IS 16087:2016 (IS 16087)

IS 16087:2016 is the Bureau of Indian Standards specification titled Bio-Compressed Natural Gas (Bio-CNG) for Automotive Purposes, which sets quality and safety requirements for compressed biogas sold as vehicle fuel under India's SATAT initiative. It is the single most important regulatory benchmark for CBG plant designers and operators because every kilogram of CBG sold to oil marketing companies (OMCs) — IOCL, BPCL, HPCL — must meet these specifications, and failure to comply results in lot rejection and revenue loss.

The principal composition limits set by IS 16087:2016 are:

• Methane (CH4): minimum 90% by volume.
• Carbon dioxide (CO2): maximum 4% by volume.
• Combined oxygen and inerts (N2, etc.): maximum 1.5%.
• Hydrogen sulfide (H2S): maximum 16 mg/Nm3.
• Total sulfur: maximum 40 mg/Nm3.
• Water dew point: 5 degC below the lowest expected ambient.
• Oil content: maximum 5 mg/Nm3.
• Hydrogen: maximum 2%.
• Mercaptan sulfur: maximum 16 mg/Nm3.

The standard also references storage pressure of 200-250 bar and incorporates safety provisions consistent with IS 15958 (CNG specification), so that bio-CNG and fossil CNG can be blended in the same infrastructure without re-engineering. Cylinder specifications and pressure equipment safety are governed in parallel by PESO under the Static and Mobile Pressure Vessels (Unfired) Rules and the Gas Cylinders Rules, 2016.

Operational compliance is verified through batch sampling at the OMC delivery point. Independent BIS-accredited labs test for methane percentage by gas chromatography, H2S by lead acetate tape or electrochemical sensor, and moisture by chilled-mirror dew-point analyser. Plants typically maintain inline gas analysers on the upgrader outlet that trigger automatic diversion of off-spec gas back to the flare or storage tank, preventing contamination of the cylinder fleet.

The trade-off in meeting IS 16087:2016 is upgrading cost versus revenue assurance. Designing the upgrading train (water scrubbing, PSA, or membrane) for 92-95% methane provides headroom against process variation, but adds 5-15% to upgrading capex compared to a tight 90% design. Operators almost universally choose the headroom because lot rejection by OMCs results in lost SATAT revenue plus the cost of re-treating or flaring the off-spec batch. The standard is periodically reviewed by the BIS Petroleum, Coal and Related Products Sectional Committee (PCD 03), and amendments under consideration include tighter siloxane limits and addition of a moisture limit in absolute terms rather than dew point.