Frontier portfolio


Turning carbon into a mineral that can be permanently stored away

A pile of solidifying minerals slowly turning to a dark grey color.

Permanent carbon removal

When carbon dioxide comes in contact with certain types of rocks, chemical reactions transform the CO₂ into a solid mineral. The CO₂ is locked away, removing it from the atmosphere permanently.

This beautiful process occurs naturally. Natural rock weathering has been happening forever, removing about one billion tons of atmospheric carbon every year. But scientists are figuring out how to speed up and scale this process to maximize the amount of CO₂ we could permanently store this way. This process is known by many names—like enhanced rock weathering and CO₂ mineralization—and it’s an exciting new field of study. Multiple methods are possible: you can inject CO₂ into rock deep underground (like Climeworks is doing with their captured carbon), or you can use the Earth’s surface.

One rock that does a really good job of carbon capture is olivine, a greenish mineral full of magnesium and iron. When you grind it up into rock dust you can sprinkle it over land or water so it comes in contact with, and stores, a bunch of CO₂. The finer the rock, the more surface area there is for the CO₂ to attach to—and unfortunately, in most cases, the more expensive and energy-intensive it is to produce. Right now, the process of refining olivine requires so much energy that it could cancel up to 80% of the positive effects. But, if done right and widely, it could capture an estimated two billion tons of CO₂ every year.Footnote 1

One promising avenue for mineralization is the mining industry. Crushed mining waste, called mine tailings, could be a very effective way to store CO₂ and decarbonize that industry. You could capture CO₂ emissions from mine operations, then apply it directly to the mine tailings on site for permanent storage.

Crushed mining waste could be an effective way to store CO₂

Massive amounts of mine tailings sit idle across the globe. Some of them are currently being tested, and if those tests prove the potential for direct air capture, this would be a huge opportunity for carbon removal that entrepreneurs and mining companies could capitalize on.

Much of this research has been done in labs, with very few field tests. There are no policies that recognize or incentivize this industry yet, and there is still much to learn about the costs, scalability, and potential impact here. We haven’t found any investments in this area yet, but we have our eye on this promising space and have earmarked 3% of our fund. Stay tuned for more.

Company spotlight


Sedimentary rock formations are by far the largest store of carbon on earth - over 1,000 times larger than any other carbon sink. On geological timescales, carbon slowly makes its way from the atmosphere into rocks, eventually forming carbonate minerals which sit, stable and safe, deep in earth’s crust. But we don’t have millions of years to slow climate change, we only have a few. Heirloom was founded to harness and accelerate the power of this natural process to help restore balance to the atmosphere.

Heirloom’s process starts by spreading thin layers of reactive oxides on trays and stacking them on top of each other, maximizing the mineral surface area exposed to the ambient air. They’ve accelerated the rate that these minerals take up CO₂ - from years in nature - to just two weeks. After absorbing CO₂ like a sponge, the minerals are heated in an electric kiln, releasing the CO₂ molecule from the mineral so it can be captured and stored underground permanently. The leftover minerals from the kiln can then be recycled and spread in thin layers and the cycle continues.

At scale, the process could cost less than traditional direct air capture and use less energy overall. The minerals Heirloom uses are highly abundant, and the process relies on these minerals passively contacting air rather than using energy-intensive fans to draw air in.

Since we launched our fund, we have been searching for a high potential mineralization solution to include in our portfolio. In mid 2020, Heirloom emerged from Carbon180’s Entrepreneur-in-Residence fellowship ready to pursue commercialization, and the rest is history.

Shopify has agreed to purchase 400 tons of carbon removal from Heirloom. This is important revenue that helps fund their initial deployment on their journey to remove 1 billion tons of carbon dioxide from the atmosphere by 2035.

“A few decades from now, carbon removal will need to be 2-3 times the scale of the oil industry,” said Heirloom’s CEO, Shashank Samala. “We can't repeat the mistakes of the past, and we need approaches that don’t make compromises. It's possible to achieve permanent, compact, environmentally-just, and low-cost carbon removal at scale and that's exactly what we are going to do."