Biochar
Biochar
What is Biochar?
Biochar is a stable form of carbon created by heating organic material (biomass) in a low-oxygen environment—a process called pyrolysis. During pyrolysis, gases released from the biomass are burned, producing heat while leaving behind pure carbon in the form of charcoal. This results in a nearly smoke-free, efficient process that both generates energy and captures carbon.
Why It Matters
Biochar offers a dual benefit: it provides heat energy while producing a soil amendment that locks carbon in the ground for centuries. By improving soil structure, porosity, and fertility, biochar enhances microbial life and supports long-term agricultural productivity. It is also a key tool for carbon sequestration, helping to combat climate change while improving food security.
Making Biochar at MMRF
At MMRF, we designed and built our own biochar system using a traditional retort model. Our setup consists of:
- A 55-gallon drum as the outer chamber.
- An inner chamber made from a repurposed propane tank, sealed at the top with a single outlet for hot gases.
- Air intakes at the bottom to feed the fire that heats the biomass.
As the fuel burns in the outer chamber, heat drives pyrolysis inside the oxygen-depleted inner tank. The released gases ignite when they exit, sustaining the process and producing a clean, efficient burn. We use rice hulls, cacao pods, bamboo, cahune seeds, coconut husks, and other small biomass materials as feedstock.
Our system cost around US$75 to build, thanks to the skill and resourcefulness of Jose Baki of Big Falls, who constructed the unit and sourced the materials.
From Charcoal to Living Biochar
Freshly made biochar is highly porous, creating perfect habitat for fungi and bacteria that improve soil health. However, before adding biochar directly to soil, we “inoculate” it—filling those pores with beneficial microbes. We do this by mixing biochar into compost, or incorporating it into animal bedding for sheep and poultry.
The animals naturally break the biochar into smaller pieces while adding manure and urine, which inoculate the material with living microorganisms. Once composted, this mixture becomes a nutrient-rich amendment that enhances soil fertility and moisture retention—especially valuable during Belize’s dry season.
Exploring the Potential of Waste Heat
Our next goal is to make better use of the heat generated by the biochar process. Potential applications include:
- Hot water systems using copper coils around the drum.
- Electric generation through a Stirling engine.
- Ammonia absorption refrigeration, which could convert heat into ice—a concept we are particularly excited about.
Alternative Method: Flame Lens Kiln
We also use a flame lens biochar kiln, sometimes created simply by digging a cone-shaped pit. By maintaining a layer of flame over the pit, biomass can be converted efficiently into char without smoke. This is an effective way to process large volumes of biomass while keeping the carbon cycle balanced.
A Tool for Regeneration
Whether made in a retort or pit kiln, biochar is a non-labile carbon—a stable form that resists decomposition and remains in the soil for hundreds or even thousands of years. By creating and applying biochar, we help restore soil ecosystems, increase productivity, and sequester atmospheric carbon—supporting both ecological health and community resilience in southern Belize.