In the housing estate of Les Indes, in Sartrouville, near Paris, entrepreneurs have set up a hydroponic farm in a disused car park. "The principle of hydroponics is very simple: it's to provide a lot of water and a lot of oxygen to the roots of different plants," explains the co-founder. The goal: boosting the local economy by employing residents and growing farm-to-table produce. IMAGES AND SOUNDBITES