Publications

With the development of an energy sector based on renewable primary sources structural changes are emerging for the entire national energy system. Initially it was estimated that energy generation based on fossil fuels would decrease until its disappearance. However the evolution of CO2 capture capacity leads to a possible coexistence for a certain period with the renewable energy sector. The paper develops this concept of the coexistence of the two systems with the positioning of green hydrogen not only within the renewable energy sector but also as a transformation vector for carbon dioxide captured in the form of synthetic fuels such as CH4 and CH3OH. The authors conducted pilot-scale research on CO2 capture with green H2 both for pure (captured) CO2 and for CO2 found in combustion gases. The positive results led to the respective recommendation. The research conducted by the authors meets the strict requirements of the current energy phase with the authors considering that wind and solar energy alone are not sufficient to meet current energy demand. The paper also analyzes the economic aspects related to price differences for energy produced in the two sectors as well as their interconnection. The technical aspect as well as the economic aspect of storage through various other solutions besides hydrogen has been highlighted. The development of the renewable energy sector and its demarcation from the fossil fuel energy sector even with the transcendent vector represented by green hydrogen leads to the deepening of dispersion aspects between the electricity sector and the thermal energy sector a less commonly mentioned aspect in current works but of great importance. The purpose of this paper is to highlight energy challenges during the current transition period towards climate neutrality along with solutions proposed by the authors to be implemented in this phase. The current stage of combustion of the CH4 − H2 mixture imposes requirements for the capture of the resulting CO2.

This paper presents an innovative approach to fast frequency control in electric grids by leveraging parked fuel cell electric vehicles (FCEVs) especially heavy-duty vehicles such as trucks. Equipped with hydrogen storage tanks and fuel cells these vehicles can be repurposed as dynamic grid-support assets while parked in designated areas. Using an external cable and inverter system FCEVs inject power into the grid by converting DC from fuel cells into AC to be compatible with grid requirements. This functionality addresses sudden power imbalances providing a rapid and efficient solution for frequency stabilization. The system’s external inverter serves as a central control hub monitoring real-time grid frequency and directing FCEVs to supply virtual inertia and primary reserves through droop control as required. Simulation results validate that FCEVs could effectively complement thermal generators preventing unacceptable frequency drops load shedding and network blackouts. A techno-economic analysis demonstrates the economic feasibility of the concept concluding that each FCEV consumes approximately 0.3 kg of hydrogen per day incurring a daily cost of around EUR 1.5. For an island grid with a nominal power of 100 MW maintaining frequency stability requires a fleet of 100 FCEVs resulting in a total daily cost of EUR 150. Compared to a grid-scale battery system offering equivalent frequency response services the proposed solution is up to three times more cost-effective highlighting its economic and technical potential for grid stabilization in renewable-rich non-interconnected power systems.

In this study we evaluate the technical viability of storing hydrogen in a deep UKCS aquifer formation through a series of numerical simulations utilising the compositional simulator CMG-GEM. Effects of various operational parameters such as injection and production rates number and length of storage cycles and shut-in periods on the performance of the underground hydrogen storage (UHS) process are investigated in this study. Results indicate that higher H2 operational rates degrade both the aquifer's working capacity and H2 recovery during the withdrawal phase. This can be attributed to the dominant viscous forces at higher rates which lead to H2 viscous fingering and gas gravity override of the native aquifer water resulting in an unstable displacement of water by the H2 gas. Furthermore analysis of simulation results shows that longer and less frequent storage cycles lead to higher storage capacity and decreased H2 retrieval. We conclude that UHS in the studied aquifer is technically feasible however a thorough evaluation of the operational parameters is necessary to optimise both storage capacity and H2 recovery efficiency.

Given the global effort to embrace research actions and technology enhancement for the energy transition innovative sustainable systems are needed both for energy production and for those sectors that are responsible for high pollution and CO2 emissions. In this context electrolytic cells and fuel cells in their variety and flexibility are energy systems characterized by high efficiency and important performance guaranteeing a sustainable solution for future energy systems and for the circular economy. The scope of this paper is therefore to present the state of the art of such systems. An overview of the electrolyzers for hydrogen production is presented by detailing the level of applications for their different technologies from low-temperature units to high-temperature units the fuel flexibility the electrolysis and co-electrolysis mode and the potential coupling with renewable sources. Fuel cell-based systems are also presented and their application in the mobility sector is investigated by considering road transport with light-duty and heavy-duty applications and marine transport. A comparison with conventional technologies will be also presented providing some hints on the potential applications of electrolytic cells and fuel cell systems given their important contribution to the sustainable and circular economy.

The increase in industrial production and energy consumption has led to excessive exploitation of non-renewable resources resulting in serious environmental problems such as greenhouse gas emissions. In response there’s a growing investment in renewable energies such as hydroelectric wind and solar power. However these sources are unable to fully meet demand leading to imbalances between consumption and production. An emerging solution to this challenge is green hydrogen produced from clean sources reducing dependence on fossil fuels and mitigating greenhouse gas emissions. The S-LCA methodology presented in the UNEP/SETAC Guidelines for the Social Life Cycle Assessment is applied to the production of green hydrogen via the electrolytic separation of water using a proton exchange electrolyser. The process involves the extraction and processing of raw materials from the electrolyser BOP and reverse osmosis system the manufacture of the systems and the production of green hydrogen. The data from each stage is inventoried and entered into the PSILCA v.3.1 and SHDB 2022FV5 databases integrated into the SimaPro software version 9.3.0.2 enabling a complete analysis of the social im pacts associated with the production of green hydrogen. The data was evaluated considering 4 stakeholder categories: workers value chain actors society and local community. The results indicate that the extraction and processing of raw materials for the electrolyser was the primary stage responsible for the social impacts in both databases. However the electrolyser manufacturing stage was the main contributor to the indicators “weekly working hours per employee” and “union density” in the PSILCA database. Nafion® and Iridium were identified as the major contributors among components in both databases. The study highlights the significant role played by countries like China and South Africa in social impacts particularly in the extraction and processing of raw materials. Despite this Portugal emerged as the largest contributor to five out of fourteen indicators in the PSILCA database while its contributions in the SHDB database were less than 7 %. Moreover a comparison between the two databases revealed that PSILCA exhibited a greater distribution of results across various stages components and countries assessed whereas SHDB showed more centralized results. The observed discrepancies between the results obtained from different databases can be attributed to three main factors: the input-output database utilized in each S-LCA tool the assumed risk levels for each indicator and the equivalence between indicators and subcategories. This exploratory study offers valuable insights for guiding strategic decisions regarding the social component of sustainability providing a detailed understanding of the social impacts associated with the specific case of green hydrogen production in a planned hub in Portugal.

