Frequently Asked Questions
Find answers to the most common queries about our biogas plants, operations, feedstock, costs, and government policies – all in one place.
1. What is the CBG yield from Napier Grass as per your technology?
Under thermophilic digestion conditions, Napier Grass with a 35% dry matter (DM) content yields approximately 7% purified CBG.
2. Which variety of Napier Grass is recommended?
While we are not specialized in agricultural sciences, based on our engineering experience in biogas plant operations, we recommend selecting a Napier Grass variety that consistently achieves a minimum of 35% dry matter (DM) at the time of harvesting and has a high methane yield potential.
The ideal variety should exhibit:
High biomass productivity
Good digestibility and lower lignin content
Proven performance in anaerobic digestion for biogas generation
We advise clients to consult with agricultural universities or agronomy experts for the selection of the most suitable local Napier cultivar that meets these parameters. However, commonly preferred hybrids in the industry include CO-4, CO-5, and IGFRI strains, subject to local agro-climatic adaptability.
3. Can the plant operate solely on Napier Grass as feedstock?
Yes, our biogas plant is engineered to operate on 100% Napier Grass without the requirement for any co-substrate, subject to proper pretreatment and feedstock management.
4. Which other feedstocks can be co-digested for improved yield or diversification?
Other viable substrates include:
-
Paddy Straw – DM: 86%, Biogas Yield: 12%
-
Poultry Litter – DM: 18%, Biogas Yield: 4.5%
-
Cow Dung – DM: 22%, Biogas Yield: 12%
These can be used in strategic ratios based on process optimization studies.
Type of Raw Material vs Yield Table:
| Type of Raw Material | Dry Matter % per Ton | CNG Output (Reference IOCL) |
|---|---|---|
| Cattle Dung | 22% | 2.50% |
| Poultry Waste | 38% | 6.00% |
| Paddy Straw | 86% | 12.00% |
| Napier Grass | 35% | 7.00% |
| Pressmud | 15% | 6.00% |
5. What is thermal pre-treatment?
Thermal pre-treatment involves the hydrolysis of lignocellulosic biomass under controlled temperature and pressure to enhance digestibility and gas yield. It is especially beneficial for fibrous substrates like Napier Grass.
6. How is your technology superior to competitors?
Our CBG plants are based on thermophilic anaerobic digestion technology (operating at 50°C–55°C), offering faster kinetics and higher methane productivity.
We also offer a hybrid VPSA purification system, comprising:
H₂S Scrubber
Water Scrubber
Vacuum Pressure Swing Adsorption (VPSA)
This ensures CBG purity of ≥98% with methane losses limited to 2–3%.
7. What is the current government subsidy available?
The central government offers ₹4 Crores for a 4.8 TPD plant. This is calculated on a pro-rata basis at ₹83 Lakhs per TPD of purified CBG capacity.
Details of Scheme:
Programme Name: Waste to Energy Programme
Category: Programme on Energy from Urban, Industrial, Agricultural Wastes/ Residues
Objective:
The objective of the programme is to support the setting up of Waste to Energy projects for generation of Biogas/ BioCNG/ Power/ producer or syngas from urban, industrial and agricultural wastes/residues.
Period: FY 2021-22 upto FY 2025-26
Salient Features:
The programme provides Central Financial Assistance (CFA) to project developers and service charges to implementing/inspection agencies in respect of successful commissioning of Waste to Energy plants for generation of Biogas, Bio-CNG/enriched Biogas/Compressed Biogas, Power/ generation of producer or syngas.
Financial assistance available under the Programme for setting up Waste to Energy plant is as follows:
BioCNG/Enriched Biogas/ Compressed Bio Gas:
a) ₹4.0 Cr per 4800 kg/day (for BioCNG generation from new biogas plant)
b) ₹3.0 Cr per 4800 kg/day (for BioCNG generation from existing Biogas plant*)Maximum CFA of ₹10.0 Cr/project for both cases.
Source: Ministry of New and Renewable Energy
🔗 MNRE Waste to Energy Programme
8. What is the financing model: bank loan vs. equity?
Typically, banks finance up to 70% of the project cost as term loan against collateral. The remaining 30% is promoter’s contribution (equity).
9. What are the provisions for grid or pipeline injection?
Grid or pipeline injection depends on the location and availability of City Gas Distribution (CGD) networks. LOI from OMCs or CGDs is a pre-requisite for planning injection points.
10. What if OMCs do not lift the gas due to low demand?
Our process begins with obtaining a Letter of Intent (LOI) and Commercial Offtake Agreement from IOCL/HPCL/BPCL/GAIL or other CGD entities.
These agreements ensure 15 years of assured offtake, with pricing based on MMBTU and methane purity.
11. What can be done with digestate other than vermicomposting?
Use as fuel in boiler operations of the plant
Market as Phosphate Rich Organic Manure (PROM)
Convert to briquettes or pellets for commercial sale
12. Is there any government incentive on digestate sales?
This varies by state and policy updates. At present, there is no direct incentive, but organic fertilizer sale benefits may apply under agricultural schemes.
