...Smith calls his endeavor "3-D farming," a sustainable network of ropes, cages, and beds that utilizes the entire water column to raise oysters, mussels, scallops, clams, and kelp. The mollusks are filter feeders; they don't need to be fed, and they cleanse the water as they eat. Best of all, they're damn tasty.
But it's the kelp that's really interesting. Seaweed is a zero-input food; it grows fast and takes little energy to produce. It scrubs the environment, soaking up carbon and nitrogen like crazy. And it makes a heck of a biofuel. Smith loves to quote a Department of Energy study that claims if we planted an area half the size of Maine, we could produce enough kelp-based fuel to replace the U.S. oil supply.