Green Concrete is Foundational to Building Climate Solutions at Scale

Green Concrete is Foundational to Building Climate Solutions at Scale

By Ethan Berg, Climate and Capital Media

Climate heavy hitters in industry and finance are betting on clean concrete. 

Above image: Heirloom facility

Climate and Capital Media Featured NewsWhat if one of the world’s most carbon-intensive industries — cement production — could be a transformative climate solution?  One that is not only carbon-neutral but capable of capturing and sequestering gigatons of CO2 from the air? 

This is the big technological challenge that has brought together an alliance of global concrete makers, Silicon Valley climate tech entrepreneurs, and billionaire Bill Gates. It is a test of what might happen when you mix private capital, moonshot climate solutions, and a money-making opportunity. If it works and is scalable, it could begin to reduce the giant carbon footprint of the industry and vault the world into a net zero economy.

An energy transition fund backed by Gates is bankrolling Heirloom Carbon, a California direct air capture (DAC) company that has teamed up with a consortium of mostly European concrete manufacturers with the ambitious goal of removing one billion tons of CO2 from the atmosphere and embedding it in concrete by 2035.

If they manage that, they would be flipping the script for an insular industry not renowned for enlightened economic and environmental practices.

“Concrete and cement contribute about 8% of global emissions,” says Monica Richter, Project Director for Materials and Embodied Carbon Leaders’ Alliance (MECLA) at WWF Australia. “And it is a ubiquitous product used everywhere in the homes we live in, the buildings we work in, and the roads we travel on.”

Worldwide, 30 billion tons of concrete are used each year. On a per capita basis, that is three times as much as 40 years ago. 

Heirloom, a startup focused on direct air capture (DAC) technology, is working with Leilac, a European-based company that specializes in decarbonization technology for the cement and lime industries. Its main backer, Calix, is a consortium of some of the world’s largest cement and lime companies. Under a deal signed in 2022, the two companies are working to combine traditional cement kiln technology with Heirloom’s cutting-edge DAC solution. 

Last year, Heirloom announced that it had raised $53 million in a Series A funding round from investors, including the Gates-backed fund Breakthrough Energy Ventures, Microsoft Climate Innovation Fund, and current Leilac shareholder Carbon Direct Capital Management

Shortly after, the European concrete consortium and Calix announced that the LEILAC 2 research and innovation project had received funding from the EU’s Horizon Europe innovation program to build an industrial-scale facility. 

Virtuous Cycle

Leilac’s carbon capture process employs a specially designed kiln to capture CO2 gas that is released as the key raw ingredient — limestone — is processed to access lime for making cement. This CO2  — process emissions — normally make up the bulk of the industry’s overall emissions. 

The technology, known as the Leilac Kiln, captures the stream of CO2, which is then pumped into underground geological storage structures. The company says successful pilot projects have demonstrated the approach is cost-effective and scalable — and is currently working to deploy its technology on a larger scale.

Leilac’s pairing with Heirloom — using 100% renewable energy in manufacturing — creates the potential for their cement production to be a carbon-negative process. At the core of Heirloom’s DAC technology is speeding up the natural process of carbon mineralization in which CO2 in the atmosphere binds to lime to form limestone. In nature, this process takes several years, but Heirloom says its process requires just three days. The reformed limestone is then fed into the Leilac kiln, where the CO2 is separated and captured in the process of making cement.

“Modular, scalable, and low-cost DAC technology, paired with geological carbon storage, can offer a path to removing ambient CO2 at the gigatonne scale,” according to a Leilac press release explaining the process.

Other Green Concrete Initiatives

The Leilac-Heirloom initiative is ambitious but far from the only effort to solve the concrete industry’s carbon problem. Among the other building materials companies and coalitions that are circling the carbon capture market is Holcim, a Swiss-French multinational building materials company, which recently announced its commitment to invest $2.2 billion in carbon capture technologies by 2030.

The nonprofit Natural Resources Defense Council (NDRC) has said that a wide array of technologies under exploration may go well beyond the decarbonization of the concrete industry. 

“Concrete’s long-term climate relevance is not limited to emissions reduction: This ubiquitous material could one day serve as a global carbon sink. New and emerging technologies that can capture, utilize and store CO2 across multiple manufacturing phases and components of cement and concrete can permanently lock away heat-trapping emissions in the future.” 

It points to leaders such as the Canadian company  CarbonCure — which has a technology that involves injecting CO2 into cement when it is wet, permanently embedding the greenhouse gas — and a plant in Redding, California, that recycles emitted CO2 back into the kiln, reducing emissions and increasing efficiency. 

Hemp Blocks

Meanwhile, other building materials companies are looking for low-carbon alternatives to concrete, such as Hempcrete.

“Thankfully, the building and construction sector is on board for the challenge, and there is a lot of exciting and cooperative effort being put into this area by researchers and industry,” Richter said. “With government and large contractors making commitments to buy green, concrete companies have the motivation to invest in innovation if they want to be around for the long term.”


Article by Ethan Berg for Climate and Capital Media. 

Article reprinted with Permission as part of GreenMoney’s ongoing collaboration with Climate and Capital Media.

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