Detection of regional industrial H2 emissions using an active Aircore and a high-precision GC-PDHID system

As result of the global energy transition, it is expected that H₂ emissions are on the rise due to increasing production, transport and usage. Leakage rates might be up to 10% of the total hydrogen production. This will lead to an increase of the global atmospheric hydrogen mole fraction, resulting in the lengthening of the lifetime of in particular methane, enhanced tropospheric ozone production, and increased stratospheric water vapor levels. Because of these effects, H₂ is called an indirect greenhouse gas. We present first results of the use of a high-precision Agilent 8890 GC-system equipped with a Pulsed Discharge Helium Ionization Detector (PDHID) combined with an ‘active’ Aircore and sampling flasks as a tool to detect and quantify industrial H₂ emissions. Our GC-PDHID measures H₂ with a precision <2 ppb and is calibrated and linked to the international NOAA-H2-X1996 hydrogen scale (e Max Planck Institute for Biogeochemistry (MPI-BGC) Jena, Germany). The ‘active’ AirCore is an atmospheric sampling system that consists of a long narrow tube (in the shape of a coil) in which atmospheric air samples are collected using a pump during the sampling experiment, in this way preserving a profile of the trace gas of interest along the measurement trajectory. In this study we focus on potential H₂ emitters in the Groningen province, mainly located at the Delfzijl Chemistry Park bordering the Wadden sea coast. During our field experiments we deployed three different complementary sampling methods. The first method involves the use of an active Aircore system with a sample volume of 4.35 L from a passenger car. This Aircore is filled to an end-pressure of up to 1.6 bar over the course of about 2 hours of sampling resulting in up to 38 discrete H₂ samples on the GC-PDHID. The second method involved the use of an active Aircore system on a UAV with a volume of 3.7 L and filled with a sampling flow of 200 ml min^-1 at atmospheric pressure, allowing for up to 21 discrete H₂ samples. The third sampling technique involved the use of dried and vacuumized 2.3 L glass flasks to collect discrete samples along the measurement trajectory. The glass flasks samples were further analysed by CRDS (Picarro G2401) on mole fractions of CO₂, CH₄, CO, to get additional information on the emission sources co-located with H₂. We found a regional H₂ background of 529 ± 5 ppb in agreement with the European background station observations at Mace Head, Ireland. Our results so far indicate constant undetected industrial H₂ emissions at the Chemistry Park Delfzijl, ranging from enhanced signals of 580 ppb up to 1.5 ppm of H₂ downwind the source area. Based on these results we present first estimates of current industrial H₂-emissions from the Delfzijl Chemistry park. Further work will focus on specific H₂ production and storage infrastructure.