Can a small cane operation fuel itself?

A small cane operation is often assumed to be fuel-self-sufficient because industrial mills burn their own bagasse. This paper tests that assumption at household and village scale, on a single-effect open pan, for a basis of 1000.0 kg of cane. A single-roller press recovering 54.0% of the soluble solids extracts 464.7 kg of juice and leaves 535.3 kg of bagasse at 60.1% moisture; it delivers 944.9 MJ of useful heat against 897.9 MJ needed to make 127.1 kg of syrup at 68% solids, a ratio of 1.052 — self-sufficient, but only just. A three-roller press without imbibition water, recovering 68.0% of the solids, also passes narrowly, at a ratio of 1.044. The same three-roller press with 180 kg of imbibition water recovers 82.0% of the solids and makes more syrup, 192.9 kg, yet fails: it delivers 1158.2 MJ against 1745.3 MJ needed, a ratio of 0.664, and requires 93.8 kg of outside wood per tonne of cane. Sun-drying the bagasse and improving the furnace narrows the deficit but does not close it. Only vapour reuse, modelled at a factor of 1.7, turns that high-extraction case self-sufficient, at a ratio of 1.33. The governing rule is therefore not extraction alone: on a single-effect pan, every kilogram of imbibition water must be evaporated again, and that second evaporation can consume more heat than the extra sugar is worth in fuel terms. All device and furnace figures in this paper are SIMULATED, NOT MEASURED.