Hydrogen will play a profound role in the transition from our present fossil-fuel based energy system towards renewables. Hydrogen (H2) produced from electrolysis of water becomes the carrier of energy to be distributed, feeding fuel cells (or combustion engines) in cars, ships, aircraft, households, and industry. During all this, leakage of H2 into the atmosphere will be unavoidable.

This extra source of H2 to the atmosphere will modify a number of chemical cycles in the atmosphere, and thereby contribute to greenhouse gas forcing [1] and stratospheric ozone loss [2]. These negative impacts are currently thought to be small compared to the positive impacts brought about by the avoided emissions of CO2, CH4, CO, NOx, and PM2.5 (fijnstof) in a fossil- based energy system. But while building our new H2-production and -distribution capacity it is wise to:

1. (a) monitor and understand ongoing changes in the regional and global atmospheric H2 abundance
2. (b) increase our knowledge of the air quality, greenhouse forcing, and stratospheric impacts of H2
3. (c) develop capacity to detect H2 leaks and attribute elevated H2-levels to specific sectors or processes.

The present two positions are part of the atmospheric H2 project carried out in the Centre for Isotope Research (CIO), financially supported by the National Program Groningen ("waterstof werkt" project) and Shell Nederland (Gas & Hydrogen Partnership).

PhD1 will install and maintain a calibrated atmospheric Hydrogen detection system at our atmospheric monitoring station Lutjewad. (S)he will also perform Radon measurements throughout the country in an attempt to improve the national Radon flux inventory. This Rn flux, together with the H2 concentration measurements, will lead to observation-based national H2-flux estimates. Next to these activities, a novel method for the measurement of the HD isotope signal in atmospheric H2 will be pursued.

PhD2 will build a high-resolution (100m) numerical model that simulates hourly H2- and HD-abundances, together with air quality (including NOx, O3, and fijnstof or PM2.5), initially focussed on the Dutch Rijnmond area, which encompasses the Maasvlakte, the port of Rotterdam, its city center, and the Westland horticulture. The model will include expected H2 sources from leakage (mostly fueling stations, but also from industrial use and shipping/aviation), as well as chemical production+loss and deposition to the land surface. The resulting numerical modeling system will be the basis for sector-specific attribution of regional atmospheric H2 increases, but also for attribution of air quality improvements from increasing H2- use.

Both PhD candidates are expected to be committed to conduct independent and original scientific research, to report on this research in international publications and presentations, and to present the results of the research in a PhD dissertation, to be completed in 4 years. About 10% of their overall workload will be spent on teaching.

You are a highly motivated candidate with:

- a MSc degree in environmental sciences, physics, chemistry, engineering, or other relevant subjects
- excellent command of English (oral and written)
- motivated to contribute to the energy transition
- strong team player who also works efficiently independently
- excellent communication skills and an affinity for writing scientific papers and delivering presentations
- for position 1: have experience in experimental lab and/or field work
- for position 2: have experience in computer programming and modelling.

Applicants are welcome to apply for PhD position 1 or 2 or both. Please indicate and explain your preference in the application letter.

Fixed-term contract: 48 months.

We offer in accordance with the Collective Labour Agreement for Dutch Universities:

• a salary of € 2,443 in the first year to a maximum of € 3,122 gross per month in the final year (PhD salary scale), based on a full-time position
• a holiday allowance of 8% gross annual income and an 8.3% year-end bonus
• a full-time position (1.0 FTE). The position is for four years. First you will be offered a temporary position of one year with the option of renewal for another three years. Prolongation of the contract is contingent on sufficient progress in the first year to indicate whether a successful completion of the PhD thesis within the contract period is to be expected. A PhD training programme is part of the agreement and the successful candidate will be enrolled in the Graduate School of Science and Engineering of the Faculty. Note that PhD2 will work in close collaboration with Wageningen University, and a possibility exists to (partly) work from there.

The two PhD positions are immediately available.

The conditions of employment are available at the University of Groningen website under Human Resources: https://www.rug.nl/about-us/work-with-us/

Faculty of Science and Engineering

Founded in 1614, the University of Groningen enjoys an international reputation as a dynamic and innovative institution of higher education offering high-quality teaching and research. Flexible study programmes and academic career opportunities in a wide variety of disciplines encourage the 36,000 students and researchers alike to develop their own individual talents. As one of the best research universities in Europe, the University of Groningen has joined forces with other top universities and networks worldwide to become a truly global center of knowledge.

This position is embedded in the Centre for Isotope Research (CIO) of the Energy and Sustainability Research Institute Groningen (ESRIG). CIO is devoted to measurements of atmospheric greenhouse gases and related substances. Modern instrumentation, and an experienced technical crew support this work. For the modelling part, a close collaboration with the Dept. of Meteorology and Air Quality of Wageningen University exists. More information on CIO's activities can be found at: https://www.rug.nl/research/centre-for-isotope-research/