a winding Solution to the space elevator power problem

52 %
48 %
Information about a winding Solution to the space elevator power problem

Published on November 17, 2007

Author: benoitmichel

Source: slideshare.net

Description

A winding solution to the space elevator power problem, as explained by Benoit Michel at the Eurospaceward "first European workshop on space elevator climber and tether design" in Luxembourg, November 10th, 2007

A winding solution to the space elevator power problem B. Michel, UCL

The ‘Reference Space Elevator’ (RSE) is 100.000 Km long with a tapered 2 mm 2 max cross section. It is made from CNT with a 150 GPa strength. It costs around 6000 M$, 1/3 dedicated to power the system. It will have to overcome many problems due to interference with the earth atmosphere, low orbit objects, and the laser power beams needed to beam energy to the climbers. The Reference Space Elevator

The ‘Reference Space Elevator’ (RSE) is 100.000 Km long with a tapered 2 mm 2 max cross section.

It is made from CNT with a 150 GPa strength.

It costs around 6000 M$, 1/3 dedicated to power the system.

It will have to overcome many problems due to interference with the earth atmosphere, low orbit objects, and the laser power beams needed to beam energy to the climbers.

A heavier, longer ribbon (150000 Km, constant section) The climbers will not climb the ribbon; they will be attached to it. The up and down translation is done by winding and unwinding the cable on reels at both ends. Energy is provided to the system only at ground level and at the counterweight station A simple winding solution

A heavier, longer ribbon (150000 Km, constant section)

The climbers will not climb the ribbon; they will be attached to it.

The up and down translation is done by winding and unwinding the cable on reels at both ends.

Energy is provided to the system only at ground level and at the counterweight station

Start : cabin at earth level, 35900km cable reeled-in on a spool on the ground. The CW is at 150000km attached to an empty spool Unreel the ground spool, reel-in the cable on the CW spool : the cabin climbs…. End : ground spool empty, cabin at GEO, CW down to 73000 km with a big spool of cable How it works (1)

Start : cabin at earth level, 35900km cable reeled-in on a spool on the ground. The CW is at 150000km attached to an empty spool

Unreel the ground spool, reel-in the cable on the CW spool : the cabin climbs….

End : ground spool empty, cabin at GEO, CW down to 73000 km with a big spool of cable

Why do we move the counterweight up and down? To keep the ribbon stress under its maximum allowed value at all times, and To keep the centre of gravity farther than the GEO. When the CW spool is heavier, it has to be moved closer to the ground. How it works (2)

Why do we move the counterweight up and down?

To keep the ribbon stress under its maximum allowed value at all times, and

To keep the centre of gravity farther than the GEO.

When the CW spool is heavier, it has to be moved closer to the ground.

How do we move the counterweight down? The CW spool is actuated by electric motors and solar panels. As the payload climbs up, the CW lowers itself from 150000 km to half that while its weight increases 20x ! (15 Tons to 313 Tons). 15 tons is the minimum weight of the CW, used for solar panels, motorised winch and a maintenance station. How it works (3)

How do we move the counterweight down?

The CW spool is actuated by electric motors and solar panels.

As the payload climbs up, the CW lowers itself from 150000 km to half that while its weight increases 20x !

(15 Tons to 313 Tons).

15 tons is the minimum weight of the CW, used for solar panels, motorised winch and a maintenance station.

While we move up… … the Earth station unwinds its winch and uses the recuperated energy to power the base station. … the CW spools its winch using the solar panel energy. While we go back to earth… … the Earth station winds its winch using low cost electricity. … the CW spool is unreeled and the energy is dissipated by radiator panels. How it works (4)

While we move up…

… the Earth station unwinds its winch and uses the recuperated energy to power the base station.

… the CW spools its winch using the solar panel energy.

While we go back to earth…

… the Earth station winds its winch using low cost electricity.

… the CW spool is unreeled and the energy is dissipated by radiator panels.

Cross section : 2mm 2 Total cable length : 185,900 Km Total cable mass : 483,600 Kg Min CW weight : 15,673 Kg @ 150,000Km Max CW weight : 313,113 Kg @ 71,500Km Max stress : 75 GPa Mass of one ‘lift’ = 2,000 Kg Some figures

Cross section : 2mm 2

Total cable length : 185,900 Km

Total cable mass : 483,600 Kg

Min CW weight : 15,673 Kg @ 150,000Km

Max CW weight : 313,113 Kg @ 71,500Km

Max stress : 75 GPa

Mass of one ‘lift’ = 2,000 Kg

Compared with the R.S.E : Heavier cable, Higher cable stress Lighter payload Downward journey wastes useful time But No need for energy transfer Very simple climbers Cable repair easy at Earth (lower part) Cable repair possible at CW, or at the GEO station (upper part) First conclusion

Compared with the R.S.E :

Heavier cable,

Higher cable stress

Lighter payload

Downward journey wastes useful time

But

No need for energy transfer

Very simple climbers

Cable repair easy at Earth (lower part)

Cable repair possible at CW, or at the GEO station (upper part)

Wind Thunderstorms and lightning Radiation Atomic oxygen Sulphuric acid LEO satellites and know debris Micrometeors Most of the above threads are directed to the lowest percent(s) of the cable. Threads to the elevator

Wind

Thunderstorms and lightning

Radiation

Atomic oxygen

Sulphuric acid

LEO satellites and know debris

Micrometeors

Most of the above threads are directed to the lowest percent(s) of the cable.

