Krish Mehta, MBA ’24: Extracting Mountains of Value from Coal Ash

Where some see a toxic eyesore, Krish Mehta, MBA ’24, sees an opportunity. Mountains of coal ash — billions of tons of it scarring rural landscapes across the U.S. — have long been dismissed as an environmental hazard. Mehta’s novel technology platform flips that script, transforming this waste into a virtually unlimited feedstock for cement, fertilizer, and the rare metals that power advanced computer chips.

After years of diligent research, a fortuitous partnership with Jorge Osio-Norgaard, a Stanford postdoc, and expert guidance from his Stanford Graduate School of Business faculty teachers and mentors, Mehta co-founded PHNX Materials. With the help of a Stanford Impact Founder Fellowship, he is poised to transform these environmental liabilities into a homegrown supply of scarce minerals needed to drive the AI revolution.

A Mission to Create a Circular Supply Chain

Long before arriving on the Stanford campus, Mehta had begun to formulate a mission.

After earning dual bachelor’s degrees in finance and renewable energy engineering from Penn’s Wharton School and School of Engineering, Mehta worked in McKinsey’s sustainability practice and managed Model 3 production at Tesla. At Tesla, he saw pandemics and trade wars choke the semiconductor supply chain, sending costs soaring and production sputtering.

Gallium is a case in point: The soft metal is crucial for high-voltage semiconductors used in telecommunications, radar systems, and the electronics that power data centers, yet its supply chain is highly vulnerable. “There’s no such thing as a gallium mine,” Mehta says. “It’s a byproduct of the aluminum smelting process, most of which is produced in China.”

Mehta became single-minded about solving critical supply bottlenecks, so much so that he wrote about it in his Stanford application. His focus: exploring industrial waste as a domestic source of critical minerals.

Exploring with Stanford’s Support

At Stanford, Mehta earned a joint MBA and MS in environment and resources as a Knight-Hennessy Scholar. His quest to identify high-potential waste-to-value opportunities quickly led him to coal ash.

Mehta explains that coal ash contains not only rare metals like gallium but also powdery calcium and silica for cement and sulfur to enrich fertilizers. A key business model insight he gained from his research and courses was that “a necessary requirement is to effectively sell 100% of all the material we take in.” According to Mehta, “People have been looking at extracting critical metals from industrial waste for over 50 years, but the economics never penciled out because the critical mineral content is too low to justify a standalone business.”

Stanford provided the perfect environment for Mehta to refine his ideas. He secured funding for his initial research on mining coal ash from the TomKat Center at Stanford and explored the idea of selling to the concrete industry in Steven Weinstein’s Innovation for Climate and Sustainability course. Mehta tested the business model assumptions of ash as a 1:1 replacement for Portland cement in Stanford Climate Ventures, under the guidance of teachers David Danielson and Jane Woodward, and further deepened his understanding of the industry landscape in EcoSprint, a Stanford summer program in which graduate students explore sustainability-focused venture ideas.

Now what Mehta needed was technology. Standard extraction methods rely on extensive chemical leaching and generate significant residuals that are uneconomical to process. For Mehta’s vision of a circular economy to work, he needed to develop an extraction technique that yielded clean, profitable leftovers. So when a chance introduction brought him to a Stanford postdoc, he was ready.

The Bucket That Built the Team

While conducting research on a visit to CalPortland’s cement facility in the Mojave Desert, Mehta was handed a bucket of cement. The staff member had meant that bucket for a different Stanford researcher: Jorge Osio-Norgaard, a chemical engineering postdoc in Tiziana Vanorio’s Rock Physics and Geomaterials lab. Osio-Norgaard was studying alternatives to limestone-based cement and has a background in high-temperature reactions.

When Mehta delivered the bucket to Osio-Norgaard back on campus, the two hit it off immediately. After a year of collaborating in Vanorio’s lab, Mehta recruited Osio-Norgaard to help him launch PHNX via an email with the subject line: “Let’s change the world.”

Together, the pair developed a core technology that boils the ash waste and isolates more than 30 metals based on their unique condensation points, leaving a valuable byproduct that outperforms traditional cement.

The exact method is patented, Mehta says, but it works at less than half the temperature of traditional chemistry, making what they call “the world’s first solids refinery” financially viable. And because concrete production accounts for 8% of global carbon emissions, this process has the potential to reduce climate impact.

A Well-Supported Launch

With his leadership team in place, Mehta launched PHNX upon graduation.

PHNX might not have happened, Mehta says, if not for frequent mentoring with Irv Grousbeck, the MBA Class of 1980 Adjunct Professor of Management, Emeritus, at Stanford GSB. Mehta was weighing a second business idea, but Grousbeck advised him not to split his time and to focus on and grow PHNX.

“And, of course, the actual Stanford Impact Founder Fellowship was what allowed me to launch the company upon graduation,” Mehta says. “I can say that 100 percent we would not be here at all without Stanford.”

To demonstrate its technology, PHNX just opened an Ohio facility for cement and fertilizer products. The company is planning a Montana site for metals extraction and finalizing a commercial site with coal communities in Texas. Mehta says that communities, utility companies, and owners of disposal sites across these states and beyond have welcomed PHNX, recognizing the value of permanently converting expensive, high-maintenance environmental liabilities into a useful product.

Planning for Scaled Impact

Gallium is the headline-grabbing treasure buried in the coal ash, and the waste sites in the U.S. alone contain over 10,000 years’ worth of gallium supply, Mehta estimates. The binding constraint, by Mehta’s own “100% in, 100% out” rule, is the amount of cement substitute and fertilizer the market can absorb, since every input must leave the plant as a saleable product. PHNX built a pilot facility across the Bay from Stanford in San Leandro using secondhand equipment, and Mehta says that, once built to scale, a single PHNX plant could match the output of a competitor’s $7.5 billion facility.

That potential production scale caught the attention of the U.S. Department of Energy and the Department of Defense, both concerned about sourcing rare metals for national security purposes, as well as private investors: PHNX closed a $6.5 million seed round, bringing its overall funding to $18 million since Mehta left Stanford.

With more than 800 coal ash disposal sites scattered across the country, Mehta envisions a distributed network of 100 plants, each one turning a local liability into a link in the domestic supply chain — a bet that America’s most valuable resources won’t come from mines, but from mountains no one wanted in the first place.