First decide what outcome the facility needs
An OWC is normally selected for a managed on-site organic-waste-to-compost workflow. A biogas plant is chosen when controlled anaerobic digestion and useful gas recovery are feasible. Neither technology makes segregation, residual handling or permits disappear.
- Record seven days of separate food-waste weights, moisture variation and contamination.
- Identify whether the site can safely use recovered gas, and who will operate that system.
- Set a realistic curing or digestate-handling destination.
OWC vs biogas: practical buying comparison
This is a decision framework, not a universal price or performance claim. Exact requirements depend on system design and the waste composition.
| Decision factor | Typical OWC approach | Typical biogas approach |
|---|---|---|
| Primary process | Mechanical preparation/controlled aerobic treatment | Anaerobic digestion in a contained reactor |
| Usable output | Processed organic material followed by compost curing | Biogas plus digestate requiring management |
| Site utilities | Electrical supply, ventilation, space for curing | Feed preparation, gas handling/safety, digestate management |
| Operational focus | Segregation, load, moisture, mixing and housekeeping | Feed stability, biological parameters, gas-system safety |
| Commercial viability | Compare electricity, spares, labour and curing costs | Evaluate gas use, gas-system O&M and digestate handling |
| Best fit | Sites prioritising routine on-site composting workflow | Sites with viable digestion feed and beneficial gas use |
100–1000 kg/day: why a single threshold cannot decide it
A stated daily load is not enough to predict plant economics. A high-moisture kitchen stream, a vegetable-market stream and mixed wet waste have very different digestion and composting behaviour. Obtain process-specific feasibility rather than copying a kg/day claim from another property.
- Estimate daily vs peak loads and feed consistency.
- Ask for measured energy/material balances at a comparable reference plant.
- Get full installed cost: civil, permits, safety, utility tie-ins, operator and by-product removal.
Questions to ask each vendor before issuing a PO
Ask both vendors for the exact accepted feedstock, hazardous exclusions, performance acceptance protocol, commissioning and operator training. For digestion, also check gas storage/usage arrangements, safety provisions and digestate management. For OWC, check realistic curing space and complete electricity/consumable costs.
Choose on full-system performance, not only machine price or a claimed 24-hour conversion.
A neutral decision workflow
Shortlist technologies only after a site survey. If the customer cannot use gas or manage digestate, a biogas value proposition may fail; if curing space and segregation are unavailable, the OWC proposal may also fail. A hybrid or decentralised collection route can sometimes fit better.
- Check applicable local requirements and fire/gas safety for biogas.
- Request references for genuinely comparable feedstocks and capacities.
- Set acceptance criteria, waste rejection rules and post-processing ownership.
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.