Engineers Develop 'Ultrarope' For World's Highest Elevator

HughPickens.com writes: Halfway up the Shard, London's tallest skyscraper, you are asked to step out of the elevator at the transfer floor, or "sky lobby," a necessary inconvenience in order to reach the upper half of the building, and a symptom of the limits of elevators today. To ascend a mile-high (1.6km) tower using the same technology could necessitate changing elevators as many as 10 times. Elevators traveling distances of more than 500m [1,640 ft] have not been feasible because the weight of the steel cables themselves becomes so great. Now, after nine years of rigorous testing, Kone has released Ultrarope — a material composed of carbon-fiber covered in a friction-proof coating that weighs a seventh of the steel cables, making elevators of up to 1km (0.6 miles) in height feasible to build.

Kone's creation was chosen to be installed in what's destined to become the world's tallest building, the Kingdom Tower in Jeddah, Saudi Arabia. When completed in 2020, the tower will stand a full kilometer in height, and will boast the world's tallest elevator at 660m (2,165ft). A 1km-tall tower may seem staggering, but is this the build-able limit? Most probably not, according to Dr. Sang Dae Kim. "With Kingdom Tower we now have a design that reaches around 1 km in height. Later on, someone will push for 1 mile, and then 2 km," says Kim. He adds that, technically speaking, 2 km might be possible at the current time. Anything higher would require new materials and building techniques.

Comments

just put a motor on the elevator itself

[Noah Haders]

i would do away with the motor at the top of the shaft, and instead electrify each individual elevator so it has motive power. seems like the best solution to me.

Re:just put a motor on the elevator itself

[BarbaraHudson]

The cable doesn't arrest the fall - brakes do.

Re:just put a motor on the elevator itself

[Anonymous Coward]

You still need a counterweight or else you are lifting the entire mass of the elevator instead of just passengers. That means a cable.

Re: just put a motor on the elevator itself

[pavon]

No, you could use a conductive rail, like a subway, and rack and pinion system to move the elevator. The rack and rail would add a fair bit more total weight to the building compared to a cable. But more importantly, the motors would have to be much much more powerful! Modern elevator systems have a counter-weight balanced on the other side of that cable, which means the motor only has to overcome friction and the small difference in weight between the elevator and counterweight (which varies depending on current payload). The motor on an elevator like Noah is suggesting would have to provide enough force to counteract the entire weight of the elevator + payload + motor + friction, which is at least an order of magnitude more than a traditional elevator.

Re: just put a motor on the elevator itself

[Anonymous Coward]

Calling out a person for behavior you present is not going to change anything.

The main problem with rails is that you need a sliding contact. That means arcing at the contact when the air gaps are eventually going to occur (nothing is 100% flat, and air pockets will eventually get between the contact and the brush). Arcing isn't going to cause immediate failure; but, it will leave a carbon / oxidation residue at the arc site. This means that future electricity will have to flow through a very small scale resistor, generating heat. Eventually the heat will cause pitting, accelerating failure.

This is why most in-wall electrical sockets are designed to scrape the plug slightly on insertion. It is a self-cleaning feature of electrical wall sockets, and any wall socket that doesn't provide some modicum of resistance when inserting a plug should be replaced as soon as possible. A loose wall socket will not clean the prongs on the plug, carbon will build up within the socket, and the heat will eventually lead to arcing that will melt the plug, the socket, or both (possibly starting a fire as a side effect).

The issues of contacts on long electrical rails can be fixed by turning the rails into flexible cables; but, that only recreates the cable problem. Even though an electrical cable could be theoretically lighter than the lift cable, it still has to lift its own weight, and an under-built electrical cable cannot entertain even micro-fractures in electrical conductivity without have an accelerated repair cycle.

Now you know why virtually all elevators use cables for lifting with a fixed motor.

Re: just put a motor on the elevator itself

[ShanghaiBill]

With a magical lightweight power cord, perhaps?

The British already have a twenty mile long extension cord that they use to power the trains going through the Channel Tunnel. They reel it out as each train goes through, and then wind it up afterwards to prepare for the next train. There is no other way to do it, since it is totally impossible to transfer electricity to a moving object through, say, a power rail.

