The “Air Tree” pavilion is to be built from recycled materials and will be 100% energy self-sufficient. The “tree,” using photo-voltaic cells, produces a substantial amount of energy, which is then sold back to the local electric companies, the profits being used for maintenance of the structure. The second byproduct is of course oxygen.
http://www.inhabitat.com/2008/01/24/...ergy/?=rssfeed