Lowtech Graph lists low-tech options for every need of a home. Here you can compare them, find tutorials to build them, and link them together into a circular system. Why low-tech?
Black soldier fly larvae composter
Passive
One of 7 ways to meet this need. Cost, carbon, footprint and rankings are relative to other solutions for the same need, not absolute.
What your site needs
A warm, sheltered corner (25 to 32 °C for the adult flies); indoors in winter.
A warm, covered bin where larvae of the black soldier fly eat kitchen scraps, cooked food included, in days rather than months. They cut the waste by 60 to 85% of its dry weight, leave a residue for the compost, and grow into a protein-rich feed for hens or fish. The flies need 25 to 32 °C to breed, so in a cool climate the bin lives indoors.
Levels are relative to the other options for this need, not absolute. Fewer dots is lighter.
Black soldier fly larvae composter (This page) Can I use it? Works in a flat · No rebuilding needed What does it cost me? Upfront cost: Low · Skill to build: Basic · Upkeep: Heavy · Change to daily life: Daily · Works without the grid: Yes Choose it if you want kitchen scraps, cooked food included, gone in days and turned into feed for hens or fish.
Active compost pile Can I use it? Not in a flat · No rebuilding needed What does it cost me? Upfront cost: Low · Skill to build: Basic · Upkeep: Regular · Change to daily life: Daily · Works without the grid: Yes Choose it if you have a garden and want compost from kitchen and garden waste, with heat to spare.
Bokashi fermentation composting Can I use it? Works in a flat · No rebuilding needed What does it cost me? Upfront cost: Low · Skill to build: Basic · Upkeep: Light · Change to daily life: Occasional · Works without the grid: Yes Choose it if you want to process cooked food and meat scraps in a sealed kitchen bin.
Biochar production (pyrolysis of woody waste) Can I use it? Not in a flat · No rebuilding needed What does it cost me? Upfront cost: Low · Skill to build: Basic · Upkeep: Light · Change to daily life: Occasional · Works without the grid: Yes Choose it if you have woody prunings and want a soil improver that lasts a very long time.
Electric kitchen food waste composter/digester Can I use it? Works in a flat · No rebuilding needed What does it cost me? Upfront cost: Medium · Skill to build: Basic · Upkeep: Regular · Change to daily life: None · Works without the grid: No Choose it if you want scraps gone in hours with no smell, pests or effort.
Household anaerobic biodigester (biogas + digestate) Can I use it? Not in a flat · No rebuilding needed What does it cost me? Upfront cost: Medium · Skill to build: Intermediate · Upkeep: Regular · Change to daily life: Daily · Works without the grid: Yes Choose it if you want cooking gas and liquid fertiliser from your food scraps.
Vermicomposting (worm bin) Can I use it? Works in a flat · No rebuilding needed What does it cost me? Upfront cost: Low · Skill to build: Basic · Upkeep: Light · Change to daily life: Daily · Works without the grid: Yes Choose it if you want compost and plant feed from scraps, indoors, with no garden.
We don’t list sizing or quantities, as the yield of each technique depends on the quality of its build. The catalogue compares options but doesn’t dimension them. Regulatory notes are indicative, with a French example, and need to be confirmed locally.