Seaweed grow in shallow and coastal areas, and capture significant amounts of carbon that can be transported to the deep ocean by oceanic mechanisms; seaweed reaching the deep ocean sequester carbon and prevent it from exchanging with the atmosphere over millennia. In addition, Seaweed grows very fast and can theoretically be harvested and processed to generate biomethane, via Anaerobic Digestion to generate electricity, via Cogeneration/CHP or as a replacement for natural gas. One study suggested that if seaweed farms covered 9% of the ocean they could produce enough biomethane to supply Earth's equivalent demand for fossil fuel energy, remove 53 gigatonnes of per year from the atmosphere and sustainably produce 200 kg per year of fish, per person, for 10 billion people. Ideal species for such farming and conversion include "Laminaria digitata", "Fucus serratus" and "Saccharina latissima".