Fifteen ways to banish CO2

They aren’t done yet but already, the innovators competing in the massive $100 million Carbon Removal XPRIZE have shown us that there is more than one way to remove carbon dioxide from our atmosphere.

In fact, there are at least 15.

That is how many teams were awarded million dollar Milestone prizes back in April 2022, on Earth Day. These innovators from Australia, Canada, France, Iceland, Kenya, the Netherlands, the Philippines, the UK and the US have shown us proven ways to capture and sequester part of the carbon dioxide that is warming our climate.

XPRIZE Feb.8, 2021

Their approaches include ecosystem restoration, biochar, agricultural solutions, organic and inorganic ocean solutions, mineralization of mine tailings and naturally occurring minerals, direct air capture with geologic sequestration, agroforestry, soil carbon and more. 

And it matters that these are proven strategies. This isn’t an ideas competition (although clearly there are many ideas about how to remove carbon permanently from our atmosphere, given that 1,133 teams entered). It is an execution and demonstration competition. 

The solutions must work, achieve net negative emissions, sequester carbon dioxide durably over at least 100 years, and show a sustainable path to ultimately achieving gigaton scale. XPrize’s aims to scale climate solutions so that at least 10 gigatons of carbon can be collected per year by 2050. (Yearly global carbon dioxide emissions were more than 36 gigatons last year.)

Seventy expert reviewers screened and ranked the proposals for scientific validity, and selected the top 60 teams. To then choose the top 15 teams, the judges went deeper on operations plans, performance data, life cycle analysis and cost estimates. 

The submission process was intentionally demanding. The field of 1,133 was narrowed to 287 teams meeting the eligibility criteria for the milestone awards. Seventy expert reviewers screened and ranked the inbound proposals for scientific validity, selecting the top 60 teams. Judges went deeper on operations plans, performance data, life cycle analysis and cost estimates to select the top 15 teams taking home the interim $1M Milestone Awards. 

The final three winners will be selected in 2025, and the milestone winners are eligible to be considered.

Here are the 15 Milestone winners:


Calcite, US: 8 Rivers Capital, in Durham, North Carolina, invented Calcite in 2019. Its innovative process enables rapid carbon uptake at large scale and low cost, using simple equipment, abundant feedstocks, and optimized chemistry. CO2 captured directly from air is sequestered underground. It will now focus on designing, building, and operating a Calcite facility by 2025, which would position Calcite to rapidly scale-up to the full-scale units necessary to remove a billion tons of carbon. 

Carbyon, Netherlands: Carbyon, which develops equipment to filter CO2 from the air and store it underground, was founded in 2019 as a spin-off company from the research institute TNO. Its goal is to create affordable and scalable technology that can be used to stop climate change. “The innovation of clusters of smaller DAC units using membranes with fast absorption/desorption cycles could be transformative for the Carbon Dioxide Removal field,” the jury said.

Heirloom and Carbfix, US & Iceland: Heirloom uses limestone, one of the world’s most abundant and inexpensive minerals, to capture CO2 directly from the atmosphere, and then store it underground or in materials like concrete. Heirloom’s technology accelerates the natural process of carbon mineralization to just days. Carbfix, which partnered on two winning submissions, provides its tested technology of safe and permanent underground mineralization to sequester the CO2 captured by Verdox and Heirloom’s novel and innovative carbon capture technologies. 

Verdox and Carbfix, US & Iceland: Verdox, founded in 2019, is making scalable, cost-effective carbon capture and removal a reality. Its electroswing adsorption (ESA) platform technology, originally developed at MIT, removes carbon dioxide from industrial emissions and the air with 70% energy savings versus conventional approaches. 

Project Hajar, UK and Oman: This joint project between Mission Zero Technologies and 44.01 combines DAC with sequestering CO2 in peridotite formations in the Al Hajar mountains of Oman in a process solely powered by renewables. Here, the natural weathering process is enhanced with the fastest mineral carbonation rates ever known.

Sustaera, US: Based in Cary, North Carolina, Sustaera’s core technology is based on several breakthroughs in material science, process design and modular manufacturing. It will use the milestone award to  help develop the engineering design for a 10-ton CO 2 per day demonstration unit by 2024, said Raghubir Gupta, PhD, Co-Founder and Chief Technology Officer. 


