Creating engry in space.

[charliebigspuds]

Sorry if I've posted this in the wrong area, but I've had an idea and wondered if it would be possible, I'm not sure of the pratical implications, obvously there are limitations due to the fact that it has to be in space.

The basic idea is, you put a machne in space which has lots of turbines on it. Attach some sort of contraption that will direct the suns rays at the turbines and they start spinning and you use this to create power some how.

My thinking is that, being in space, these thing should be able to spin increadibley fast as there will be no friction and thus creating a lot of power? Whould it not create more power than a standard solar panel.

 

[theridane]

Nope. Solar cells have efficiencies of over 20% now, that's about 300 W/m². That's a lot. Compare with a photomechanical turbine - a square meter of anything in space doesn't even begin to move. That tubine would have to be ludicrously huge to even start doing its sh..tuff.

One more thing: an object that huge would need to have some serious stationkeeping going on to stay aimed at the sun, to overcome the tidal forces like gravity-gradient torque and others. My guess is that the stationkeeping expenses would be greater than the energy output (by several orders of magnitude).

Let's stick with solar cells for now

 

[neuvik]

A turbine type Sterling engine would work fine, as the media is closed cycle. Not sure what you would use for a condenser, but theres gotta be something. I'd imagine a parabolic reflector would still be needed to focus any light on the collector.

An open turbine, that uses just light to move the blades...sounds incredibly impractical. Just use solar sails.

 

[undidly]

A turbine type Sterling engine would work fine, as the media is closed cycle. Not sure what you would use for a condenser, but theres gotta be something. I'd imagine a parabolic reflector would still be needed to focus any light on the collector.

An open turbine, that uses just light to move the blades...sounds incredibly impractical. Just use solar sails.

Solar sails produce thrust.Not what this thread is about.

A turbine could be no more than a thin disc with twisted blades like a wind mill ,spin axis pointing to the sun.
Not heavy so it would spin up quickly.
Electricity can be taken from the disc magnetically or electrically without contact and its position can be set the same way.
The system is cheap and reliable but the output is limited by the maximum spin speed.
Solar cells are damaged by radiation but for size and cost give out more engry.

 

[neuvik]

Solar sails produce thrust.Not what this thread is about.

Ahaha, what do turbine blades do? They convert thermal and kinetic energy to mechanical energy. You might say the blades are thrust in a circle, allowing the shaft to power something down range….

What I was implying is to use the solar sails as the turbine blades, instead of the incredibly expensive alloys I’m used to for steam and gas turbines. And as you stated, yes the sail produces thrust. Coupled on a shaft with a concentric patter it should convert that thrust to rotational energy (mechanical).

 

[SpaceTas]

Sticking close to original post. YES your idea already exists. A combination of solar reflector concentrating solar energy onto a steam engine (Sterling engine is most efficient form) that through expansion/contraction of gas pushes a piston through a shaft can give you turbines. This is done in solar power stations on earth. NASA has looked at the idea for use in space. It could be more efficient than solar panels. It would be more efficient than straight solar cells. The problem appears to be getting a high enough power to weight ratio to make it worthwhile.

 

[dryson]

I think I understand his question. CharlieBigBugs is refering to using a turbine to harness the power of the solar winds that are produced from the Sun. The only question is how would we be able to energize the surface of each turbine blade to react against the atoms that are comprised in a solar wind stream. I think that helium and hydrogen are present in a solar flare. When the surface of the turbine blade comes in contact with the atoms in the Solar Flare the result would be kinetic so that an equal and opposite action of energetic reactions occurs between the helium, hydrogen and the atoms of the turbine blade surface to cause the turbine to rotate in the same direction of solar flar flow thus creating a useable electrical source. How the electrical power is going to get from point C to point A is another problem in and of itself.

Actually the new material graphene would be perfect for this task. The graphene would trap the gas atoms ejected from the Sun in its lattice thus creating a force that would turn the turbine shaft that is part of the generator. Graphene would work acceptionally well becaus it is extremely durable and light and would not add weight to the vanes of the turbine.