Re:just put a motor on the elevator itself

[ihtoit]

you can build as high as you want as long as you can build a cable long enough to service the elevator. Cable length isn't a problem, the weight of the cable is. In systems such as this very simplified model of a counterweighted elevator http://s.hswstatic.com/gif/bt4... it's assumed that the rope weighs nothing, therefore the counterweight only needs to weigh 25lb - even taking into account the rope's weight, all other things being equal it balances itself. That's handy, scaling up you only need a 400lb counterweight for a lift rated at MGW: 1600lb (ten persons (800lb) + 800lb car). This arrangement does of course necessitate four times the length of cable as the height of the shaft, and with another shaft-length you can actually mount the motor at the bottom, negating the requirement for a counterweight - the motor only has to overcome the weight of the car through the system, which practically means it's pulling against a quarter of it. For some reason that's not really practical, so in this arrangement you'd have a counterweight one side, top-anchor the other end of the rope and have the motor roll the cable somewhere in between. FWIW when you see an elevator car with four cables, you're not seeing four cables, it's one cable. It's this arrangement of three (strictly, four, but the car pulley can be and often is a twin) pulleys, a counterweight and a top anchor. Other setups have the anchor point actually on the roof of the car, still others have the car and the counterweight on their own bottom pulleys, both ends top-anchored and the motor in the middle sharing rope between essentially two double systems.

(grew up in a tower where the elevator spent more time stuck between floors than enough, often with me trapped in it. Hearing firefighters clambering around up there to attach car batteries to the brake solenoids so they can lower the car to the ground after eight hours is a terrifying thing for a four year old. Nerd points for spotting the ropes and asking about them when they were fixing the thing, though).

Re:just put a motor on the elevator itself

[germansausage]

He has it exactly right. The tension on the cable pulls on the elevator brake to release them. If there is no tension on the cable, ie pulley or cable fails, the cable looses tension and the brakes apply.

Re: just put a motor on the elevator itself

[fustakrakich]

Maybe we should apply this great cable technology to subway trains. I do notice the pits on the third rail. They always have to send some poor guy out to sand them out real quick before the next train comes.

Re:just put a motor on the elevator itself

[inasity_rules]

I have been down a 2km mineshaft(the shaft is deeper, but they only go down in +/-2km sections) in a 'cage'. There is no counterweight, but the AC winder that drops (yes, 'drops' is the right word) you and hauls you back out is pretty powerful. They account for cable weight and extension because there are rails in the cages and they need precision to match them up. They get about +/- 1cm. Operator skill is important..

Yes. It is possible even with old style cables, but to get anywhere in a reasonable time, you have to go bloody fast, and it is honestly really scary. It took us about 5 minutes to reach the bottom most of that time was slowing down. I don't recommend it for the the general public. Many shorter elevators are a far better idea. Can you imagine stopping at every floor for 1km?

Re: just put a motor on the elevator itself

[Anonymous Coward]

Train rails are excessively thick. This coupled with scrubbers around the brushes means that the rail is cleaned prior to contact, and the wear of the (cleaner) rail is minimized. This coupled with the minimal movement of a ground fixed tie and a very large amount of metal to wear through leaves the effective life of the rail in the +10 year range (if not +50 year range).

A building will have few of these advantages. Buildings in the 30+ story range sway. Excessively thick rails get far more expensive to run vertically, so the rail thickness will be minimized. This increases the chance of flex and decreases the amount of rail to wear out by scrubbing or pitting. It isn't that it can't be done, it's just that it can't be done easily, which translates to cheaply.

Re: just put a motor on the elevator itself

[fahrbot-bot]

With a magical lightweight power cord, perhaps?

Power it using lasers - duh.

Re: just put a motor on the elevator itself

[Anonymous Coward]

Induction incurs a lot of losses. Yes, it can travel a small air gap easily; however, it does so with a lot of compromises. Some of the main challenges is heat generation and low power transmission efficiency. Increasing the power can attempt to address the latter but only at a cost of more heat. Also, induction has extra challenges when considering a moving receiver, and if you decide to address these by moving the transmitter, you then have a lift problem to solve for your transmitter.

