Italy

The transition to cleaner energy sources particularly in hard-to-abate industrial sectors often requires the gradual integration of new technologies. Hydrogen crucial for decarbonization is explored as a fuel in blended combustions. Blending or replacing fuels impacts combustion stability and heat transfer rates due to differing densities. An extensive literature review examines blended combustion focusing on hydrogen/methane mixtures. While industrial burners claim to accommodate up to 20% hydrogen theoretical support is lacking. A novel thermodynamic analysis methodology is introduced evaluating methane/hydrogen combustion using the Wobbe index. The findings highlight practical limitations beyond 25% hydrogen volume necessitating a shift to “totally hydrogen” combustion. Blended combustion can be proposed as a medium-term strategy acknowledging hydrogen’s limited penetration. Higher percentages require burner and infrastructure redesign.

A promising energy carrier and storage solution for integrating renewable energies into the power grid currently being investigated is hydrogen produced via electrolysis. It already serves various purposes but it might also enable the development of hydrogen-based electricity storage systems made up of electrolyzers hydrogen storage systems and generators (fuel cells or engines). The adoption of hydrogen-based technologies is strictly linked to the electrification of end uses and to multicarrier energy grids. This study introduces a generic method to integrate and optimize the sizing and operation phases of hydrogen-based power systems using an energy hub optimization model which can manage and coordinate multiple energy carriers and equipment. Furthermore the uncertainty related to renewables and final demands was carefully assessed. A case study on an urban microgrid with high hydrogen demand for mobility demonstrates the method’s applicability showing how the multi-objective optimization of hydrogen-based power systems can reduce total costs primary energy demand and carbon equivalent emissions for both power grids and mobility down to  −145%. Furthermore the adoption of the uncertainty assessment can give additional benefits allowing a downsizing of the equipment.

In recent years there has been a significant increase in research on hydrogen due to the urgent need to move away from carbon-intensive energy sources. This transition highlights the critical role of hydrogen storage technology where hydrogen tanks are crucial for achieving cleaner energy solutions. This paper aims to provide a general overview of hydrogen treatment from a mechanical viewpoint and to create a comprehensive review that integrates the concepts of hydrogen safety and storage. This study explores the potential of hydrogen applications as a clean energy alternative and their role in various sectors including industry automotive aerospace and marine fields. The review also discusses design technologies safety measures material improvements social impacts and the regulatory landscape of hydrogen storage tanks and safety technology. This work provides a historical literature review up to 2014 and a systematic literature review from 2014 to the present to fill the gap between hydrogen storage and safety. In particular a fundamental feature of this work is leveraging systematic procedural techniques for performing an unbiased review study to offer a detailed analysis of contemporary advancements. This innovative approach differs significantly from conventional review methods since it involves a replicable scientific and transparent process which culminates in minimizing bias and allows for highlighting the fundamental issues about the topics of interest and the main conclusions of the experts in the field of reference. The systematic approach employed in the paper was used to analyze 55 scientific articles resulting in the identification of six primary categories. The key findings of this review work underline the need for improved materials enhanced safety protocols and robust infrastructure to support hydrogen adoption. More importantly one of the fundamental results of the present review analysis is pinpointing the central role that composite materials will play during the transition toward hydrogen applications based on thin-walled industrial vessels. Future research directions are also proposed in the paper thereby emphasizing the importance of interdisciplinary collaboration to overcome existing challenges and facilitate the safe and efficient use of hydrogen.

This study presents and analyses three plant configurations of the Ocean Thermal Energy Conversion (OTEC) technology. All the solutions are based on using the OTEC system to obtain hydrogen through an electrolyzer. The hydrogen is then compressed and stored. In the first and second layouts a Rankine cycle with ammonia and a mixture of water and ethanol is utilised respectively; in the third layout a Kalina cycle is considered. In each configuration the OTEC cycle is coupled with a polymer electrolyte membrane (PEM) electrolyzer and the compression and storage system. The water entering the electrolyzer is pre-heated to 80 ◦C by a solar collector. Energy exergy and exergo-economic studies were conducted to evaluate the cost of producing compressing and storing hydrogen. A parametric analysis examining the main design constraints was performed based on the temperature range of the condenser the mass flow ratio of hot and cold resource flows and the mass fraction. The maximum value of the overall exergy efficiency calculated is equal to 93.5% for the Kalina cycle and 0.524 €/kWh is the minimum cost of hydrogen production achieved. The results were compared with typical data from other hydrogen production systems.

