Coal-fired power plants have long been associated with environmental degradation and significant health risks, from driving climate change and acid rain to devastating ailments like black lung and heart disease. Yet, within their ashes lies a surprising resource with the potential to substantially reduce the carbon footprint of the concrete industry.
PHNX Materials, a pioneering startup, has developed an effective technique to extract valuable compounds from coal ash, transforming a problematic waste product into an essential component of environmentally friendly concrete mixes. Krish Mehta, co-founder and CEO of PHNX Materials, explains that processed fly ash can substitute for up to 30% of the cement typically used in concrete production, significantly lowering emissions associated with traditional cement manufacturing.
Historically, ash has played a critical role in concrete formulation. The Romans, known for their durable architecture, employed volcanic ash to create resilient structures. In modern times, transportation agencies like California’s Caltrans mandate a minimum of 25% fly ash content in their infrastructure projects. According to PHNX Materials co-founder and CTO Jorge Osio-Norgaard, fly ash stabilizes concrete mixtures, preventing a detrimental chemical reaction that can cause cracking and compromise structural integrity over time.
The recent closure of numerous coal-fired plants, however, has reduced the availability of fly ash, coinciding with a critical shortage for the concrete industry. Previously responsible for 51% of electricity generation in the United States, coal’s contributions have plummeted to just 15%, sharply constraining the supply of quality fly ash. As demand surpasses the supply and ash prices rise, construction companies have been limiting fly ash content in concrete mixtures to about 8%, opting instead to fill the gap with additional cement. This substitution is not only costlier—cement costing nearly double per ton—but also environmentally disadvantageous, given that cement production releases around 0.8 tons of CO₂ per ton manufactured.
Recognizing this gap, PHNX Materials seeks to revive an underutilized resource. Its innovative extraction process yields high-quality fly ash free of undesirable impurities, namely sulfur and aluminum, and simultaneously creates valuable by-products marketable to other industries. Sulfur, for instance, finds lucrative uses in fertilizer production, while recovered aluminum serves industrial applications, paving the way for additional revenue streams.
PHNX has successfully secured a seed investment of $2.5 million, led by Divergent Capital, KdT Ventures, and Overture, with further participation from investor Jane Woodward. Beyond sulfur and aluminum, PHNX Materials is actively exploring opportunities to extract rare earth elements from ash, amplifying both environmental and economic benefits.
With approximately 843 ash landfills spread across the U.S. representing substantial potential, PHNX Materials envisions reducing the concrete industry’s carbon emissions at scale—and potentially reshaping a vital material sector in the process. As CEO Krish Mehta succinctly stated, “Unlocking a new supply of ash is the most scalable and quickest way to decarbonize the sector.”
