Sentence:  A “moving platform” scheme...is more technologically ambitious than maglev trains even though it relies on conventional rails....This set-up solves several problems [...]. Stopping high-speed trains <WSD>wastes</WSD> energy and time, so why not simply slow them down enough for a moving platform to pull alongside? 
Meaning of the word marked with <WSD> tags:  To squander (money or resources) uselessly; to spend (time) idly.