Airhive is building a geochemical direct air capture system using a sorbent that can be made out of cheap and abundant minerals. This sorbent reacts rapidly with atmospheric CO₂ when mixed with air in Airhive’s fluidized bed reactor. Coupled with a regeneration process that’s powered by electricity to release the CO₂ for geologic storage, this provides a promising approach to low-cost DAC.

Alkali Earth uses alkaline byproducts from industrial processes as carbon-removing gravel to apply to roads. These minerals act as a sink for atmospheric CO₂, storing it permanently while cementing road surfaces. The formation of CO₂-containing minerals within the gravel can be directly measured, leading to high-confidence in resulting removals.

Banyu Carbon uses sunlight to capture CO₂ from seawater. A reusable, light-activated molecule that becomes acidic when exposed to light causes carbon dissolved in seawater to degas as CO₂, which is then stored permanently. Because only a small portion of the visible light spectrum is needed to trigger the reaction, this is a highly energy-efficient approach to direct ocean removal.

Carbon Atlantis is using a process known as electrochemical pH-swing. Their system uses a solvent to capture CO₂ and an acid to release it. This approach is inspired by recent innovation in Proton Exchange Membrane fuel cells and electrolyzers, making the process both cost-effective and energy-efficient. The CO₂ is then run through Paebbl’s mineralization process for permanent storage in construction materials.

CarbonBlue uses calcium in a closed-loop cycle to mineralize, separate, and remove dissolved CO₂ from water. This results in a pure stream of CO₂ that can be durably sequestered. Their approach can operate in freshwater or saltwater and can rely on waste heat for the regeneration process. The team plans to integrate with desalination plants and other water-withdrawing industries, reducing energy usage and costs.

CarbonRun enhances the natural ability of river currents to weather abundant, low-cost limestone and reduce river acidity levels. This benefits river ecosystems locally and enhances the rivers’ ability to capture CO₂ from the atmosphere. Rivers, which are natural carbon transport systems, then deliver CO₂ to the ocean for permanent storage in the form of bicarbonate.

EDAC Labs uses an electrochemical process to produce acid and base. The acid is used to start the recovery of valuable metals from mining waste, and the base is used to capture CO₂ from air. The acid and base streams are then combined to produce metals that can be sold for applications such as batteries, and solid carbonates, which permanently store CO₂.

Holocene captures CO₂ from air using organic molecules that can be produced at low cost. In the first step of their process, CO₂ is captured from air when it comes into contact with a liquid solution. In the second step, a chemical reaction crystallizes the material as a solid. That solid is heated up to release the CO₂, minimizing energy wasted in heating water. Holocene’s process runs at lower temperatures, further reducing the energy required, increasing energy flexibility, and lowering overall cost.

Mati applies silicate rock powders to agricultural fields, starting with rice paddy farms in India. These rocks react with water and CO₂ to produce dissolved inorganic carbon that is subsequently stored in the local watershed and eventually in the ocean. Mati relies on rice field flooding and higher subtropical temperatures to accelerate weathering, and extensive sampling and soil and river modeling to measure removal and deliver co-benefits to smallholder farmers.

Planetary harnesses the ocean for scalable removal. They introduce alkaline materials to existing ocean outfalls like wastewater plants and power station cooling loops. This speeds up the sequestration of CO₂ safely and permanently as bicarbonate ions in the ocean. Planetary then verifies the removal through advanced measurement and modeling techniques.

Spiritus uses a sorbent made from commercially-available materials and a passive air contactor that requires little energy to capture CO₂. The CO₂-saturated sorbent is then regenerated using a novel desorption process, capturing the CO₂ and allowing the sorbent to be reused with less energy than a higher-heat vacuum chamber typically used in direct air capture approaches. The high-performance, inexpensive sorbent and lower regeneration energy provide a path to low cost.

Vaulted Deep injects organic waste into durable wells, where the carbon in the waste is sequestered as it decomposes. Using a specialized slurry injection technology, their process can handle a wide range of organic carbon sources with minimal energy and upfront processing. Their system has the potential to be deployed quickly at large scales.

Arbon uses a 'humidity-swing' process to capture CO₂ from the air. The sorbent binds CO₂ when dry and releases it when wet. This process uses less energy than approaches that rely on changing temperature and pressure to release CO₂. The sorbent’s ability to bind CO₂ has been shown to remain stable over thousands of cycles. Both of these innovations could reduce the cost of DAC.

Vycarb uses a reactor to add limestone alkalinity to coastal ocean water, resulting in the drawdown and storage of atmospheric CO₂. Their dissolution system has a novel sensing apparatus that base tests water, dissolves calcium carbonate, and doses alkalinity into the water at a controlled amount safe for dispersion. Their closed system makes it easier to measure the amount of dissolved alkalinity added and CO₂ removed.

