Arca Climate Technologies ($16.4 million to capture and sequester atmospheric CO2 using peridotite rocks)

Arca Climate Technologies (Arca, formerly Carbin Minerals), a Canadian cleantech startup founded in 2021, develops a carbon mineralization technology that uses high-intensity bursts of energy to convert peridotite rocks into caustic magnesia (MgO) sorbent material for capturing and sequestering atmospheric CO₂. The company collaborates with mining companies to help them quantify, maximize, and commercialize the carbon sequestration potential of their mining byproducts, thereby transforming mine waste into a valuable resource and climate solution.

(This article contains 4 diagrams and 1654 words.)

Challenges: carbon emissions and enhanced carbon mineralization

Carbon emissions

Since the early 1900s, carbon dioxide (CO₂) levels in the atmosphere have increased by 50% due to human activities. When fossil fuels (such as coal, oil, and natural gas) are burned for energy production, transportation, and industrial processes, CO₂ is released into the atmosphere. This excess CO₂ acts as a greenhouse gas, trapping heat and causing the air and ocean temperatures to rise. CO₂ emissions play a crucial role in driving climate change.

This warming effect has caused the global average temperature to rise by about 1.1 ºC since the pre-industrial period. This has led to rising in the frequency and intensity of extreme weather events, melting of polar ice caps and glaciers and rising sea levels, shifts in species ranges and increased risk of species extinction, agriculture and food security,  and ocean acidification.

To mitigate these impacts, the Paris Agreement aims to limit global warming to well below 2 ºC above pre-industrial levels. The Intergovernmental Panel on Climate Change (IPCC) estimates that a “carbon budget” of about 500 GtCO₂, which corresponds to about ten years at current emission rates, provides a 66% chance of limiting global warming to 1.5 ºC.

Carbon mineralization

Carbon mineralization is the process of converting CO₂ into a solid carbonate mineral in order to sequester carbon permanently. Certain rocks, like olivine or basalt, undergo carbon mineralization when exposed to CO₂ and water. Carbon mineralization occurs naturally over hundreds or thousands of years. It has been found that the rate of natural carbonation of peridotite rock is surprisingly fast compared to other types of rock.

Peridotite rock is abundant on earth. It primarily consists of the silicate minerals olivine and pyroxene. The natural weathering of peridotite involves the following chemical reactions:

Mg₂SiO₄ (olivine) + 2CO₂ → 2MgCO₃ (magnesite) + SiO₂ (quartz);

2Mg₂SiO₄ (olivine) + Mg₂Si₂O₆ (pyroxene) + 4H₂O → 2Mg₃Si₂O₅(OH)₄ (serpentine);

Mg₂SiO₄ (olivine) + CaMgSi₂O₆ (pyroxene) + 2CO₂ + 2H₂O → Mg₃Si₂O₅(OH)₄ (serpentine) + CaCO₃ (calcite) + MgCO₃ (magnesite)

Enhanced weathering technologies aim to accelerate the natural carbon mineralization process and make it more efficient for carbon capture, storage, and utilization, which can be scaled up to mitigate climate change impacts.

Arca Technology

Arca has developed a carbon mineralization system that uses high-intensity energy bursts to convert peridotite rocks into caustic magnesia (MgO) sorbent material for efficiently capturing and sequestering CO₂ from the air.

Peridotite rocks are mined primarily for production of magnesium (Mg) metal, as well as for many other industries, such as limestone for cement, MgCO₃ for refractory, and agriculture. Weathered peridotite rock comprises Mg₃Si₂O₅(OH)₄ (serpentine), MgCO₃, and CaCO₃. Cycled heating of weathered peridotite at 600 ºC produces caustic magnesia (reactive MgO), which can rapidly react with atmospheric CO₂ and water to form MgCO₃.

MgCO₃ can be reintroduced into the calciner to produce caustic magnesia and a CO₂ gas stream. The caustic magnesia is reused for the next CO₂ capture cycle, while the CO₂ gas stream is sequestered. This looping process makes the cost relatively robust compared to other more complex Direct Air Capture methods.

Arca carbon sequestration system

The diagram below depicts the Arca’s carbon sequestration system.