The calculation buyers should use
Use an electricity submeter or a carefully logged period. A machine with a 6 kW connected load does not necessarily consume 6 kWh every hour because motors and heaters may cycle.
| Input | Illustrative example |
|---|---|
| Waste processed | 100 kg/day × 26 operating days = 2,600 kg |
| Meter reading difference | 390 kWh in the same period |
| Energy tariff | ₹9 per kWh (illustrative; use your bill) |
| Electricity expense | 390 × ₹9 = ₹3,510 |
| Electricity cost per kg | ₹3,510 ÷ 2,600 kg = ₹1.35/kg |
Why connected load gives misleading estimates
The nameplate rating represents electrical equipment design or connected power, not guaranteed continuous operation. The heating elements may cycle under temperature control; shredding and mixing may run intermittently. Standby, auxiliaries and power factor or billing terms may also matter.
- Prefer separate kWh meter readings over guessed operating hours.
- Log actual accepted organic-waste quantity, not mixed garbage collected.
- Include relevant fixed/demand charges if comparing the true incremental bill.
Low-load days can raise cost per kg
Electricity consumed for maintaining chamber conditions may not fall in direct proportion to input mass. That means running a much larger machine with very little waste can increase the cost per accepted kg, even when total monthly kWh is stable.
- Compare normal and peak load days rather than one demonstration run.
- Check machine size against measured waste input and batch scheduling.
- Separate electricity from labour, AMC, sawdust, curing and rejects when estimating total treatment cost.
Monthly tracking format
A defensible operating report includes: meter start/end, daily waste weighment, tariff, dates of operation, material rejected before loading and abnormal cycles.
| Metric | Recommended record |
|---|---|
| kWh consumed | Submeter reading at start/end |
| Accepted input kg | Weighed source-segregated wet waste |
| ₹/kWh | Applicable tariff plus relevant billing charges |
| Machine use | Number of operating days and any unusual batches |
| Cost per kg | Actual electricity expense ÷ accepted kg |
Questions to ask in a commercial quotation
Ask suppliers to separately declare connected load, heater kW, motor ratings, whether connected load is single- or three-phase and any metered case data under stated feed conditions.
Published kWh/kg performance cannot be transferred blindly across feedstock moisture, site loading, ambient conditions and machine controls. Treat vendor estimates as conditional unless independently metered.
When the question becomes model-specific
This guide stays general. For exact figures on a particular machine, these published pages from the COMPOSTO range are the reference.
Want a second opinion on your site?
Send your site type, city and measured daily wet waste. The COMPOSTO technical team replies with the capacity and checks worth doing next.