The Case for Biochar
by Paul Belanger
Soil Regeneration and Carbon Sequestration
Biochar, also known as terra preta, is nothing more than charcoal that has not been combusted. It is most commonly put in the soil, but other applications exist, as mentioned in the book, links and video recommended at the end of this article. Char is produced by the burning of organic matter in the absence of oxygen, a process known as pyrolysis.
I’m a paleoclimate geologist who has been a promoter of biochar for the past 12 years as a way of sequestering carbon, in this case in the soil, because it lasts hundreds of years. Since moving here in March of 2019, I’ve focused more of my energy on the topic of sequestration. This year I attended three conferences and workshops, where I met some wonderful like-minded biochar enthusiasts.
The other big benefit of biochar, and the focus of most of us at Tilth, is that it adds organic matter to the soil. Although inert, the honeycomb structure of char benefits the soil biology by encouraging and retaining fungi, bacteria and moisture in the soil.
I was originally scheduled to do a talk on biochar in Coupeville on Earth Day, and, along with fellow Tilth member Tom Vincent, demonstrate a Top-Lit Up-Draft gasifier stove (TLUD) and kiln in operation at the Pacific Rim Institute (PRI). We’ve been accumulating scrap construction timber in a couple of sheds at PRI for upcoming demos, as well as for case studies to look at the results of growing plants with biochar-compost blends versus without. Stay tuned!
More recently I convinced a neighbor to allow me to salvage and accumulate some one- to three-inch Douglas fir logs that he was going to burn in his slash pile. The wood contained 15-25% moisture, so I tarped it and recently flame-top kilned it in three burns making some 150 gallons by volume (0.75 cubic yards) of char (see photos). I purchased the kiln at Freeland’s recycle center and can make it available to others who want to make biochar.
I have plans for building various TLUDs and kilns; at present I’m looking for a 55-gallon drum with a cover to make a TLUD. I’m also looking for scrap metal and/or a welder to help. Ideally a retort unit would be the most efficient way to make char, but they are expensive.
I will post some personal videos and links on my biochar page by the time this newsletter reaches you: denverclimatestudygroup.com/?page_id=28. Feel free to contact me by email or text/call (please put biochar in subject line to capture my attention): pebelanger@glassdesignresources.com, 303-249-7966.
In the meantime, save your scrap dry wood and/or tarp it to dry out next summer for a fall burn. I recommend doing a burn on misty, cloudy days with high humidity, which helps nucleate particulates. Also, use a raised sheet-metal skirt to burn off smoke and particulates, and quench with a spray hose versus a water dump. There’s no denying that making biochar is a labor-intensive process—but worth the value for soil-enrichment and sequestration.
Resources:
Learn more about biochar at en.wikipedia.org/wiki/Biochar
See the learning center at U.S. Biochar Initiative’s website, filled with introductory materials, applications, studies, videos and more: biochar-us.org/welcome-new-biochar-learning-center
Wilson Biochar is a great resource that includes purchase of kilns and handbooks: wilsonbiochar.com
Alan Bates talks about biochar as a climate solution: www.youtube.com/watch?v=2B2GQ2FQmWs