Biodiesel production through transesterification results in a large quantity of crude glycerol as a byproduct, the utilization of which is technically and economically challenging. Because of the ability to efficiently process wet feedstocks, supercritical water gasification (SCWG) is utilized in this study to convert crude glycerol into hydrogen-rich syngas. A significant challenge addressed through this study is the decomposition routes of different heterogeneous components of crude glycerol during SCWG. Pure glycerol, methanol and oleic acid were investigated for SCWG as the model compounds of crude glycerol. SCWG of model compounds at temperature, pressure, feedstock concentration and reaction time of 500 °C, 23−25 MPa, 10 wt% and 1 h, respectively, revealed methanol to exhibit the highest H2 yield of 7.7 mmol/g, followed by pure glycerol (4.4 mmol/g) and oleic acid (1.1 mmol/g). The effects of feedstock concentration from 30 wt% to 10 wt% increased H2 yield from all model compound... [more]

As we move away from internal combustion engines to tackle climate change, the importance of hydrogen-powered vehicles and polymer electrolyte membrane fuel cell (PEMFC) technology has dramatically increased. In the present study, we aimed to determine the optimal configuration for the power output of a PEMFC system using computational fluid dynamics (CFD) modelling to analyse variations of the primary serpentine design of gas flow channels. This helps improve efficiency and save on valuable materials used, reducing potential carbon emissions from the production of hydrogen vehicles. Different numbers of serpentine gas channels were represented with various spacing between them, within the defined CFD model, to optimise the gas channel geometry. The results show that the optimum configuration was found to have 11 serpentine channels with a spacing of 3.25 mm. In this optimum configuration, the ratio between the channel width, channel spacing, and serpentine channel length was found to... [more]

Air contaminants can have detrimental effects on the performance and durability of proton exchange membrane (PEM) fuel cell vehicles. This research focuses on the experimental investigation of the effect of nitrogen monoxide (NO) in the cathode gas stream, which provokes a cell voltage decrease due to the partially reversible adsorption of NO on the platinum catalyst. The concentration and exposure time of NO in the cathode gas stream are varied at selected constant current densities and load ramps to assess the effects throughout the fuel cell system operating range. The results show the cell voltage loss in the presence of NO and reveal a near-catalyst saturation with increased injected NO mass. Additionally, several voltage recovery and mitigation strategies are introduced and discussed by presenting conclusions about the general effect of NO on a fuel cell system in operation. The most promising recovery strategy for fuel cell systems is identified, and the overall system degradati... [more]

Currently, the issue of creating decarbonized energy systems in various spheres of life is acute. Therefore, for gas turbine power systems including hybrid power plants with fuel cells, it is relevant to transfer the existing engines to pure hydrogen or mixtures of hydrogen with natural gas. However, significant problems arise associated with the possibility of the appearance of flashback zones and acoustic instability of combustion, an increase in the temperature of the walls of the flame tubes, and an increase in the emission of nitrogen oxides, in some cases. This work is devoted to improving the efficiency of gas turbine power systems by combusting pure hydrogen and mixtures of natural gas with hydrogen. The organization of working processes in the premixed combustion chamber and the combustion chamber with a sequential injection of ecological and energy steam for the “Aquarius” type power plant is considered. The conducted studies of the basic aerodynamic and energy parameters of... [more]

Humankind has an urgent need to reduce carbon dioxide emissions. Such a challenge requires deep transformation of the current energy system in our society. Achieving this goal has given an unprecedented role to decarbonized energy vectors. Electricity is the most consolidated of such vectors, and a molecular vector is in the agenda to contribute in the future to those end uses that are difficult to electrify. Additionally, energy storage is a critical issue for both energy vectors. In this communication, discussion on the status, hopes and perspectives of the hydrogen contribution to decarbonization are presented, emphasizing bottlenecks in key aspects, such as education, reskilling and storage capacity, and some concerns about the development of a flexible portfolio of technologies that could affect the contribution and impact of the whole hydrogen value chain in society. This communication would serve to the debate and boost discussion about the topic.

