Publications

Fuel cells (FCs) and hydrogen technologies are emerging renewable energy sources with promising results when applied to wastewater treatment (WWT). These devices serve not only for power generation but some specific FCs can be employed for degradation of pollutants and synthesis of intermediates needed in WWT. Microbial FCs are potent devices for WWT even containing refractory pollutants. Despite being a nascent technology with high capital expenses the use of cost-effective materials reduction of operational cost and increased generation of energy and value-added chemicals such as hydrogen will facilitate the market penetration through selected niches and hybridization with alternative WWT technologies.

The current study comprehensively examines the application of wave tidal and undersea current energy sources of Turkiye for green hydrogen fuel production and cost analysis. The estimated potential capacity of each city is derived from official data and acceptable assumptions and is subject to discussion and evaluation in the context of a viable hydrogen economy. According to the findings the potential for green hydrogen generation in Turkiye is projected to be 7.33 million tons using a proton exchange membrane electrolyser (PEMEL). Cities with the highest hydrogen production capacities from marine applications are Mugla Izmir Antalya and Canakkale with 998.10 kt 840.31 kt 605.46 kt and 550.42 kt respectively. The study calculations obviously show that there is a great potential by using excess power in producing hydrogen which will result in an economic value of 3.01 billion US dollars. This study further helps develop a detailed hydrogen map for every city in Turkiye using the identified potential capacities of renewable energy sources and the utilization of electrolysers to make green hydrogen by green power. The potentials and specific capacities for every city are also highlighted. Furthermore the study results are expected to provide clear guidance for government authorities and industries to utilize such a potential of renewable energy for investment and promote clean energy projects by further addressing concerns caused by the usage of carbon-based (fossil fuels dependent) energy options. Moreover green hydrogen production and utilization in every sector will help achieve the national targets for a net zero economy and cope with international targets to achieve the United Nation's sustainable development goals.

To inject green hydrogen (H2) into the existing natural gas (NG) infrastructure is one way to decarbonize the European energy system. However asset readiness is necessary to be successful. Preliminary analysis and experimental results about the compatibility of hydrogen and natural gas mixtures (H2NG) with the actual gas grids make the scientific community confident about the feasibility. Nevertheless specific technical questions need more research. A significant topic of debate is the impact of H2NG mixtures on the performance of state-ofthe-art fiscal measuring devices which are essential for accurate billing. Identifying and addressing any potential degradation in their metrological performance due to H2NG is critical for decision-making. However the literature lacks data about the gas meters’ technologies currently installed in the NG grids such as a comprehensive overview of their readiness at different concentrations while data are fragmented among different sources. This paper addresses these gaps by analyzing the main characteristics and categorizing more than 20000 gas meters installed in THOTH2 project partners’ grids and by summarizing the performance of traditional technologies with H2NG mixtures and pure H2 based on literature review operators experience and manufacturers knowledge. Based on these insights recommendations are given to stakeholders on overcoming the identified barriers to facilitate a smooth transition.

Conventional methods of parameterizing fuel cell hybrid power systems (FCHPS) often rely on engineering experience which leads to problems such as increased economic costs and excessive weight of the system. These shortcomings limit the performance of FCHPS in real-world applications. To address these issues this paper proposes a novel method for optimizing the parameter configuration of FCHPS. First the power and energy requirements of the vehicle are determined through traction calculations and a real-time energy management strategy is used to ensure efficient power distribution. On this basis a multi-objective parameter configuration optimization model is developed which comprehensively considers economic cost and system weight and uses a particle swarm optimization (PSO) algorithm to determine the optimal configuration of each power source. The optimization results show that the system economic cost is reduced by 8.76% and 18.05% and the weight is reduced by 11.47% and 9.13% respectively compared with the initial configuration. These results verify the effectiveness of the proposed optimization strategy and demonstrate its potential to improve the overall performance of the FCHPS.

Until recently electrified aircraft propulsion (EAP) technology development has been driven by the dual objectives of reducing greenhouse gas (GHG) emissions and addressing the depletion of fossil fuels. However the increasing severity of climate change posing a significant threat to all life forms has resulted in the global consensus of achieving net-zero GHG emissions by 2050. This major shift has alerted the aviation electrification industry to consider the following: What is the clear path forward for EAP technology development to support the net-zero GHG goals for large commercial transport aviation? The purpose of this paper is to answer this question. After identifying four types of GHG emissions that should be used as metrics to measure the effectiveness of each technology for GHG reduction the paper presents three significant categories of GHG reduction efforts regarding the engine evaluates the potential of EAP technologies within each category as well as combinations of technologies among the different categories using the identified metrics and thus determines the path forward to support the net-zero GHG objective. Specifically the paper underscores the need for the aviation electrification industry to adapt adjust and integrate its EAP technology development into the emerging new engine classes. These innovations and collaborations are crucial to accelerate net-zero GHG efforts effectively.

