Capturing methane in a barn environment: the CH4 Livestock Emission (CH4rLiE) project

TL;DR

The paper addresses methane emissions from livestock and the challenge of mitigating CH4 that has already entered barn air. It proposes CH4rLiE, a prototype that uses adsorption on porous solids (zeolites, pyrolytic carbon) to capture CH4 from barn air, leveraging concepts from Direct Air Capture and adapted gas-recovery systems from CERN. To support feasibility, the study combines direct barn measurements with QEPAS sensing, diffusion modeling in COMSOL, and materials screening for CH4 selectivity under realistic gas mixtures, followed by a lab-to-field prototype testing plan. Under baseline assumptions, the estimated recoverable CH4 is around $0.9~kg~CH_4~month^{-1}$ for a 250-animal barn processing about $3{,}000~m^3~day^{-1}$, highlighting potential energy-efficiency routes via pressure-swing regeneration and the possibility of extending deployment to pigsties or landfills, with NH3 capture slated as a future enhancement.

Abstract

The CH4 Livestock Emission (CH4rLiE) project explores the development of a prototype system for capturing methane emissions in barn environments, offering an alternative approach to mitigating greenhouse gas emissions from livestock farming. Methane (CH4), with a global warming potential significantly higher than CO2 (GWP100 = 27), accounts for ~23% of anthropogenic climate impact. In 2021, The Assessment Report 6 of Intergovernmental Panel on Climate Change quantified CH4 livestock emissions in 123 Mt/yr, which, together with substantial N2O and CO2 emissions, contributed with a 12% to global emissions. Unlike strategies focused on altering animal feed, CH4rLiE investigates post-emission capture using porous materials, such as zeolites, to adsorb methane from barn air. The project draws on CERN's experience with gas recovery systems for particle detectors, adapting similar technologies to agricultural settings. Preliminary estimates, based on measured CH4 concentrations (~20 mg/m3) and partial air filtration in a 250-animal barn, suggest a low but detectable recovery potential, subject to validation through simulation and in-situ testing. Prototype development considers the potential for energy-efficient operation - possibly through pressure swing regeneration - and compatibility with existing ventilation infrastructure, though these aspects remain under evaluation. If methane concentrations in barns prove too diluted, the system may be better suited for environments with higher gas levels, such as pigsties or landfills. NH3 capture for fertilizer production is planned as a future enhancement. CH4rLiE aims to assess the feasibility of emission recovery in livestock settings without affecting animal welfare, contributing to sustainable farming practices, resource efficiency, and circular bioeconomy goals.

Figures (8)

• Figure 1: Head of cattle by region in Italy.
• Figure 2: Simplified layout of the barn in Volvera chosen for the measurement campaigns.
• Figure 3: Average concentration of CH$_4$ in 5 measurement points along the barn as a function of the mean temperature recorded inside the barn. The error bars are the standard deviation of each sample.
• Figure 4: Concentration of CH$_4$ measured over a 24-hour period, shown separately for each season and for the overall average. The error bars are the standard deviation of each sample.
• Figure 5: Inside picture of the real barn