Calcium hydroxide – commonly known as lime – is the filter medium of choice for a direct air capture (DAC) technology now being exploited at scale by San Fransisco-based Heirloom.
The company has just raised $150 million in Series B funding led by Future Positive and Lowercarbon Capital, with significant participation from companies including Japan Airlines, Mitsubishi Corporation, Mitsui and Siemens representing difficult to decarbonize sectors of the economy such as aviation, automotive, shipping and advanced manufacturing.
The funding will be used to continue to drive down the cost of the technology, develop additional projects and access infrastructure capital.
Affordable scale
“We believe DAC is all about cost, cost and cost – and that it will only scale to make a meaningful difference on climate change if it is affordable,” said Heirloom CEO Shashank Samala. “This is precisely why people are investing in Heirloom. Through our real-world deployments and continued technological advancements we are demonstrating not only that Heirloom has a clear trajectory to the lowest-cost DAC solution – but that we are executing on that vision and delivering results.”
Since its founding in 2020, Heirloom has progressed rapidly to become one of the world’s leading DAC companies. It is part of the team building Project Cypress a DoE supported DAC Hub, which is eligible for up to $600 million in government funding, and which will bring one million tons of yearly CO2 removal capacity to Louisiana and create nearly 1,000 new jobs.
Heirloom has received strong bi-partisan US political support, as demonstrated by its recently unveiled plans for a number of Louisiana facilities, including an initial 17,000 ton plant set to be operational in 2026.
Late last year, Heirloom began operating North America’s first commercial DAC facility in Tracy, California, shortly after signing one of the largest CO2 removal deals to date with Microsoft. The company has also signed deals to provide carbon removal to Stripe, Meta, Shopify, JPMorgan, McKinsey, Workday, H&M Group, Autodesk and others.
CO2 sponge
The Heirloom process starts with natural limestone, nearly 50% of which is CO2. By extracting CO2 from the limestone and adding water, the Heirloom process creates a material that is thirsty for CO2 so it can return to a natural limestone state. This material acts like a sponge, pulling CO2 from the atmosphere.
Heirloom’s technology accelerates this process, reducing the time it takes to absorb CO2 in nature from years to just three days. Once the CO2 is absorbed, it is extracted from the limestone material using a renewable energy-powered kiln and stored permanently underground.
Even if the world stopped emitting CO2 tomorrow, the planet would continue to warm as a result of the massive amounts of emissions already blanketing the atmosphere. To keep the rise in global below 1.5 degrees Celsius, billions of tons of CO2 will need to be removed from the atmosphere each year – a volume equivalent to 10-20% of today’s annual global emissions.
Heirloom’s DAC platform is one of the few low-cost carbon removal technologies capable of reaching billion-ton scale.
