🌱 Biomass Industry Desk
Bio-CNG Plant Cost, Feedstock, Land and WBPCB Consent — the Full Compliance Guide
CBG (bio-CNG) plant capex breakdown, digester and purification technology, long-term feedstock contracts, land and water needs, WBPCB Consent to Establish/Operate, and a compliance checklist.
A SATAT LOI and an MNRE subsidy are the paperwork side; a bio-CNG plant actually stands on the ground side — feedstock security, land, digester technology and consents. A pellet plant can be built in a godown; a CBG plant cannot — it is a processing industry. This guide covers the cost breakdown, choosing the technology, feedstock contracts and WBPCB compliance.
In brief: four cost heads — digester, gas purification (water scrubbing/PSA), compressor-cascade, civil and utilities. No step moves forward without a written MoU for raw material. Take WBPCB’s Consent to Establish as soon as the land is finalised — wbpcb.gov.in.
1. Capex breakdown (approximate)
Varies widely with scale and technology — the figures are indicative only:
| Head | Description | Approximate share |
|---|---|---|
| Digester | Anaerobic digester (wet/dry fermentation), the largest cost | A large portion of total capex |
| Gas purification | Separating CO₂ and H₂S — water scrubbing or PSA | Second-largest head |
| Compressor and cascade | 250-bar compression, delivery cascade | Mid-sized head |
| Civil, site preparation, utilities | Real civil works — not a prefab shed | Significant, varies by location |
Land: roughly two acres for an approximate 5 TPD plant — you have to plan separate space for the digester, gas holding, feedstock yard and digestate storage. If the land is leased, only a long-term registered lease is accepted on the portal.
2. Feedstock: the plant’s lifeline
| Feedstock | Methane yield | Availability in West Bengal |
|---|---|---|
| Cow dung (dairy farms/goshalas) | Good, stable | MoUs with dairy farms |
| Paddy straw and agri residue | Needs pre-treatment | Abundant — the economics of selling instead of burning |
| Sugar-mill press mud | Excellent | Near the district’s sugar mills |
| Poultry litter | High | Near poultry belts |
| Organic fraction of municipal waste | Works at large scale | MoU with the municipality |
Golden rule: written MoUs with at least two independent sources within a 25 km diameter — if one source falls ill, the plant stops, and a stopped plant means the LOI’s progress conditions are breached. See the raw-material collection math in our pellet raw material guide — the idea is the same.
3. WBPCB and other consents
- Consent to Establish (CTE): as soon as land is finalised, before construction — online application on the wbpcb.gov.in portal.
- Consent to Operate (CTO): before commissioning; must be renewed periodically.
- Others: power connection (a big load — with WBSEDCL), explosives/gas-storage related rules, and a factory licence where applicable.
- Digestate: if the digestate is sold as organic fertiliser, the Fertiliser Regulatory Department’s rules also apply — this is the second revenue stream.
4. Five questions to ask before construction
- Feedstock: do you have two signed MoUs within 25 km?
- Route: is the OMC outlet/cascade delivery within 25 km?
- Water and wastewater: is the site’s water source and effluent plan final?
- Consents: is the CTE in hand?
- The math: does the project survive without the subsidy and LOI price?
If you don’t get ‘yes’ to all five, don’t sprint — in CBG, the game is played on the field, not on paper.
5. Frequently Asked Questions (FAQ)
1. Can you upgrade a pellet plant into CBG?
Not directly — they are two different technologies (pellets are mechanical compression, CBG is biological digestion). But the straw-collection network serves both, and there is a separate path to upgrade old biogas plants into CBG.
2. How valuable is digestate (digestion residue) really?
A market is forming for processed organic fertiliser (FOM/LFOM) — a significant second revenue head for large plants. But it needs quality control and fertiliser-regulator compliance, so treat it as a ‘bonus’ in your math.
3. What disaster risks should you plan for?
Feedstock is season-dependent (straw in the monsoon, shortfall in summer), the digester’s technical downtime, and gas quality variation — keep buffer storage and a two-source feedstock plan for all three.
4. How do I choose an EPC contractor?
Quotations from at least three, a condition of seeing a working reference plant, and a performance guarantee in writing — if a ‘crore-rupee turnkey’ offer cannot show references, walk away.
6. Beware of Fraud
🛡️ ‘Cheap Chinese digester, running in three months’ — without a reference plant, this proposal sinks half your capital. ‘Fixers can arrange the WBPCB consent’ is also a scam — CTE/CTO happen online on the portal itself. If defrauded, call the 1930 helpline or complain at cybercrime.gov.in.
Related guides: purchase security — SATAT CBG LOI guide; subsidy — MNRE CFA guide for CBG; the loan route — CGTMSE and plant finance.
❓ Frequently asked questions
How much does a CBG plant actually cost?
It varies enormously with scale — small (2–5 TPD) plants typically run from a few crore to around ₹10 crore, and large plants go well above that. The digester, gas purification (water scrubbing/PSA), compressor-cascade and civil works are the four big cost heads. Run the numbers without the subsidy.
Can it run on feedstock other than cow dung?
Yes — paddy straw and other agricultural residue, sugar-mill press mud, poultry litter and the organic fraction of municipal solid waste are all viable feedstocks. What matters is methane yield and security of supply. Don't rely on a single source; a mix of two or three is safer.
When do I need WBPCB consent?
Consent to Establish (CTE) comes right after land is finalised — before construction begins. Consent to Operate (CTO) comes before the plant starts running. Both are applied for online on the wbpcb.gov.in portal.
How much water does the plant need?
Digestion mixes a significant amount of water with the feedstock (especially dry feedstock), and process water can be recycled. Settle the water source and effluent plan while choosing the site itself — it also comes up in the WBPCB approval.