By Katie Wiebke ’15
What is biochar?
There is nothing out there quite like biochar; it is the latest of the alternative energies. As a product of renewable, fuel-efficient, high-yielding heat production, biochar is a special kind of charcoal that is used as a soil amendment. Still in the pioneering phases, biochar technologies have an incredible amount of potential. That is why Antioch College is now experimenting with these new methods.
In a collaborative effort between Antioch Kitchens, the Antioch Farm, and the facilities department of Antioch College, students, alumni, and volunteers constructed Antioch’s first biochar stove during Reunion Weekend 2012.
Industrial agriculture has taken a significant toll on our land and our people. Agricultural byproducts alone account for 12% of all greenhouse gas emissions. These petrochemical fertilizers are the largest source of methane (40%) and nitrous oxide (62%) emissions, both greenhouse gases that are much more toxic than carbon dioxide. (Methane is 20 times more potent than CO2 at trapping heat in the atmosphere.) And that doesn’t include all of the emissions involved in actually mining, producing, and applying these fertilizers.
Not only is industrial agriculture a huge source of toxic emissions, but it is destroying our soils, too. Adding these petrochemical fertilizers destroy soil biota, ruin watersheds, cause leaching, salinization, and desertification, not to mention the ensuing sociopolitical consequences.
The author with the Antioch biochar stove.
But even in the breadbasket of the United States, where glaciers once deposited rich masses of organic matter and minerals across the lands, our soils are still poor. Industrial agriculture has moved all of that fertility down the Ohio and Mississippi rivers to the Gulf of Mexico, where it is now causing a eutrophic environment of excessive nutrients, also known as “the dead zone.”
Biochar is an Antioch experiment remedy to this. Countering the geological effects of years of industrial agriculture may sound overly ambitious, but if anyone can tackle it, Antiochians can.
How it works: soil amending and carbon sequestering
When you look at biochar, it looks just like whatever it looked like before it became biochar, only it is black and weighs almost nothing. Biochar is made from any source of dry organic matter—Antioch’s team used old twigs and fallen branches gathered from the campus grounds. Because of the way that it is made, the cellulosic structrure of the plant matter is maintained, preserving the integrity of all of those microscopic tubes, holes, and passageways. This is what gives biochar its incredible porosity.
In fact, scientists have examined biochar under microsopes and discovered that not only is it teeming with pores, but there are pores inside of the pores, and pores inside of those pores, etc. Basically, it’s a supersponge. Biochar has an incredibly high surface-area-to-volume ratio. One gram of biochar has 1,000 m2 of surface area.
This incredibly large amount of surface area provides an incredibly large area of habitat for soil microbes, bacteria, and fungi. But it’s not just a house for microbes to move into; it might as well be a huge skyscraping condominium.
Once the biochar is ready, it gets inoculated with life (by being thrown into a compost pile, defecated on, mixed with food scraps, etc). Microbes come inhabit the biochar and build a beneficial life web. Then that densely populated piece of char can be thrown into your garden bed (or anywhere in the soil) and plants will thrive.
Due to the chemistry of carbon, biochar is an incredibly stable molecule. It doesn’t break down easily (only at extremely high temperatures, which is why charcoal can be burned for such audacious tasks as melting metal) and nothing really eats it. You can eat it—it’s actually a great way to cleanse out the many toxins we ingest from food/drink encased in plastic—but it won’t get digested or broken down. Basically, this gigantic soil microbe habitat just got a conservation easement. That skyrise housing will never get torn down. Soil biota will come, go, be born, and die, and for generations they will always have an inviting home.
The carbon put into the soil—the same carbon that doesn’t break down so easily—will still be there 1,000 years from now. Actually, a study by the University of Hawaii estimates it can remain there for up to 4,000 years. So by making biochar from old dry organic matter and putting it into the garden, aside from all the soil amending, that carbon that would have been released to the atmosphere as methane during decomposition was sunk into the soil for at least another 1,000 years.
How is it made?
Biochar is made just like charcoal, at least on a non-industrial scale. Basically, organic matter is heated in the absence of oxygen. In the chemistry and physics world, this is called pyrolysis. The design of a special biochar stove allows for temperatures to heat high enough to break down all of the bonds in the organic matter except for those of carbon, leaving behind the black char. There are many ways to do this, and the greatest thing about it is that it’s DIY.
Freshly cooked biochar.
In Antioch’s double barrel retort design, old metal drums and pieces of scrap metal were used to make the stove. A 30-gallon barrel with small holes drilled around the top was filled with dry biomass (which will turn into biochar) and inverted into a 55-gallon barrel. A small amount of dried wood, or other source of fuel, was added around the inner barrel into the donut-shaped space. Small openings were cut around the base of the outer barrel to allow airflow into that space. It was then covered with a lid and small cylindrical chimney to create draft.
