Complete Roadmap for Bio-CNG/CBG Plant in Dairy Farm

A comprehensive guide to establish a Bio-CNG plant at your dairy farm, covering everything from planning to operation.

1. Feasibility Assessment

Raw Material Availability

Cattle dung requirement:

Number of Cattle Daily Dung Production
50 cattle 1,250 kg/day (25 kg/cow/day average)
100 cattle 2,500 kg/day
200 cattle 5,000 kg/day

Biogas Yield

35-40 m³ Biogas per ton of wet dung
55-65% Methane content in raw biogas
90-95% Methane in CBG after purification

2. Plant Capacity Options & Requirements

OPTION A

Small Scale (10-15 kg CBG/day)

Suitable For

40-60 cattle

Daily Input: 1,000-1,500 kg dung

Output

  • 40-60 m³ biogas/day
  • 10-15 kg CBG/day (equivalent to 15-22 liters diesel)
  • Can fill 2-3 CNG vehicles/day

Major Equipment

  1. Biogas Digester (30-40 m³ capacity)
    • Fixed dome or floating drum type
    • Hydraulic retention time: 30-40 days
  2. Gas Holder/Storage (15-20 m³)
    • Low-pressure storage balloon
  3. Biogas Purification Unit
    • Water scrubbing column OR PSA (Pressure Swing Adsorption) unit
    • H₂S removal (iron oxide scrubber)
    • CO₂ removal system
    • Moisture removal (silica gel/dryer)
  4. Compression System
    • Multi-stage compressor (up to 200-250 bar)
    • Capacity: 5-10 m³/hour
  5. CBG Storage
    • Cascade of cylinders (200-250 bar)
    • Storage capacity: 50-75 kg
  6. Dispensing Unit
    • Slow-fill dispenser
    • Pressure gauges and safety valves
  7. Auxiliary Equipment
    • Feed preparation tank
    • Mixing system
    • Heating system (for cold regions)
    • Control panel

Estimated Cost: ₹25-35 lakhs

Space Requirement: 500-750 sq.ft.

OPTION B

Medium Scale (25-40 kg CBG/day)

Suitable For

100-150 cattle

Daily Input: 2,500-3,500 kg dung

Output

  • 100-140 m³ biogas/day
  • 25-40 kg CBG/day (equivalent to 37-60 liters diesel)
  • Can fill 5-8 CNG vehicles/day

Major Equipment

  1. Biogas Digester (75-100 m³ capacity)
    • CSTR (Continuously Stirred Tank Reactor) recommended
    • With mechanical stirrer
  2. Gas Holder (40-50 m³)
  3. Biogas Purification Unit
    • Water scrubbing system (preferred at this scale)
    • Multi-stage scrubbing columns
    • Regeneration unit for water
    • H₂S and moisture removal
  4. Compression System
    • 3-stage compressor (15-20 m³/hour)
    • Inter-coolers and after-coolers
  5. CBG Storage
    • Cascade system (150-200 kg capacity)
  6. Dispensing Unit
    • Fast-fill option available
    • Digital flow meter
  7. Automation
    • PLC-based control system
    • Temperature and pressure monitoring
    • Gas quality analyzer

Estimated Cost: ₹50-75 lakhs

Space Requirement: 1,000-1,500 sq.ft.

OPTION C

Commercial Scale (80-100 kg CBG/day)

Suitable For

250-300 cattle

Daily Input: 6,000-7,500 kg dung

Output

  • 240-300 m³ biogas/day
  • 80-100 kg CBG/day (equivalent to 120-150 liters diesel)
  • Can fill 15-20 CNG vehicles/day

Major Equipment

  1. Biogas Digester (200-250 m³ capacity)
    • CSTR with automated feeding
    • Insulated and heated
  2. Gas Holder (100-120 m³)
  3. Biogas Purification Unit
    • PSA or membrane-based system
    • Automated regeneration
    • Online gas quality monitoring
  4. Compression System
    • Multi-stage booster compressor (30-40 m³/hour)
    • Dryer and filter units
  5. CBG Storage
    • Mother-daughter cascade (300-400 kg)
  6. Dispensing Station
    • Multiple nozzles
    • Fast-fill and slow-fill options
    • Payment integration system
  7. Advanced Features
    • SCADA system
    • Remote monitoring
    • Automated alarms
    • Safety interlocks

Estimated Cost: ₹1.2-1.8 crores

Space Requirement: 2,500-3,500 sq.ft.

