Now, since that seaweed does nothing else but photosynthesis, how would it differ in principle from harvesting weeds like kudzu vines and turning them in the fuel? To become important it would have to become seaweed harvesting in open sea, and not in a small size pool. And carbonizing open sae is an iffy proposition.
The point of it is, this is a really cheap scrubber for stack emissions from power plants. And biodiesel is a byproduct.