Detroit Zoo crowdfunds to harness energy from poop

Proposed digester would turn manure into electricity

By: Kevin Bunch | C&G Newspapers | Published April 27, 2015

ROYAL OAK — The Detroit Zoological Society is seeking $55,000 through online donations to construct a “biodigester,” a device that would collect the methane from animal waste and turn it into electricity.


The money is part of the final effort needed to construct the digester, Detroit Zoo Chief Operating Officer Gerry Van Acker said. The zoo already has raised $900,000.


The digester would consist of four air-proof cells, each the size of a “quick oil change garage,” Van Acker said. A cell would be filled up over the course of the week before being latched shut. It would then be heated to around 140 degrees and sprayed with a leachate.


This would cause anaerobic bacteria to feed on the waste more quickly, breaking it down and producing methane gas as waste. Van Acker said that a large rubber bladder would then collect the gas and feed it into a diesel generator to create electricity.


After 28 days, the zoo would empty the cell, and the remaining material — now odorless and with the consistency of peat moss — could be used as composting material primarily within the zoo, Van Acker said.


“The electricity will power about 75 percent of the needs at the animal hospital and produce $70,000-$80,000 in electricity (savings) each year,” Van Acker said. “There are some operational savings, as well, about $30,000-$40,000, so in total we’re looking to save $100,000-$110,000 a year in operation of this.”


He said that right now, the zoo trucks its animal waste downtown to compost. The zoo would save money on man-hours spent trucking the waste.


Van Acker said the biodigester idea first formed a few years ago when the state was promoting different kinds of renewable energy and offering grants to research possible options. The zoo is interested in becoming a zero-waste facility by 2020 for sustainability reasons, and animal waste accounts for about 20-25 percent of the zoo’s output.


“It reduces our carbon footprint,” Van Acker said. “If you let the manure naturally decompose, all that methane eats away at the ozone layer and reduces the amount of ozone in the atmosphere, and makes our carbon footprint larger.


“If you capture it and use it for energy, it’s doing two things: You aren’t reducing the ozone layer, and you don’t need to use fossil fuels to create electricity. So it’s a truly renewable source.”


He said that after getting in touch with the Michigan Economic Development Corporation and Michigan State University’s anaerobic digestion research education center, zoo administrators decided that the idea was not only feasible, but a good option going forward.


The MEDC has agreed to match the $55,000 if the zoo can meet its goal by June 15.


“We are pleased to partner with the Detroit Zoo and support this eco-friendly, energy-saving project,” MEDC Community Development Director Katharine Czarnecki said in a statement. “This campaign will allow residents, businesses and everyone who appreciates the zoo and the positive impact it has on metro Detroit to be a part of this innovative undertaking.”


If the crowdfunding succeeds, work would begin in the summer — most likely in July or August — and continue for about six to eight months. Van Acker said MSU would be contracted for a year to help with the operations.


If the zoo fails to raise the money by June 15, Van Acker said, the zoo could pull the remaining money from its capital projects fund, but he said it would be “really nice” to get support from the community for that last push.


While this would make the Detroit Zoo the first in North America to use a biodigester for fuel, several zoos in Europe have been utilizing the technology for some time now. Van Acker said that while he was on a personal trip to Germany, he visited the Munich Zoo and saw a biodigester working well.


For more information or to donate, visit www.patronicity.com/DetroitZoo. As of April 23, the zoo had raised $11,000 through the site.