Microalgae carbon fixation and sinking projects are a carbon-removal project type within the ocean & water segment of the carbon market. They involve enhanced growth and controlled sinking of microalgae or algal biomass for deep-ocean sequestration. In practice, atmospheric carbon fixed biologically is exported toward long-lived deep-ocean storage. Common project configurations include Engineered substrate-assisted microalgae fixation and sinking under controlled methodology conditions.

This is one of the more experimental ocean pathways and hinges on difficult questions about durability, ecosystem effects, and how much carbon remains stored. Ocean-based pathways are developing quickly and can be scientifically compelling, but they generally require especially careful MRV, strong ecological safeguards, and a clear accounting framework for permanence and reversals. For buyers and program designers, the most important diligence questions are: How durable is deep-ocean storage in practice? Are marine ecosystem effects and measurement uncertainty adequately addressed?