UNB start-up Seagreen Solutions turns seaweed into biochar to lock carbon and help gardens survive dry spells

A University of New Brunswick start-up is turning seaweed into biochar, a soil product that holds moisture and locks carbon in the ground. Seagreen Solutions NB, founded by PhD candidate Marie Dankworth, uses pyrolysis to convert Bay of Fundy seaweed into a charcoal-like amendment that retains about 30 percent more water than untreated soil. The City of Fredericton is piloting the product in summer planters this season. Unlike wood-based biochar, seaweed biochar contains natural minerals like potassium, calcium, and magnesium, so it provides nutrients without needing additives. The company won first prize in the growth category at UNB's RBC Pitch Competition and was selected for the 2026 Ocean Idea Challenge. Seagreen is currently focusing on business-to-business sales and expects to sell through independent garden centres in Fredericton. The approach addresses two problems at once: soil stress from drought and excess atmospheric carbon. By locking carbon in a stable form that also improves growing conditions, the method offers a practical path for coastal biomass to contribute to climate goals.