Australia Plans 1-Km High Structure, Taller Than CN Tower Thu Jan 2, 9:11 PM ET By Michelle Nichols MELBOURNE (Reuters) - The world's tallest man-made structure could soon be towering over the Australian outback as part of a plan to capitalize on the global push for greater use of renewable energy. By 2006, Australian power company EnviroMission Ltd hopes to build a 1,000 m (3,300 feet) solar tower in southwest New South Wales state, a structure that would be more than twice the height of Malaysia's Petronas Towers, the world's tallest buildings. Currently, the world's tallest free-standing structure is the...