Carboniferous sinks bundles of leftover sugarcane fiber and corn stover into deep, salty, oxygenless basins in the Gulf of Mexico. The lack of oxygen in these environments–and therefore absence of animals and most microbes–slows the breakdown of biomass so it is efficiently preserved and stored durably in ocean sediments. The team will conduct experiments to determine the functional stability of sunken biomass as well as the interaction with ocean biogeochemistry.

Rewind uses cranes off of boats to sink agricultural and forest residues to the oxygenless bottom of the Black Sea, the largest anoxic body of water on Earth. Oxygenless water dramatically slows biomass decomposition. The lack of living organisms in the Black Sea limits any potential ecosystem risks. This process allows for affordable and environmentally safe carbon removal.

Arbor is developing a modular, compact approach to Biomass Carbon Removal and Storage (BiCRS), the process of removing carbon by converting biomass waste to products such as electricity and permanently storing the CO₂ underground. Their technology combines a gasifier that can work flexibly across biomass types with an advanced turbine that maximizes electrical efficiency. Arbor’s modular system can be quickly deployed and is designed to be manufactured at substantially lower costs.

Arca is capturing CO₂ from the atmosphere and mineralizing it into rock. They work with producers of critical metals, transforming mine waste into a massive carbon sink. With autonomous rovers, their approach accelerates carbon mineralization, a natural process storing CO₂ permanently as new carbonate minerals. By creating a system that works directly at the mine site, Arca avoids the cost and emissions of moving material to processing facilities.

Captura is harnessing the ocean for scalable removal by designing an electrochemical process to separate acid and base from seawater. The acid is used to remove CO₂ that’s present in seawater, which is injected for permanent geologic storage. The base is used to treat and return the remaining water safely to the ocean, and the ocean then draws down further CO₂ from the atmosphere. Captura is developing optimized membranes to increase electrical efficiency and reduce removal costs.

Carbon To Stone is developing a new form of direct air capture, in which a solvent that binds CO₂ is regenerated by reacting with alkaline waste materials. By replacing conventional solvent regeneration using heat or pressure changes with direct mineralization of low-cost alkaline wastes such as steel slag, the team can significantly reduce the energy, and thus the cost, required. The CO₂ is durably stored as solid carbonate materials that can be used for alternative cements.

Cella increases the options for safe and secure carbon storage via mineralization. They accelerate the natural process that converts CO₂ into solid mineral form by injecting it into volcanic rock formations together with saline water and geothermal brine waste, with an approach that lowers cost and minimizes environmental impacts. Cella’s technology integrates low-carbon geothermal heat and can be paired with a variety of capture methods.

CREW is building specialized reactors to enhance natural weathering. The container-based system creates optimized conditions to speed up the weathering of alkaline minerals, and the discharged water stores CO₂ from wastewater safely and permanently as bicarbonate ions in the ocean. CREW’s system makes measuring CO₂ removed easier and can react with CO₂ from a variety of sources, including direct air capture and biomass systems, to maximize scale.

Inplanet accelerates natural mineral weathering to permanently sequester CO₂ and regenerate tropical soils. They partner with farmers to apply safe silicate rock powders under warmer and wetter conditions that can result in faster weathering rates and thus faster CO₂ drawdown. ​​The team is developing monitoring stations to generate public field trial data to improve the field’s understanding of how weathering rates vary under tropical soil and weather conditions across Brazil.

Kodama and the Yale Carbon Containment Lab are deploying a proof-of-concept method of storing waste woody biomass by burying it in anoxic chambers underground, preventing decomposition. The team will experiment with how chamber conditions and above-ground disturbances impact durability and reversal risk.

Nitricity is exploring the potential of integrating carbon removal into a novel process for the electrified production of clean fertilizer. This process combines carbon-neutral nitrogen compounds, phosphate rock and CO₂, producing nitrophosphates for the fertilizer industry and storing CO₂ durably as limestone. This new pathway could present a low-cost storage solution for dilute CO₂ streams with co-benefits of decarbonizing the fertilizer industry.

AspiraDAC is building a modular, solar-powered direct air capture system with the energy supply integrated into the modules. Their metal-organic framework sorbent has low temperature heat requirements and a path to cheap material costs, and their modular approach allows them to experiment with a more distributed scale-up.

Mineral weathering already naturally captures CO₂ at gigaton scale. Lithos accelerates this by spreading basalt on croplands to increase dissolved inorganic carbon in the soil. Their technology uses novel soil models and machine learning to maximize CO₂ removal while boosting crop growth. The team is scaling their empirical verification, river network, and plant-tissue studies to advance measurement of CO₂ drawdown and ecosystem impact.

Travertine is re-engineering chemical production for carbon removal. Using electrochemistry, Travertine produces sulfuric acid to accelerate the weathering of ultramafic mine tailings, releasing reactive elements that convert carbon dioxide from the air into carbonate minerals that are stable on geologic timescales. Their process turns mining waste into a source of carbon removal as well as raw materials for other clean transition technologies such as batteries.

