Publications

: The global demand for energy and the need to mitigate climate change require a shift from traditional fossil fuels to sustainable and renewable energy alternatives. Hydrogen is recognized as a significant component for achieving a carbon-neutral economy. This comprehensive review examines the underground hydrogen storage and particularly laboratory-scale studies related to rock– hydrogen interaction exploring current knowledge. Using bibliometric analysis of data from the Scopus and Web of Science databases this study reveals an exponential increase in scientific publications post-2015 which accounts for approximately 85.26% of total research output in this field and the relevance of laboratory experiments to understand the physicochemical interactions of hydrogen with geological formations. Processes in underground hydrogen storage are controlled by a set of multi-scale parameters including solid properties (permeability porosity composition and geomechanical properties) and fluid properties (liquid and gas density viscosity etc.) together with fluid–fluid and solid–fluid interactions (controlled by solubility wettability chemical reactions etc.). Laboratory experiments aim to characterize these parameters and their evolution simulating real-world storage conditions to enhance the reliability and applicability of findings. The review emphasizes the need to expand research efforts globally to comprehensively address the currently existing issues and knowledge gaps.

Hydrogen recombination catalyst is useful tool for reducing hydrogen in closed area. The catalyst is known to be poisoned under wet condition in long time use. The study is focused on the behavior of pre-oxidized Pd nanoparticle as the hard-used catalyst in high humidity environment by comparison of alumina and titanium oxide supports using in situ X-ray absorption spectroscopy technique. The reduction of surface oxide layer of Pd/TiO2 was promoted by water during hydrogen recombination although the reduction reaction of Pd/Al2O3 was inhibited by water.

The transformation of fossil fuel-based power generation systems towards greenhouse gas-neutral ones based on renewable energy sources is one of the key challenges facing contemporary society. The temporal volatility that accompanies the integration of renewable energy (e.g. solar radiation and wind) must be compensated to ensure that at any given time a sufficient supply of electrical energy for the demands of different sectors is available. Green hydrogen which is produced using renewable energy sources via electrolysis can be used to chemically store electrical energy on a seasonal basis. Reconversion technologies are needed to generate electricity from stored hydrogen during periods of low renewable electricity generation. This study presents a detailed technoeconomic assessment of hydrogen gas turbines. These technologies are also superior to fuel cells due to their comparatively low investment costs especially when it comes to covering the residual loads. As of today hydrogen gas turbines are only available in laboratory or small-scale settings and have no market penetration or high technology readiness level. The primary focus of this study is to analyze the effects on gas turbine component costs when hydrogen is used instead of natural gas. Based on these findings an economic analysis addressing the current state of these turbine components is conducted. A literature review on the subsystems is performed considering statements from leading manufactures and researchers to derive the cost deviations and total cost per installed capacity (€/kWel). The results reveal that a hydrogen gas turbine power plant has an expected cost increase of 8.5% compared to a conventional gas turbine one. This leads to an average cost of 542.5 €/kWel for hydrogen gas turbines. For hydrogen combined cycle power plants the expected cost increase corresponds to the cost of the gas turbine system as the steam turbine subsystem remains unaffected by fuel switching. Additionally power plant retrofit potentials were calculated and the respective costs in the case of an upgrade were estimated. For Germany as a case study for an industrialized country the potential of a possible retrofit is between 2.7 and 11.4 GW resulting to a total investment between 0.3 and 1.1 billion €.

One of the most important problems in the widespread use of electric vehicles is the lack of charging infrastructure. Especially in tourist areas where historical buildings are located the installation of a power grid for the installation of electric vehicle charging stations or generating electrical energy by installing renewable energy production systems such as large-sized PV (photovoltaic) and wind turbines poses a problem because it causes the deterioration of the historical texture. Considering the need for renewable energy sources in the transportation sector our aim in this study is to model an electric vehicle charging station using PVPS (photovoltaic power system) and FC (fuel cell) power systems by using irradiation and temperature data from historical regions. This designed charging station model performs electric vehicle charging meeting the energy demand of a house and hydrogen production by feeding the electrolyzer with the surplus energy from producing electrical energy with the PVPS during the daytime. At night when there is no solar radiation electric vehicle charging and residential energy demand are met with an FC power system. One of the most important advantages of this system is the use of hydrogen storage instead of a battery system for energy storage and the conversion of hydrogen into electrical energy with an FC. Unlike other studies in our study fossil energy sources such as diesel generators are not included for the stable operation of the system. The system in this study may need hydrogen refueling in unfavorable climatic conditions and the energy storage capacity is limited by the hydrogen fuel tank capacity.

In response to the European Union’s initiative toward achieving carbon neutrality the utilization of water electrolysis for hydrogen production has emerged as a promising avenue for decarbonizing current energy systems. Among the various approaches Solid Oxide Electrolysis Cell (SOEC) presents an attractive solution especially due to its potential to utilize impure water sources. This study focuses on modeling a SOEC supplied with four distinct streams of treated municipal wastewaters using the Aspen Plus software. Through the simulation analysis it was determined that two of the wastewater streams could be effectively evaporated and treated within the cell without generating waste liquids containing excessive pollutant concentrations. Specifically by evaporating 27% of the first current and 10% of the second it was estimated that 26.2 kg/m3 and 9.7 kg/m3 of green hydrogen could be produced respectively. Considering the EU’s target for Italy is to have 5 GW of installed power capacity by 2030 and the mass flowrate of the analyzed wastewater streams this hydrogen production could meet anywhere from 0.4% to 20% of Italy’s projected electricity demand.