Almost all damage to the cable can be fixed when the cable is on the ground. We can even replace sections of the cable if needed! No more need to beam energy to the climbers Better climber payload/dead weight ratio In case of major damage, we can uncoil fresh ribbon at the bottom while discarding the top section from the CW. The same method can be used to progressively increase the ribbon section. Advantages of the winding solution

Almost all damage to the cable can be fixed when the cable is on the ground. We can even replace sections of the cable if needed!

No more need to beam energy to the climbers

Better climber payload/dead weight ratio

In case of major damage, we can uncoil fresh ribbon at the bottom while discarding the top section from the CW.

The same method can be used to progressively increase the ribbon section.

Seeing the above conclusions, why not trying to keep the best of both words? A tapered cable, relatively lightweight Beam powered climbers But A winch at the earth station and a winch in the CW Why not an hybrid compromise ?

Seeing the above conclusions, why not trying to keep the best of both words?

A tapered cable, relatively lightweight

Beam powered climbers

But

A winch at the earth station and a winch in the CW



The operating mode will be a compromise too: We lock the climber to the cable and use the winch for the first 2600 Km We play with the CW altitude to keep the centre of gravity above GEO and the stress in the cable at an acceptable level. The rest of the journey to GEO is classical with energy beaming When at GEO, we disconnect the climber from the cable for our cable roll-back The hybrid compromise

The operating mode will be a compromise too:

We lock the climber to the cable and use the winch for the first 2600 Km

We play with the CW altitude to keep the centre of gravity above GEO and the stress in the cable at an acceptable level.

The rest of the journey to GEO is classical with energy beaming

When at GEO, we disconnect the climber from the cable for our cable roll-back



The lower 1% of the cable is regularly accessible on earth for maintenance (and the major threads are in the lower area) For exceptional repairs in the lower 5%, we can roll-in slightly more cable on ground if no climber attached and if the CW is winched down. Power beaming requirement are lower (75% at 1000Km, 50% at 2600 Km, 30% at 5200 Km) Smaller PV panels Better efficiency Power beaming accidents at low altitudes no more possible. Power beaming from GEO becomes possible The hybrid advantages

The lower 1% of the cable is regularly accessible on earth for maintenance (and the major threads are in the lower area)

For exceptional repairs in the lower 5%, we can roll-in slightly more cable on ground if no climber attached and if the CW is winched down.

Power beaming requirement are lower (75% at 1000Km, 50% at 2600 Km, 30% at 5200 Km)

Smaller PV panels

Better efficiency

Power beaming accidents at low altitudes no more possible.

Power beaming from GEO becomes possible



The main parameter is the reel-in/reel-out distance We have to balance the reel-in/reel-out distance against Cable strength and taper value Additional weight and complexity at the CW Power beaming lower requirements Easy maintenance for the reeled part of the cable For low values of the parameter, A fixed CW without winch could be used Higher cable stress Lower maximal payload More simulations are required to find the best compromise The compromise parameters

The main parameter is the reel-in/reel-out distance

We have to balance the reel-in/reel-out distance against

Cable strength and taper value

Additional weight and complexity at the CW

Power beaming lower requirements

Easy maintenance for the reeled part of the cable

For low values of the parameter, A fixed CW without winch could be used

Higher cable stress

Lower maximal payload

More simulations are required to find the best compromise



www.benoitmichel.be Benoit MICHEL, November 2007 Images copyright Alan Chan & his space elevator visualisation group

Add a comment

Related presentations

Related pages

A winding solution to the space elevator power problem

“A winding solution to the space elevator power problem” presented at Space Exploration 2007 1 Abstract— A solution to the space elevator power ...
Read more

A winding solution to the space elevator power problem B ...

A winding solution to the space elevator power problem B. Michel, UCL. Published byBeatrice Haynes Modified about 1 year ago
Read more

A winding solution to the space elevator power problem B ...

A winding solution to the space elevator power problem B. Michel, UCL The â Reference Space Elevatorâ (RSE) is 100.000 Km long with a tapered 2 mm2 ...
Read more

Design of a Space Elevator - Documents

a winding Solution to the space elevator power problem A winding solution to the space elevator power problem, ...
Read more

Damper Winding Problem - Engineering - documents.mx

Share Damper Winding Problem. ... a winding Solution to the space elevator power problem. Stockbridge Damper. Fire Damper. Electromagnetic Damper. Damper ...
Read more

Module A-3 Carbon Nanotubes. Space Elevators First ...

Space Elevators First elevator: ... Analysis Design Verification Contest Problem. ... A winding solution to the space elevator power problem ...
Read more

GREENDROID: A SOLUTION TO THE BATTERY PROBLEM OF ...

Share GREENDROID: A SOLUTION TO THE BATTERY PROBLEM OF SMARTPHONE. ... a winding Solution to the space elevator power problem.
Read more

ABSTRACTS Nov 10 : Space Elevator System

modern space elevator and is leading the global effort to develop and build a space elevator. He is ... A hybrid winding solution to the SE power problem
Read more