Biogas and biomethane: Emissions

How manure gas can score below zero on carbon

What this tab covers The greenhouse-gas footprint per tonne, split by lifecycle phase (feedstock, production, movement, use, end of life), the global total, other environmental impacts, levers and low-carbon routes, India's position, and where the investment opportunity lies. Emission intensity 1.00 t CO2e per t range about -10 (manure with methane capture; California in-state bio-CNG averaged -198 g/MJ in 2025) to about 1.5-2.5 for energy-crop biomethane with high methane slip; fossil CNG about 3.5-4 t per t (indicative) · indicative 20 g CO2e/MJ for a waste and residue mix without manure credit, x 50 GJ/t Global emissions per year 32.0 Mt CO2e per year 2024 · 1.0 t/t x about 32 Mt methane in about 45 bcm biogas and biomethane (indicative); manure and landfill capture avoid far more

Per t of biomethane (per MJ x 50 GJ/t), life cycle; combustion CO2 is biogenic; shown excluding the avoided-methane credit for manure. Intensity: Transport Project, RNG in California 2025 (Jun 2026, CARB LCFS data); RED II Annex VI and CARB LCFS pathways (indicative). Global total: derived (indicative).

Share of footprint by lifecycle phase

Feedstock 15% Production / process 60% Movement 20% Use 5%

Footprint by lifecycle phase

Phase	Intensity	Share	Main sources of emissions	Notes	Source
Feedstock	zero burden for wastes; about 0.5-1 t CO2e/t for energy crops (indicative)	15%	silage cultivation and fertiliser; manure storage before digestion	manure digestion avoids lagoon methane, which credit systems count as a negative emission	indicative
Production / process	about 0.6 t CO2e/t	60%	methane leaks from digesters (0-12%) and upgrading (0.2-10%), digestate storage, power and heat	leak ranges are for European plants (IEA 2025); each 1% methane slip adds about 0.3 t CO2e per t biomethane at GWP100 30 (derived)	IEA Outlook for Biogas and Biomethane (May 2025), via World Biogas Association and BioCycle
Movement	about 0.2 t CO2e/t	20%	compression to 200-250 bar, trucking cascades, grid losses	low for grid injection, higher for India's cascade logistics	indicative
Use	about 0.05 t CO2e/t	5%	unburnt methane from engines	combustion CO2 is biogenic	indicative
End of life	not applicable to the gas; digestate spreading emits N2O and ammonia	–	digestate handling	covered storage and injection into soil reduce emissions; digestate replaces mineral fertiliser	European Biogas Association Statistical Report 2025, via Renewable Energy Magazine, 10 Dec 2025

Other environmental impacts

Cuts open burning of paddy straw and untreated dung; digestate replaces fertiliser (Europe 25 Mt dry matter, 17% of EU nitrogen fertiliser equivalent). Odour, ammonia and H2S safety risks; energy crops compete for land.

Levers to cut emissions

Manure and food-waste feedstocks with methane credits
Leak detection and repair, covered digestate storage and off-gas combustion
Capturing and selling upgrading CO2 (food grade or for e-methanol)
Renewable power for compression
Digestate replacing urea (IEA: about 10% of India's fertiliser need by 2050 with full use)

India

India's main climate gains are avoided stubble burning and dung methane plus displaced imported LNG; the IEA says digestate could meet about 10% of India's projected fertiliser needs by 2050 (World Biogas Association summary, 2025).

Emission figures are indicative global averages from the life-cycle studies named; actual footprints vary widely by site, energy mix and method.

Low-carbon routes

Route	Intensity	Cost premium	Status	Source
Dairy manure RNG with methane capture	California in-state bio-CNG averaged -198 g CO2e/MJ in 2025	relies on LCFS and RIN credits	98% of California on-road natural gas vehicle fuel is RNG; 7.9 Mt CO2e avoided in 2025	Transport Project, RNG in California 2025 (Jun 2026, CARB LCFS data)
Paddy straw CBG in Punjab and Haryana	low (residue that would be burned; indicative)	straw logistics add cost (indicative)	commercial plants such as Verbio's in Punjab and OMC-backed units (indicative)	indicative

For a climate investor India's CBG obligation turns biomethane into a mandated market of roughly 1.75 MMSCMD by 2028-29 (derived from the 1% = 0.35 MMSCMD rule), against about 0.65 MMSCMD sold today. The investable pieces are plants near press mud, dairy clusters and paddy straw, feedstock aggregation, digestate marketing and upgrading equipment. What has to be true: bankable offtake at 85% of CNG retail, reliable feedstock contracts and leak control. Reliance, Adani TotalEnergies, Petronet-Gruner and the OMCs are building.