For a long time all bikes were made of steel, then came aluminium and then carbon fibre. For fairly similar reasons (improved strength per unit weight) KONE have developed the Ultrarope (TM) lift cables based on a carbon fibre core. The limiting factor for the length of current lifts is the strength to weight ratio of steel that the cables are made of. At a certain length the weight of the steel is greater than the steel itself can withstand. This currently limits lifts to around 500m tall. Hope the ride quality is more comfortable than a carbon fibre bike!
Website link: KONE Ultrarope (TM), press release, 10th June 2013