Poo Power at the Denver Zoo
One elephant produces a lot of poop — nearly 200 pounds per day, on average. Twelve elephants produce a shitload.
It was that fact that got George Pond, the Denver Zoo's vice president for planning and capital projects, thinking. Would there be a way, he wondered, to turn the thousands of pounds of poop that were sure to come along with the zoo's bigger, better elephant exhibit into something useful? Could all that poo help power the zoo?
In 2005, as planning for the Asian Tropics exhibit was under way, Pond helped get a grant from the U.S. Department of Energy to set up a brainstorming session with the folks at the National Renewable Energy Laboratory in Golden to find out.
There they learned about something called gasification — the conversion of solid fuel into a combustible gas, which can then be converted into electricity and heat.
In the zoo's case, the solid fuel will include everything from animal waste to the trash thrown away by visitors to rubbish from the zoo's office staff. The heat that is created will be stored in water, then used to heat several buildings in Asian Tropics, including the 18,000-square-foot elephant barn and the 11,000-square-foot rhino and tapir holding facility. The water will also be used in the exhibit's three outdoor pools, which will essentially be like hot tubs for the bigger animals.
When Asian Tropics opens in 2011 or 2012, 90 percent of the zoo's waste and trash will be run through a biomass gasification system and converted into energy for the exhibit.
"We're very systematically dealing with not just this cool idea of making hot water, but literally changing our entire environmental footprint," Pond says. The ten-acre exhibit is on track to become LEED Gold-certified, the second-highest green-building rating awarded by the U.S. Green Building Council. Pond believes it will be the first time an entire zoo exhibit has qualified for the designation.
Since much of the zoo's waste will end up in the gasifier, the organization is also taking a closer look at what it buys. With a $30,000 grant from the city Department of Environmental Health, the zoo developed a piece of software called greenworks that rates different products' and suppliers' environmental impact. The program also helps weed out products that contain materials that can't be put in a gasifier, such as metal.
"Through a series of literally hundreds of questions, [the program] gives a quantifiable score to you — Home Depot versus Lowe's versus Office Depot versus Pilot Pens blue seven-millimeter ballpoint versus Bic seven-millimeter gel ballpoint," Pond says. "It gets down into the minutiae, but that's important.
"The pens I like, I'm probably not going to be able to use eventually because they have a piece of metal on them," he adds.
Zoo President and CEO Craig Piper says greenworks could potentially have a wide-ranging impact on other businesses with diverse waste streams. "We see this as potentially spinning off to schools, universities, office parks, other mid-sized businesses," Piper says.
Add to that the fact that the gasification system will reduce the zoo's contributions to a landfill by 1.5 million pounds of waste a year, and that the building of the exhibit will create hundreds of short-term construction jobs and about 25 permanent zoo positions, and Piper sees a project that the city and county can be proud of.
In other words, it's the shit.