Examples
The method applied to real flows
Every example follows the same rule: identify the real level of a residue, transform it at the highest level possible, and only turn into char what is left.
Invasive plants: from clearing sites to filters
Water primrose, prickly pear, ice plant: local authorities already pay to remove them. This biomass can become filtering agents for water and soil.
Remove
Collect the biomass from clearing and pruning sites.
Transform
Drying, pyrolysis, extraction of natural flocculants such as prickly pear mucilage.
Filter
Capture phosphates and metals, then return the carbon to the soil.
Levels used: 4 (biochar). For prickly pear, the pads first yield a flocculating mucilage, and the remaining fibre becomes biochar.
Food waste: from the bin to the trough
Unsold produce and kitchen leftovers are heat-treated, then fermented to feed pigs and poultry. This is level 1: no compost and no biogas as long as the material can still feed.
In Austin (Texas), the company Grubtubs collects restaurant leftovers, hands them to farms that turn them into food, then delivers that food back to the same restaurants.
Manure: larvae rather than methane
Fresh manure, collected on dry, odourless bedding, feeds black soldier fly larvae and then earthworms. The larvae feed poultry and fish, and the vermicompost fertilises crops. This is level 2.
Heat and biochar at the same time
A top-lit updraft gasifier (TLUD) fuelled with husks, shells or wood pellets produces clean heat for cooking, roasting or drying, and leaves biochar behind. The heat pays for the biochar, or the other way round. This is level 4.