General information

Reference

2026-4032  

Position description

Category

F08 Geochemistry - Engineer / Researcher

Job title

PhD in Microbial CO₂ Bioprocessing in Geothermal Systems

Contract

Thesis

Contractual hours

Full-time

Contract duration

36 months

Context and contributions of the position

Joining BRGM means becoming part of France's leading public institution in Earth sciences, where 1,000 experts work across 25 sites to address environmental and energy challenges. Within its Energy and Decarbonization Division (DED), BRGM develops innovative solutions for the sustainable use of the subsurface, including geothermal energy, carbon storage, natural hydrogen, and radioactive waste management.
The European MiningBrines project, to which BRGM contributes, trains 19 PhD candidates in the valorization of geothermal brines to extract critical raw materials and energy gases while minimizing environmental impact. Through an interdisciplinary approach (geosciences, biogeochemistry, AI, socio-economics…), doctoral candidates develop experimental and modeling tools aligned with the objectives of the European Green Deal. Together, BRGM and MiningBrines strengthen Europe's strategic autonomy in sustainable resources while training future experts of the green transition.

Job description

This PhD focuses on optimizing the energy efficiency of a geothermal system in Draškovec (Croatia), whose fluids mainly contain methane (CH₄) and carbon dioxide (CO₂). The main objective is to control and enhance the biological conversion of dissolved CO₂ into CH₄ using microorganisms in a surface bioreactor. These microorganisms may be naturally occurring (from geothermal fluids) or selected in the laboratory. The extreme reservoir conditions (up to 250 bar and 100 °C), as well as those related to geothermal operations, strongly influence these biological processes. A detailed understanding of microbial requirements (temperature, pressure, nutrients) is therefore essential to optimize methanogenesis.
A second objective is to assess the impact of CO₂ reinjection—resulting from methane combustion—on deep microbial communities and geochemical equilibria, as well as to investigate the fate of this CO₂, including its potential mineralization through biogeochemical processes.
The PhD addresses several scientific questions: identification of microbial communities under extreme conditions, understanding methane production pathways from CO₂, evaluating the effects of CO₂ reinjection on deep ecosystems and its mineralization, and integrating these biological processes into geothermal systems.
The work begins with geochemical and microbiological characterization of the reservoir through water and rock sampling campaigns. These analyses will identify microbial communities and provide samples for laboratory experiments, in collaboration with industrial and academic partners. In parallel, methanogenic microorganisms adapted to site conditions will be selected.
The second phase involves laboratory experiments to assess methane production under varying conditions (temperature, pH, salinity). The most promising strains will be studied in detail to determine their nutritional needs and performance drivers. CO₂ mineralization pathways will also be explored.
Finally, results will be integrated through pilot tests and geochemical simulations to evaluate the feasibility of coupling methane production with CO₂ reinjection under real conditions.
Expected outcomes include improved knowledge of deep microbial ecosystems, identification of optimal conditions for CO₂-to-CH₄ conversion, and insights into CO₂ mineralization mechanisms. This project opens new perspectives for combining geothermal energy, renewable gas production, and carbon storage.
The full PhD position is available on the Euraxess website: https://euraxess.ec.europa.eu/jobs/410970

Profile

Requested start date: 2026-09-01
Education: Master's degree
You will demonstrate the following skills and qualities:
- Ability to design and carry out laboratory experimental tests and conduct fieldwork ;
- Strong knowledge in microbiology and geochemistry ;
- Ability to work effectively in multidisciplinary teams ;
- Strong communication skills to present and promote research results ;
- Initiative and proactive mindset ;
- Ability to work independently in organizing daily tasks while also integrating into a multidisciplinary team ;
- Good communication and interpersonal skills, regardless of group size (internally or with clients) ;
- Proficiency in English (reading, writing, and speaking) ;
Although not mandatory, the following skills would be considered an asset:
- Experience conducting experiments under anoxic conditions and/or controlled pressure and temperature conditions ;
- Microorganism characterization techniques, particularly DNA-based methods (PCR, sequencing) ;
- Bioinformatics and statistical analysis of community DNA data and field-related datasets ;
- Knowledge of water and gas analysis techniques

Working conditions

The PhD will be mainly based at BRGM (Orléans, France), with several international secondments: at HGI-CGS (Croatia, Jan–May 2028) for field sampling; at GFZ (Germany, Aug–Nov 2028) for CO₂ biomineralization experiments under reservoir conditions; and at AATG (Croatia, Mar–May 2028) to validate or upscale the CO₂ conversion process.
The candidate will join the MiningBrines Marie Skłodowska-Curie Doctoral Network, benefiting from interdisciplinary training, international mobility, and access to state-of-the-art facilities. The position includes a competitive salary, social security, and coverage of research and travel expenses.
The role involves regular travel in France and abroad. BRGM offers a supportive work environment with work-life balance, career development opportunities, and benefits (leave, catering, leisure activities). Committed to diversity and holding the HRS4R label, BRGM ensures a transparent recruitment process. Applications (CV and cover letter) are due by April 30, 2026, followed by interviews with a scientific and HR panel.

Position location

Job location

France, Centre-Val de Loire, Loiret (45)

Location