How many dogs does it take to fuel a lamppost?

Many experts believe the future of dog-waste management belongs to something called “methane digesters” — hermetically sealed tanks where feces are broken down into methane, the main component of natural gas, and turned into fuel. If Melody Kelemu, a New York University junior, has it her way, the next methane digester will soon be part of the Dog Run at Washington Square Park. Kelemu has applied for a $20,000 Green Grant from NYU’s Sustainability Task Force to help implement, what she calls, “a dream come true,” to an environmentalist, at least. Here’s how it will work:

NYU student Melody Kelemu with Winnie, a friend who frequents the dog run at Washington Square Park where Kelemu hopes to install her digester.

“The poop is deposited into a large tank that holds sludge,” said Kelemu, a 21-year-old Neuroscience and Environmental Studies student who grew up in Ethiopia. “The sludge is a combination of anaerobic (meaning that it doesn’t need oxygen) bacteria and water. The bacteria degrade the poop and release the methane gas, which escapes into a tube at the top of the tank. This tube leads to an igniter so that the sparks from the igniter can fuel and sustain a flame.”

How many dogs does it take to light up a lamppost? Depending on the size of the pooch, and other variables (including the temperature in the tank), it could take as few as 10 dogs an hour to keep the torch burning. Just to make sure, Kelemu’s proposed project is designed to handle the waste of 200 dogs each day. “I am doing this,” said Kelemu, “because environmental issues cannot be solved solely by advances in academic circles or solely by advances in social circles. It takes both.”

To be sure, society has made huge strides over the last dozen or so years — thanks to all the pooper-scooper laws, ordinances, campaigns, and efforts—to pick up after our pets. Today, most of us (including the Duchess of Cambridge, who has been spotted with Lupo, the royal Springer Spaniel) will bend over backwards to put our dog’s poop in plastic bags or biodegradable plastic. But to what end? Of the estimated 10 million tons of pet poop produced each year, the bulk gets tossed into garbage cans, and “ends up in landfills across the world,” said Kelemu. “By and large, biodegradable bags do not biodegrade when they enter landfill. It is not the conditions it takes to biodegrade.” San Francisco State University Biologist Jonathan Stern adds, “What we’re doing now is redistributing the poop from one place to another. It’s like a chess game.”

Put that way — either storing poop in landfill, where it could potentially ooze methane (that’s if it’s not preserved for a lifetime in plastic) or harnessing it for its energy potential — it’s easy to see why projects like Kelemu’s that turn poop to power are the way of the future. Still, a variation of her idea has been tried — but without much success. Consider the case of the city of San Francisco. Back in 2006, waste managers had planned to install methane digesters in high traffic dog-parks (the city has a mandate to stop using landfills by 2020) but it never got past the planning stages. Instead, officials discovered that collecting undigested food scraps from restaurants yielded more potential energy than the dog droppings. It was less messy too. Today, the city is successfully turning food scraps into fuel as well as high-quality compost, which is being used in the vineyards of Napa Valley.

According to Robert Reed, a waste expert with Sunset Scavenger, the company that picks up all the garbage in San Francisco, the city would be a good place for another possible peek at poop’s powerful potential. “There are more dogs and cats than children here and residents pick up the droppings.” he said, “But the biggest challenge we see are plastic bags. Unfortunately, plastic bags would plug up the methane digester.” Recently, San Francisco banned plastic bags at large grocery stores, but, said Reed, “plastic bags are still omnipresent.”

Converting dog waste into energy that powers gas lamps via the methane digester. (Photo credit: Park Spark Project)