 

[SpaceTas]

To impart momentum and hence possible motion you do not need to trap solar wind particles; having them bounce off works.

 

[theridane]

No matter what you do with the momentum, it's still ludicrously inefficient when compared to actually capturing the photon and using all of its its energy to excite an electron. I can get a solar cell off of radio shack for $4.99 that would beat a one-ton multi-million solar windmill hands down.

 

[SteveCNC]

I have to agree with most in that solar wind energy isn't the most efficient way to go . Part of the reason I say solar wind isn't a way you want to go is from reading about Voyager I&II and their encounter with it at the edge of our solar system . It looks like there is a lot of energy there except it occupies a very large area and if you look at it from a e/m^2 point of view its incredibly small but one more thing about solar wind is it's a very destructive type of energy also . Sort of like the inside of a super-collider , anything those particles hit is gonna take some damage and so you would also have to deal with erosion on anything you use to collect solar wind . At least that's how it would seem to me .

Best power source for a spaceship on a extremely long voyage is the one they bring with (like voyager's nuclear power) , as much as I like solar panels and think its a safer way to go they also have limitations .

 

[MeteorWayne]

Again, back to the OP, OK, the solar wind (or light) puts force on the turbine blades. What keeps the thing in place...without that, it just floats away downstream. If you spin the turbine blades, what holds the rest (including whatever you use to take the mechanical motion into some other energy) in place. The whole structure would just spin, and you could not extract any energy.

 

[theridane]

Well you could have two of these windmills counter-rotating, bringing the net torque to 0.

Good point about the stationkeeping... another reason why this wouldn't pay for itself

 

[undidly]

Again, back to the OP, OK, the solar wind (or light) puts force on the turbine blades. What keeps the thing in place...without that, it just floats away downstream. If you spin the turbine blades, what holds the rest (including whatever you use to take the mechanical motion into some other energy) in place. The whole structure would just spin, and you could not extract any energy.

The thing is orbiting the sun.
To get nearer to the sun the the turbine can be tilted to produce a force (by reflected light)against the orbit direction.
To get further from the sun the tilt can be the other way,so the reflected light pushes in the direction of the orbit.

Spin can be canceled by counter rotating turbines or a torque arm as on a helicopter.

A major advantage of the turbine system is that it is very cheap and does not wear.

 

[theridane]

A major advantage of the turbine system is that it is very cheap (...)

Don't take this personally, but... :lol:

In Earth's orbit, one sq. meter "solar turbine", if perfectly aligned and perfectly efficient (and we all know that ain't gonna happen), produces less than 5 µNm of torque! That's enough to get you over 300 µW of output power at 600 RPM, way to go! That would probably be enough to feed my wristwatch.

A piss poor Radioshack-quality solar panel, 25% efficient with just eyeballed alignment, will get you over 0.27 kW of raw power and won't even force you through eons of waiting for it to spin up. Sick, huh?

So if your whirly rig wanted to match the output of the solar panel, how big would it have to be? That's right, divide them: 870,000 sq. meters. :mrgreen: That's a circle over 1 km in diameter. And it would need to spin at 600 RPM to match the shaft power of that puny little solar cell (also not gonna happen).

So no big deal, it just needs to be huge, but it's still worth it, right? Wrong. In commercial spaceflight, all hardware costs exactly $0. It's the lifting that puts price tags on things. That radioshack solar panel weighs about 10 kg, which translates to about $56,000 on an Atlas V Heavy. Your solar rig, at 870,000 m², weighs about 87 metric tonnes (assuming same density as NanoSail-D, 1 kg/10 m²). So you've already wasted 4 fully loaded Atlas V Heavies just to lug your windmill to space. That's $440 million + tax. For a freaking solar cell substitute. Insane.

There's a reason there are no windmills in space.

(...) and does not wear.