I'm not saying that it is impossible, but it is far, far cheaper and more reliable at this time to not attempt to use inductive charging on a self-powered elevator.

And keep in mind that we are blessed with elevator brakes that are actively held open. A self-powered electrical elevator car would have a pretty high constant draw to replicate the braking system, as it would have to pull solenoids against the breaking springs.

Finally, current elevators don't lift the car. It is counter balanced with a set of stacked weights. The elevator motor (a fixed mounted motor pulling the cables) only needs to lift the difference between the two weights of the loaded car and the counterbalance weight stack. A fully self-powered car of the kind we are considering would not have a counter balance (because it would lack the connecting cable) and therefore would need even more power to lift the entire mass of the car.

That's a large increase of needed power coupled with a large decrease in power delivery. It is far from a trivial engineering problem to solve, and is unlikely to be solved favorable within our lifetime.

Re:just put a motor on the elevator itself

[ihtoit]

I saw a programme that dealt with this a while ago, it was using the WTC Twin Towers as a use case in splitting elevator loads and why the decision was made to stagger the system rather than have shafts that went from the basement to the roof. It wasn't a question of cabling, it was a question of how many full-height shafts can you cram into a building and stil have a habitable space?

Re: just put a motor on the elevator itself

[houghi]

The main problem with rails is that you need a sliding contact.

You could use a wheel. As you will need at least three wheels and most likely more to hold the cage stable, each wheel could be a contact point and each rail could be a slider.
Just look at any roller coaster and imagine the rails carrying the current and the wheels being the contact.

And even the slider has been resolved. Just look at trains.

The reason elevators use cables is because of the counterweight. That means less weight and thus less powerfull motors and thus cheaper.

However if the cable becomes heavier then the counterweight, it could become doable to use an on board electrical motor. The distance of 1 KM is nothing when you compare it to the distances metros, trams and trains travel each day.

Re: just put a motor on the elevator itself

[rizole]

This is rediculous...British ingenuity did away with the mile long extension cord years ago. We now have a cordless extension cord to do the job.

Re: just put a motor on the elevator itself

[Half-pint HAL]

Use just a little more creativity. One possibility: Have brakes that are actively held open; hold them open with a quick release mechanism; for the quick release, hold its release via the constant power. If power is cut, it'll trigger the quick release, which will release the stored energy in the springs. It doesn't take much to hold back lots of stored power. Batteries and capacitors could also be employed at various points. Basically, this isn't a problem.

The current system is very simple, and very reliable. The car is suspended from the cable via the brake. The tension generated by the weight of the car disengages the brake (because even when going down, the car still accelerates at less than the rate of gravitational acceleration. If the cable fails, the tension vanishes instantly, and the brake is engaged. This mechanism works instantly, even if the car is at rest when the cable breaks. Your suggestion works when the mode of failure is power loss, but in a self-powered electric lift, the loss of power would be less of an issue than loss of traction. The safety mechanism would only be able to detect loss of traction when the car is in motion, which means losing vital seconds as the elevator gains momentum, and therefore will result in needing a more powerful brake. And that means adding in more powerful, heavier systems to hold the break open, as opposed to the current system which just uses the weight the elevator already has. So now you're shifting more bulk again.

And all that for what? To create a lift that is far, far less efficient than the current model, because as the GP AC said, elevators use counterbalancing weights so that the only work they're doing is in moving the contents of the elevator -- the lift car and the counterweights practically move themselves.

What?/ Just 2 Km? That's it?!

[140Mandak262Jamuna]

So I guess the space elevator is not coming any time soon.

Why use a cable?

[fuzzyfuzzyfungus]

Does anyone know why they wouldn't sidestep the infeasibility of particularly long cable runs by having the elevator climb the walls of the shaft directly, rather than being raised and lowered on a cable? I imagine that a cable and counterweight arrangement is more energy efficient for shorter runs; but if that isn't an option wouldn't a cog railway style mechanism, with 'track' on one or more walls of the elevator shaft, result in a system where the weight that has to be moved doesn't change at all with the height of the building? There would be some additional weight per unit height from the track structure; but that would be static and connected to the building's frame rather than being forced to support its own weight.

Too energy intensive? Wears too quickly? Safety breaks infeasible leading to risk of sickening plummet to doom?

