The DeepGreen OCS-4 is an underwater installation that accelerates natural oceanic carbon absorption by stimulating phytoplankton growth across vast areas of ocean surface. The system consists of a network of seafloor-mounted nutrient dispersal units that release precisely calibrated mixtures of iron, nitrogen, and phosphorus compounds into upwelling currents, fertilizing the surface waters and triggering massive phytoplankton blooms. The phytoplankton absorb CO2 through photosynthesis, and when they die, their carbon-rich remains sink to the deep ocean floor, sequestering the carbon for geological timescales.

A single DeepGreen installation — a network of 200 dispersal units covering a 100-square-kilometer seafloor area — can stimulate phytoplankton growth sufficient to sequester approximately 2 million metric tons of carbon per year. Crucible operates 35 installations worldwide, predominantly in nutrient-poor tropical ocean regions where natural upwelling is limited and the potential for bloom stimulation is highest. The installations are entirely automated, with dispersal timing and nutrient ratios controlled by AI systems that monitor ocean chemistry, water temperature, and existing biological activity to optimize bloom conditions.

The ecological side effects of large-scale ocean fertilization have been debated for over a century, and DeepGreen has not resolved the controversy. The phytoplankton blooms alter local marine food webs — some species benefit enormously from the increased primary production while others are displaced. Oxygen depletion in the deep ocean beneath bloom zones has been documented, creating dead zones at depth even as surface productivity increases. Crucible publishes annual environmental impact reports that emphasize the carbon sequestration benefits while acknowledging 'localized ecological adjustments' — a phrase that marine biologists consider dangerously euphemistic.