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U-M’s botanical gardens taking steps toward carbon neutrality

Derek Smith

Lynn Hansen, one of first female members of Michigan Marching Band, conducting at U-M 2022 Homecoming

University of Michigan researchers are turning trash into treasure.

The U-M team, along with researchers and staff from Eastern Michigan University, Duke University and cleantech company 374Water, received $200,000 to fund research around converting lawn, garden and food waste from U-M’s Matthaei Botanical Gardens into valuable products, as well as heat and energy for the gardens’ facilities.

The project is funded as part of the Graham Sustainability Institute’s Carbon Neutrality Acceleration Program, which provided a total of $1,160,000 to six research projects that help U-M meet its goal to establish a carbon neutral campus by 2040.

Spearheaded by Professor Margaret Wooldridge of U-M’s Department of Mechanical Engineering, the team has set out to reduce greenhouse gas emissions by preventing organic waste from going into landfills, where it then rots and emits greenhouse gasses like carbon dioxide and methane.

A pile of organic waste from Matthaei Botanical Gardens. It looks like trash now, but Wooldridge’s team sees its potential value. Image credit: Tony Kolenic

Rather than toss Matthaei’s organic waste into landfills where it can contribute harmful elements to the environment, Wooldridge’s team plans to upcycle that waste into useful products like acetone, packaging fibers, fertilizers, biofuels, or to heat Matthaei Botanical Gardens and Nichols Arboretum’s facilities.

The team estimates that for every ton of organic waste upcycled, they will avoid an equal mass of carbon-dioxide-equivalent greenhouse gasses from emitting from landfills.

Landfills emit approximately 14.5% of the United States’ total methane, which is 80 times more effective than carbon dioxide at trapping heat in the atmosphere over a 20-year period. In 2020, methane emissions from landfills were equal to the energy needed to power 11.9 million homes, according to the U.S. Environmental Protection Agency.

Despite their large carbon footprint, landfills remain the main way that Americans dispose of their municipal solid waste.

By upcycling Matthaei’s waste, Tony Kolenic, the director of MBGNA, also hopes to retain the value of Matthaei’s living collections after their death.

“Across the botanical gardens and arboretum, our plant collections start as seeds. We care for them. We provide them resilience. They bloom, have their annual and perennial cycles, and at some point there could be another life available to them in other valued products,” he said.

When food and other organic waste goes to landfills, it rots and emits methane, a potent greenhouse gas. A team of researchers plan to reduce Matthaei’s organic waste emissions by upcycling it into useful products and energy. Image credit: jbloom via Openverse

The team believes that by upcycling organic waste locally, they can save on costs of transporting waste, engage local stakeholders in waste upcycling, and reduce the complexity of the waste, which impacts the types of products that can be produced, as well as the infrastructure required for pre- and post-processing of the resulting biocrude.

“The (waste) materials dictate the outcome,” said Wooldridge, so the question is “what are the potential products that we can make … and how much can we make?”

The initial experiments will use less than 1% of the waste generated at Matthaei Botanical Gardens, but Kolenic hopes the team can reach a point where essentially all of Matthaei’s organic waste is either composted or upcycled into products and energy using prototype reactors installed at the botanical gardens.

Having on-site reactors also creates a unique education and outreach opportunity by displaying the process of converting organic waste into biofuels and other products for Matthaei Botanical Gardens’ visitors.

“Instead of the normal academic modality of research taking place in a closed lab setting, the whole process can be disseminated,” Kolenic said. “We have the opportunity to gain new kinds of collections and truly become that living, learning lab that we strive to be.”

This project was supported in-part by U-M’s Graham Sustainability Institute’s Carbon Neutrality Acceleration Program, designed to amplify U-M’s efforts in mobilizing the research community’s collective power to advance a low-carbon future. All U-M faculty are eligible to apply for funding that supports carbon neutrality research with the potential to effect real change in the world.