Re:Why use a cable?

[quenda]

Such lifts certainly exist, and are used on construction and industrial sites.
I expect noise, speed, power use and maintenance cost might be areas where cable wins out.

http://www.gedausa.com/rack-an...

Re:Why use a cable?

[stephenpeters]

I think one of the reasons is that it is possible for fire fighters to manually move the winding drum in the event of a power failure to move the lift car to the nearest floor. Without a drum and cable any rescue attempt during a power loss would require lifting equipment and would involve climbing into the lift shaft to reach the car with all the related falling from height issues.

Re:trains don't need rope...

[luvirini]

Trains also do not need to pull straight up.

The real reason for the cables is to allow counterweights to balance much of the load. Thus with counterweight you are lifting only the carried weight, without you are lifting also the elevator chassis and any engine and such, a much larger load.

LSM

[jklovanc]

Linear Synchronous Motor Elevators Become a Reality

Re:LSM

[Warbothong]

Well this is the best thing I've seen! Why haven't these been pushed out into the commercial area?

For the same reason that maglev trains and HyperLoop-style vacuum tubes aren't ubiquitous: sending a dumb carriage along a smart track is far more expensive than sending a smart carriage along a dumb track, since there's much more track than there is carriage.

Narrowboats used to be the best way of moving materials around in-land, but "laying the track" (digging the canals, building the locks, etc.) took a lot of work.

Dumb boats were overshadowed by smarter locomotives: more difficult and expensive to build, but ran on much cheaper tracks.

Locomotives were overshadowed by smarter automobiles: more difficult to invent and require a smarter fuel network, but in some cases don't need *any* track laying.

The same argument applies to lifts: it's much cheaper to have a smart motor at the top and/or a smart carriage, with 660m of dumb shaft and cable, than having 660m of smart shaft.

World's highest dick-waving contest

[localroger]

Highest skyscraper is a hell of an expensive way to show your ability to get an erection. How much of the Burj Dubai is even occupied? Or for that matter even the *cough* whatever they're calling it now in NYC which gets a third of its patriotic 1776 feet from a totally nonfuctional dick-waving spire.

Re:Worthless

[TechyImmigrant]

Or build the building horizontally and put in moving walkways.

Just as much space, at a fraction of the cost and it doesn't have to exist to massage the ego of an oil rich prince who murders atheists for fun.

Re:The rate at which oil prices are dropping ...

[ShanghaiBill]

... we may have use the 2km long ultra strong ultra light cable to dredge the Saudi economy from the bottom of the Persian Gulf.

Nope. The Persian Gulf is very shallow, with an average depth of only 50 meters, and a deepest point of only 90 meters. Citation: Persian Gulf Geography

Re:trains don't need rope...

[ihtoit]

that's the ticket - you want the car + load to be as light as possible. Basically all you want on the car is the anchor point for hte rope, some way to get power inside the car and power for the emergency system. That's enough weight, the big building that isn't going anywhere can take the several-hundred-pound motor and gearbox and keep it sequestered in the roof.

Armchair engineering at its finest

[mcrbids]

I'm probably going to lose some karma for this...

I, too, could come with a half-dozen answers that would be "far superior" to what 100+ years of the finest minds in the industry could come up with. But in reality, I really, seriously doubt that my designs would hold up because there's a *reason* that things are done the way they are.

Mechanical engineering is a *very old* industry, and any radical, new design would have significant hurdles to pass before it could be accepted and used in a real scenario. The cost of failure is very high and there are real lives on the line.

My first thought was to use something like a caterpillar drive along the sides of the shaft, each of which would operate like a mini elevator for perhaps 10 floors. But, very quickly, I can see that this type of system would have many, many more moving parts and consequently many more points of failure.

So, I think it *might* be best to trust that 100+ years of experience are, in fact, at work, and that we should first understand that there is *real knowledge* at work before assuming that our half-baked and thoroughly unproven ideas hold any merit in reality.... ?

Re:Armchair engineering at its finest

[NoNonAlphaCharsHere]

That has GOT to be the most trollish post I've ever ever ever read here. You have NO IDEA how Slashdot works, do you?

