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 enhanced weathering process that captures and sequesters CO₂ from the air. 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. The company was selected as one of the 60 teams to receive a $1M Milestone Prize in the XPRIZE Carbon Removal competition.
Challenges: carbon emissions and enhanced carbon mineralization
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.
Negative Emission Technology
To achieve the Paris Agreement’s climate goals, it is necessary not only to reduce greenhouse gas emissions but also to actively remove excess CO₂ from the atmosphere. As a component of the mitigation portfolio, Negative Emission Technology (NET) removes and sequesters more CO₂ from the atmosphere than it emits in the process. NET aims to counterbalance emissions from difficult-to-decarbonize sectors, such as steel or cement production. According to the Intergovernmental Panel on Climate Change (IPCC), between now and 2050, NET may be required to capture 20 billion tons of carbon annually in order to prevent catastrophic climate change.
There are three major categories of NET: biological, technological, and geochemical processes. Biological processes include reforestation, soil management, and the restoration of coastal wetlands and peatlands. Technological and geochemical processes involve carbon capture, use, and storage (CCUS).
Some climate tech companies have developed NETs, such as Direct Air Capture (DAC), Bioenergy with Carbon Capture and Storage (BECCS), afforestation, ocean-based carbon removal, and land-based 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.
Carbon mineralization companies
Several companies, such as 44.01 and Silicate, have developed carbon mineralization technologies.
44.01 has developed an in situ mineralization system to mineralize CO₂ into peridotite rock formations in a controlled and efficient manner, thus removing carbon permanently from the atmosphere. 44.01’s CO₂ mineralization system shortens the peridotite CO₂ mineralization process to 12 months. Powered by renewable energy, the system uses CO₂ gas from Direct Air Capture methods and mixes it with cold water to form a CO₂-rich solution. The CO₂-rich water is injected into peridotite rock formation and efficient mineralization reaction occurs by conversion peridotite into magnesite (MgCO₃) and calcite (CaCO₃).
Silicate Carbon has used recycled concrete as soil additives to permanently remove CO₂ from the atmosphere by enhancing the weathering process. Compared to other carbon removal soil additives, such as basalt and olivine, recycled concrete also reduces carbon emissions by requiring less energy for transport and processing. Silicate has demonstrated that the recycled concrete as soil additive is hardly harmful to soil chemistry, even beneficial to soil pH and a valuable source of base cation fertilization.
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.
The system comprises a carbonation station, a calciner, a sequestration space, a condensation space, a hydration station, and a grinding station.
- Carbonation station
In the carbonation station, caustic magnesia sorbent material reacts with atmospheric CO₂ and water to form MgCO₃.
The carbonation station includes carbonation plots, sprayers, and sensors. Carbonation plots are arranged in stacked columns in order to expose caustic magnesia sorbent material to ambient conditions for CO₂ absorption. Sprayers apply water to maintain the desired moisture levels for hydrating caustic magnesia for efficient CO₂ capture. Sensors monitor temperature, humidity, and flow rate of ambient airflow in the vicinity of the carbonation plots.
The calciner receives and heats at 600 ºC weathered peridotite rocks from the grinding station and MgCO₃ from the carbonation station. Thermal decomposition of Mg₃Si₂O₅(OH)₄ (serpentine) and MgCO₃ produces caustic magnesia and CO₂/water gas stream. The caustic magnesia sorbent is sent to a hydration station to form Mg(OH)₂ prior to being fed to the carbonation station to absorb atmospheric CO₂, while the gas stream is conducted to sequestration space.
The calciner can be heated via electric resistance heating which can be powered by renewable electricity. The renewable electricity can be supplied by wind power, solar power, geothermal power, and/or nuclear power.
- Sequestration space
The sequestration space is fluidically coupled to the calciner. The sequestration space receives the CO₂ gas stream from the calciner.
- Condensation space
A condenser is used to increase the purity of the CO₂ gas stream and remove water from the CO₂ gas stream. The water can be used for sprayers in the carbonization station.
- Hydration station
The hydration station is positioned between the calciner and the carbonation station. At the hydration station, caustic magnesia from the calciner is hydrated to form Mg(OH)₂. Mg(OH)₂ rapidly reacts with CO₂ and water in the carbonation station to form MgCO₃.
- Grinding station
The grinding station grinds MgCO₃ and/or weathered peridotite rocks that are then fed to the carbonation station and/or the calciner.
Arca carbon mineralization process
The caustic magnesia sorbent produced from the calciner is fed into the hydration station to become Mg(OH)₂ via the chemical reaction:
MgO + H₂O → Mg(OH)₂
This reaction is exothermic. The released heat is reusable for the calciner and other processes. The produced Mg(OH)₂ is fed to the carbonation plots of the carbonation station.
In the carbonation station, the sprayers spray water on the carbonation plots. Atmospheric CO₂ dissolves in water and forms H₂CO₃ via the chemical reaction:
CO₂ + H₂O → H₂CO₃
Under weathering conditions, Mg(OH)₂ in the carbonation plots rapidly reacts with H₂CO₃ to form MgCO₃ via the chemical reaction:
Mg(OH)₂ + H₂CO₃ → MgCO₃ + 2H₂O
After the sorbent material is saturated with CO₂, MgCO₃ is fed to the calciner. The grinded weathered peridotite rocks are fed concurrently with MgCO₃ to the calciner.
In the calciner at 600 ºC, MgCO₃ and peridotite thermally decompose into a CO₂ gas stream and a caustic magnesia stream. The caustic magnesia is fed back to the hydration station for the subsequent cycle of CO₂ capture, while the CO₂ gas stream is fed to the sequestration space through the condensation space to obtain pure CO₂ gas.
The recycled stream of water from the condensation station is fed to a sprayer. A new stream of water is also fed to the sprayer. The sprayer sprays water on the carbonation station.
- WO2022187336A1 Systems and methods for enhanced weathering and calcining for co2 removal from air
Carbon offset credit market
The market value of carbon offset credits varies widely. In current carbon markets, the price of one carbon credit can range from a few cents per metric ton of CO₂ emissions to $15/mtCO₂e (metric tons of CO₂ equivalent) or even $20/mtCO₂e. However, the voluntary carbon offset market, which was worth about $2 billion in 2021, is projected to grow to $10-40 billion by 2030, transacting 0.5-1.5 billion tons of CO₂ equivalent, as opposed to the current 500 million tons. The total value of carbon credits produced and sold to help companies and individuals meet their de-carbonization goals could approach $1 trillion as soon as 2037.
The cost of Arca’s CO₂ removal system may currently be the lowest peer-reviewed cost estimate for Direct Air Capture, being estimated to be $48 to $159/ton CO₂ net-removed from air. The cost of produced CO₂ is estimated to be $24 to $79/ton.
Arca has collaborated with several global nickel producers, including Vale, Talon Metals, Poseidon Nickel, NickelSearch, and Blackstone Minerals, to advance CO₂ removal at mine sites.
Arca has raised a total of $6M in funding.
Arca is funded by 4 investors, including
Paul Needham is CEO.