Hydrogen fuel cell vehicles (HFCVs) represent an important breakthrough in the hydrogen energy industry. The safe utilization of hydrogen is critical for the sustainable and healthy development of hydrogen fuel cell vehicles. In this study risk factors and preventive measures are proposed for on-board hydrogen systems during the process of transportation storage and use of fuel cell vehicles. The relevant hydrogen safety standards in China are also analyzed and suggestions involving four safety strategies and three safety standards are proposed.

This study investigates the spillover effects between hydrogen energy nuclear energy and artificial intelligence (AI) sectors in the context of the global clean energy transition with a particular focus on the impact of climate policy uncertainty (CPU) and geopolitical risks (GPR). Employing the TVP-VAR extended joint connectedness approach the findings show a high connectedness that indicates significant spillovers among these sectors. Hydrogen energy emerges as a dominant transmitter of shocks reflecting its sensitivity to regulatory changes and fluctuating demand. However nuclear energy acts as a stabilising force that offers hedging opportunities and resilience against market turbulence. The AI sector exhibits strong connectedness primarily as a net receiver of shocks driven by its dependency on clean energy sources and vulnerability to energy market volatility. Using the GARCHMIDAS framework the study identifies a temporal asymmetry in market responses to CPU and GPR. CPU triggers immediate but short-lived disruptions while GPR induces delayed yet persistent effects that intensify cross-sector spillovers over time. These results underline the vulnerabilities of sectors reliant on regulatory clarity and geopolitical stability. This study provides practical insights for investors policymakers technology and energy companies to better manage systemic risks at the crossroads of clean energy technological innovation and uncertainty.

Over the last few years hydrogen has emerged as a promising solution for problems related to energy sources and pollution concerns. The integration of hydrogen in the transport sector is one of the possible various applications and involves the implementation of hydrogen refueling stations (HRSs). A key obstacle for HRS deployment in addition to the need for well-developed technologies is the economic factor since these infrastructures require high capital investments costs and are largely dependent on annual operating costs. In this study we review hydrogen’s application as a fuel summarizing the principal systems involved in HRS from production to the final refueling stage. In addition we also analyze the main equipment involved in the production compression and storage processes of hydrogen. The current work also highlights the main refueling processes that impact energy consumption and the methodologies presented in the literature for energy management strategies in HRSs. With the aim of reducing energy costs due to processes that require high energy consumption most energy management strategies are based on the use of renewable energy sources in addition to the use of the power grid.

This review explores recent advancements in hydrogen gas (H2 ) safety through the lens of artificial intelligence (AI) techniques. As hydrogen gains prominence as a clean energy source ensuring its safe handling becomes paramount. The paper critically evaluates the implementation of AI methodologies including artificial neural networks (ANN) machine learning algorithms computer vision (CV) and data fusion techniques in enhancing hydrogen safety measures. By examining the integration of wireless sensor networks and AI for real-time monitoring and leveraging CV for interpreting visual indicators related to hydrogen leakage issues this review highlights the transformative potential of AI in revolutionizing safety frameworks. Moreover it addresses key challenges such as the scarcity of standardized datasets the optimization of AI models for diverse environmental conditions etc. while also identifying opportunities for further research and development. This review foresees faster response times reduced false alarms and overall improved safety for hydrogen-related applications. This paper serves as a valuable resource for researchers engineers and practitioners seeking to leverage state-of-the-art AI technologies for enhanced hydrogen safety systems.

During the last decade developing more sustainable transportation modes has become a primary objective for car manufacturers and governments around the world to mitigate environmental issues such as climate change the continuous increase in greenhouse gas (GHG) emissions and energy depletion. The use of hydrogen fuel cell technology as a source of energy in electric vehicles is considered an emerging and promising technology that could contribute significantly to addressing these environmental issues. In this study the effects of Hydrogen Fuel Cell Battery Electric Vehicles (HFCBEVs) on global GHG emissions compared to other technologies such as BEVs were determined based on different relevant factors such as predicted sales for 2050 (the result of the developed prediction model) estimated daily traveling distance estimated future average global electricity emission factors future average Battery Electric Vehicle (BEV) emission factors future global hydrogen production emission factors and future average HFCBEV emission factors. As a result the annual GHG emissions produced by passenger cars that are expected to be sold in 2050 were determined by considering BEV sales in the first scenario and HFCBEV replacement in the second scenario. The results indicate that the environmental benefits of HFCBEVs are expected to increase over time compared to those of BEVs due to the eco-friendly methods that are expected to be used in hydrogen production in the future. For instance in 2021 HFCBEVs could produce more GHG emissions than BEVs by 54.9% per km of travel whereas in 2050 BEVs could produce more GHG emissions than HFCBEVs by 225% per km of travel.