Milkywire Blog Post
CONTACT Robert Höglund

* Content was first published on Milkywire’s site and was edited for Holocene – find the original article here.

Expanding carbon removal horizons – Milkywire selects thirteen new cutting-edge projects.

Picture from Holocene’s lab. A DAC startup selected for the CTF in 2024.

ilkywire received over 1,000 proposals in their recent open call across the Climate Transformations fund’s three pillars, with about a quarter stemming from CDR. The fund supports projects within CDR, emission reductions and advocacy, as well as nature solutions to help reach global net zero, providing a beyond-value-chain-mitigation alternative to offsetting.

Overall, the quality of the CDR proposals was very high. They shortlisted around a third to submit an extended application, assessing them against the selection criteria and taking input from our advisory group. They were not just looking for high-quality projects, but also to catalyze as much change as possible, identifying where funds are most impactful.

CDR is essential to achieve net zero and eventually stabilize global temperatures, but it is still in its infancy. Currently, only a few hundred thousand tonnes are durably removed each year, whereas we will need billions of tonnes annually to reach net zero.

No one yet knows which CDR technologies will prove to be the best, cheapest, most sustainable and scalable. Discovering this is arguably the most crucial goal for CDR in the 2020s, along with laying the groundwork for an industry that can scale to gigatonnes in the coming decades.

Milkywire selected thirteen outstanding CDR suppliers from which they intend to make a pre-purchase this year.

Geochemical solutions: Aquarry, Flux, Mati Carbon, Vycarb, Alkali Earth.

Direct air capture with storage: Gaia Refinery, Yama, Ucaneo, Carbon Atlantis, Holocene

Biochar: Solidaridad/Planboo, Biosorra, PyroCCS.

These new partnerships include ventures in new geochemical solutions such as Aquarry’s method of using mine pit lakes, novel direct air capture methods such as Gaia Refineries mix of biomass removal and DAC, and biochar technologies that are very scalable and provide significant co-benefits through increasing the incomes of vulnerable farmers, such as in Planboo and Solidaridads project. See full descriptions of all companies at the end of this document.

Full list of new CDR projects selected for the fund in 2024: 


Aquarry – Pit Lake Alkalinity Enhancement, United States

Aquarry proposes a new approach to carbon removal called pit lake alkalinity enhancement. This involves adding alkaline materials to flooded surface mines, transforming them into carbon removal and storage assets while also improving water quality. The technology is similar to ocean alkalinity enhancement, but with less environmental risk and more measurable results. The technology has the potential to store millions of tonnes permanently at a low cost. This innovative approach is in its early stages, with laboratory work to confirm measurement and verification methods underway and larger-scale demonstrations planned.

Flux – Enhanced Rock Weathering, Kenya

Flux is the first company to start doing Enhanced Rock Weathering (ERW) in Africa where the potential co-benefits of the method are the highest. They spread crushed silicate rocks on farmlands in Africa to remove CO₂  from the atmosphere and to improve soil quality, improving farmers’ yields and climate resilience. Flux is currently conducting a pilot project with smallholder farmers in Kenya and partnering with large-scale commercial farms and existing rock quarries across the continent for rapid scaling. Their gathering of data on how ERW works in African soils will help develop the method and be a catalyst for ERW across the continent.

Mati Carbon – Enhanced Rock Weathering, India

Mati Carbon is pioneering a unique approach to carbon removal by enhancing rock weathering in paddy rice fields. The project is particularly noteworthy for its focus on smallholder farmers in the global south, and its ongoing research into reducing methane emissions from paddy farms. Mati Carbon is committed to maximizing the carbon dioxide removal value transfer to these farmers showing a potential for very high social and environmental co-benefits. The company also has a strong focus on measurement, reporting and verification, using methods developed in collaboration with the Yale Center for Natural Carbon Capture.

Alkali Earth – Surficial Mineralization, United States

Alkali Earth is a unique project utilizing steel slag, a byproduct of the steel industry, to remove CO₂  from the atmosphere. The process involves crushing the slag to increase its surface area and using it in various applications such as on gravel roads. This process converts atmospheric CO₂ into stable carbonate minerals, effectively removing it from the environment. Alkali Earth is currently the only company using steel slag aggregates for carbon removal, providing a low-cost pathway to scale CDR through an industry that already moves gigatons of materials each year.