3. Detailed Process Flow

Stage 1: Feedstock Collection & Preparation
  1. Daily collection of cattle dung
  2. Mixing with water (1:1 ratio for 8-10% total solids)
  3. Screening to remove stones, plastics
  4. Grinding/chopping for uniform consistency
  5. Storage in feed preparation tank
Stage 2: Anaerobic Digestion

Loading

Continuous/batch feeding into digester

Digestion

  • Mesophilic (35-40°C) OR Thermophilic (50-55°C)
  • Retention time: 30-40 days
  • pH maintenance: 6.8-7.5

Monitoring

  • Temperature control
  • Mixing (2-4 times/day)
  • Gas pressure monitoring

Output

Raw biogas (55-65% CH₄, 30-40% CO₂, traces of H₂S, H₂O)

Stage 3: Biogas Purification (Upgrading)

Step 3a: H₂S Removal

  • Iron oxide scrubber OR biological desulfurization
  • Target: <10 ppm H₂S

Step 3b: Moisture Removal

  • Refrigeration drying OR desiccant drying
  • Target: Dew point < -40°C

Step 3c: CO₂ Removal (Main Upgrading)

Option 1: Water Scrubbing (Most common)

  • Pressurize gas to 6-10 bar
  • Pass through water scrubbing column
  • CO₂ dissolves in water, CH₄ remains
  • Regenerate water by depressurization

Option 2: PSA (Pressure Swing Adsorption)

  • Selective adsorption on molecular sieves
  • Alternating pressure cycles
  • Higher methane recovery (>98%)

Option 3: Membrane Separation

  • Semi-permeable membranes
  • Compact system
  • Lower initial cost but higher operational cost

Output: Upgraded biogas (90-95% CH₄)

Stage 4: Compression
  1. Stage 1: Compress to 40-50 bar
  2. Cooling: Inter-stage cooling
  3. Stage 2: Compress to 100-120 bar
  4. Cooling: After-cooling
  5. Stage 3: Final compression to 200-250 bar
  6. Final drying: Remove any residual moisture
Stage 5: Storage
  • Fill cascade cylinders
  • Maintain pressure at 200-250 bar
  • Regular pressure monitoring
  • Temperature control
Stage 6: Dispensing
  • Slow Fill: 4-8 hours (overnight charging)
  • Fast Fill: 3-5 minutes (like petrol pump)
  • Pressure regulation during filling
  • Safety interlocks active

4. Cost-Benefit Analysis

Small Scale (15 kg CBG/day)

Capital Investment: ₹30 lakhs (average)

Annual Operating Costs

Item Annual Cost
Electricity (compressor, pumps) ₹60,000
Maintenance ₹40,000
Labor (part-time) ₹60,000
Consumables ₹20,000
Total ₹1.8 lakhs/year

Annual Benefits

Item Value
CBG production 15 kg/day × 365 = 5,475 kg/year
Equivalent diesel ~8,200 liters
Savings @ ₹95/liter diesel ₹7.8 lakhs
Slurry (bio-fertilizer) ₹50,000/year
Total Benefits ₹8.3 lakhs/year

Net Annual Benefit: ₹6.5 lakhs

Payback Period: 4.6 years

IRR: ~18-20%

Medium Scale (32 kg CBG/day)

Capital Investment: ₹62 lakhs (average)

Annual Operating Costs

Item Annual Cost
Electricity ₹1.2 lakhs
Maintenance ₹80,000
Labor (1 operator) ₹1.8 lakhs
Consumables ₹40,000
Total ₹4.2 lakhs/year

Annual Benefits

Item Value
CBG production 32 kg/day × 365 = 11,680 kg/year
Equivalent diesel ~17,500 liters
Savings @ ₹95/liter ₹16.6 lakhs
Slurry sales ₹1.5 lakhs/year
Carbon credits (potential) ₹1 lakh/year
Total Benefits ₹19.2 lakhs/year

Net Annual Benefit: ₹15 lakhs

Payback Period: 4.1 years

IRR: ~22-25%

Commercial Scale (90 kg CBG/day)

Capital Investment: ₹1.5 crores (average)

Annual Operating Costs

Item Annual Cost
Electricity ₹3 lakhs
Maintenance ₹2 lakhs
Labor (2 operators) ₹4.5 lakhs
Consumables ₹1 lakh
Total ₹10.5 lakhs/year

Annual Benefits

Item Value
CBG production 90 kg/day × 365 = 32,850 kg/year
Equivalent diesel ~49,000 liters
Own use (30%) ₹14 lakhs savings
Sale to others (70%) ₹32 lakhs revenue @ ₹65/kg
Slurry sales ₹4 lakhs/year
Carbon credits ₹3 lakhs/year
Total Benefits ₹53 lakhs/year

Net Annual Benefit: ₹42.5 lakhs

Payback Period: 3.5 years

IRR: ~26-30%

5. Government Subsidies & Support

SATAT Scheme (Sustainable Alternative Towards Affordable Transportation)

Financial Support

1. NABARD

2. State Schemes

3. MNRE (Ministry of New & Renewable Energy)

4. Carbon Credits

6. Testing & Quality Control

Raw Biogas Testing

Frequency: Daily

Parameter Target Value
CH₄ content 55-65%
CO₂ content 30-40%
H₂S <100 ppm (before purification)
Moisture Saturated
Pressure 0.1-0.3 bar

