HySelect – Deliverable D2.1: Subsystems Requirements for Solar Platform Testing

HySelect – Deliverable D2.1: Subsystems Requirements for Solar Platform Testing

This public deliverable was developed within Work Package 2 (WP2) of the European research project HySelect – Efficient water splitting via a flexible solar-powered Hybrid thermochemical-Sulphur dioxide depolarized Electrolysis Cycle (Grant Agreement No. 101101498).

The report presents the process analysis and preliminary system requirements for integrating the main subsystems of a solar-powered Hybrid Sulphur (HyS) cycle for renewable hydrogen production. The work, led by the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), evaluates alternative process configurations and defines the technical and operational basis for the HySelect demonstration plant.

The analysis considers energy efficiency, technical feasibility, material compatibility, controllability and the challenges associated with intermittent solar energy supply.

The main topics addressed include:

• Sulphuric acid decomposition (SAD) and sulphur trioxide splitting (STS): Evaluation of reactor concepts, operating temperatures, reaction conditions and thermal integration.
• SO2 separation and storage: Assessment of alternative separation technologies, including absorption, liquefaction, pressure/temperature swing adsorption and membrane separation.
• SO2-depolarized electrolysis (SDE): Analysis of process requirements and operating conditions for electrochemical hydrogen production.
• Sulphuric acid concentration: Comparison of evaporation and distillation technologies, including heat recovery opportunities and selection of suitable concentration processes.
• Process simulation and energy analysis: Aspen Plus modelling, thermodynamic analysis and calculation of material and energy balances for the main process sections.
• Preliminary demonstration plant configuration: Definition of the initial process scheme, subsystem interfaces, operating requirements and preliminary process flow diagram.
• Operating and control strategy: Development of preliminary control concepts to coordinate intermittent solar thermal energy supply, thermal storage and hydrogen production.
• Preliminary plant sizing: Evaluation of alternative operating scenarios and subsystem capacity requirements for the solar-powered demonstration plant.

Main results: The study identifies promising process configurations for the HySelect demonstration plant, including high-temperature sulphuric acid decomposition using particle-based solar heating, SO2/O2 separation by compression and liquefaction, and multi-effect evaporation for sulphuric acid concentration.

A preliminary integrated plant configuration is established, including mass and energy balances, subsystem sizing requirements and operating strategies. The evaluated operating scenarios indicate a calculated solar-to-fuel efficiency above 12%, providing a technical basis for subsequent process design, optimisation and control system development.

The results support the integration of the HySelect subsystems into a complete solar-driven hydrogen production process and provide essential inputs for the detailed plant layout, process flow diagram and control strategy.

Document information

• Project: HySelect
• Deliverable: D2.1 – Subsystems Requirements for Solar Platform Testing
• Work Package: WP2 – Process design, simulation and techno-economics
• Lead beneficiary: ENEA
• Actual delivery date: 31 December 2023
• Dissemination level: Public
• Grant Agreement: 101101498
• Funding: Clean Hydrogen Partnership / European Union
• DOI: https://doi.org/10.5281/zenodo.17515252
• Project website: https://hyselect.eu/
• Project resources: https://hyselect.eu/resources/