Conventional wastewater treatment plants (CWTPs) are intensive energy consumers. New technologies are emerging for wastewater treatment such as microbial electrolysis cells (MECs) that can simultaneously treat wastewater and generate hydrogen as a renewable energy source. Mathematical modeling of single and dual-chamber microbial electrolysis cells (SMEC and DMEC) has been developed based on microbial population growth in this study. The model outputs were validated successfully with previous works, and are then used for comparisons between the SMEC and DMEC regarding the hydrogen production rate (HPR). The results reveal that the daily HPR in DMEC is higher than in SMEC, with about 0.86 l H2 and 0.52 l H2, respectively, per 1 L of wastewater. Moreover, the results have been used to compare the HPR in water electrolysis (WE) processes and MECs. WE consume 51 kWh to generate 1 kg of hydrogen, while SMEC and DMEC require only 30 kWh and 24.5 kWh, respectively.

The paper presents the possibilities of low-emission-powered vehicles based mainly on compressed hydrogen. It shows currently used forms of powering vehicles based on their genesis, process of obtention, and popularity. They are also compared to each other, presenting the advantages and disadvantages of a given solution. The share of electricity in transport, its forecasts for the future, and the possibilities of combination with conventional energy sources are also described. Based on current technological capabilities, hydrogen plays a crucial role, as presented in the above work, constituting a fundamental basis for future transport solutions.

Green hydrogen is set to become the energy carrier of the future, provided that production technologies such as electrolysis and solar water splitting can be scaled to global dimensions. Testing these hydrogen technologies on the MW scale requires the development of dedicated new test facilities for which there is no precedent. This perspective highlights the challenges to be met on the path to implementing a test facility for large-scale water electrolysis, photoelectrochemical and photocatalytic water splitting and aims to serve as a much-needed blueprint for future test facilities based on the authors’ own experience in establishing the Hydrogen Lab Leuna. Key aspects to be considered are the electricity and utility requirements of the devices under testing, the analysis of the produced H2 and O2 and the safety regulations for handling large quantities of H2. Choosing the right location is crucial not only for meeting these device requirements, but also for improving financial viabi... [more]

With growing concern about risks related to energy security around the world, the development of hydrogen cooperation between India and Japan has become very important to ensure the economic security of the two countries and to deepen economic cooperation. This report covers both public and private initiatives in the hydrogen area in both countries and visualizes the high potential and potential areas where both countries could cooperate in the hydrogen area, as well as the challenges that are necessary for cooperation. The following four factors are strong incentives for India and Japan to deepen cooperation in the hydrogen field: (1) India has a high potential hydrogen supply capacity, (2) India is very active in implementing hydrogen in society, (3) Japan is already conducting R&D in areas of high interest to India and (4) Japan will need to import hydrogen from other countries in the future. The issues of (1) cost visualization, including transportation costs, (2) harmonization of... [more]

The increasing market share of electric vehicles and the politically intended phase-out of the internal combustion engine require reliable and realistic predictions for future consumption and greenhouse gas emissions as a function of technological solutions. This also includes the consumption- and emission-intensive transport of goods. We consider both passenger vehicles and commercial vehicle traffic in our study and have investigated whether there are drive alternatives to the battery electric vehicle that enable uninterrupted trips with a long range, especially for regional delivery services and internationally active freight forwarders. To this end, we have analysed three system architectures and their expected technological progress until 2050: battery electric vehicles (BEV), fuel cell electric vehicles (FCEV), and internal combustion engine vehicles (ICEV) running on compressed natural gas (CNG). The latter case serves as a best-practice reference from a combustion technology pe... [more]

