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Posted by on February 14, 2006, 9:57 am
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Flywheel energy storage has been suggested for use on the Moon (see
http://www.asi.org/adb/04/03/03/flywheel-energy-storage.html ). But I
haven't seen a proposal to use lunar materials in the systems to reduce
cost. I suggest that we import bearings, generator/motors, and carbon
fiber or Kevlar arms/containers from Earth to the Moon. Each unit
might have a capacity of about 100kWh so, for a small colony using
100kW, we would need a farm of 336 such units to hold enough energy for
a lunar night. Rather than the compact flywheel units available on
Earth (see Active Power Co. or Piller GMB), these units would take
advantage of the vacuum and elbow room on the Moon. Each would be atop
a short tower with solar panels on the sides, have two 10m arms tipped
with sacks or containers for 100kg of regolith, and would spin at 3000
rpm. Perhaps 90% of the total mass could be regolith. One such
standardized unit might be used to power a small research shack,
emergency shelter, or 'gas station' for a rover/buggy.
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Posted by Nog on February 25, 2006, 6:59 pm
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wbogen@visteon.com wrote:
show/hide quoted text
> Flywheel energy storage has been suggested for use on the Moon (see
> http://www.asi.org/adb/04/03/03/flywheel-energy-storage.html ). But I
> haven't seen a proposal to use lunar materials in the systems to reduce
> cost. I suggest that we import bearings, generator/motors, and carbon
> fiber or Kevlar arms/containers from Earth to the Moon. Each unit
> might have a capacity of about 100kWh so, for a small colony using
> 100kW, we would need a farm of 336 such units to hold enough energy for
> a lunar night. Rather than the compact flywheel units available on
> Earth (see Active Power Co. or Piller GMB), these units would take
> advantage of the vacuum and elbow room on the Moon. Each would be atop
> a short tower with solar panels on the sides, have two 10m arms tipped
> with sacks or containers for 100kg of regolith, and would spin at 3000
> rpm. Perhaps 90% of the total mass could be regolith. One such
> standardized unit might be used to power a small research shack,
> emergency shelter, or 'gas station' for a rover/buggy.
Lunar night? The dark side is always night. The daylight side is always
light. It's rotational period equals it orbital period. Why use combersome
flywheels when solar cells can do the same thing without moving parts. 100
150 watt panels will generate 15 k watts 110/220 volts. 1000 panes will
generate 150 kilowatts. Would it make more sense to bring the technology up
to the moon to manufacture them up there? There is plenty of sand and
silica. It would be full time power since the sun always shines. You could
run power lines to the dark side and illuminate it.
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Posted by David M. Palmer on March 15, 2006, 2:40 pm
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show/hide quoted text
> Flywheel energy storage has been suggested for use on the Moon (see
> http://www.asi.org/adb/04/03/03/flywheel-energy-storage.html ). But I
> haven't seen a proposal to use lunar materials in the systems to reduce
> cost. I suggest that we import bearings, generator/motors, and carbon
> fiber or Kevlar arms/containers from Earth to the Moon.
> ...have two 10m arms tipped
> with sacks or containers for 100kg of regolith, and would spin at 3000
> rpm. Perhaps 90% of the total mass could be regolith.
At least to first order, the limit on the amount of energy that a
flywheel can store before tearing itself apart is set by the physical
strength of its construction materials.
If you spin two long strong arms that have sacks of dirt at the end,
the arms will break at about the same rotational energy (but different
speeds) whether the sacks are full or empty. (Both the tension on the
arms and rotational energy go proportional to m v^2 .)
If you aren't running the flywheel fast enough to almost fly apart,
then you are probably wasting expensive Earth-manufactured mass.
Indigenous material is only a win if it provides structural strength
(and the strength doesn't have to be nearly as much as carbon fiber, if
you can get the local/imported mass ratio high enough).
--
David M. Palmer dmpalmer@email.com (formerly @clark.net, @ematic.com)
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Posted by on March 25, 2006, 4:50 am
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David M. Palmer wrote:
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> > Flywheel energy storage has been suggested for use on the Moon (see
> > http://www.asi.org/adb/04/03/03/flywheel-energy-storage.html ). But I
> > haven't seen a proposal to use lunar materials in the systems to reduce
> > cost. I suggest that we import bearings, generator/motors, and carbon
> > fiber or Kevlar arms/containers from Earth to the Moon.
