Our Atmosphere

CO2 removal is a necessity

Even if the world stopped emitting CO2 tomorrow, the planet would continue to warm because of the massive amounts of emissions already blanketing our atmosphere. To keep global temperature rise below 1.5 degrees celsius, we’ll need to remove billions of tons of CO2 each year – a volume equivalent to 10–20% of today’s annual global emissions. Heirloom’s unique DAC platform is one of the few low-cost carbon removal technologies capable of reaching billion-ton scale.
mineral photo

Our process

Designed for scale, engineered for impact

Our approach is unique; it combines the best of two well-established CO2 removal technologies – carbon mineralization and Direct Air Capture – to build a truly scalable, low-cost carbon removal solution. We use limestone, one of the world’s most abundant and inexpensive minerals, to capture CO2 directly from the atmosphere, and then permanently and safely store it underground.
A diagram of Heirloom Direct Air Capture process

How our Direct Air Capture system works

Using limestone like a sponge

Limestone is made up of calcium oxide and CO2. When CO2 is removed from the limestone, the remaining calcium oxide is hydrated with water to form calcium hydroxide, commonly known as “lime”. Lime is “thirsty” for CO2 because it wants to return to its natural limestone state and acts like a sponge – pulling CO2 from the atmosphere. Our technology accelerates this natural property of limestone, reducing the time it takes to absorb CO2 from years to less than 3 days.

Removing CO2 from limestone

We heat limestone mineral powder in a renewable-energy powered kiln to remove the CO2. Our partners then permanently and safely sequester this CO2 underground or in concrete.

Soaking up CO2 from the atmosphere

Once the CO2 is removed, we spread the CO2-thirsty material onto vertically-stacked trays, add water, and “treat” it to optimize its ability to uptake CO2 quickly.

Repeating the process

Like repeatedly wringing a sponge, we loop this limestone through our system to continuously suck CO2 from the atmosphere – a cyclic process that not only lowers costs but also reduces how much limestone must be mined.

Our Technical Advantage

The fastest path to low-cost, permanent carbon removal

Our technology is designed to enable rapid cost reduction through scale, allowing us to meaningfully impact climate change as quickly as possible.

Low-cost inputs

Our technology is powered by limestone – a low-cost and easy-to-source material. By working with abundant and mature supply chains, we have a clear path to driving down costs and scaling quickly.


Our DAC facilities are carbon-absorbing warehouses – designed to be modular, mass manufacturable and easy to scale rapidly around the world.

Learning from every ton

We collect tens of millions of data points each month to further optimize our CO2 uptake rate – which further increases our output and reduces cost.

Our facility

America’s first commercial DAC facility

In a world first for Direct Air Capture technology, our facility in Tracy, California, is capturing CO2 from the atmosphere which is then embedded permanently in concrete. Working with our partner CarbonCure, this CO2-enriched concrete is laid in the foundations of buildings and structures, with the added benefit of creating stronger concrete.

We’re also proud to be implementing a community governance model, which will gather stakeholder input on financial and programmatic investments into Tracy and San Joaquin County community organizations beginning in Q1 of 2024.
two people in blue helmets
photo of people working on facility
two hands in blue gloves
image: minerals

Your impact

Take action on climate change with Heirloom

Help us permanently remove 1 billion tons of CO2 from our atmosphere by 2035.