Circular Bioeconomy Systems
- Title:
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Circular Bioeconomy Systems
- Funding Body:
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Research Ireland
- Coordinator:
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Dr. Richard O’Shea
- Research Area:
Introduction
The optimization of circular bioeconomy systems with a focus on Power to X to valorise renewable electricity is required to maximise the value of surplus renewable electricity and biogenic CO2. Surplus renewable electricity will be produced in a future with large scale deployment of variable renewable generators (such as onshore and offshore wind). Biogenic CO2 is a by-product of biomethane production via the upgrading of biogas from anaerobic digestion (a key player in the circular bioeconomy).
Renewable electricity may be used to produce hydrogen via water electrolysis, this hydrogen may be used directly as a fuel, or, as a reagent for the synthesis of higher value fuels and chemicals when combined with biogenic CO2. Microbial processes to convert hydrogen and CO2 into compounds including but not limited to methane, acetic acid, and caproic acid are of great interest in maximising the value of surplus renewable electricity.
Work packages which may be completed as part of this project include Planned experimental work with the H₂ biomethanation rig will focus on developing an optimised ex-situ biological methanation process capable of high methane yields and stable long-term performance under realistic operating conditions. The research aims to investigate how hydrogen mass transfer, microbial activity, and operational conditions influence methane production efficiency, with a strong emphasis on optimising the key process variables that govern reactor performance. This includes systematic screening of gas-phase composition (H₂:CO₂ ratios), temperature and pH settings, microbial abundance and enrichment strategies, trace-metal supplementation levels, nutrient balance, and the system’s resilience to fluctuating and intermittent hydrogen supply. Each of these factors directly affect hydrogen uptake kinetics, metabolic activity of hydrogenotrophic methanogens, and the overall robustness of the biomethanation process. By investigating these parameters individually and in combination, the work package will identify operational windows that maximise methane productivity while ensuring reactor stability under variable renewable energy condition.
Summary
The experimental programme will proceed through several structured stages. The initial stage will establish baseline reactor behaviour under controlled H₂:CO₂ ratios, defined temperature and pH, and standardised inoculum preparation. This ensures reproducible starting conditions for all optimisation studies. The next stage will target parameter optimisation by adjusting gas composition, temperature, and pH, followed by controlled supplementation of trace metals and nutrients to evaluate their influence on hydrogen uptake and methanogenic activity. Microbial community responses including changes in abundance and enrichment of hydrogenotrophic methanogens will be assessed to refine strategies that maintain stable biomass and high methane conversion rates.
A further stage will test reactor resilience by introducing intermittent and fluctuating hydrogen supply to mimic realistic renewable-driven Power-to-Gas conditions. This will provide insight into dormancy and reactivation behaviour, community robustness, and the capacity of the system to maintain performance during variable H₂ availability. The final stage will integrate the optimised conditions into a continuous-operation framework, generating high-quality data to support the scale-up and development of next-generation biomethanation frameworks
