CarbonDrop

CarbonDrop is a carbon dioxide removal company developing molecular tools for engineering macroalgae — the large seaweeds that grow in coastal waters. The aim is to supercharge photosynthesis so the engineered seaweed captures atmospheric CO2 at scale and stores it on what the company calls geologically-relevant timescales, targeting sequestration measured in gigatonnes per year. Founded in 2021 and based in Palo Alto, California, it has raised roughly $33M across a $13.5M seed and a $19.6M Series A backed by Benchmark and Collaborative Fund. Its public web presence is a single landing page describing the work as the most ambitious CO2 removal idea yet conceived.

Engineers the seaweed itself at the molecular level to raise photosynthetic carbon capture, rather than relying on mechanical direct air capture or ocean chemistry alteration, and targets storage durable over geological timescales.