Household biodigesters
Approved Phase I delivery ambition.
A biodigester becomesan asset only when itkeeps working.
Green Flame separates contracted installation, reported delivery and the evidence still required to establish sustained use, servicing and household value.
Contracted ambition
Four hundred household systems were approved across two districts.
The signed Phase I design establishes the delivery ambition, geography, financing and implementation responsibilities. It does not establish what was ultimately installed, commissioned, functioning or used.
Sirajganj + Bogra
200 systems planned in each district.
Main implementation window
Approved programme schedule in the supplied agreement.
Source: signed City Bank Project Green Flame agreement and Annexure 1 · contracted design, not delivery evidence.
The evidence record
What is known, reportedand still to be established.
Every figure is paired with its evidence class. The ledger avoids converting an approximate installation update into a completion rate or impact claim.
| Measure | Current record | Evidence class | Interpretation |
|---|---|---|---|
| Contracted Phase I target | 400 systems | ContractedSigned agreement · October 2025 | Approved ambition, including 200 in Sirajganj and 200 in Bogra. |
| Latest installation update | ≈300 systems | Project-reportedLatest supplied update · June 2026 | Requires household, asset and commissioning reconciliation before performance is inferred. |
| Currently functioning | Pending physical verification | To verifyInspection protocol required | Installation cannot yet be translated into operating performance. |
| Sustained household use | Not yet established | To verifyRepeat checks required | Requires observation at defined intervals and across seasons. |
Signature evidence instrument
One asset. Six proofs.
Installation is one point in a longer evidence chain. The persistent record shows what is contracted, reported and still required before replication.
Swipe through six proofs 1 / 6
01 · Eligibility proofContracted design
Start with a householdthat can operate the system.
Eligibility requires more than interest. Livestock, water, labour, affordability, location and consent shape whether the asset can function over time.
- Proof required
- Household profile, livestock, water, affordability, GPS and signed consent
- Evidence presently available
- Eligibility criteria appear in the contracted design
- Gap remaining
- No reconciled household eligibility register has been supplied
- Replication implication
- Count the system only when operating inputs and consent are traceable
02 · Installation proofProject-reported
Match every reported unit to a household and asset.
The supplied delivery update places installations at approximately 300. The record still needs household matching, asset identity, installation date and ownership evidence.
- Proof required
- Household, asset ID, installer, serial, GPS, date and ownership
- Evidence presently available
- Approximately 300 installations are project-reported
- Gap remaining
- Asset, household and supporting records require reconciliation
- Replication implication
- Installation is an output, not proof of commissioning, function or use
03 · Commissioning proofTo verify
An installation must pass a defined commissioning check.
Completion should include leak testing, flame testing, component checks, user training and time-stamped evidence before the asset enters the operating record.
- Proof required
- Checklist, leak test, flame test, component check and training
- Evidence presently available
- Commissioning is part of the contracted delivery pathway
- Gap remaining
- Reconciled commissioning records have not been supplied
- Replication implication
- Commissioning distinguishes construction from an asset ready to operate
04 · Functionality proofPending verification
Functionality requires a physical operating check.
The asset must produce usable gas, retain working components and have an identifiable fault and repair history at the time of inspection.
- Proof required
- Inspection, gas production, working components and repair history
- Evidence presently available
- Current functionality is not established in the supplied record
- Gap remaining
- Operating status requires household-level physical verification
- Replication implication
- Use cost per verified functioning asset, not cost per installation
05 · Sustained-use proofNot yet measured
A working flame on one day is not sustained use.
Regular cooking, seasonal continuity, feedstock, cleaning, downtime and fuel stacking must be observed over defined intervals.
- Proof required
- 6- and 12-month checks, cooking, feedstock, cleaning, downtime and fuel stacking
- Evidence presently available
- Household interest and use remain project-reported signals
- Gap remaining
- Repeat seasonal observations are not available
- Replication implication
- Replication depends on continued operation, not a single inspection
06 · Household-value proofTo verify
The evidence chain closes when operation creates household value.
Fuel displacement, time, expenditure, digestate use, transactions and household benefit must be measured together.
- Proof required
- Fuel, time, expenditure, digestate quantity, use, sales and payment
- Evidence presently available
- Slurry usefulness and 15 sales are project-reported signals
- Gap remaining
- Savings, digestate quality, transactions and net benefit remain unverified
- Replication implication
- Replication should follow measured household and agricultural value
Stage 1 of 6: Eligible
Supplied project image. Product specification, volume, buyer acceptance, price and household payment remain to be reconciled.
