Summer Biochar Blitz
Guest post by Abel Beyene, 2022 Sustainability Intern
"I spent the past six weeks in a backyard burning wood to save the planet, as paradoxical as that sounds."
Here, I light one of the collected species from the top of the Ring of Fire to create conditions with as little oxygen as possible. My fellow intern, Colin Hartnett is in the background.
Believe it or not, heating wood will not emit much carbon dioxide, provided you’re doing it without oxygen, and it yields a stable carbon residual mass, called biochar. This incredible substance is gaining traction and credibility as a carbon removal solution. That is because it is made from dead organic matter that would have decomposed and emitted greenhouse gases like CO2. When the volatile gases (e.g. H2, water vapor) are burned off in a reaction called pyrolysis, what remains is a pure and stable form of carbon - similar to graphite.
When we bury biochar in the soil, the carbon can remain in the soil indefinitely if left undisturbed. With an abundance of soil carbon, microorganisms critical for nitrogen fixation reactions, such as rhizobacteria, will maintain their growth and structure. This expedites nitrogen delivery to nearby vegetation, which contributes to their biomass. It is no surprise that biochar is an innovator in both the carbon and nitrogen cycles.
So how do I fit into this? Well, Colin Hartnett and I are Sustainability Interns for the ecological nonprofit Howard EcoWorks, which provides stormwater management and landscaping services. Our goal is to see what happens when biochar is applied to stormwater management installations such as a rain garden or a conservation landscape. We hope biochar will offset the organization’s carbon footprint. Our project tested its ability to absorb pollutants and reduce flooding by acting as a buffer along with the rain garden. The project was funded by Transform Howard Innovation Grant.
Colin and I used four species to produce unique biochar products. We wanted to see if the species’ carbon content influenced how much biochar was produced. We examined Autumn Olive (Elaeagnus umbellata), Chinese Privet (Ligustrum sinense), Ash (Fraxinus sp.), and Princess Tree (Paulownia tomentosa).
When mature, the fruit of Autumn olive (also known as silverberry) is red and has silvery specks. © Lazaregagnidze via Wikimedia Commons (CC BY-SA 4.0)
Now here comes the moment of truth: the burn. First, we collected each species. Then we set the feedstock ablaze in a Ring of Fire kiln. Kilns are a smaller-scale approach to burning wood and are built in a way that fosters anaerobic conditions. Once charcoal formed we cooled it with hose water. Once cool and dry we measured our yield. And…voilà, a fresh batch of kiln-produced biochar was made!
We are still awaiting results to find out how well this biochar will capture carbon dioxide and other pollutants. Partnering with Dr. Paul Imhoff at the University of Delaware and Howard Community College, we are testing biochar made from each species for various indicators of carbon retention. Working with biochar and getting familiar with its production were among the most rewarding parts of my whole internship. It still amazes me how burning wood anaerobically directly sequesters carbon and can mitigate our climate crisis.
I am thankful I got a firsthand look at the procedure that makes biochar possible!