Drive out of any Tier-II town in Maharashtra, Karnataka, Andhra Pradesh or Punjab today and somewhere along the highway you will pass a board announcing an upcoming compressed biogas (CBG) plant. Some boards are crisp and corporate. Others are weather-beaten, the project clearly stalled. A few are freshly painted over older boards from a different promoter who gave up. This roadside archaeology tells you almost everything you need to know about the state of India’s BioCNG sector, one the Government of India has staked considerable policy capital on, and one that is, in stretches, quietly failing to deliver on its own promise.
The vision is genuinely beautiful. Under the SATAT initiative launched in 2018, the country was to see five thousand compressed biogas plants producing 15 million tonnes of CBG annually, displacing imported LNG, cleaning up agricultural waste, generating rural employment, and giving the oil marketing companies a domestic green molecule to blend. GOBARdhan added a sanitation and rural livelihoods layer. The carbon credit framework added a financial sweetener. Banks were nudged. Subsidies were structured. Off take was promised at attractive rates.
And then reality arrived, slowly, in the form of a tall, fast-growing grass.
Napier grass known variously as elephant grass, hybrid Napier, Super Napier, Pakchong-1, CO-5, or Red Napier depending on which seed company you spoke to last became the great hope of feedstock based BioCNG. Unlike cattle dung, which is geographically fragmented and seasonally inconsistent, unlike crop residue, which is monsoon locked and politically sensitive, Napier was supposed to be the disciplined, plantation style energy crop India had been waiting for. The numbers were intoxicating. Yields of 250, 300, even 400 tonnes per acre per year. Three to four harvests annually. Methane potentials that, on paper, made the financial models sing.
Visit those same farms today and the picture is more complicated.
I have spent time on Napier fields across three states over the past two years, and the variation is staggering. On one well-managed farm in interior Andhra Pradesh, with drip irrigation, disciplined fertigation and timely harvesting, the crop genuinely delivered close to 280 tonnes per acre annually. Forty kilometres away, on similar looking soil but with bore well water of higher salinity and a farmer who could not get labour during the second cutting window, the same hybrid struggled past 130 tonnes. Neither farmer was lying. Neither seed supplier was lying. The land was simply telling a more honest story than any DPR could capture.
This is the first quiet scandal of the sector. The yield numbers driving project financial models in India are largely borrowed from research station data or from Thailand and the Philippines, where Pakchong 1 was originally bred. They are not lies, but they are not promises either. And when a project’s entire economics rest on a feedstock yield that can swing by a factor of two depending on soil microbiome, irrigation discipline and labour availability, the gap between the spreadsheet and the digester becomes the place where promoters lose their savings.
The second scandal is even less discussed, because it requires understanding what happens to Napier between the field and the plant.
Fresh Napier cannot be fed continuously into a digester. A serious BioCNG plant needs feedstock available 365 days a year, which means the grass must be ensiled chopped, compacted, sealed under plastic, and allowed to ferment anaerobically for weeks before use. This sounds straightforward. It is not. The age of the grass at harvest matters enormously. A crop cut at 45 days is biochemically a different substance from one cut at 60 days, which is different again at 75 days. As the plant matures, lignin climbs, digestibility falls, and the methane you can extract per tonne declines even as your tonnage rises. Most farmers, left to their own rhythms, harvest late. Most plants, designed on early harvest data, then under perform.
Silage adds another layer. A Napier pile ensiled for 30 days, tested in a laboratory, will give one BMP reading. The same pile tested at 45 days gives another. At 60 days, another still. Dry matter losses during ensiling can range from 8 to 22 percent depending on chopping length, compaction quality, and whether the plastic sheet held against monsoon winds. I have personally seen project promoters sign engineering, procurement and construction contracts based on a single BMP test performed on day one fresh grass the most flattering possible number only to find their plant producing 60 per cent of designed capacity once real silage starts moving through it.
Who pays for this gap? Not the EPC vendor, whose contract typically says “design basis” rather than “guaranteed output.” Not the technology consultant, who has long since invoiced and moved on. Not the seed supplier, who sold a hybrid not a yield. The promoter pays. Increasingly, the lending bank pays. And in a country trying to scale this sector to thousands of plants, the public exchequer ultimately pays, because every stalled project is a viability gap subsidy that did not produce a molecule of gas.
None of this is an argument against BioCNG. The country needs it. The carbon arithmetic is real. The rural employment is real. The import substitution is real. The technology, properly deployed, works there are excellent plants at few locations quietly producing close to their design output, run by promoters who did their homework.
But the homework matters. India needs a more honest conversation about feedstock realism before we keep approving plants. Yield claims for energy crops should be backed by location specific, multi season data, not borrowed brochures. In-house low cost testing should be mandated across silage age groups, not single point. EPC contracts should carry performance guarantees tied to realistic feedstock, with penalties that bite. State agriculture universities should be funded to publish district level Napier performance data the way they publish for paddy and cotton. And first time promoters need access to plain spoken pre investment advisory that is not paid for by the people selling them the plant.
The Napier grass on the highway boards is real. So is the policy. So is the opportunity. What is missing is the inconvenient middle the soil, the silage pit, the September rain, the harvest that came two weeks late because the tractor broke down. Until India's BioCNG sector learns to plan for that middle, the gap between announced capacity and operating capacity will keep widening, and a genuinely transformative idea will keep getting buried under its own optimism.
We owe this sector better than that. We owe ourselves better than that too.
Srinivas Kasulla is a global expert in biogas, bio-CNG and circular bioeconomy
Views expressed are the author’s own and don’t necessarily reflect those of Down To Earth