Algae-grown limestone.
Your questions answered.

Tiny single-celled marine microalgae called coccolithophores built the White Cliffs of Dover, a famous chalk formation in southern England, in the Late Cretaceous Period. Inspired by this feat, we asked ourselves, “if nature can grow limestone, why can’t we?”

So where did we start? We studied biomineralizing algae, single- and multi-cellular photosynthetic organisms that produce limestone (calcium carbonate/CaCO₃).

Our research has yielded a highly efficient, scalable, and economical process for cultivating biomineralizing algae. The algae – through photosynthesis – sequesters and stores carbon dioxide in mineral form, while producing large amounts of limestone at a significantly faster rate than occurs in nature.

• Limestone is a critical and versatile industrial material. Minus Materials leverages calcifying algae that actually pull carbon dioxide out of the atmosphere and store it in mineral form, making our limestone net carbon-negative. Algae-produced limestone is naturally produced and harvested as a fine powder, reducing or eliminating the need for grinding prior to industrial use.
• Quicklime (CaO) is produced through calcination of limestone, where the limestone is heated driving off massive amounts of CO₂ to the atmosphere. By replacing conventional quarried limestone with algae-grown limestone as a feedstock for quicklime production, the CO₂ emitted would be offset by that captured by the algae during growth and biomineralization. This results in neutralization of the process emissions associated with calcination of limestone.
• Limestone is the main feedstock for the manufacture of portland cement. Cement producers do not have to change a thing relative to their cement process. Because the cement producer is starting with a familiar raw material – limestone – no new equipment is needed. If cement producers layered other solutions into their process, such as switching to renewable energy, processing limestone at ambient temperate, carbon capture, and other emerging solutions, carbon-negative cement is achievable.
• Minus Materials’ algae-grown limestone is an ideal filler material in portland limestone cement, where “raw” limestone is blended with portland cement at a mass ratio between 5-15%. By using our limestone instead of a quarried limestone as the filler, the mixture would yield significant carbon reductions.
• Ease of adoption requires meeting industry standards. That is why Minus Materials decided to pursue a proven product – limestone – over novel new materials.