Modern Marvels: From the prairies of Saskatchewan to a Manhattan skyscraper we'll see the 21st Century's cutting-edge "green" technologies in action. New technologies such as carbon sequestration and bioremediation take on our most daunting environmental crises, from global warming and deforestation to nuclear waste and resource scarcity. See how blue-green algae are converted into automotive biofuel and methane from decomposing garbage is turned into clean-burning natural gas. Finally, see how trees and other natural environments can be used as engineering materials to control flooding and rejuvenate dying rivers.