Engineering the overlooked
As a Stanford undergraduate, William Tarpeh learned to spot problems others ignore. Financial aid gave him a path forward—all the way to a MacArthur Fellowship.
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Assistant Professor of Chemical Engineering William Tarpeh. Photo: Jess Alvarenga, Design: Jonathan Chaves.
When your research subject is human waste, there’s a certain point at which delicacy becomes beside the point. As a PhD student at the University of California, Berkeley, William Tarpeh needed large quantities of the stuff. He was studying how to recover nitrogen from urine—an idea that treats one of the most universal human waste streams as a potential resource. So he taped a sign above the lab’s collection containers: Urine luck! Today’s your day to donate.
The joke did its job. It also hinted at something deeper: a curiosity about what most people prefer not to think about, and an ability to see possibility where others see waste. That instinct would come to define Tarpeh’s work—and, eventually, earn him one of the most coveted recognitions in American science.
Last October, Tarpeh—now a professor of chemical engineering at Stanford—learned he had been named a MacArthur Fellow. The award, often referred to as a “genius grant,” recognizes people who combine intellectual range with a tolerance for slow, unglamorous problems. Sanitation research qualifies on both counts.
Tarpeh’s path to that work began years earlier, when he arrived at Stanford as an undergraduate in 2008. He knew he wanted to be an engineer. He also knew that engineering, to him, was only interesting if it intersected with the world’s messier failures.
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Teaching, for Tarpeh, begins with giving students the freedom to explore. Photo: Jess Alvarenga
“At 18, my definition of a big problem wasn’t that different from now,” he says. “Something that could drastically improve a lot of people’s lives. Clean water, sanitation, global poverty, global hunger.”
Stanford did not push him toward a narrower version of those ambitions. Instead, it encouraged him to roam. Tarpeh majored in chemical engineering but spent significant time elsewhere, minoring in African studies, studying abroad in Cape Town, and building friendships far outside the engineering quad.
“I chose Stanford because I wanted to be around people who weren’t just scientists and engineers,” he says. “Most quarters I took at least one class outside engineering.”
That intellectual cross-training mattered. Alongside thermodynamics and fluid mechanics, Tarpeh was learning how history, economics, and political power shape infrastructure—and how engineering solutions often fail when they ignore those forces. Over time, three interests began to converge: chemical engineering and sustainability; the history of South Africa; and water engineering and public health.
“If you combine them,” he says, “that’s basically what I do now.”
That sense that these interests could cohere into a life’s work snapped into focus in a small seminar on water engineering and public health, taught by Professor Jenna Davis. Tarpeh had a simple realization: This wasn’t a side interest—it was a field. “Jenna studies this all the time,” he recalls. “You can make a whole career out of this.”
The moment offered something like permission. Sanitation and water systems—underfunded, politically invisible, rarely glamorous—could sit at the center of serious scholarship. Tarpeh leaned in. He joined Engineers for a Sustainable World, spent a summer in Mexico with a toilet nonprofit, and began mapping engineering abstractions onto problems he actually cared about.
“Once those connections clicked,” he says, “I felt confident that the skills I was learning could help me scope problems I could actually attempt to solve.”
Those habits of mind now define Tarpeh’s research. He approaches engineering problems as social systems with pipes attached, shaped as much by economics and maintenance realities as by chemistry. Stanford, he says, taught him not just how to solve problems, but how to notice the right ones.
At the center of his lab’s work is an eye-opening fact: Wastewater is loaded with valuable elements. Nitrogen is a prime example. It’s a major pollutant in rivers and lakes—and a critical ingredient in fertilizers that sustain global agriculture. Modern society spends enormous energy pulling nitrogen from the air to make fertilizer, then spends more energy removing nitrogen from wastewater before releasing it back into the environment.
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Photo: Jess Alvarenga
Tarpeh’s research asks, is there a better way? His lab develops electrochemical systems that recover nitrogen in usable forms, converting a regulatory burden into a productive resource. One prototype captures fertilizer from urine using solar energy, reducing pollution while producing an agricultural input—an approach with particular promise in places where infrastructure is limited and fertilizer is expensive.
“My goal,” Tarpeh has said, “is to get sanitation to a point where it pays for itself.”
It’s deceptively radical, the idea that waste might underwrite its own management. The MacArthur Foundation cited this capacity to rethink entrenched systems—and to do so with tools that are technically rigorous and practically scalable—in awarding Tarpeh the fellowship.
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“My goal,” Tarpeh has said, “is to get sanitation to a point where it pays for itself.”William Tarpeh, Assistant Professor of Chemical Engineering
At Stanford, his lab has grown into an interdisciplinary workshop, drawing students and postdoctoral scholars from chemistry, materials science, engineering, and environmental science. Together they build membranes, electrocatalysts, and reactors, then test them outside the lab, where real constraints tend to challenge elegant theories. That work rests on more than ingenuity. It depends on Stanford’s research infrastructure—and on philanthropic support, including endowed graduate fellowships that allow Tarpeh to recruit exceptional young scientists from around the world and give them the time and freedom to pursue questions still taking shape.
The roots of that work trace back to an undergraduate experience defined by breadth—and the freedom afforded by Stanford’s commitment to need-based financial aid, and the donors who make that possible. His room and board covered, Tarpeh was able to carry a demanding course load, study abroad, immerse himself in undergraduate research, and explore widely across disciplines. He graduated debt-free, able to say yes to opportunity rather than calculate its cost.
“That changed everything,” he says. “I could study abroad without worrying about money. I could focus entirely on learning and research. It allowed me to dream.”
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Photo: Jess Alvarenga
That freedom—to explore without immediately monetizing curiosity, to pursue questions whose value isn’t obvious on a balance sheet—became foundational. It’s also what Tarpeh now wants for his own students.
“Now, as a professor, I want students to be unoccupied by anything except their interests,” he says. “In the end, that’s really the ideal here.”
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William Tarpeh is Assistant Professor of Chemical Engineering, by courtesy, of Civil and Environmental Engineering and Center Fellow at the Precourt Institute for Energy and, by courtesy, at the Woods Institute for the Environment. Jenna Davis is Professor of Civil and Environmental Engineering, of Environmental Social Sciences and Higgins-Magid Senior Fellow at the Woods Institute.
Stanford Engineering: The impact
Why it matters
William Tarpeh’s undergraduate education at Stanford gave him the freedom and breadth to pursue ambitious research that shaped his life’s work. Philanthropy made possible not only need-based aid, but also the study abroad and undergraduate research experiences that helped him connect engineering to real-world systems and communities. Without those opportunities, students like Tarpeh might never discover the questions that define their work—or the tools to answer them.
The opportunity
Scholarships enable a student to focus fully on rigorous study, research, and service. Expanding these resources multiplies the number of students who can take intellectual risks, pursue interdisciplinary work, and translate ideas into meaningful action. Supporting aid is a direct investment in the next generation of innovators and leaders.
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