An Israeli startup called Gigablue is running deep ocean trials 200 km off Dunedin, New Zealand, using plant-based pods to grow phytoplankton that capture carbon dioxide and sink it to the ocean floor. The company says the method, called microalgae carbon fixation and sinking (MCFS), could remove excess CO2 from the ocean and generate carbon credits worth hundreds of millions of dollars for the local economy, along with thousands of jobs. But University of Otago Associate Professor Linn Hoffmann says the company has not published any studies describing its method and is vague on key details. She questions whether the mechanism will work reliably in open ocean conditions, whether seabirds or fish might ingest the pods, and what the carbon footprint of large scale manufacturing and deployment would be. Hoffmann notes that carbon dioxide removal is now unavoidable as a complement to emissions cuts, but stresses that transparency and peer reviewed testing are needed before any claims can be assessed. The story highlights a tension that runs through many carbon removal projects: bold promises from startups versus academic calls for proof. Gigablue has invested about $12 million in New Zealand organisations so far and completed three trials since 2024, but without published results the credibility gap remains wide.
