I retired after 30 years as an environmental research scientist.  I have a "hobby" business creating metal landscape and garden art.  I've been working to create a small scale backyard BioChar pyrolysis unit capable of producing sufficient volume for a large garden area or several neighborhood gardens.  My experimentation has been mostly successful, solving several of the issues with a two barrel approach.   I've held demonstrations of the approach and discussions of the usefulness of BioChar in my community.

My website www.weldingwizardry.net/biochar has diagrams, pictures, and instructions for building the unit.