New ways of measuring atmospheric hydrogen: paving the way for hydrogen leak quantification

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The aim of this project is to develop and demonstrate how mobile measurements of atmospheric hydrogen can be used to locate and quantify fugitive emissions of hydrogen to the atmosphere. With proposals to increase use of hydrogen as a fuel as we move towards net-zero, there is an urgent need to quantify the amount of hydrogen that will be released to the atmosphere. Hydrogen leaks easily, e.g. through joints in pipework and during vehicle fuelling. There are climate and air quality consequences of this. Hydrogen is an indirect greenhouse gas because increased amounts of hydrogen in the atmosphere will react with and reduce the amount of hydroxyl in the atmosphere, hence increasing the lifetime of methane. Increased emissions of hydrogen in the atmosphere would also lead to formation of ozone in the troposphere (another greenhouse gas and damaging to air quality) and reduce stratospheric ozone and water vapour. We need to quantify how much hydrogen will be emitted to the atmosphere, and identify where leaks are likely to occur so that better infrastructure design is implemented ahead of widespread hydrogen use in energy production. Whether or not adoption of hydrogen will lead to a positive or negative net radiative forcing depends on the hydrogen leakage rate as well as on the associated changes in carbon emissions and the method of hydrogen production. Laser spectroscopy has proved to be very useful in recent years for mobile detection of methane leaks by vehicle, aircraft and drone. Recent studies have quantified methane leak rates and shown where emissions can be cut, providing the science behind the recent Global Methane Pledge. Similar studies for hydrogen are necessary, but a suitable high precision and portable instrument is not currently available. In this project an inlet system will be built to compress and dry ambient air which will then be measured by a commercially available instrument that is designed for use in industry for measuring hydrogen in dry compressed air. The instrument oxidises hydrogen over a catalyst and then uses spectroscopic analysis of the resultant water vapour to quantify the hydrogen mole fraction. Initially the instrument will be run in the laboratory and measurements will be compared with established (but not portable) gas chromatography techniques for atmospheric hydrogen measurements. It is envisaged that this instrument will then be operational as a mobile measurement system installed in Royal Holloway's mobile greenhouse gas laboratory vehicle. Experiments will also be designed and carried out to measure leak rates of hydrogen and methane when they are blended in pipelines as is being proposed and tested in the UK. Recommendations on measurement techniques to quantify hydrogen leakage will be published. Ultimately the development of techniques to locate fugitive emissions of hydrogen that will help reduce leaks to the atmosphere will improve the climate and environment benefit of a transition to hydrogen based energy production.