The road transport sector is one of the major contributors to greenhouse gas emissions as it still largely relies on traditional powertrain solutions. While some progress has been made in the passenger car sector with the diffusion of battery electric vehicles heavy-duty transport remains predominantly dependent on diesel internal combustion engines. This research aims to evaluate and compare three potential solutions for the decarbonisation of heavy-duty freight transport from an economic perspective: Battery Electric Trucks (BETs) Fuel Cell Electric Trucks (FCETs) and Hydrogen-fuelled Internal Combustion Engine Trucks (H2ICETs). The study focuses on the Finnish market and road network where affordable and low-carbon electricity creates an ideal environment for the development of alternative powertrain vehicles. The analysis employs the Total Cost of Ownership (TCO) method which allows for a comprehensive assessment of all cost components associated with the vehicles throughout their entire lifecycle encompassing both initial expenses and operational costs. Among the several factors affecting the results the impact of the three powertrain technologies on the admissible payloads has been taken into account. The study specifically focuses on the costs directly incurred by the truck owner. Additionally to evaluate the cost effectiveness of the proposed powertrain technologies under different scenarios a sensitivity analysis on electricity and hydrogen prices is conducted. The outcomes of this study reveal that no single powertrain solution emerges as universally optimal as the most cost-effective choice depends strongly on the truck type and its use (i.e. daily mileage). For relatively small trucks (18 t) covering short driving distances (approximately 100 to 200 km/day) BETs prove to be the best solution due to their higher efficiency and lower vehicle costs compared to FCETs. Conversely for larger trucks (42 and 76 t) engaged in longer hauls (>300 km/day) H2ICETs exhibit larger cost benefits due to their lower vehicle costs among the three options under investigation. Finally for small trucks (18 t) travelling long distances (200 km/day or more) FCETs represent a competitive choice due to their high efficiency and costeffective energy storage system. Considering future advancements in FCETs and BETs in terms of improved performance and reduced investment cost the fuel cell-based solution is expected to emerge as the best option across various combinations of truck sizes and daily mileages.

To reduce the impact of the agricultural sector on the environment human health and resource depletion several steps should be taken to develop innovative powertrain systems. The agricultural sector must be involved in this innovation since diesel-powered tractors are an important source in terms of pollution. In this context fuel-cell systems have gained importance making them one of the possible substitutes due to their characteristics featuring almost zero local emissions low refueling time and high efficiency. However to effectively assess the sustainability of a fuel-cell tractor a cradle-to-grave life cycle assessment comprising production use phase and end of life must be performed. This article presents a comparative analysis according to different impact categories of the life cycle impacts of a traditional diesel-powered tractor and a fuel-cell hybrid tractor designed considering operative requirements and functional constraints. The study was conducted according to the LCA technique (defined by ISO 14040 and ISO 14044 standards) combining secondary data mainly derived from studies and reports available in the literature with the use of the Ecoinvent 3.0 database. The results are presented according to ten different impact categories defined by ReCiPe 2016 v 1.03 at the midpoint level. The findings obtained showed that the fuel-cell tractor allows for a relevant reduction in all the considered categories. The highest-impact reduction more than 92% was obtained in the human toxicity non-carcinogenic category while the lowest reduction around 4.55% was observed for the fossil fuel scarcity category mainly due to the adoption of gray hydrogen which is produced from fossil fuels. As for the climate change category the fuel-cell tractor showed a reduction of more than 34% in the life cycle impact. Finally the authors also considered the case of green hydrogen produced using solar energy. In this case further reductions in the impact on climate change and fossil fuel resource depletion were obtained. However for the other impact categories the results were worse compared to using gray hydrogen.

For centuries fossil fuels have been the primary energy source but their unchecked use has led to significant environmental and economic challenges that now shape the global energy landscape. The combustion of these fuels releases greenhouse gases which are critical contributors to the acceleration of climate change resulting in severe consequences for both the environment and human health. Therefore this article examines the potential of hydrogen as a sustainable alternative energy source capable of mitigating these climate impacts. It explores the properties of hydrogen with particular emphasis on its application in industrial burners and furnaces underscoring its clean combustion and high energy density in comparison to fossil fuels and also examines hydrogen production through thermochemical and electrochemical methods covering green gray blue and turquoise pathways. It discusses storage and transportation challenges highlighting methods like compression liquefaction chemical carriers (e.g. ammonia) and transport via pipelines and vehicles. Hydrogen combustion mechanisms and optimized burner and furnace designs are explored along with the environmental benefits of lower emissions contrasted with economic concerns like production and infrastructure costs. Additionally industrial and energy applications safety concerns and the challenges of large-scale adoption are addressed presenting hydrogen as a promising yet complex alternative to fossil fuels.