In the context of “dual carbon” restrictions on carbon emissions have aĴracted widespread aĴention from researchers. In order to solve the issue of the insufficient exploration of the synergistic emission reduction effects of various low-carbon policies and technologies applied to multiple microgrids we propose a multi-microgrid electricity cooperation optimization scheduling strategy based on stepped carbon trading a hydrogen-doped natural gas system and P2G–CCS coupled operation. Firstly a multi-energy microgrid model is developed coupled with hydrogendoped natural gas system and P2G–CCS and then carbon trading and a carbon emission restriction mechanism are introduced. Based on this a model for multi-microgrid electricity cooperation is established. Secondly design optimization strategies for solving the model are divided into the dayahead stage and the intraday stage. In the day-ahead stage an improved alternating direction multiplier method is used to distribute the model to minimize the cooperative costs of multiple microgrids. In the intraday stage based on the day-ahead scheduling results an intraday scheduling model is established and a rolling optimization strategy to adjust the output of microgrid equipment and energy purchases is adopted which reduces the impact of uncertainties in new energy output and load forecasting and improves the economic and low-carbon operation of multiple microgrids. SeĴing up different scenarios for experimental validation demonstrates the effectiveness of the introduced low-carbon policies and technologies as well as the effectiveness of their synergistic interaction

Hydrogen produced from renewable energy is being promoted to decarbonise global energy systems. To support this energy transition standards certification and labelling schemes (SCLs) aim to differentiate hydrogen products based on their system-wide carbon emissions and method of production characteristics. However being certified as low-carbon clean or green hydrogen does not guarantee broader sustainability across economic environmental social or governance dimensions. Through an international survey of energy-sector and sustainability professionals (n = 179) we investigated the desirable sustainability features for renewable hydrogen SCLs and the perceived advantages and disadvantages of sustainability certification. Our mixed-method study revealed general accordance on the feasible inclusion of diverse sustainability criteria in SCLs albeit with varying degrees of perceived essentiality. Within the confines of the data some differences in viewpoints emerged based on respondents’ geographical and supply chain locations which were associated with the sharing of costs and benefits. Qualitatively respondents found the idea of SCL harmonisation attractive but weighed this against the risks of duplication complicated administrative procedures and contradictory regulation. The implications of this research centre on the need for further studies to inform policy recommendations for an overarching SCL sustainability framework that embodies the principles of harmonisation in the context of multistakeholder governance.

Hydrogen storage is crucial to developing secure renewable energy systems to meet the European Union’s 2050 carbon neutrality objectives. However a knowledge gap exists concerning the site-specific performance and economic viability of utilizing underground gas storage (UGS) sites for hydrogen storage in Europe. We compile information on European UGS sites to assess potential hydrogen storage capacity and evaluate the associated current and future costs. The total hydrogen storage potential in Europe is 349 TWh of working gas energy (WGE) with site-specific capital costs ranging from $10 million to $1 billion. Porous media and salt caverns boasting a minimum storage capacity of 0.5 TWh WGE exhibit levelized costs of $1.5 and $0.8 per kilogram of hydrogen respectively. It is estimated that future levelized costs associated with hydrogen storage can potentially decrease to as low as $0.4 per kilogram after three experience cycles. Leveraging these techno-economic considerations we identify suitable storage sites.

In the framework of the “Multidisciplinary Optimization and Regulations for Low-boom and Environmentally Sustainable Supersonic aviation” project pursued by a consortium of European government and academic institutions coordinated by Politecnico di Torino under the European Commission Horizon 2020 financial support the Italian Aerospace Research Centre is computationally investigating the high-pressure hydrogen/air kinetic combustion in the operative conditions typically encountered in supersonic aeronautic ramjet engines. This task is being carried out starting from the zero-dimensional and one-dimensional chemical kinetic assessment of the complex and strongly pressure-sensitive ignition behavior and flame propagation characteristics of hydrogen combustion through the validation against experimental shock tube and laminar flame speed measurements. The 0D results indicate that the kinetic mechanism by Politecnico di Milano and the scheme formulated by Kéromnès et al. provide the best matching with the experimental ignition delay time measurements carried out in high-pressure shock tube strongly argon-diluted reaction conditions. Otherwise the best behavior in terms of laminar flame propagation is achieved by the Mueller scheme while the other investigated kinetic mechanisms fail to predict the flame speeds at elevated pressures. This confirms the non-linear and intensive pressure-sensitive behavior of hydrogen combustion especially in the critical high-pressure and low-temperature region which is hard to be described by a single all-encompassing chemical model.

The concept of underground gas storage is based on the natural capacity of geological formations such as aquifers depleted oil and gas reservoirs and salt caverns to store gases. Underground storage systems can be used to inject and store natural gas (NG) or hydrogen which can be withdrawn for transport to end-users or for use in industrial processes. Geological formations can additionally be used to securely contain harmful gases such as carbon dioxide deep underground by means of carbon capture and sequestration technologies. This paper defines and discusses underground gas storage highlighting commercial and pilot projects and the behavior of different gases (i.e. CH4 H2 and CO2) when stored underground as well as associated modeling investigations. For underground NG/H2 storage the maintenance of optimal subsurface conditions for efficient gas storage necessitates the use of a cushion gas. Cushion gas is injected before the injection of the working gas (NG/H2). The behavior of cushion gas varies based on the type of gas injected. Underground NG and H2 storage systems operate similarly. However compared to NG storage several challenges could be faced during H2 storage due to its low molecular mass. Underground NG storage is widely recognized and utilized as a reference for subsurface H2 storage systems. Furthermore this paper defines and briefly discusses carbon capture and sequestration underground. Most reported studies investigated the operating and cushion gas mixture. The mixture of operating and cushion gas was studied to explore how it could affect the recovered gas quality from the reservoir. The cushion gas was shown to influence the H2 capacity. By understanding and studying the different underground system technologies future directions for better management and successful operation of such systems are thereby highlighted.