Step back a little. Why are there places in cities where trees "can't grow"? What's the problem - water, land, sunlight? And why not fix whatever is keeping trees from growing, and then grow trees, instead of dropping in a tub of algae? And if these tanks are 50 times more "efficient" than a normal tree, how much more expensive is manufacturing and maintaining them than planting and watering a tree is?

This feels like carbon capture technology to me - a technological patch on a social and ecological problem, meant not to help the environment but to funnel tax money to venture capitalists and tech companies in the name of environmentalism.