The energy conversion of nickel-impregnated coconut shells using supercritical water has not yet been explored. The impregnation process was conducted at room temperature and a pH of 5.80 for 72 h. Characterization of the prepared sample confirmed the presence of nickel nanoparticles with an average size of 7.15 nm. The gasification of control and impregnated samples was performed at 400−500 °C, biomass loading from 20 to 30 wt% and residence time from 20 to 60 min. The response surface methodology (RSM) approach, with a Box−Behnken method, was used to design the experiments. The optimization model showed that the non-catalytic process at 500 °C, 60 min and 20 wt% of biomass loading could promote an H2 yield of 8.8 mol% and gasification efficiency of 47.6%. The gasification of nickel-impregnated coconut shells showed significantly higher gasification efficiency (58.6%) and hydrogen yield (17.2 mol%) with greater carbon and hydrogen efficiencies (109.4 and 116.9%) when compared to the n... [more]

The holistic green energy transition of non-interconnected islands faces several challenges if all the energy sectors are included, i.e., electricity, heating/cooling, and mobility. On the one hand, the penetration of renewable energy systems (RES) is limited due to design restrictions with respect to the peak demand. On the other hand, energy-intensive heating and mobility sectors pose significant challenges and may be difficult to electrify. The focus of this study is on implementing a hybrid Wind−PV system on the non-interconnected island of Anafi (Greece) that utilizes surplus renewable energy production for both building heating through heat pumps and hydrogen generation. This comprehensive study aims to achieve a holistic green transition by addressing all three main sectors—electricity, heating, and transportation. The produced hydrogen is utilized to address the energy needs of the mobility sector (H2 mobility), focusing primarily on public transportation vehicles (buses) and s... [more]

Hydrogen is attracting attention as a good energy-storage medium for renewable energy. Among hydrogen production technologies using renewable energy, water electrolysis is drawing attention as a key technology for green hydrogen production using renewable energy. In particular, polymeric electrolyte membrane water electrolysis systems have several advantages compared to other types of water electrolysis technologies, such as small size and mass, high efficiency, low operating temperature, and low power consumption. However, until now, proton-exchange membrane (PEM) water electrolysis systems have not been reliable. In this study, system failure diagnosis techniques were presented among the various methods for improving reliability. We developed PEM water electrolysis stack models and system models to predict the performance of the system and analyze the dynamic properties using MATLAB/Simulink® 2018a, which have been validated under various conditions. The developed dynamic characteris... [more]

Arguably, one of the most important issues the world is facing currently is climate change. At the current rate of fossil fuel consumption, the world is heading towards extreme levels of global temperature rise if immediate actions are not taken. Transforming the current energy system from one largely based on fossil fuels to a carbon-neutral one requires unprecedented speed. Based on the current state of development, direct electrification of the future energy system alone is technically challenging and not enough, especially in hard-to-abate sectors like heavy industry, road trucking, international shipping, and aviation. This leaves a considerable demand for alternative carbon-neutral fuels such as green ammonia and hydrogen and renewable methanol. From this perspective, we discuss the overarching roles of each fuel in reaching net zero emission within the next three decades. The challenges and future directions associated with the fuels conclude the current perspective paper.

This article was aimed to answer the question of whether local energy communities have a sufficient energy surplus for storage purposes, including hydrogen production. The article presents an innovative approach to current research and a discussion of the concepts of the collective prosumer and virtual prosumer that have been implemented in the legal order and further amended in the law. From this perspective, it was of utmost importance to analyze the model of functioning of an energy cluster consisting of energy consumers, energy producers, and hydrogen storage, whose goal is to maximize the obtained benefits, assuming the coopetitive nature of the relationship. The announced and clear perspective of the planned benefits will provide the cluster members a measurable basis for participation in such an energy community. However, the catalogue of benefits will be conditioned by the fulfillment of several requirements related to both the scale of covering energy demand from own sources a... [more]

Hydrogen adsorption measurements were taken by the weighting method using the Sartorius low-pressure microbalance. Experiments were conducted at two temperatures: 77.5 and 300 K; the adsorbent used was active carbon obtained from wood and modified with potassium hydroxide. The porous structure of the carbon prior to and after modification was evaluated based on the nitrogen adsorption and desorption data. Thus, the densimetric characteristic of active carbon was modified; porous structures were developed in the range of micro-, meso- and macropores and the volume of hydrogen adsorbed at 77.5 K showed an almost four-fold increase. Modified active carbons are found to be suitable for applications in hydrogen storage systems.

