Petronilla Fragiacomo

The expansion of hydrogen storage and distribution infrastructure demands elastomeric seals that maintain integrity under high pressure, thermal variations, pressure cycling, and rapid decompression. Hydrogen permeation, swelling, mechanical degradation, and gas-induced damage can impair sealing performance and increase leakage risk. This review examines elastomeric hydrogen seals from a component-level perspective, building on material characterization to assess how formulation, operating conditions, and seal design affect reliability. The literature is organized around elastomer formulations, hydrogen transport and property evolution, degradation and durability, and seal performance, numerical modeling, and qualification. Particular emphasis is placed on the interaction between hydrogen uptake and desorption, dimensional recovery, contact-pressure retention, groove geometry, squeeze, extrusion, and rapid gas decompression resistance. Seal failure results from coupled processes, including swelling, cavitation, blistering, crack growth, fatigue, aging, and loss of sealing contact. Existing qualification methods remain fragmented and do not consistently represent realistic hydrogen exposure and service cycles. More reliable seal design and lifetime prediction require standardized testing protocols and integrated experimental–numerical assessments connecting material behavior with component-level leakage and durability.

Proton-exchange-membrane reversible fuel cells (rPEM) are emerging as key technologies for integrated hydrogen-based energy storage systems, enabling both electricity generation and hydrogen production within a single electrochemical device. However, the transition from laboratory-scale characterization to system-level deployment requires a consistent framework linking electrochemical modeling, parameter calibration, and system design. In this work, a semi-empirical electrochemical model of an rPEM cell is developed and calibrated against literature experimental data in both fuel cell (FC) and water electrolysis (WE) modes. The calibrated model achieves high predictive accuracy, with coefficients of determination exceeding 0.997. The validated model is subsequently extended to a preliminary system-level design, enabling the development of a 100 kW reversible PEM system coupled with a 300 kW electrolyzer configuration. The proposed system features symmetric hydrogen flow (6 kg h⁻¹), a 200 kWh hydrogen storage buffer, and operating conditions of 2.5 bar/70 °C in FC mode and 30 bar/65 °C in WE mode. Thermal effects and efficiency trends are analyzed, highlighting the critical role of heat management and balance of plant proposed design. The proposed methodology provides a consistent framework for scaling rPEM technology toward industrial applications.

This paper provides a comprehensive review of Type IV hydrogen tanks, with a focus on materials, manufacturing technologies and structural issues related to high-pressure hydrogen storage. Recent advances in the use of advanced composite materials, such as carbon fibers and polyamide liners, useful for improving mechanical strength and permeability, have been reviewed. The present review also discusses solutions to reduce hydrogen blistering and embrittlement, as well as exploring geometric optimization methodologies and manufacturing techniques, such as helical winding. Additionally, emerging technologies, such as integrated smart sensors for real-time monitoring of tank performance, are explored. The review concludes with an assessment of future trends and potential solutions to overcome current technical limitations, with the aim of fostering a wider adoption of Type IV tanks in mobility and stationary applications.

The objective of this paper is to study and analyze an integrated anaerobic digester (AD)–solid oxide fuel cell (SOFC) system, to achieve an energy-efficient waste-to-energy solution. A detailed numerical modeling is developed for plant dimensioning and energy evaluations. The calculation pathway involves determining operational parameters based on specific variables such as the net electric power produced by the SOFC system or the amount of biogas produced by the AD. Three types of biomass—sewage sludge, slaughter waste, and the organic fraction of municipal solid waste (OFMSW)—are considered. The reactor volume required is approximately 24,000 m³ per 1 kg/s of biogas, processing a daily organic substrate of around 900 m³. The calculations reveal a SOFC electric efficiency of 51% and a thermal efficiency of 39%, under the most favorable conditions. In the integrated AD-SOFC layout, net electrical and thermal efficiencies of 47% and 35%, respectively, are achieved. The economic analysis evaluates the investment feasibility under current incentive schemes, considering both the standalone sale of biomethane and the sale of electricity and thermal energy through SOFC integration. A case study evaluates a biomethane facility producing 508 Sm³/h, integrated with an SOFC system capable of generating 2.36 MW_el and 1.74 MW_th of electric and thermal powers. Various scenarios are examined using net present value (NPV) and payback period (PB) analyses. Results show that the PB for the biomethane-only case is 6.46 years. When integrating the SOFC system, the PB is slightly longer—6.58 years in the most favorable scenario—while it increases to 11.55 years under the most likely scenario.