Madrid's 'Air Tree' Creates Its Own Energy, Oxygen

In Madrid, Spain, a unique, hulking structure is currently being built. An "Air Tree," it's designed to both affect the surrounding environment and act as a social center. It's loaded up with solar panels that create electricity that's sold to the local electric company. It's completely self-sufficient, powering itself… » 12/19/07 12:59pm 12/19/07 12:59pm