A four-year long competition to develop carbon dioxide removal technologies that could be scalable to gigatonne level has announced the winners, who take a share of the $100m prize money.
The XPrize Carbon Removal competition set teams the challenge of developing carbon capture options that could remove CO₂ from the atmosphere and oceans.
Excess CO2 in both of these environments is the main driver of climate change, with human-produced CO₂ emissions accounting for more than two-thirds of all greenhouse gas emissions, the XPrize organisation said. This means that - in addition to reducing ongoing greenhouse gas emissions - carbon capture, utilisation and storage (CCUS) technologies will be needed to keep average global temperatures from rising 2°C above pre-industrial levels which is generally considered a critical threshold.
In May 2024, 20 finalist were asked to demonstrate their approach at the kilotonne scale over a one-year testing period, and were asked to model their expected cost at megatonne scale - and show a viable pathway to scaling their innovation sustainably to gigatonne scale.
The winners and runners-up each removed more than 1,000 net tonnes of CO₂ in the final year of the competition XPrize said.
The top prize of $50m went to Mati Carbon for its enhanced rock weathering approach, while runners-up NetZero, Vaulted Deep and UNDO Carbon were awarded $15m, $8m and $5m, respectively. Awards of $1m each were awarded to Planetary and Project Hajar, a partnership between Aircapture and 44.01. Another $20m in prizes had been awarded at previous stages of the competition.
Mati Carbon’s approach is to apply finely crushed basalt over agricultural lands in India to accelerate a natural weathering process that permanently draws down atmospheric CO₂. As the basalt dissolves, cations such as calcium and magnesium (Ca2+ and Mg2+) are released into the groundwater, the company said. The addition of cations to the ground water results in a series of chemical reactions involving carbonic acid through which CO₂ in the soil is converted to dissolved bicarbonate (HCO3–). Carbonic acid (H2CO3) is formed naturally in soils by plant respiration.
“Conversion of dissolved carbonic acid sources to bicarbonate effectively removes CO₂ from the atmosphere. Next, the bicarbonate percolates into streams and rivers, and is later delivered to the oceans. Once bicarbonate is transported to deep aquifers or deposited in the ocean it stably stores carbon for >10,000 years,” the company explained.
It notes that basalt is an ideal material for this sort of project because of its effectiveness in reacting with CO₂, and also because it also improves soil health by supplying essential minerals and correcting soil pH levels. “This also bolster farmers' livelihoods through improved soil health, reduced agricultural inputs, and increased income at zero cost to them,” XPrize said.
"Being named the grand prize winner of XPrize Carbon Removal is not just a validation of our approach to carbon dioxide removal, it also represents a major catalyst to building out the science and infrastructure needed to deliver on our mission – generating climate resilience and economic empowerment for the more than 100 million smallholder farmers in developing economies worldwide," said Shantanu Agarwal, founder and CEO of Mati Carbon.
Of the other top companies, NetZero is a French biochar company operating in Brazil, which was awarded $15M for developing a “highly efficient” circular model to source and process tropical crop residues, then returning the biochar to local farmers to improve crop yields.
Vaulted Deep, a US-based waste management company, earned recognition as second runner-up and $8m for permanently storing otherwise unusable organic waste deep underground. Vaulted's approach provides permanent carbon storage by injecting non-hazardous organic waste—such as biosolids, paper mill sludge, crop residues, and excess manure—deep underground. It’s an alternative to landfilling, incineration, or land application which also durably stores carbon.
UNDO Carbon, an enhanced rock weathering solution operating in Scotland and Canada, was the third runner-up and was awarded $5m for accelerating the natural process of rock weathering to permanently remove atmospheric CO₂.
Across the competition, funded by the Musk Foundation, over 1,300 teams from over 88 countries worked to develop new methodologies for carbon dioxide removal across four pathways - air, rocks, ocean, and land.
More on carbon capture utilisation and storage (CCUS)
- Advances in carbon capture and utilisation: A new SCI virtual collection
- Carbon capture: Major bio-CCS project gets the go ahead
- SCItalk video: How we build a renewable carbon economy
- CCUS: New carbon capture targets needed says report
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