Because the thought of a square kilometer of tinfoil getting mangled by gajillions of space debris every day is soo preposterous that it borders on impossiblity, right?

Let's stick with solar cells for making engry in space.

 

[amshak]

Actually I had the same idea but a little bit different.
You dont need any solar or sun to do that. Space means Zero Gravity . So I have an Idea. You have to keep a Electric Generator with no Turbines.[Like a Dynomo or Something] You have to Keep a magnet Inside a copper coil . And you have to turn the Magnet. It keeps on turning without Friction . So electricity can be Created . And I am Sure THat energy is much more than Solar Panals . May be Future Energy for Space Flights. What do you say can this help?

 

[theridane]

As soon as you connect a load to that generator the free-spinning magnet will start to slow down. A couple seconds later you end up with a still magnet and no power.

Plus in real life you'd have all kinds of forces yanking on that magnet - Earth's magnetic field, Sun's magnetic field, influences from charged particles, and even from your own spacestation. It'd be an adventure just keeping that magnet in one place

 

[undidly]

As soon as you connect a load to that generator the free-spinning magnet will start to slow down. A couple seconds later you end up with a still magnet and no power.

Plus in real life you'd have all kinds of forces yanking on that magnet - Earth's magnetic field, Sun's magnetic field, influences from charged particles, and even from your own spacestation. It'd be an adventure just keeping that magnet in one place

You are right that a free spinning magnet will slow to a stop as energy is taken from the spin.
What is the magnet was in the shape of a windmill and the sun was shining on it.
Sunshine concentrated by mirrors but not so much as to make the magnet hot.

It is easy to keep the magnet in place with position sensors and simple electronics.
The magnet could spin up to a hundred thousand RPM for more output.

Dyson , the vacuum cleaner people have motor that does 100,000 RPM.

 

[amshak]

I think I have a better Idea .
What if we use a Photometric Propeller :?: It works on this prinsiple- One Side is Painted black which do not absorb light and other side with white . it turns on this principle by the action of photons, And turbine turns, and the Zero Gravity makes it Perfect.
I guess this would work.

 

[theridane]

What is the magnet was in the shape of a windmill and the sun was shining on it.
Sunshine concentrated by mirrors but not so much as to make the magnet hot.

So now instead of a lightweight solar-sail-like "turbine" that already needs 4 of the largest rockets available today to deliver an equivalent of a single Soyuz solar panel we're hauling a gigantic magnet shaped like a windmill and a truckload of mirrors to focus light on it? I thought magnets were heavy.

 

[MeteorWayne]

Again, what holds the outer part still so the spining creates work? In space, as the turbine spins, so does the turbine holder and generator so there is no net motion to create electricity. To hold the genberator in place, you need to supply as much energy as the turbine creates!

 

[Jimmyboy]

.........

 

[Jimmyboy]

Again, what holds the outer part still so the spining creates work? In space, as the turbine spins, so does the turbine holder and generator so there is no net motion to create electricity. To hold the genberator in place, you need to supply as much energy as the turbine creates!

Couldnt you have two turbines, one that faces the sun where say the propellers are angled to turn clockwise, then a turbine behind the one in front with turbine propellers angled so they turn in the opposite direction.. The forces would canx, and there will still be rotation??Also adjust the front propeller so its surface area is less than the back propeller so both front and back propellers receive the same amount of photons hence spin..

 

[theridane]

Or have two of those windmills, one with clockwise and the other with counter-clockwise turbines. Join them with a truss and voila, net momentum equals zero. It's why V-22 Osprey doesn't spin itself to death.

 

[BurgerB75]

Other than the fact that it will still be pushed away from the sun.

 

[theridane]

Not if it was in orbit around a minor body. In a sun-synchronous polar orbit (or any other type) it would keep doing momentary plane changes, but the net delta-phi would be zero.

That being said, the photonic push would be the least of its worries. Magnetic fields, debris, gravitational disturbances and general infeasibility of the idea would be the killers here.