October 9, 2026 -  For decades, coal ash has been viewed as one of industry's most troublesome waste products. The fine, powdery residue left behind after coal is burned for electricity generation has accumulated in storage ponds, landfills, and disposal sites across North America, often requiring ongoing environmental monitoring and management.

Now, a U.S. startup believes those massive stockpiles could become a valuable resource for agriculture, construction, and high-tech manufacturing.

PHNX Materials, co-founded by Stanford University graduate Krish Mehta, has developed a technology platform designed to recover useful materials from coal ash while ensuring that virtually every component of the waste stream is transformed into a marketable product. According to the company, coal ash contains valuable compounds including calcium, silica, sulfur, and critical minerals such as gallium, a metal used in advanced semiconductors and telecommunications equipment. 

The concept is based on a simple principle: waste should not remain waste if its components can be put back into productive use.

Fertilizer Potential Draws Agricultural Interest

While the rare metals often attract headlines, the agricultural applications may be just as significant.

Coal ash contains sulfur and other materials that can be recovered and repurposed for fertilizer products, creating an additional revenue stream while supporting crop production. The company says a successful business model depends on finding uses for all recovered materials, including products destined for agriculture. 

Mehta's research concluded that previous efforts to extract valuable minerals from industrial waste often struggled economically because they focused on recovering only small amounts of high-value metals. By creating markets for fertilizer ingredients and cement materials alongside critical minerals, the economics become more attractive.

For our Small Farm Canada readers, the story highlights a broader trend toward circular economy solutions that transform by-products and waste streams into useful agricultural inputs rather than sending them to long-term disposal sites.

From Environmental Liability to Economic Opportunity

The idea emerged from Mehta's interest in securing domestic supplies of critical minerals. While pursuing a joint MBA and environmental resources degree at Stanford University, he explored industrial waste as a potential source of materials traditionally obtained through mining.

His work eventually led to the establishment of PHNX Materials alongside Stanford researcher Jorge Osio-Norgaard. The company developed technology capable of separating valuable materials from coal ash while producing products for multiple industries, including agriculture and construction.

The startup recently opened an Ohio facility focused on producing cement and fertilizer materials and is planning additional operations dedicated to metals extraction. According to the company and related reports, communities with legacy coal ash disposal sites have shown interest in turning costly environmental liabilities into revenue-generating assets. 

Why Gallium Matters

Part of the interest in coal ash comes from its potential to supply gallium, a critical mineral used in semiconductors, radar systems, telecommunications equipment, and data-centre electronics. Much of the world's gallium supply is currently tied to production processes concentrated in China.

PHNX Materials argues that the billions of tonnes of coal ash already stored across the United States represent an untapped domestic resource containing significant quantities of these strategic materials. 

However, the company's model depends equally on finding markets for by-products such as fertilizer ingredients and cement substitutes, ensuring that all recovered materials can be sold and utilized.

Could the Concept Work in Canada?

Although Canada is steadily moving away from coal-fired electricity generation, the country still has significant legacy coal ash storage sites.

Alberta, which completed its coal power phase-out in 2024, retains millions of tonnes of historical coal ash near former generating stations. Saskatchewan continues to operate coal-fired facilities, while Nova Scotia maintains active ash-management sites associated with its power plants. Ontario and Manitoba have also undertaken remediation projects involving former coal and ash storage locations.

These legacy sites raise an intriguing question: could some of Canada's coal ash inventories eventually become feedstocks for fertilizer ingredients, construction materials, or critical mineral recovery?

While no comparable large-scale Canadian projects have yet emerged, the U.S. initiative demonstrates how technologies designed around waste reduction and resource recovery can potentially create value from materials once considered environmental liabilities.

For agriculture, the story is another example of how innovation aimed at reducing waste can generate additional benefits, including new sources of fertilizer materials and greater resource efficiency across the economy.

As governments, industries, and farmers increasingly focus on sustainability and waste reduction, technologies that convert industrial by-products into productive agricultural inputs may become an increasingly important part of the conversation.