind that thermodynamics specifies that everything is basically something converted to something, which was converted from something, etc. 

You're saying that one is a converter and the other is a container. I'm saying that both are potentially both, and such processes are already being used. If you disagree with that, you're disagreeing with physicists, not me.

Take for example light coming from the sun toward us, and a meteor that's flying at us. Both things have potential energy, and as we speak, humans are harnessing such energy. I can point you to more explanatory sources if you'd like.

Everything I'm talking about has been done before, either in the same way that I'm describing, or in different forms. Such technologies will be used all the time in the coming space economy. It's inevitable.
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Offline Billzbub

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Re: Kinetic Batteries... In Space!
« Reply #27 on: April 10, 2019, 12:48:18 PM »
Okay, consider this.  Let's say we want to de-orbit the space junk as our primary mission.  However, since we have to spend the energy to somehow de-orbit it, we might as well harness some of it's energy while we are there.  For example, we could send up a satellite that shoots a harpoon at space junk as it passes by that attaches a drag wire to the junk.  The wire generates a current as the junk travels through earth's magnetic field, and that generation of energy slows the junk in it's orbit just enough to eventually de-orbit it.  This is converting kinetic energy into electricity through the use of the earth's magnetic field.  If that energy is then used by some mini ion drive encased in the harpoon mechanism to further de-orbit the junk, then we could accelerate the effort to clean up our local space by such harvesting of kinetic energy.
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Offline daniel1948

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Re: Kinetic Batteries... In Space!
« Reply #28 on: April 10, 2019, 01:14:44 PM »
@DanDanDan:

The concrete block battery was discussed as being much less practical and much less cost-effective than other means of storing energy. And note, please, that the blocks are raised or lowered on cables connected to the motor/generator which supplies the energy to raise them and recovers the energy when it's time to release it.

On thermodynamics: the universe is a closed system, but the Earth is not. The Earth receives energy from a thermonuclear power station we call the sun, located at a convenient distance. This is irrelevant to your idea of harnessing energy from space junk.

Specifically, how do you propose to capture the gravitational and/or kinetic energy of the space junk? Any method of recovering either involves connecting the moving and/or raised mass to something that captures the energy by slowing or lowering the object. Regenerative braking on an electric car works because the generator in the car (which is also its motor) applies drag to the wheels. Your cement-block tower recovers energy via a cable that is connected to a generator that applies drag to the weight as it falls. What are you going to attach to the space junk to apply the drag that can be converted into useful energy?

You are correct in saying that all energy has to come from some other form of energy. In the case of solar, the sun is converting mass into photons and conveniently sending some of them our way. A solar panel catches them and converts them to electricity. In the case of a battery, unless it's a one-use battery, which is wasteful of resources, you need a source of energy to charge it.

It's true that we've expended the energy to put all that space junk up there. But it's so spread out that recapturing that energy would be massively cost-prohibitive. Also note (thermodynamics again here) that you cannot get more energy out than you put in: all the energy contained in all the space junk is only a fraction of the energy in the fuel used to put it up there. If you could recover all that energy, you could probably power one large U.S. city for about a minute. At a cost of many trillions of dollars in infrastructure.

The space battery is just not a cost-effective method of either storing or recovering energy. And there's actually no practical way to recover it. Pointing out that it has both kinetic energy and gravitational potential energy does not get you any closer to an actual mechanism for recovering it.
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Offline DanDanDan

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Re: Kinetic Batteries... In Space!
« Reply #29 on: April 10, 2019, 02:05:14 PM »
@daniel1948
Yep, something is getting lost in translation between us. Not sure what else I can say, other than my conclusion at this point.

I was a bit confused by their flip flopping on it, but as of episode 716 @1:09:00, they are back to praising concrete-tower batteries.

Of course their opinion doesn't matter as much as the evidence, which if you have followed the links, is there. Engineers are on board, scientists are on board, investors are on board, that's good enough for me.

The separate and original question has been answered: Yes, this method is being researched, and yes, it's being researched because objects in orbit contain usable potential energy and we have the tech to use it. In time, I'm betting that this will be a more commonly used method.

Space garbage, your days are numbered!

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