The University of Belgrade’s Institute for Multidisciplinary Research invented an urban photo-bioreactor. Liquid 3 cleans the air and serves as a bench in the Belgrade city centre.
It's a tank filled with microalgae, a solar panel on the top generates electricity for USB charging ports for citizens and a pump that pumps air into the tank where the algae process the CO² and produce Oxygen.
https://balkangreenenergynews.com/liquid-tree-to-combat-air-pollution-in-belgrade/
Really cool! But the pessimist in me wonders how quickly this would be destroyed by random people who have no respect for public property.
Just takes one angry teenager with a baseball bat or drunk moron with an automobile. I'd like to see the automotive crash test data on survivability of this water tank vs say, an oak tree.
Also how well it would hold up in a cold snap. Would be fairly limited to warm climates I imagine but even warm climates get a few days of freezing temperatures occasionally.