13. What is the current market price of CNG?
CNG pricing is dynamic and region-specific. As of the latest data, retail prices range between ₹56.70 to ₹78.01 per kg.
However, offtake rates for producers are governed by contractual agreements.
Detailed Procurement Price Table (as per latest notification):
| S No | Lower Retail Selling Price of CBG in Slab (₹/kg incl. tax) | Higher Retail Selling Price of CBG in Slab (₹/kg incl. tax) | Procurement price of CBG (Without GST) ₹/kg | Procurement price of CBG (With GST) ₹/kg |
|---|---|---|---|---|
| 1 | Retail Selling Price of CBG up to 70 | 54.00 | 56.70 | |
| 2 | 70.01 | 75.00 | 55.25 | 58.01 |
| 3 | 75.01 | 80.00 | 59.06 | 62.01 |
| 4 | 80.01 | 85.00 | 62.86 | 66.01 |
| 5 | 85.01 | 90.00 | 66.67 | 70.01 |
| 6 | 90.01 | 95.00 | 70.48 | 74.01 |
| 7 | 95.01 | 100.00 | 74.29 | 78.01 |
14. What is the operational cost excluding raw material?
Including Raw Material Cost, OPEX typically ranges between ₹35–₹40 per kg of CBG, influenced by labor, maintenance, utilities, and logistics.
15. What is the annual maintenance cost of a typical plant?
We consider an annual maintenance provision of approximately ₹17 Lakhs per annum in the P&L accounting of a standard 6 TPD facility.
16. What is the methane recovery from Napier Grass?
CBG purity achieved post-purification is ≥98% methane, with overall methane recovery efficiency ranging between 7% and more from Napier-based feedstock, under thermophilic conditions.
17. What is the designed operational life of the plant?
All our plants are designed for a minimum operational life of 20 years, with proper maintenance and periodic upgrades.
18. Is carbon credit applicable?
Yes, biogas plants are eligible under carbon credit mechanisms such as Verified Carbon Standard (VCS) and Gold Standard, depending on project validation.
19. Are there other government incentives?
Yes. Apart from the central subsidy, many states offer:
- Capital Subsidies
- Stamp Duty Exemption
- Electricity Duty Waivers
- Interest Subvention
Policies vary; detailed evaluation is done per state.
20. What is the ROI when feedstock is cultivated vs. procured?
• 6 TPD Plant – Cultivated Feedstock: ROI = 3.5 – 4 years
• 3 TPD Plant – Market-purchased Feedstock: ROI = 4.5 – 5 years
21. What is the cost breakup per kg of CBG production?
Cost structure varies, but major heads include:
- Electricity: ₹5–6/kg
- Manpower: ₹3–4/kg
- O&M: ₹4/kg
- Feedstock (if purchased): ₹10–12/kg
- Miscellaneous: ₹3–4/kg
22. What is the electricity consumption per TPD?
• 3 TPD: 2500 kWh/day
• 6 TPD: 3800 kWh/day
• 12 TPD: 5500 kWh/day
23. Can the plant run on DG sets using its own CBG?
No. Running the purification unit on DG is economically unviable due to high operating cost.
DG sets are reserved for emergency power backup only (e.g., flare, compressors, control room, safety systems).
24. What is the manpower requirement for plant operation?
A typical 6 TPD plant requires approximately 15 personnel:
- 5 Operators
- 4 Helpers
- 1 Plant Head
- 1 Assistant Plant Head
- 1 Lab Assistant
- 2 Security Staff
25. What is the duration of free service support post-commissioning?
We offer 1 year of comprehensive technical support post-commissioning, inclusive of remote and on-site troubleshooting.
27. What are the local authority approvals required?
Mandatory approvals include:
- Land Diversion (Agriculture to Industrial)
- Water and Electricity Clearance
- Local Panchayat/Municipality NOC
- PCB (Pollution Control Board)
- TNCP (if applicable)
- Industrial Health & Safety Certification
- PESO Approval (we assist with documentation and drawings)
28. What about land issues like HT lines or canals?
This is site-specific. However, we recommend maintaining safe distance from HT transmission lines and irrigation canals for compliance and operational safety.
29. How many projects are completed and operational?
• Completed & Operational: Jaipur (Rajasthan), Badnawar (M.P.)
• Under Construction: Haryana
• Projects in Hand: 8 nos. under active execution
30. Which Napier harvester is recommended?
We recommend self-propelled forage harvesters with precision chopping capability, such as Mahindra Forage Cruiser or CLAAS Jaguar 25 series, for optimum productivity.
31. What is the ideal chopping size of Napier Grass?
For slurry preparation, an optimal chopping size of 2 mm ensures maximum surface area for enzymatic action and digestion.
32. What is the recommended solid content in slurry?
The ideal dry matter (DM) content in slurry should be maintained at 10% w/w for optimal flow and digestion.
33. When is the best time to harvest Napier Grass, and what DM is required?
Harvest when the grass appears greenish-yellow to yellowish-green – typically at 60–75 days after planting.
The desired dry matter content is ≥35% at harvest.