The durability and performance of electrochemical energy converters, such as fuel cells and electrolysers, are not only dependent on the properties and the quality of the used materials. They strongly depend on the operational conditions. Variations in external parameters, such as flow, pressure, temperature and, obviously, load, can lead to significant local changes in current density, even local transients. Segmented cell technology was developed with the purpose to gain insight into the local operational conditions in electrochemical cells during operation. The operando measurement of the local current density and temperature distribution allows effective improvement of operation conditions, mitigation of potentially critical events and assessment of the performance of new materials. The segmented cell, which can replace a regular bipolar plate in the current state of the technology, can be used as a monitoring tool and for targeted developments. This article gives an overview of th... [more]

Biomass occupies a significant proportion of municipal solid waste. For the high-value processing of waste biomass, a hydrothermal-carbonization method was chosen because of the advantages of effective and mild conditions. Four typical types of waste biomass (banana peel, mangosteen peel, orange peel, and pomelo peel) were used in this work to prepare high-value carbon aerogels (CA) via hydrothermal-carbonization treatment for cracking ethanol. Four kinds of CA all had good performances in the ethanol cracking reaction and improved the yield of H2 from 21 wt% to about 40 wt%. The banana peel-based carbon aerogel (BPCA) showed the best performance in the reaction; it cracked ethanol and obtained 41.86 wt% of H2. The mechanism of ethanol cracking by CA was revealed: On one hand, the self-cracking of ethanol was improved due to the extension of residence time, which benefited from the abundant pores in CA. On the other hand, the heterogeneous reaction occurred on the surface of CA where t... [more]

This article reviews a method of hydrogen production based on partial non-catalytic oxidation of natural gas in an original synthesis gas generator. The working principles of the unit are similar to those of liquid-propellant rocket engines. This paper presents a description of the operation and technical characteristics of the synthesis gas generator. Its application in the creation of small-scaled plants with a capacity of up to 5−7 thousand m3/h of hydrogen is justified. Hydrogen production in the developed installation requires a two-stage method and includes a technological unit for producing a hydrogen-containing gas. Typical balance compositions of hydrogen-containing gas at the synthesis gas generator’s outlet are given. To increase the hydrogen concentration, it is proposed to carry out a two-stage steam catalytic conversion of carbon monoxide contained in the hydrogen-containing gas at the synthesis gas generator’s outlet using a single Cu−Zn−cement-containing composition. Ba... [more]

The deployment of low-carbon hydrogen in gas grids comes with strategic benefits in terms of energy system integration and decarbonization. However, hydrogen thermophysical properties substantially differ from natural gas and pose concerns of technical and regulatory nature. The present study investigates the blending of hydrogen into distribution gas networks, focusing on the steady-state fluid dynamic response of the grids and gas quality compliance issues at increasing hydrogen admixture levels. Two blending strategies are analyzed, the first of which involves the supply of NG−H2 blends at the city gate, while the latter addresses the injection of pure hydrogen in internal grid locations. In contrast with traditional case-specific analyses, results are derived from simulations executed over a large number (i.e., one thousand) of synthetic models of gas networks. The responses of the grids are therefore analyzed in a statistical fashion. The results highlight that lower probabilities... [more]

