Established in 1996 this ecological education facility enjoys a lovely rural location and functions as an experiential centre for permaculture techniques. It is the headquarters of Greenheart Ibiza, an environmental charity. Visitors are welcome (Sundays only) to tour its bottle houses, and to drink at its juice bar (try the 'health booster' with aloe vera, honey, mint and lemon).
It's a tricky place to find; consult their website.