Equipment Required

Upgraded CBG Testing

Frequency: Every batch/weekly

Standards: As per BIS 17464:2020

Parameter Specification
Methane (CH₄) >90% (minimum)
CO₂ <6%
O₂ <1%
H₂S <10 mg/m³
Water dew point < -10°C at 200 bar
Ammonia <100 mg/m³
Total sulfur <30 mg/m³
Mercaptans <6 mg/m³
Calorific value >8,300 kcal/m³
Wobbe Index 11,100-13,100 kcal/m³

Testing Equipment

Certification

7. Safety Procedures & Standards

Design Standards

Safety Equipment - Mandatory

1. Gas Detection System

2. Fire Safety

3. Ventilation

4. Pressure Safety Devices

5. Electrical Safety

6. Personal Safety

Safety Zones

Zone 0 (Highly Hazardous): Inside storage vessels

Zone 1 (Hazardous): 3m radius around compressor, valves

Zone 2 (Less Hazardous): 6m radius from Zone 1

Restrictions

Operating Safety Procedures

Daily Checks

  1. Visual inspection for leaks (soapy water test)
  2. Check all pressure gauges
  3. Test gas detectors
  4. Verify emergency systems
  5. Log all readings

Weekly Checks

  1. Calibrate gas detectors
  2. Test emergency alarms
  3. Inspect fire extinguishers
  4. Check grounding resistance
  5. Inspect safety valves

Monthly Checks

  1. Full system leak test
  2. Pressure relief valve testing
  3. Fire drill
  4. Emergency evacuation drill
  5. Update emergency contact list

Annual Inspections

  1. Third-party safety audit
  2. Pressure vessel inspection (statutory)
  3. Electrical system audit
  4. Fire NOC renewal
  5. PESO license renewal

Emergency Response Plan

Gas Leak

  1. Activate alarm
  2. Evacuate non-essential personnel
  3. Stop all ignition sources
  4. Close main gas valves
  5. Ventilate area
  6. Identify and repair leak
  7. Resume only after clearance

Fire

  1. Raise alarm
  2. Evacuate all personnel
  3. Close gas supply valves
  4. Use fire extinguishers (if small)
  5. Call fire brigade (large fire)
  6. Cool surrounding vessels
  7. Don't approach vessels under pressure

High Pressure

  1. Check pressure gauges
  2. Activate pressure relief if needed
  3. Stop compression
  4. Bleed gas safely to atmosphere
  5. Investigate cause

Emergency Contacts (Display prominently)

  • Fire: 101
  • Ambulance: 108
  • PESO: [Regional office]
  • Gas supplier: [Contact]
  • Plant manager: [Mobile]

8. Licensing & Approvals

Required Licenses

1. PESO License (Petroleum & Explosives Safety Organisation)

2. State Pollution Control Board

3. Fire NOC (No Objection Certificate)

4. Electrical Safety Certificate

5. Building Plan Approval

6. SATAT Registration (if selling CBG)

7. BIS Certification (Optional but recommended)

9. Implementation Timeline

Month 1-2: Planning & Approvals
  • Feasibility study
  • Site selection
  • Apply for licenses
  • Vendor identification
Month 3-4: Design & Financial Closure
  • Detailed engineering
  • Equipment procurement
  • Loan processing
  • Civil work start
Month 5-7: Construction & Installation
  • Civil construction
  • Equipment installation
  • Electrical & instrumentation
  • Pipeline laying
Month 8: Testing & Commissioning
  • Mechanical completion
  • Pre-commissioning checks
  • Trial runs
  • Biogas production start
Month 9: Stabilization
  • Process optimization
  • Operator training
  • Safety drills
  • Fine-tuning
Month 10: Commercial Operation
  • PESO inspection & approval
  • Regular production
  • Quality testing
  • Start CBG filling

10. Operational Best Practices

For Maximum Biogas Production

  1. Maintain digester temperature (35-40°C)
  2. Regular mixing (3-4 times/day)
  3. Maintain pH 6.8-7.5
  4. Add co-substrates (kitchen waste, crop residue) for higher yield
  5. Monitor C:N ratio (25:1 to 30:1 optimal)
  6. Avoid antibiotics/chemicals in feed

For Equipment Longevity

  1. Regular maintenance schedule
  2. Use quality spares
  3. Train operators properly
  4. Keep equipment log
  5. Annual maintenance contract with vendors

For Cost Optimization

  1. Sell surplus electricity (if biogas genset added)
  2. Market bio-fertilizer actively
  3. Register for carbon credits
  4. Optimize compression cycles
  5. Negotiate bulk gas sale contracts

11. Recommended Vendors (India)

Turnkey Solutions

Equipment Suppliers

Recommended Starting Point

Based on typical dairy farms:

  • For 50-80 cattle: Start with Small Scale (15 kg/day)
  • For 100-150 cattle: Medium Scale (32 kg/day)
  • For 200+ cattle: Commercial Scale (90 kg/day)

Next Steps

  1. Count your cattle and calculate dung availability
  2. Get quotations from 3-4 vendors
  3. Apply for NABARD/state subsidies
  4. Prepare detailed project report (DPR)
  5. Start license applications in parallel

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