This paper presents a novel minimum seeking algorithm referred to as the Hunger Games Search (HGS) algorithm. The HGS is used to obtain optimal values in the model describing proton exchange membrane fuel cells (PEMFCs). The PEMFC model has many parameters that are linked in a nonlinear manner, as well as a set of constraints. The HGS was used with the aforementioned model to test its performance against nonlinear models. The main aim of the optimization problem was to obtain accurate values of PEMFC parameters. The proposed heuristic algorithm was used with two commercial PEMFCs: the Ballard Mark V and the BCS 500 W. The simulation results obtained using the HGS-based model were compared to the experimental results. The effectiveness of the proposed model was verified under various temperature and partial pressure conditions. The numerical output results of the HGS-based fuel cell model were compared with other optimization algorithm-based models with respect to their efficiency. More... [more]

Spatial heating and cooking account for a significant fraction of global domestic energy consumption. It is therefore likely that hydrogen combustion will form part of a hydrogen-based energy economy. Catalytic hydrogen combustion (CHC) is considered a promising technology for this purpose. CHC is an exothermic reaction, with water as the only by-product. Compared to direct flame-based hydrogen combustion, CHC is relatively safe as it foregoes COx, CH4, and under certain conditions NOx formation. More so, the risk of blow-off (flame extinguished due to the high fuel flow speed required for H2 combustion) is adverted. CHC is, however, perplexed by the occurrence of hotspots, which are defined as areas where the localized surface temperature is higher than the average surface temperature over the catalyst surface. Hotspots may result in hydrogen’s autoignition and accelerated catalyst degradation. In this review, catalyst materials along with the hydrogen technologies investigated for CH... [more]

The popularity of climate neutral new energy vehicles for reduced emissions and improved air quality has been raising great attention for many years. World-wide, a strong commitment continues to drive the demand for zero-emission through alternative energy sources and propulsion systems. Despite the fact that 71.27% of hydrogen is produced from natural gas, green hydrogen is a promising clean way to contribute to and maintain a climate neutral ecosystem. Thereby, reaching CO2 targets for 2030 and beyond requires cross-sectoral changes. However, the strong motivation of governments for climate neutrality is challenging many sectors. One of them is the transport sector, as it is challenged to find viable all-in solutions that satisfy social, economic, and sustainable requirements. Currently, the use of new energy vehicles operating on green sustainable hydrogen technologies, such as batteries or fuel cells, has been the focus for reducing the mobility induced emissions. In Europe, 50% of... [more]

In this study, uncertainty and sensitivity analyses were performed with MELCOR 2.2.18 to study the hydrogen generation (figure-of-merit (FoM)) during the in-vessel phase of a severe accident in a light water reactor. The focus of this work was laid on a large generation-III pressurized water reactor (PWR) and a double-ended hot leg (HL) large break loss of coolant accident (LB-LOCA) without a safety injection (SI). The FPT-1 Phebus integral experiment emulating LOCA was studied, where the experiment outcomes were applied for the plant scale modelling. The best estimate calculations were supplemented with an uncertainty analysis (UA) based on 400 input-decks and Latin hypercube sampling (LHS). Additionally, the sensitivity analysis (SA) utilizing the linear regression and linear and rank correlation coefficients was performed. The study was prepared with a new open-source MELCOR sensitivity and uncertainty tool (MelSUA), which was supplemented with this work. The FPT-1 best-estimate mod... [more]

Hydrogen is currently receiving significant attention and investment as a key enabler of defossilised global energy systems. Many believe this will eventually result in the international trade of hydrogen as a commodity from countries with significant renewable energy resources, for example New Zealand and Australia, to net energy importing countries including Japan and Korea. Japan has, since 2014, been actively exploring the components of the necessary supply chains, including the assessment of different hydrogen carriers. Public/private partnerships have invested in demonstration projects to assess the comparative merits of liquid hydrogen, ammonia, and organic carriers. On the supply side, significant projects have been proposed in Australia while the impending closure of New Zealand’s Tiwai Point aluminium smelter at the end of 2024 may provide an opportunity for green hydrogen production. However, it is also evident that the transition to a hydrogen economy will take some years a... [more]