How the Liquid Tree Might Be a Game-Changer for Urban Air Pollution

"We are not trying to replace trees. We are trying to replace benches."

That's the clever pitch of a project imagined and created by Serbian scientist Dr. Ivan Spasojevic who invented an urban photo-bioreactor called a "Liquid Tree" which uses a combination of water and microalgae to produce pure oxygen through the process of photosynthesis. As Dr. Spasojevic explains:

"Microalgae are 10 to 50 times more efficient than trees in binding CO2. This is equivalent to the CO2-binding capacity of two 10-year-old trees or 200 square meters of lawn. The goal of the liquid tree, however, is not to replace forests but to fill urban pockets where there is no space for planting trees."

There are plenty of places across the world where space is at a premium, so this is a brilliant solution to a tough problem. Even better, it's highly visual and the more the microalgae clean the air - the greener the liquid gets. The Liquid Tree is already being tested in Belgrade with plans to expand the idea to replace benches in New Delhi, Paris and New York.