Vycarb – Ocean/River alkalinity Enhancement, USA

Vycarb’s innovative approach to carbon removal focuses on converting biogenic CO₂  in water into stable bicarbonate and carbonate. The system targets high-CO₂ waters and uses a continuous flow alkaline reactor where direct measurements of the removal are made by their real-time sensing technology. A modular, solar-powered design allows for scalability and autonomy, making it adaptable to various settings. The system also utilizes multiple alkalinity sources, requiring minimal upkeep. This unique solution addresses the challenges of water-based CDR, offering a promising avenue for reducing atmospheric CO2 emissions.

For enhanced rock weathering It should be noted that there are uncertainties around how long it will take for the rock to capture CO₂ and how much will be captured per tonne of rock in a reasonable time. Companies may need to deploy more rock than originally expected to fulfil contracts, and timelines for delivery pushed forward.


Direct Air Capture with storage (DACCS)

Gaia Refinery – Direct Air Capture (DACCS/Biomass), Canada

Gaia Refinery is pioneering a unique carbon dioxide removal technology that merges Direct Air Capture with Biomass Carbon Removal. This innovative approach utilizes liquid DAC capture technology and biogenic sources of acetic acid to capture three streams of CO2, offering a potentially more cost-effective solution than current DAC technologies. The hybrid technology requires less electricity, captures more CO2 per ton of biomass, and can achieve efficient scale at a smaller plant size.

Yama – Direct Air Capture (DACCS), France

Yama is a pioneering Direct Air Capture company with innovative technology that integrates a scalable, low-grade heat source with electrochemistry. Yama’s solution addresses key limitations in existing approaches by enhancing energy efficiency, large scale carbon capture, combined with strategic partnerships, indicates a strong potential for scalability.

Ucaneo – Direct Air Capture (DACCS), Germany

Ucaneo is pioneering a biomimetic Direct Air Capture technology. Their innovative approach combines solvents with (bio)catalytic properties and electrochemistry, resulting in a process that can be more energy and cost-efficient than traditional methods. Ucaneo’s prototype has demonstrated the capacity to remove roughly 1 ton of CO2 per year, with scalable modular units designed to remove ~500-1000 tons of CO2 annually. Their unique use of electrochemistry and (bio)catalysts, along with an interchangeable modular and scalable design, sets them apart.

Carbon Atlantis – Direct Air Capture (DACCS), Germany

Carbon Atlantis is pioneering a novel Direct air capture approach utilizing an innovative electrochemical technology. This process captures CO₂ from the atmosphere with a basified solvent, transforming it into bicarbonates, and then releasing it as gaseous CO₂. The technology is uniquely capable of matching renewable electricity generation curves and is designed to be cost-effective, energy-efficient, and scalable, with the potential for rapid upscaling due to its modularity and reliance on existing supply chains. The project is currently at a promising stage of development, with a clear path to commercialization.

Holocene – Direct Air Capture (DACCS), USA

Holocene has developed a continuous, low-temperature, thermochemical direct air capture technology, which combines the best of both traditional DAC approaches. The continuous, liquid absorption system coupled with a solid, low-temperature desorption, brings the benefits of affordability, scale, and flexibility inherent in such an approach. Holocene’s proprietary combination of organic sorbents unlocks this whitespace, which can be more scalable and affordable than alternatives.



Solidaridad/Planboo – Biochar, Zambia

Solidaridad and Planboo are teaming up to transform agricultural practices and combat climate change by utilizing biochar in a decentralized way. By collaborating, Solidaridad’s extensive experience in sustainable agriculture and Planboo’s innovative digital MRV system which includes an internet-connected (IoT) device, verification at scale can be achieved. Their partnership hopes to empower over 100,000 smallholder farmers in Zambia converting cotton stalks into biochar, increasing their incomes, improving soil health and permanently removing carbon from the atmosphere.

BIOSORRA – Biochar, Kenya

BIOSORRA aims to revolutionize sustainable agriculture in the Global South by transforming crop waste into biochar, enhancing soil health and crop yields. Partnering with over 2,036 farmers to date, BIOSORRA’s patented pyrolysis technology creates a durable carbon sink and improves farming efficiency. Emphasizing community and climate justice, BIOSORRA supports women-led businesses and empowers local farmers with affordable biochar, boosting food security and environmental resilience.

PyroCCS – Biochar, Namibia

PyroCCS pioneers sustainable industrial biochar carbon removal in the Global South, deploying its own low-cost, robust, pyrolysis systems powered by renewable energy and backed by a digital measurement and reporting solution. These plants efficiently convert invasive acacia bushes in Namibia, a significant threat to the savanna ecosystem, into high-quality biochar, while providing critical employment in regions with high youth unemployment rates. PyroCCS’s scalable technology, which they are also offering as a solution to other project developers, not only captures carbon but also supports local agricultural and environmental recovery as well as food security.