Time-resolved measurement of simulated methane emissions from livestock, using wavelength modulation spectroscopy

Wavelength modulation spectroscopy (WMS), using a 1654 nm diode laser and an annular polygon-reflector multipass optical cell, has been developed for quantitative measurement of enteric emissions of methane (CH₄) from ruminant livestock at atmospheric pressure. WMS is molecule-specific and able to detect sub-parts-per-million concentrations of CH₄ in ambient air. Periodic bursts of CH₄ from a pulsed solenoid valve enable laboratory-based simulation of such animal emissions, demonstrating the feasibility of using WMS to time-resolve individual simulated eructations of CH₄ in cattle breath and providing the basis for subsequent field-based instruments designed to measure CH₄ emissions from livestock.