RepAir uses clean electricity to capture CO₂ from the air using a novel electrochemical cell and partners with Carbfix to inject and mineralize the CO₂ underground. The demonstrated energy efficiency of RepAir’s capture step is already notable and continues to advance. This approach has the potential to deliver low-cost carbon removal that minimizes added strain to the electric grid.

This project, a collaboration between 8 Rivers' Calcite and Origen, accelerates the natural process of carbon mineralization by contacting highly reactive slaked lime with ambient air to capture CO₂. The resulting carbonate minerals are calcined to create a concentrated CO₂ stream for geologic storage, and then looped continuously. The inexpensive materials and fast cycle time make this a promising approach to affordable capture at scale.

Living Carbon wants to engineer algae to rapidly produce sporopollenin, a highly durable biopolymer which can then be dried, harvested and stored. Initial research aims to better understand the field's thinking on the durability of sporopollenin as well as the optimal algae strain to quickly produce it. Applying synthetic biology tools to engineer natural systems for improved and durable carbon capture has the potential to be a low-cost and scalable removal pathway.

44.01 turns CO₂ into rock, harnessing the natural power of mineralization. Their technology injects CO₂ into peridotite, an abundantly available rock, where it is stored permanently. This storage approach can be paired with a variety of capture technologies.

Ebb Carbon mitigates ocean acidification while capturing CO₂. Using membranes and electrochemistry, Ebb removes acid from the ocean and enhances its natural ability to draw down CO₂ from the air for storage as oceanic bicarbonate.

Eion accelerates mineral weathering by mixing silicate rocks into soil. Their pelletized product is applied by farmers and ranchers to increase carbon in the soil, which over time makes its way into the ocean where it’s permanently stored as bicarbonate. Alongside their technology development, Eion is also conducting a novel soil study to improve the field's measurement of CO₂ uptake.

Sustaera uses ceramic monolith air contactors to capture CO₂ directly from the air for permanent storage underground. Their direct air capture system, powered by carbon-free electricity and built with modular components, is designed for quick manufacturing and capture at scale.

Equatic leverages the power and scale of the world’s oceans to remove carbon. Their experimental electrochemical process sequesters CO₂ in seawater as carbonates, an inert material comparable to seashells, thereby enabling energy-efficient and permanent CO₂ removal.

Running Tide amplifies natural processes to remove carbon in the open ocean. Their buoys are made from carbon-rich forestry byproducts, coated with carbonate material, and seeded with macroalgae. The floating buoys increase ocean alkalinity and grow macroalgae before sinking biomass to the deep ocean. Their scalable approach is powered by photosynthesis, ocean currents, and gravity.

Over geological timescales, CO₂ chemically binds to minerals and permanently turns to stone. Heirloom is building a direct air capture solution that enhances this process to absorb CO₂ from the ambient air in days rather than years, and then extracts the CO₂ to be stored permanently underground.

Mission Zero electrochemically removes CO₂ from the air and concentrates it for a variety of sequestration pathways. Their experimental room-temperature process can be powered with clean electricity and has the potential to achieve low costs and high volumes using modular, off-the-shelf equipment.

CarbonBuilt’s process readily converts dilute CO₂ into calcium carbonate, creating a “no compromise” low-carbon alternative to traditional concrete. As a profitable and scalable solution for permanent CO₂ storage, CarbonBuilt’s technology platform can serve as a critical component of future carbon removal systems using direct air capture.

UNDO spreads crushed basalt rock on agricultural land, accelerating the natural process of rock weathering. CO₂ dissolved in rainwater reacts with the rock, mineralizes and is safely stored on geologic timescales as bicarbonate. The team is conducting lab and field trials to further the evidence of enhanced rock weathering as a permanent, scalable, nature-enabled technology for carbon removal.

Climeworks uses renewable geothermal energy and waste heat to capture CO₂ directly from the air, concentrate it, and permanently sequester it underground in basaltic rock formations with Carbfix. While it’s early in scaling, it’s permanent, easy to measure, and the capacity of this approach is theoretically nearly limitless.

CarbonCure injects CO₂ into fresh concrete, where it mineralizes and is permanently stored while improving the concrete’s compressive strength. Today they source waste CO₂, but represent a promising platform technology for permanent CO₂ storage, a key component of future carbon removal systems.

Project Vesta captures CO₂ by using an abundant, naturally occurring mineral called olivine. Ocean waves grind down the olivine, increasing its surface area. As the olivine breaks down, it captures atmospheric CO₂ from within the ocean and stabilizes it as limestone on the seafloor.

Charm Industrial has created a novel process for preparing and injecting bio-oil into geologic storage. Bio-oil is produced from biomass and maintains much of the carbon that was captured naturally by the plants. By injecting it into secure geologic storage, they’re making the carbon storage permanent.