Some engineers use their training to build bridges or develop new products. Kartik Chandran, a new MacArthur “genius” grant winner, has a different dream: transform rivers of feces into usable fuel.
The Columbia University professor and environmental engineer’s goal is both filthy and ingenious. His focus is “fecal sludge” — a more genteel term for the liquid human refuse that pools in portable toilets and chamber pots. In developing nations that lack wastewater facilities, this foul sludge makes its way into dumps and bodies of water. To Chandran, that isn’t just disgusting — it’s wasteful. Why not figure out a way to convert human waste into something productive and improve sanitation at the same time?
Armed with big bioprocess dreams and a novel method for converting organic material into fuel, Chandran opened a pilot facility in Kumasi, Ghana, to test his experimental fuel conversion process. But early attempts to efficiently extract biodiesel from poop weren’t too successful. Though Chandran and his colleagues were able to use a kind of fermentation process to isolate fats, their initial experiments didn’t yield as much fat as hoped — and biodiesel needs both fat and methanol to become fuel.
Faced with an inefficient process and low yields, Chandran had to reconsider. “If we had just stopped there, we would have failed,” he says. Instead, he pushed forward, coming up with a process that relies on more than just the inherent fat content of feces. Instead of simply extracting fat from poo, the new method converts leftover sugars and proteins into fat as well, freeing up more for fuel.
“Ironically, one of the byproducts of our process is methane gas,” he says — biogas that can be used as fuel too. The process also leaves behind solids that can be turned into rich fertilizer with a bit of disinfection. And that’s just the beginning, says Chandran. His objective is not to compete with the existing biodiesel or biogas industries, but to use poop to fuel sanitation efforts in the developing world.
In the Ghanan dump where his most encouraging experiments have taken place, says Chandran, “the only thing that is guaranteed is that we’ll see a truck filled with fecal sludge drive by every few minutes.” Faced with the challenge of going from zero to sanitary, says Chandran, it makes sense to use poop to fuel poop cleanup itself.
The dump's biodiesel has already been used to power vehicles, so the pilot program seems to be a great success. But Chandran isn't planning on scaling up in the traditional sense. “Instead of scaling up systems, I’m interested in scaling up impact,” he says. That means creating the smallest system possible and seeing how low prices can go — not creating bigger, better, faster poop-converting technologies.
It may be hard to build efficiency into fecal fuel technologies now, acknowledges Chandran. “But we don’t have to give up because of that. Otherwise we won’t make any progress.” It isn’t enough to continually develop solutions, either — in fact, Chandran hopes that his MacArthur grant money can be used to ask more questions, not just come up with answers.
“This might be a good time to pause for a moment,” he says. “Is there a different way to look at sanitation or fuel? Can we continue to import food and energy into cities and then discard everything?”
Chandran envisions a world full of small-scale poop conversion facilities that could decentralize wastewater management and create more power for more people. But, he says, “scientists can’t do it alone.” He says it’s time to get people like architects, public health officials and the public involved in envisioning a world where poop can fuel sanitation efforts and even cars — one dump truck of fecal sludge at a time.