In the last few decades the problem of pollution resulting from human activities has pushed research toward zero or net-zero carbon solutions for transportation. The main objective of this paper is to perform a preliminary performance assessment of the use of hydrogen in conventional turbine engines for aeronautical applications. A 0-D dynamic model of the Allison 250 C-18 turboshaft engine was designed and validated using conventional aviation fuel (kerosene Jet A-1). A dedicated experimental campaign covering the whole engine operating range was conducted to obtain the thermodynamic data for the main engine components: the compressor lateral ducts combustion chamber high- and low-pressure turbines and exhaust nozzle. A theoretical chemical combustion model based on the NASA-CEA database was used to account for the energy conversion process in the combustor and to obtain quantitative feedback from the model in terms of fuel consumption. Once the engine and the turbomachinery of the engine were characterized the work focused on designing a 0-D dynamic engine model based on the engine’s characteristics and the experimental data using the MATLAB/Simulink environment which is capable of replicating the real engine behavior. Then the 0-D dynamic model was validated by the acquired data and used to predict the engine’s performance with a different throttle profile (close to realistic request profiles during flight). Finally the 0-D dynamic engine model was used to predict the performance of the engine using hydrogen as the input of the theoretical combustion model. The outputs of simulations running conventional kerosene Jet A-1 and hydrogen using different throttle profiles were compared showing up to a 64% reduction in fuel mass flow rate and a 3% increase in thermal efficiency using hydrogen in flight-like conditions. The results confirm the potential of hydrogen as a suitable alternative fuel for small turbine engines and aircraft.

Green hydrogen production and storage are vital in mitigating carbon emissions and sustainable transition. However the high investment cost and management requirements are the bottleneck of utilizing hybrid hydrogen-based systems in microgrids. Given the necessity of cost-effective and optimal design of these systems the present study examines techno-economic feasibility of integrating hybrid hydrogen-based systems into an outdoor test facility. With this perspective several solar-driven hybrid scenarios are introduced at two energy storage levels namely the battery and hydrogen energy storage systems including the high-pressure gaseous hydrogen and metal hydride storage tanks. Dynamic simulations are carried out to address subtle interactions in components of the hybrid system by establishing a TRNSYS model coupled to a Fortran code simulating the metal hydride storage system. The OpenStudio-EnergyPlus plugin is used to simulate the building load validate against experimental data according to the measured data and monitored operating conditions. Aimed at enabling efficient integration of energy storage systems a techno-enviro-economic optimization algorithm is developed to simultaneously minimize the levelized cost of the electricity and maximize the CO2 mitigation in each proposed hybrid scenario. The results indicate that integrating the gaseous hydrogen and metal hydride storages into the photovoltaic-alone scenario enhances 22.6% and 14.4% of the annual renewable factor. Accordingly the inclusion of battery system to these hybrid scenarios gives a 30.4% and 20.3 % boost to the renewable factor value respectively. Although the inclusion of battery energy storage into the hybrid systems increases the renewable factor the results imply that it reduces the hydrogen production rate via electrolysis. The optimized values of the levelized cost of electricity and CO2 emission for different scenarios vary in the range of 0.376–0.789 $/kWh and 6.57–9.75 ton respectively. The multi-criteria optimizations improve the levelized cost of electricity and CO2 emission by up to 46.2% and 11.3% with respect to their preliminary design.

The transport sector heavily relies on the use of fossil fuels which are causing major environmental concerns. Solutions relying on the direct or indirect use of electricity through efuel production are emerging to power the transport sector. To ensure environmental benefits are achieved over this transition an accurate estimation of the impact of the use of electricity is needed. This requires a high temporal resolution to capture the high variability of electricity. This paper presents a previously unseen temporal analysis of the carbon intensity of e-fuels using grid electricity in countries that are members of the European Network of Transmission System Operators (ENTSO-E). It also provides an estimation of the potential load factor for producing low-carbon e-fuels according to the European Union legislative framework. This was achieved by building on top of the existing EcoDynElec tool to develop EcoDynElec_xr a python tool enabling—with an hourly time resolution—the calculation visualisation and analysis of the historical time-series of electricity mixing from the ENTSO-E. The results highlight that in 2023 very few European countries were reaching low carbon intensity for electricity that enables the use of grid electricity for the production of green electrolytic hydrogen. The methodological assumptions consider the consumption of the electricity mix instead of the production mix and the considered time step is of paramount importance and drastically impacts the potential load factor of green hydrogen production. The developed tools are released under an open-source license to ensure transparency result reproducibility and reuse regarding newer data for other territories or for other purposes.