Re:Armchair engineering at its finest

[serviscope_minor]

Indeed, and I think it's reasonable to call out the posters who say "oh they're idiots, why don't they just..." and so on and so forth.

However, it IS fun to speculate with a bunch of reasonably knowledgable people on mechanisms for going beyond what is currently technically feasible.

The powered lift with a rack and pinion is an interesting idea. I'm struggling to work out how much additional power it would take. With a short lift, you can discount the weight of the cable, and so you can have the lift counterbalanced easily and the motor must lift the ddifference between the two sides plus the friction.

With a long cable, the weight to be lifted changes with height: the further down the lift goes, the higher the weight. If you counterbalance with the same mechanism, then the balance will only be equal in the middle. At the bottom, you need to lift the entire weight of the cable, which in a high lift can be more than the lift.

At that point, having a motor which can lift the entire lift minus the cable isn't infeasible. Of course, you have to lift the motor too. And then there's the problem of power delivery. Maybe something like a train pickup could be adapted to work.

The power will be enormous, but one could offset it at a building scale using energy recovery, either have lifts run in oppsition where the descending one powers the rising one, or have the lifts all connected into a busbar which has some large piece of rotating flywheel storage to absorb or emit energy as required.

Apparently there are a few companies working on cableless elevators for exactly these reasons. Some have linear motors instead of a rack and pinion.

Re:Armchair engineering at its finest

[Hodr]

I wouldn't presume to know more than a mechanical engineer at an elevator company. But I might still be able to figure out why someone who has spent their entire career building one style of system, with the only variance being the size of the motor and the length of the cable, with investments into the supply chain for those specific components and technicians familiar with working and installing those components, might tell you that the old way is the best way without seriously considering an alternative.

Hey, I mean If I was staring at the choice of selling 10 of my most expensive systems to a client, or telling him to hire an engineering firm and materials scientist to reinvent the wheel (or elevator), I know which one is better for my bottom line.

Re:Armchair engineering at its finest

[Half-pint HAL]

Ah, rampant speculation -- I'm game. I'm wondering about the possibility of a three part lift -- a car with two independent cradles. The first cradle is cabled for a third of the height of the building, and is left behind when the lift goes above that point. The second cradle is cabled for two-thirds of the building, and disengages once the car ascends above two-thirds of the building. On descent, the car reaches the cradles again and continues down. Each of the cradles is counterweighted to provide a displacement load for the shifting weight of the cable. Each cradle would have its own independent brake (as would the car), which would add extra safety mechanisms to the lift

Now I'm also wondering if there's some way of using waste water from the upper floors as additional ballast, carried partway down the building alongside the counterweights before being released into the sewage system on a lower floor. Or maybe a partially-passive aircon using a liquid medium that is cooled by high-altitude winds before being shuttled to the centre of the building for circulation.

Better Way

[JimSadler]

The RCA building in NYC uses compressed air and the elevator is effectively a dart flying up the shaft. With an accelerometer installed to trip the brake if too rapid a descent occurs there is no need at all for cables.

hello turbolift? Re:LSM

[Fubari]

That was a cool article, thanks for the link, this part made me think StarTrek style turbolift:
from the linked article (emphasis added):

Flexible configuration: LSM elevators can propel a vehicle in any direction, and cabs can be switched from hoistway to hoistway, enabling the creation of “one-way” hoistways with multiple cabs in each. Modular stators allow the height of the elevator to be customized at installation and extended in the future with minimal disruption. LSM elevators can also accommodate inclined layouts, providing an alternative to stairways or escalators.

Linear Synchronous Motor Elevators Become a Reality

Re:Electrically-coupled counterweight

[Dereck1701]

While such an elevator system would use more power one of the inherent abilities of any electric motor system is the ability to use regenerative braking. You'd probably have a bank of super-capacitors in a utility room, when the elevator was going up it would use the capacitor bank and some power from the mains, when it was going down it would refill the capacitors. Even if you had to put the motors on the elevator car itself this shouldn't be an issue as we have centuries of technology (subways, trains, trolly cars, bumper cars, etc) proving that you can provide power to a moving transportation system and electric motors are quite small (the ones powering electric cars are about the size of a watermelon).