Sealed, oxygen-free (anaerobic) digestion of food scraps, and optionally manure or dry-toilet residue, by methane-producing bacteria, yielding two outputs at once: biogas (mostly methane, usable directly at a stove burner) and digestate, a nutrient-rich liquid fertilizer, distinct from the aerobic compost pile's dry compost output. Real constraint for this climate: the bacteria work best in a 30-40C mesophilic range, and food-waste-only digesters need a weekly average above roughly 18C to keep working, a Normandy installation likely needs supplemental insulation or heating to perform through winter, or accepts a seasonal biogas yield drop of 10-30% rather than constant output. Digestate's main use as fertilizer waits on food production being back in scope, same treatment as the biochar entry logged 2026-08-08.
Note: Cost, carbon and footprint are rated against the other options for this same need, not in absolute terms.
Supplemental insulation or heating likely needed to sustain mesophilic temperatures through a Normandy winter (per its own description)
No sizing or quantities: how much a technique yields, and how much a household needs, both depend on the build and the people, so the catalogue compares options rather than dimensioning them. It carries no bill of materials and no build sequence, and it is written for an oceanic, clay-soil climate (Normandy, France). Regulatory notes are indicative and need confirming locally.