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