US Plant Targets Atmospheric Carbon Reduction Using Limestone

Heirloom, a company based in Tracy, California, recently launched an innovative climate solution at its new warehouse. This facility, the first commercial direct air capture (DAC) plant in the United States, employs a unique method using limestone to extract carbon dioxide directly from the air. The process involves storing the captured carbon in concrete, effectively removing it from the atmosphere.

The significance of this technology lies in its ability to address the increasing concerns over the climate crisis. While the idea of capturing carbon from the air was once deemed far-fetched, it has now gained traction among scientists and political leaders as a critical tool in mitigating climate change. The Biden administration has shown support by allocating at least $3.7 billion to initiate DAC and other carbon removal projects across the nation.

Heirloom's approach involves heating limestone to high temperatures, breaking it down into carbon dioxide and calcium oxide. The carbon dioxide is then stored in concrete, useful for construction projects. The remaining calcium oxide is exposed to the open air on trays, naturally absorbing carbon dioxide. This cyclic process is energy-efficient, relying on limestone's inherent property to capture carbon molecules from the air.

The impetus behind Heirloom's initiative comes from its CEO, Shashank Samala, who was motivated by his experiences of heatwaves and droughts in southeast India. He aims for Heirloom's technology to have a significant and scalable impact on climate change. However, achieving a substantial reduction in atmospheric carbon remains a challenge. The current facility can absorb a maximum of 1,000 metric tons of CO2 annually, which is a small fraction compared to the emissions of a gas-fired power plant. Heirloom aims to remove 1 billion tons of carbon dioxide by 2035, but this requires a substantial increase in capacity.

Financial backing for such scaling up is coming from various tech firms. Microsoft, for instance, has signed a contract with Heirloom to offset its emissions as part of its net-zero goals. Additionally, a fund named Frontier has committed $46.6 million to Heirloom and another carbon-sucking venture.

Heirloom emphasizes its commitment to environmental values, choosing renewable energy sources and avoiding investments from oil and gas companies. They are particularly cautious about the use of captured carbon, ensuring it doesn't indirectly contribute to further CO2 emissions.

According to The Guardian, further support comes from the Department of Energy, which awarded Heirloom $600 million to build a larger facility in Louisiana capable of processing up to a million tons a year. The modular design of their facilities allows for scalability by simply using larger trays and stacking more trays.

Experts acknowledge the challenges of DAC technology, highlighting its high costs and energy requirements. The process involves moving vast amounts of air to extract a relatively small fraction of carbon, making it an expensive endeavor. Despite these hurdles, experts like Brad Sageman, an earth and planetary scientist, stress the importance of exploring all possible solutions to the climate crisis.

Samala envisions a future where the role of direct air capture is widely recognized, akin to how city governments manage waste. He advocates for a societal shift in thinking, where people acknowledge the need to pay for the carbon dioxide they produce, marking a significant step towards addressing environmental challenges.