The ProJect

Low-Tech Off-Grid Biochar

Installed

May 1, 2012

Team

T Gray Shaw

Components

1. trails, to access steep terrain

2. a portable kiln, to make biochar where the brush is

3. a hand-powered charcoal grinder

4. a powered wheelbarrow, to neutralize the terrain

The goal was to design a biochar system to match the existing scale of operations and power sources (solar and human power) for small acreage in the woods. This system was designed to be affordable and accessible.

1. Trails

To approach the problem at this scale, the first step was to build trails, paying careful attention to grade for wheelbarrow access. This was begun in year one (2010). Finished trails are surfaced with wood chips.

2. The Kiln

The kiln design is licensed by Vuthisa in South Africa. It is a flame cap type, consisting of a steel cylinder in three flanged sections joined by bolts, plus a lid. Snuffing the fire with the lid and sealing air leaks with mud makes water unnecessary for extinguishing the fire. Most of the forest is too far from water sources. (Inaugurated in 2015)

3. The Grinder

4. Powered Wheelbarrow

The grinder is my own design, based on an obsolete compost grinder (Rotocrop). It makes very little dust and converts all the char to a suitable size for biochar using the least work. The hopper holds a wooden cylinder with a 1/4" gap on either side, studded with decking screws and turned by hand. It fits on the lid of an ordinary 5-gallon bucket. Plans are available here. This work is licensed under a Creative Commons Attribution 4.0 International License. (Built in 2018) There is now a fruit grinder made by EJWOX that appears to be capable of the same thing.

To move the kiln, char, and other materials along the trails, I retrofitted a wheelbarrow with a powered hub from China and a 24V battery that recharges from the house solar system. (Completed in 2019)

The three panels of the kiln itself can be strapped on and carried with much less effort, not to mention tools, soil, and anything else that fits in the bin. Char is moved to a central location for grinding and inoculation.

This is the Wellmade HD6 brand of wheelbarrow, which is widely available. Modification included cutting slots in the dropouts for the chamfered spindle so that the hub can turn against them, plus turning handle extensions on a lathe for the controls, which are designed to fit scooter handlebars. The battery and controller are strapped on with a tie-down. The electrical parts are not weatherproof, but the modifications can be reversed in about five minutes.