I disagree. Pavement is valuable to pedestrians, cyclists, emergency and service vehicles, and the disabled. While it’s important to preserve nature as much as possible, some urbanisation is also a good thing. That said, I’m not sure algae tanks would be necessary in areas where huge tracts of land aren’t dedicated to parking. I can’t really think of where my city would benefit from them.

Yes to ripping up roads for greenspace, not to removing sidewalks too.

Make the city green and walkable, and you solve so many problems in one go