> > ...have two 10m arms tipped
> > with sacks or containers for 100kg of regolith, and would spin at 3000
> > rpm. Perhaps 90% of the total mass could be regolith.
> At least to first order, the limit on the amount of energy that a
> flywheel can store before tearing itself apart is set by the physical
> strength of its construction materials.
> If you spin two long strong arms that have sacks of dirt at the end,
> the arms will break at about the same rotational energy (but different
> speeds) whether the sacks are full or empty. (Both the tension on the
> arms and rotational energy go proportional to m v^2 .)
> If you aren't running the flywheel fast enough to almost fly apart,
> then you are probably wasting expensive Earth-manufactured mass.
> Indigenous material is only a win if it provides structural strength
> (and the strength doesn't have to be nearly as much as carbon fiber, if
> you can get the local/imported mass ratio high enough).
Sounds like we need to make flywheels from lunar glass fibers. I have
the impression that glass can be quite strong if made in an anhydrous
environment, which Luna certainly is. Has anyone tried melting lunar
simulant (maybe with most of its metal contamination removed) in a
vacuum to make glass, then strength-tested the glass while still in a
vacuum?
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Posted by pete on March 25, 2006, 4:51 am
Please log in for more thread options In sci.space.tech, on Wed, 15 Mar 2006 19:40:54 -0000,
show/hide quoted text
` > Flywheel energy storage has been suggested for use on the Moon (see
` > http://www.asi.org/adb/04/03/03/flywheel-energy-storage.html ). But I
` > haven't seen a proposal to use lunar materials in the systems to reduce
` > cost. I suggest that we import bearings, generator/motors, and carbon
` > fiber or Kevlar arms/containers from Earth to the Moon.
` > ...have two 10m arms tipped
` > with sacks or containers for 100kg of regolith, and would spin at 3000
` > rpm. Perhaps 90% of the total mass could be regolith.
` At least to first order, the limit on the amount of energy that a
` flywheel can store before tearing itself apart is set by the physical
` strength of its construction materials.
` If you spin two long strong arms that have sacks of dirt at the end,
` the arms will break at about the same rotational energy (but different
` speeds) whether the sacks are full or empty. (Both the tension on the
` arms and rotational energy go proportional to m v^2 .)
` If you aren't running the flywheel fast enough to almost fly apart,
` then you are probably wasting expensive Earth-manufactured mass.
` Indigenous material is only a win if it provides structural strength
` (and the strength doesn't have to be nearly as much as carbon fiber, if
` you can get the local/imported mass ratio high enough).
What about wear on the bearings? With higher mass you get lower
rotational velocity at the same stored energy, ...let's see,
half the mass is sqrt 2 times v for the same energy, so force
is sqrt2/2 ie less for the lighter case. How does bearing wear
relate to force and angular velocity?
--
==========================================================================
vincent@triumf[munge].ca Pete Vincent
Disclaimer: all I know I learned from reading Usenet.
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> http://www.asi.org/adb/04/03/03/flywheel-energy-storage.html ). But I
> haven't seen a proposal to use lunar materials in the systems to reduce
> cost. I suggest that we import bearings, generator/motors, and carbon
> fiber or Kevlar arms/containers from Earth to the Moon. Each unit
> might have a capacity of about 100kWh so, for a small colony using
> 100kW, we would need a farm of 336 such units to hold enough energy for
> a lunar night. Rather than the compact flywheel units available on
> Earth (see Active Power Co. or Piller GMB), these units would take
> advantage of the vacuum and elbow room on the Moon. Each would be atop
> a short tower with solar panels on the sides, have two 10m arms tipped
> with sacks or containers for 100kg of regolith, and would spin at 3000
> rpm. Perhaps 90% of the total mass could be regolith. One such
> standardized unit might be used to power a small research shack,
> emergency shelter, or 'gas station' for a rover/buggy.