What Phase I suggests
Four Phase I signals. None is yet an impact finding.
These are project-reported signals and operating interpretations. Each still requires reconciliation or field verification.
Households showed interest.
Strong uptake was reported across Sirajganj and Bogra.
Clusters improved field delivery.
Concentrated sites reportedly eased mobilisation, installation, monitoring and after-sales routes.
After-sales support is part of the asset.
Repairs, parts, technician access and operating guidance determine whether hardware remains usable.
Slurry support affected usefulness.
Households reportedly valued help converting digester output into a usable farm input.
Serviceability is the operating model
Density matters because installed assets need repeatable service.
A large 2025 Nepal household-biogas study found component failure, insufficient feedstock, weak cleaning and limited repair services among the mechanisms associated with abandonment. It is a comparator, not a Green Flame failure-rate estimate.
Long routes. Thin records. Slow repairs.
- High technician travel cost
- Inconsistent follow-up
- Difficult parts and fault tracking
- Weak digestate aggregation economics
Repeatable routes. Comparable evidence. Faster response.
- Defined technician and spare-parts route
- Comparable functionality checks
- Lower monitoring and collection friction
- More credible cost per functioning asset
Comparator: Lohani et al., Scientific Reports, 2025 · 2,559-household Nepal sample · used to illustrate failure mechanisms only.
Digestate evidence chain
Potential farm value becomes credible only through evidence.
Digestate can carry useful nutrients, while quality and safe application depend on feedstock, operation, characterisation, handling and processing.
- 01Produced
Mass and household source recorded.
- 02Measured
Wet and dry quantity established.
- 03Characterised
Nutrient and safety properties tested.
- 04Handled
Storage, processing and transport defined.
- 05Used or sold
Farm application or buyer acceptance documented.
- 06Paid
Transaction and net household benefit recorded.
One traceable operating record
One household. One asset. One audit trail.
Digital entry is not verification. Each record should show who entered the data, what supporting evidence exists, whether the asset was physically checked and whether an independent reviewer confirmed the result.
Household, location, commissioning, use, service, digestate and verification history stay connected through one persistent asset ID.
Persistent asset IDGF–HH–0001Household · asset · evidence history
Household + consent
Identity, cattle, water, affordability and data rights.
GPS + commissioning
Location, serial, installer, completion and flame test.
Kitchen behaviour
Use, traditional stove and fuel-stacking checks.
Service + downtime
Fault, response, repair, parts and cost.
Digestate + payments
Quantity, quality, buyer, invoice and household payment.
Verification history
Document support, field check and independent review.
Replication decision
Six measures decide whether Phase I can be repeated.
The unresolved questions are consolidated here. Every measure requires a dated source, defined protocol, household or asset match, field check and independent review where applicable.
| Decision measure | Current status | Evidence required |
|---|---|---|
| Verified functioning assets | Pending | Reconciled register, physical inspection and flame test. |
| Sustained household use | Not yet measured | Repeat household checks at defined intervals and seasons. |
| Service performance | Not yet consolidated | Fault, response, downtime, repair, parts and route-cost records. |
| Household value | Not yet measured | Baseline and follow-up fuel, time, expenditure and affordability data. |
| Digestate value | Not yet established | Quantity, characterisation, use, sales and household-payment evidence. |
| Cost per verified functioning asset | Pending preceding measures | Reconciled programme cost and independently defined functionality status. |
Case conclusion
Installed hardware must become a serviced, traceable and functioning circular-energy asset.
The next step is a defined verification brief that reconciles Phase I before any repeat decision.
Evidence notes
Contracted evidence: signed City Bank Project Green Flame agreement and Annexure 1. Authoritative for approved design, not results.
Project-reported evidence: latest supplied implementation update. Useful for signals; not independently verified.
Comparator: 2025 Nepal household-biogas survey of 2,559 households. Used for service and abandonment mechanisms, not a Bangladesh rate.
Digestate: recent reviews support nutrient potential while identifying quality, pathogen, contaminant and application risks.
National context: IDCOL reports 68,000+ household systems financed by December 2023. This supports investigation, not proof of current function, use or Green Flame replication.
Evidence gap found · Current decision
Verify Phase I before replication.
The evidence record identifies what remains unresolved: reconcile household, asset, function, use, service and value records before any repeat decision.