Scientists in Belgrade came up with the idea of “planting” large tanks of water and algae in places where trees can’t grow. The tanks are 10-50x more efficient than a normal tree for the space it takes up and is in general highly sustainable, even creating excellent fertilizer in the process. You can skip about halfway through the video for the actual information about them.
yes all the negativity in the thread is making the false supposition that you have to choose between an algae tank and trees. the choice is an algae tank or no algae tank.