Biomass: reported northern fuel prices (October 2026)

No public price index exists; DEDE lists buyers, not prices. Reported
market prices: fresh chips 1,350-1,800 THB/t (LH Bank, Mar 2026),
rubberwood firewood >1 THB/kg farm gate (OIE RIU 2026, doubled since late
2025), corn residue 2 THB/kg (Sunsweet, Mae Chaem), rice husk ~1.5 THB/kg,
pellets 3,000-5,000 THB/t. Planning price 1.35-2 THB/kg delivered, so the
mature fuel bill is ~0.6M-1.2M THB/yr (was 0.35M-0.8M): still a quarter
to a tenth of electric steam. Prices follow diesel; Ratch Pathana's Pa Sak
(Lamphun) buying centre is the local price-setter. Sources filed under
docs/finance/biomass/; sustainability.md and README follow.

docs/sustainability.md

@@ -37,8 +37,9 @@ at 10 bar / 180 °C) and the 250 kW cooling system.
   abundant fuel); solar-thermal pre-heating of boiler feedwater was
   considered and is not recommended. No technology choice has been made
   yet; it will be driven by honest numbers on load profiles, storage, and
-  grid backup, not by what sounds greenest. At PEA's tariff, biomass heat
-  costs about a tenth of electric steam
+  grid backup, not by what sounds greenest. At PEA's tariff and current
+  northern fuel prices, biomass heat costs a quarter to a tenth of electric
+  steam
   ([grid tariff](#grid-tariff-pea-and-what-it-decides)).
 - Whole-factory HVAC (continuous temperature, humidity, and PM control, see
   [facility systems](facility-security.md)) adds a major tropical-climate
@@ -202,16 +203,16 @@ solar, 0.5M to 0.7M of it demand charge (estimate).
 
 | | Electric boiler (~98 %) | Biomass boiler (~80 %) |
 |---|---|---|
-| Price of heat | ~3.9 THB/kWh, plus the demand charge | ~0.3 to 0.6 THB/kWh at 1 to 2 THB/kg of fuel (fuel price not yet checked with local suppliers) |
-| Running cost, mature two shifts | **~4.7M to 5.5M THB/yr**: 1,140 to 1,310 MWh plus 200 to 300 kW of extra peak demand (0.3M to 0.5M) | **~0.35M to 0.8M THB/yr** of fuel, plus fuel handling and ash |
+| Price of heat | ~3.9 THB/kWh, plus the demand charge | ~0.5 to 0.9 THB/kWh at 1.35 to 2 THB/kg delivered ([reported market prices](biomass.md#fuel-prices-market-check-october-2026), October 2026; no supplier quote yet) |
+| Running cost, mature two shifts | **~4.7M to 5.5M THB/yr**: 1,140 to 1,310 MWh plus 200 to 300 kW of extra peak demand (0.3M to 0.5M) | **~0.6M to 1.2M THB/yr** of fuel, plus fuel handling and ash |
 | Boiler package ([utilities CSV](finance/utilities-investment.csv)) | 2.5M to 4M THB | 4M to 7M THB, plus the fuel store |
 | Grid | peak demand 600 to 750 kW: bigger transformer and deposit | unchanged |
 
 The electric boiler is the more efficient machine; biomass is by far the
-cheaper heat. At maturity the fuel saving of ~4M to 5M THB a year repays
-the biomass premium in about a year (estimate). Even early, at a quarter of
-the heat, electric steam costs ~1.4M to 1.7M THB a year against ~0.1M to
-0.2M of fuel, because the demand charge is set by the boiler's full-power
+cheaper heat. At maturity the fuel saving of ~3.5M to 4.9M THB a year
+repays the biomass premium in under a year (estimate). Even early, at a
+quarter of the heat, electric steam costs ~1.4M to 1.7M THB a year against
+~0.15M to 0.3M of fuel, because the demand charge is set by the boiler's full-power
 draw, not by its average. Moving electric steam to off-peak hours barely
 helps: the presses need steam while they run, and the peak window covers
 13 of the 16 production hours. The staged electric-first path in