Se você acha que poderia ter sido Clarke, eu tentaria As Fontes do Paraíso . Não me lembro da passagem específica de que você está falando, mas antecede (e provavelmente causou) a era da ficção científica em que os elevadores espaciais são um tropo comum, então, se bem me lembro, ela passa mais tempo descrevendo-os do que a maioria. .
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Capítulo 10 "A Ultimate Bridge"
Cotação entregue pelo holograma de Vannevar Morgan, engenheiro chefe da Divisão Terrestre da Terran Construction.
"Capsules for passengers, freight, fuel would ride up and down the tubes, at several thousand kilometers an hour. Fusion power stations at intervals would provide all the energy needed: since ninety percent of it would be recovered, the net cost per passenger would be only a few dollars. As the capsules fall earthward again, their motors will act as magnetic brakes, generating electricity. Unlike re-entering spacecraft, they won't waste all their energy heating up the atmosphere and making sonic booms, it will be pumped back into the system. You could say that the down trains will power the up ones. So even at the most conservative estimate, the Space Elevator will be a hundred times more efficient than any rocket."