The maritime transportation sector is a large and growing contributor of greenhouse gas and other emissions. Therefore stringent measures have been taken by the International Maritime Organization to mitigate the environmental impact of the international shipping. These lead to the adoption of new technical solutions involving clean fuels such as hydrogen and high efficiency propulsion technologies that is fuel cells. In this framework this paper proposes a methodological approach aimed at supporting the retrofit design process of a car-passenger ferry operating in the Greece’s western maritime zone whose conventional powertrain is replaced with a fuel cell hybrid system. To this aim first the energy/power requirements and the expected hydrogen consumption of the vessel are determined basing on a typical operational profile retrieved from data provided by the shipping company. Three hybrid powertrain configurations are then proposed where fuel cell and batteries are balanced out according to different design criteria. Hence a new vessel layout is defined for each of the considered options by taking into account on-board weight and space constraints to allocate the components of the new hydrogen-based propulsion systems. Finally the developed vessel configurations are simulated in a virtual towing tank environment in order to assess their hydrodynamic response and compare them with the original one thus providing crucial insights for the design process of new hydrogen-fueled vessel solutions. Findings from this study reveal that the hydrogen-based configurations of the vessel are all characterized by a slight reduction of the payload mainly due to the space required to allocate the hydrogen storage system; instead the hydrodynamic behavior of the H2 powered vessels is found to be similar to the one of the original Diesel configuration; also from a hydrodynamic point of view the results show that mid load operating conditions get relevance for the design process of the hybrid vessels.

This paper presents an innovative Fuel Cell Combined Heat and Power (FC–CHP) system designed to enhance energy efficiency in hospital settings. The system primarily utilizes solar energy captured through photovoltaic (PV) panels for electricity generation. Excess electricity is directed to an electrolyzer for water electrolysis producing hydrogen which is stored in high-pressure tanks. This hydrogen serves a dual purpose: it fuels a boiler for heating and hot water needs and powers a fuel cell for additional electricity when solar production is low. The system also features an intelligent energy management system that dynamically allocates electrical energy between immediate consumption hydrogen production and storage while also managing hydrogen release for energy production. This study focuses on optimization using genetic algorithms to optimize key components including the peak power of photovoltaic panels the nominal power of the electrolyzer fuel cell and storage tank sizes. The objective function minimizes the sum of investment and electricity costs from the grid considering a penalty coefficient. This approach ensures optimal use of renewable energy sources contributing to energy efficiency and sustainability in healthcare facilities.

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.

The transition from traditional aviation fuels to low-emission alternatives such as hydrogen is a crucial step towards a sustainable future for aviation. Conventional jet fuels substantially contribute to greenhouse gas emissions and climate change. Hydrogen fuel especially "green" hydrogen offers great potential for achieving full sustainability in aviation. Hybrid/electric/fuel cell technologies may be used for shorter flights while longrange aircraft are more likely to combust hydrogen in gas turbines. Liquid hydrogen is necessary to minimize storage tank weight but the required fuel systems are at a low technology readiness level and differ significantly from Jet A-1 systems in architecture operation and performance. This paper provides an in-depth review covering the development of liquid hydrogen fuel system design concepts for gas turbines since the 1950s compares insights from key projects such as NASA studies and ENABLEH2 alongside an analysis of recent publications and patent applications and identifies the technological advancements required for achieving zeroemission targets through hydrogen-fuelled propulsion.

Green hydrogen is often promoted as a key facilitator for the clean energy transition but its implementation raises concerns around energy justice. This paper examines the socio-political and techno-economic challenges that green hydrogen projects may pose to the three tenets of energy justice: distributive procedural and recognition justice. From a socio-political perspective the risk of neocolonial resource extraction uneven distribution of benefits exclusion of local communities from decision-making and disregard for indigenous rights and cultures threaten all three justice tenets. Techno-economic factors such as water scarcity land disputes and resource-related conflicts in potential production hotspots further jeopardise distributive and recognition justice. The analysis framed by an adapted PEST model reveals that while green hydrogen holds promise for sustainable development its implementation must proactively address these justice challenges. Failure to do so could perpetuate injustices exploitation and marginalisation of vulnerable communities undermining the sustainability goals it aims to achieve. The paper highlights the need for inclusive and equitable approaches that respect local sovereignty integrate diverse stakeholders and ensure fair access and benefit-sharing. Only by centring justice considerations can the transition to green hydrogen catalyse positive social change and realise its full potential as a driver of sustainable energy systems.