Heirloom Carbon

Heirloom Carbon

Direct air capture to mineralize CO2

Overview

Heirloom Carbon develops Direct Air Capture technology that uses limestone to speed up carbon mineralization, turning atmospheric CO2 into rock within days. Its main offering is carbon removal credits, representing permanent CO2 removal and storage either underground or in building materials like concrete. The approach differs by leveraging abundant limestone and targeting credits under $100 per ton by 2035, backed by a commercial facility opened in 2020. The company aims to help other businesses reach carbon neutrality with affordable, permanent removal while creating green jobs and minimizing environmental impact.

About Heirloom Carbon

Simplify's Rating
Why Heirloom Carbon is rated
B-
Rated B on Competitive Edge
Rated B on Growth Potential
Rated C on Differentiation

Industries

Industrial & Manufacturing

Energy

Social Impact

Company Size

51-200

Company Stage

Series B

Total Funding

$204M

Headquarters

San Francisco, California

Founded

2020

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Simplify's Take

What believers are saying

  • Louisiana's $475 million buildout targets 17,000 annual tons by 2026.
  • Major customers include Microsoft, Meta, JPMorgan, Shopify, H&M, and Autodesk.
  • Japanese and U.S. investors validate demand and support international scaling.

What critics are saying

  • Louisiana construction depends on permitting, execution, and storage coordination.
  • Federal funding exposure creates schedule risk if DOE approvals slip.
  • DAC credit demand weakens if buyers reject premium-priced removal claims.

What makes Heirloom Carbon unique

  • Limestone-based DAC accelerates mineralization from years to under three days.
  • Heirloom operates North America's first commercial DAC facility in California.
  • The company combines capture with permanent underground storage or concrete sequestration.

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Funding

Total Funding

$204M

Above

Industry Average

Funded Over

3 Rounds

Series B funding is typically for startups that have proven their business model and need more funding to expand rapidly—often by entering new markets or adding more products. Investors are usually venture capital firms that specialize in later-stage investments.
Series B Funding Comparison
Above Average

Industry standards

$35M
$45M
Linktree
$65M
Substack
$100M
ClickUp
$150M
Heirloom Carbon

Benefits

Covered health, dental and vision

Generous parental leave. 16 weeks paid leave for all Heirloom employees, regardless of primary/secondary caregiver status.

Generous stock options

Flexible time off. Unlimited PTO for exempt (salaried) employees & 80 hours for full time non-exempt (hourly) employees.

Stay healthy. Monthly health and wellness reimbursement.

Learn on the job. Robust annual education and conference budget, including airfare and hotel costs.

Growth & Insights and Company News

Headcount

6 month growth

0%

1 year growth

0%

2 year growth

4%
ESG Today
Feb 27th, 2025
United Airlines Backs Carbon Removal Tech Company Heirloom - ESG Today

United Airlines announced that its United Airlines Ventures (UAV) Sustainable Flight Fund has made an investment in Direct Air Capture (DAC) company Heirloom, alongside an agreement for the right to purchase up to 500,000 tons of carbon dioxide removal to make sustainable aviation fuel. Launched in 2023, the UAV Sustainable Flight Fund invests in and […]

Wow Partners, Inc.
Dec 8th, 2024
Heirloom Carbon secures $150M funding

Heirloom Carbon, a carbon capture startup, raised $150 million in a Series B round led by Future Positive and Lowercarbon Capital, with participation from investors like Ahren Innovation Capital and Japan Airlines. Heirloom's technology captures CO2 from the air using a unique process involving limestone. The funds will be used to build a carbon capture facility in Louisiana by 2026. The company aims to reduce carbon removal costs to $200-$300 per metric ton by the early 2030s.

株式会社PR TIMES
Dec 5th, 2024
Heirloom Carbon secures $150M funding

MOL Switch LLC, a subsidiary of Mitsui O.S.K. Lines, has invested in Heirloom Carbon Technologies, a U.S. company developing Direct Air Capture (DAC) technology. This investment is part of a $150 million funding round, which includes other Japanese companies like Mitsui & Co. and Japan Airlines. Heirloom's DAC technology uses limestone to reduce costs and aims to remove 1 million tons of CO2 annually, supported by up to $600 million from the U.S. Department of Energy.

Business Wire
Dec 5th, 2024
Heirloom Raises $150 Million Series B to Rapidly Scale Commercial Direct Air Capture

Heirloom, America’s leading Direct Air Capture (DAC) technology provider, has raised $150 million in Series B funding. The round was co-led by Future

Nikkei Asia
Dec 4th, 2024
Heirloom Carbon secures Japanese investments.

Four Japanese companies, including Mitsui & Co., Mitsubishi Corp., Mitsui O.S.K. Lines, and Japan Airlines, are investing in Heirloom Carbon Technologies, the first commercially operational U.S. business focused on removing carbon dioxide from the air.

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