The Big Idea Giant sea kelp, the world’s largest species of marine algae, is an attractive source for making biofuels. In a recent study, we tested a novel strategy for growing kelp that could make it possible to produce it continuously on a large scale. The key idea is moving kelp stocks daily up to near-surface waters for sunlight and down to darker waters for nutrients. Unlike today’s energy crops, such as corn and soybeans, growing kelp doesn’t require land, fresh water or fertilizer. And giant kelp can grow over a foot per day under ideal conditions.