The Role of Biogas and Bio-CNG in India's Carbon Economy

Walk through a large livestock-keeping village in Tamil Nadu in the morning, and the evidence is everywhere. Cattle sheds generate tonnes of organic waste every day. Paddy straw is piled in fields, waiting to be burned. Market waste accumulates in unsorted heaps. Household organic waste is mixed with dry refuse and buried or burned.

Every one of those waste streams represents two things simultaneously: an environmental problem, a source of methane, a fire risk, a health hazard, and an untapped energy resource.

Biogas technology converts organic waste into combustible gas through a process called anaerobic digestion. Community biogas plants, scaled for village-level feedstock availability and energy needs, convert what is currently a liability into an asset: clean cooking fuel, electricity, and bioslurry fertiliser.

And in the context of carbon markets, biogas projects also generate something else: carbon credits. Two kinds, in fact, and understanding both is essential for any FPO or development organisation evaluating biogas as a sustainability project.

The Carbon Case for Biogas: Two Revenue Streams

Biogas projects generate carbon credits through two distinct mechanisms, both of which can be credited under applicable carbon market methodologies.

The first mechanism is avoided methane emissions from waste decomposition. Organic waste, animal manure, crop residue, food waste, that decomposes in open conditions (a dung heap, an open field, a landfill) releases methane as a byproduct of anaerobic decomposition. Methane is a greenhouse gas approximately 28 times more potent than CO₂ over a 100-year horizon. When that waste is instead fed into a biogas digester, the methane is captured and combusted, converting it to CO₂ and water. This dramatically reduces the climate impact, and the reduction is creditable under multiple carbon market methodologies including AMS-III.D (Methane Recovery in Animal Manure Management) under the CDM, and equivalent VCS and ICM methodologies.

The second mechanism is displacement of fossil fuels. Biogas replacing LPG or kerosene for cooking, or diesel for electricity generation, displaces the CO₂ that those fossil fuels would have emitted. Under AMS-I.C and related small-scale CDM/VCS methodologies, this fossil fuel displacement is creditable as an emission reduction.

In a well-designed community biogas project, both streams can be credited simultaneously, essentially doubling the credit generation potential relative to a project that addresses only one mechanism.

A community biogas plant eliminates methane from decomposing waste and replaces fossil fuels with clean energy. Both of those benefits generate carbon credits. Most biogas projects are only crediting one.

Bio-CNG: The Commercial Scale-Up

Community biogas, at village scale, produces gas that is used directly for cooking or lighting within the community. This is the most socially immediate benefit, household energy access, but the commercial revenue from this model is limited by the scale of production.

Bio-CNG, Compressed Biogas, is the large-scale commercial version of the same process. Biogas is purified to remove CO₂ and hydrogen sulphide, then compressed to produce a product that is chemically equivalent to Compressed Natural Gas (CNG) and can be used as a vehicle fuel or sold into the gas distribution network.

The Government of India's SATAT (Sustainable Alternative Towards Affordable Transportation) scheme has, since 2018, created a clear commercial pathway for Bio-CNG: Oil Marketing Companies are mandated to purchase Bio-CNG from registered producers at a fixed procurement price, creating a stable demand channel.

For FPOs or agricultural cooperatives with access to large volumes of organic feedstock, paddy straw, sugarcane waste, maize stalks, cattle manure, Bio-CNG production offers a commercial revenue stream that goes beyond the carbon credit value alone. The combined revenue from SATAT procurement, bioslurry sales (the organic fertiliser by-product of the digestion process), and carbon credits from methane avoidance and fossil fuel displacement can make Bio-CNG projects commercially attractive at scales of 500 to 1,500 tonnes per day of feedstock input.

The Feedstock Aggregation Challenge

The primary challenge for community biogas and Bio-CNG projects in the agricultural sector is not the technology: anaerobic digestion is a mature, well-understood process with decades of commercial deployment in India and internationally. The challenge is feedstock aggregation.

A village-scale biogas plant running on cattle manure needs a reliable, consistent daily supply of fresh dung from a stable cattle population. A Bio-CNG plant at commercial scale needs paddy straw or other lignocellulosic biomass delivered in large, consistent quantities year-round, but paddy straw is available only at harvest time, which in Tamil Nadu means two concentrated seasonal windows (kharif and rabi harvests).

Solving the feedstock aggregation challenge, seasonal storage of biomass, logistics from farm to plant, collection economics at the village level, is precisely the kind of coordination problem that FPOs, with their existing member networks and collective logistics capacity, are best positioned to solve.

An FPO that can commit to delivering a defined quantity of paddy straw or cattle manure to a community biogas facility on a reliable schedule becomes an essential link in the Bio-CNG supply chain, and that supply chain role has economic value that can be structured into the project revenue sharing.

Where Karimam Sits in This Space

Karimam's engagement with biogas and Bio-CNG is currently at the exploration and evaluation stage. It is not an active operational service.

What we have done is identify, through our FPO partnerships in Madurai, Dindigul, and Theni districts, several concrete situations where biogas opportunity is visible on the ground: cattle shed operations generating unmanaged dung at significant volume; paddy straw accumulated in fields and burned at harvest for lack of an alternative; agricultural processing units generating organic waste from rice milling, groundnut shelling, and vegetable processing.

Each of these represents a potential feedstock stream for a community biogas project. The question we are currently evaluating is not whether the technology works, it does, but whether the economics work at the scale accessible through FPO aggregation in our current operating area, and which carbon methodology provides the most defensible credit structure for the specific feedstock and process involved.

We anticipate that biogas at the community scale, if not yet the Bio-CNG commercial scale, will become part of our active project portfolio within the next 18 to 24 months, either as a standalone project type or as a component of a stacked multi-methodology project with existing FPO partners.

What FPOs Should Know Now

If you are an FPO leader reading this, the key things to understand about biogas as a carbon project are the following.

The technology is proven and accessible. Village-level biogas plants are available from multiple Indian manufacturers, with installation costs that have fallen significantly over the past decade.

The carbon credit potential is real. Methane avoidance is one of the highest-value carbon credit categories in terms of tonnes per unit of investment, because of methane's high global warming potential relative to CO₂.

The feedstock question determines everything. Before evaluating any biogas project, an honest assessment of feedstock volume, consistency, and collection cost is essential. Projects that overestimate feedstock availability, and many do, struggle commercially and operationally.

And the bioslurry by-product may be as commercially valuable as the gas itself. The liquid biofertiliser produced by the digestion process is a high-quality organic fertiliser that can replace a significant share of synthetic fertiliser input, reducing the FPO's member farmers' input costs while also being saleable as a premium organic product.

Biogas is not a silver bullet. But in the right FPO context, one with reliable organic feedstock, willing farmer members, and an appropriate implementation partner, it is one of the most complete sustainability interventions available: it solves a waste management problem, provides clean energy, produces organic fertiliser, reduces greenhouse gas emissions, and generates carbon credit income. Few agricultural technologies do all five simultaneously.

The biogas and Bio-CNG opportunity areas described in this article are part of Karimam's Explore programme: areas of active evaluation rather than current operational services. For enquiries about biogas project development partnerships, contact info@karimamglobal.com.