To start the stove, fuel in the outer donut space is ignited and begins to burn. Because of the chimney effect, it is quite efficient, and the barrel holds in heat so that less is lost into the atmosphere. This creates prime conditions for the pyrolysis (breaking down of chemical bonds in the absence of oxygen) of the biomass that is inside the inner barrel. Basically, a ring of fire engulfs the inner barrel, heating it up to a high temperature. However, because there is no oxygen inside (any residual air is consumed by the outer donut of fire), the biomass pyrolyzes rather than combusting. As that happens, off-gases are released through the small holes at the bottom of the inner can and meet with the outer flame. These gases are then burned off in the outer ring, providing more heat, which allows more pyrolysis, which makes more off-gases, to make more heat. This cycle continues until the biomass is done pyrolyzing, when all of the gases have been released, making the process almost self-maintaining.
By harvesting these off-gases, the stove becomes even more fuel efficient. Furthermore, since these gases are burned off, there is virtually no smoke nor harmful toxins released into the air, making biochar stoves incredibly clean-burning as well.
A Cultural Shift
More than half of the world’s population still cooks on wood fires, which could be easily switched to biochar stoves. This would reduce smoke pollution and the demand for increasingly scarce wood—important goals to hold as urbanization trends continue.
But the other half of the world’s population is also cause for concern. Petro-fuels are horrendous to the atmosphere and environment, from mining to production to burning. Peak oil is here, and we need to find alternatives.
Building a biochar stove creates alternative energy and soil restoration.
Biochar has tremendous potential. It is renewable, efficient, clean burning, and economically affordable, and the resulting char is a possible solution to our ominous issue of food security and development-induced land degradation.
How Antioch came to biochar—and then biochar came to Antioch
It all started when Steve Duffy ’77, knowing my interest in ecological agriculture and my affinity for the tropics, had keenly introduced me to the Maya Mountain Research Farm (MMRF). Managed by Antiochian Christopher Nesbitt ’88, this is one of the oldest ongoing permaculture projects in Central America, where they host interns, students, groups, and volunteers in one of the finest examples of biodiversity and agroforestry.
That was back in fall 2011. I had just gotten to Antioch and was still trying to figure things out. It wasn’t until the end of winter break creeped in that I started to realize that I was beginning to dread going back to Ohio and the frigid temperatures, short days, and suffocating blanket of gray. About that same time I also started to realize that I was going to be spending quite a bit of time, at least for the next four years, in Ohio. That’s when I thought about checking out that Maya Mountain place Duffy had showed me.
In the meantime, I was thinking about designing a major that combined the social and environmental sciences for a more practical approach to global issues. Honestly I don’t understand why we separate them; half of the problems we have today probably wouldn’t exist if we had this integrated approach. I got this idea in high school when I was simultaneously taking an environmental science course (taught by an Antiochian, no less—Ben Gillock ’04) with a cultural anthropology course.
I wanted to explore this idea further. That’s when I applied for the permaculture design course at Maya Mountain Research Farm. Permaculture is a philosophy based on an integrated understanding of ourselves, our environment, and the two put together. So in February, I took off Block B to take this course at MMRF. I learned so much—about permaculture, about community, about designing projects and implementing them. It was tough getting intimate with the reality of our climate situation, and I definitely suffered from information overload, but I left inspired and empowered.
When I got back to Yellow Springs, I was seeing permaculture everywhere. We could be doing so much here, I thought. Why not have a college permaculturist? That’s when I proposed a new co-op job, and that’s how I ultimately got involved in making Antioch’s first biochar stove.
The completed biochar stove at the Antioch Farm. (L–R: Katie Wiebke, an unidentified volunteer, Kat Christen)
I was first introduced to the idea of biochar on day seven of MMRF’s permaculture design course. Albert Bates, author of The Biochar Solution, introduced me to the concept. I was awestruck.
When I returned to Antioch, biochar was one of my permaculture priorities. Most folks hadn’t heard of biochar—and then I met up with Kat Christen, our farm manager. She was interested in producing biochar to improve our farm’s soil.
I consulted David Kammler, associate professor of chemistry, about the science that I didn’t understand, and he graciously gave me a mini crash course. He suggested I start small, at least to make sure I didn’t blow anything up. So I collected some old tin cans from the dining hall and made a makeshift stove. It made some biochar, but it needed some major engineering assistance.
In the meantime, I had written a piece about my time at MMRF for The Independent. Alumnus Peter King ’86, also a biochar fanatic, read it and contacted us about building a stove for Antioch. That’s when things got rolling. The Reunion was coming up, and Peter was attending. He wanted to help us get this project off the ground.
We got in contact and worked out a plan. I found a barrel and wood (collaborating with my classmate Rachel Smith ’15 to get honeysuckle woodchips from the South Glen Restoration Project), Peter brought tools and some fantastic designs, and on Thursday, June 14, Antioch’s biochar stove was born.
Special thanks to the volunteers who helped us in the workshop and to Michael Casselli ’87 for letting us use his plasma cutter. And an even bigger thanks to Peter King, the biochar expert and engineer. This project was a truly collaborative effort, involving Antiochians across generations and geography.
To get involved in this project, contact Katie Wiebke