Bioeconomy Institute Carbon Removal Team, US: The research team at Iowa State University’s Bioeconomy Institute will use its award to advance its vision of turning biomass from crop residues and other sources into soil amendment and other valuable products. “We need to look at solutions that actively remove carbon dioxide from the atmosphere,” says Institute co-director Robert Brown. “We think pyrolysis will be one of those solutions.”

PlantVillage, US: An international team led by David Hughes, founder of Penn State’s PlantVillage project, will use its award to demonstrate their capacity to draw down one billion tons of carbon per year in a sound and economically attractive way that benefits low-income farmers in Africa.. “We believe African farmers and African land offer the realistic potential of 1 ton of carbon, permanently sequestered at less than $25/ton. This prize money allows us to prove that case.”

NetZero, France: NetZero‘s unique model makes biochar affordable for farmers, helps companies neutralize their unavoidable emissions, and co-generates renewable energy – all at once. Biochar is a scientifically proven way to remove carbon from the atmosphere long term while durably improving soil quality, allowing for higher yields and lower fertilizer use in agriculture.

Takachar & Safi Organics, Kenya: Takachar wants to transform massive amounts of waste biomass into marketable products around the world.​ Worldwide, $120 billion worth of crop and forest residues are burned in the open each year.  If used productively, these residues represent a $10 billion market globally. Takachar says its process can be a profitable way to make economic use of this biomass, while reducing air pollution.

Global Algae Innovations, US: Algae cultivation captures carbon dioxide from the atmosphere, and part of the algae oil is converted to polymer products for long term sequestration, it says. The production of protein and oil with 31 times less land and water will enable rainforest regrowth to capture CO2 and store it both above ground and below ground biomass. The initial megaton scale project will capture and sequester 12 million metric tons per year, 1 million tons in polymer products and 11 million tons in rainforest regrowth.


Captura Corp., US: Founded in 2021 utilizing technology developed in Caltech’s laboratories, Captura provides low-cost atmospheric carbon removal by leveraging the world’s largest natural CO2 absorber – the ocean. Using only renewable electricity and ocean water as inputs, its patented electrodialysis process generates a stream of pure CO2 that can then be sequestered or utilized to make other low-carbon products.  

Marine Permaculture SeaForestation, US, Philippines & Australia: SeaForestation uses deepwater-irrigated, open-ocean seaweed mariculture as a strategy for food security, regeneration of ecosystem services and carbon sequestration. At scale, deepwater irrigation can regenerate seaweed forests offshore, from tropical to seasonally temperate waters, as demonstrated by its Philippines site since 2019.

Planetary Technologies, Canada: Planetary purifies mine waste into a mild, nontoxic antacid which is then released into the ocean through existing, regulated outfalls such as wastewater or stormwater streams where it is consistently monitored. When mixed with seawater, the antacid restores the ocean’s pH levels and accelerates the ocean’s natural process of pulling carbon dioxide from the atmosphere. Planetary will use the $1 million prize to achieve a full-scale demonstration of its technology. 


Arca Climate, Canada: Arca Climate (formerly Carbin Minerals) is doing ‘carbon-negative mining’, partnering with the mining companies delivering the minerals essential for the clean energy transition. Arca helps them transform their mine waste into industrial-scale direct air capture and storage facilities. “The clean energy transition presents a challenge and a paradox. On the one hand, the world will need 10-20 times more nickel and other critical metals to successfully transition to clean energy. On the other hand, modern mining processes are carbon intensive,” says CEO Paul Needham. 

“One year in, we already see the positive impact of the prize: hundreds of groups working on a wide range of promising carbon removal solutions,” chief scientist Dr. Marcius Extavour said in 2022 as the Milestone prizes were announced. “Not just ideas, but development and deployment plans, which is exactly what we need. The pace and depth of initiatives in carbon removal and other crucial climate solutions has never been greater, but we still need more—more and deeper emissions cuts, and more reliable, validated carbon removal solutions. That’s why we launched this prize in the first place.”

Cover image: Porapak Apichodilok, Pexels