Academic literature on the topic 'Optimal hydrogen use'

The state of the energy complex of Ukraine and its ecological component is consideredin this paper. Data on the prospects for the production of "green hydrogen" due to the use of excess maneuvering capacity of "green energy" and the problems associated with it presented. The issues related to the extension of the service life of Ukrainian nuclear power plants is described. Prospects for the use of hydrogen in industrial combustion processes, rather than as a process gas, are considered. Original experimental data on the combustion of natural gas with impurities of different hydrogen concentrations are presented. Data were obtained on the effect of oxidant content on the formation of nitrogen oxides in the flame front of the laminar torch.Influence of the solutions containing hydrogen on process of nitrogen oxides formation and additional oxidation of NO in NO2 in combustion processes is studied and results are presented. The most favorable conditions (concentration of hydrogen solution content and temperature regime) of NO oxidation in NO2 are determined. Recommendations on the main directions of development of hydrogen energy of Ukraine are given. The need to determine the optimal proportion of hydrogen that may be present in the gas transmission system of Ukraine is emphasized.

Diesel generators are currently used as an off-grid solution for backup power, but this causes CO2 and GHG emissions, noise emissions, and the negative effects of the volatile diesel market influencing operating costs. Green hydrogen production, by means of water electrolysis, has been proposed as a feasible solution to fill the gaps between demand and production, the main handicaps of using exclusively renewable energy in isolated applications. This manuscript presents a business case of an off-grid hydrogen production by electrolysis applied to the electrification of isolated sites. This study is part of the European Ely4off project (n° 700359). Under certain techno-economic hypothesis, four different system configurations supplied exclusively by photovoltaic are compared to find the optimal Levelized Cost of Electricity (LCoE): photovoltaic-batteries, photovoltaic-hydrogen-batteries, photovoltaic-diesel generator, and diesel generator; the influence of the location and the impact of different consumptions profiles is explored. Several simulations developed through specific modeling software are carried out and discussed. The main finding is that diesel-based systems still allow lower costs than any other solution, although hydrogen-based solutions can compete with other technologies under certain conditions.

High-performance hydrogen sensors are important in many industries to effectively address safety concerns related to the production, delivering, storage and use of H2 gas. Herein, we present a highly sensitive hydrogen gas sensor based on SnO2-loaded ZnO nanofibers (NFs). The xSnO2-loaded (x = 0.05, 0.1 and 0.15) ZnO NFs were fabricated using an electrospinning technique followed by calcination at high temperature. Microscopic analyses demonstrated the formation of NFs with expected morphology and chemical composition. Hydrogen sensing studies were performed at various temperatures and the optimal working temperature was selected as 300 °C. The optimal gas sensor (0.1 SnO2 loaded ZnO NFs) not only showed a high response to 50 ppb hydrogen gas, but also showed an excellent selectivity to hydrogen gas. The excellent performance of the gas sensor to hydrogen gas was mainly related to the formation of SnO2-ZnO heterojunctions and the metallization effect of ZnO.

Penggunaan bahan baku dari jenis kertas SWL (sorted white ledger) yang berasal dari proses mekanikal dan jenis kertas bekas yang mengandung banyak tinta memiliki dampak negatif karena menyebabkan sifat optik dari deinked pulp yang dihasilkan tidak optimal. Penyebab dari masalah tersebut adalah tingginya kandungan logam dan lignin pada SWL dan kertas bekas. Untuk mengatasi masalah tersebut, pada penlitian ini dilakukan penambahkan DTPA (Diethylene Triamine Pentaacetic Acid) sebagai penghilang kandungan logam dan bahan pemutih untuk menghilangkan lignin. Bahan pemutih yang digunakan adalah natrium perkarbonat, hidrogen peroksida, hipoklorit, dan xilanase. Dilakukan variasi dosis (1%; 1,5%; dan 2%) dan suhu pemutih (50°C, 70°C, dan 90°C) untuk menentukan titik optimal. Hasil penelitian menunjukkan bahwa bahan pemutih yang digunakan mampu meningkatkan derajat cerah dan derajat putih dari deinked pulp. Nilai sifat optik yang paling optimal didapat pada proses pemutihan menggunakan 2% natrium perkarbonat pada suhu 70°C, dengan nilai derajat cerah sebesar 85,30% ISO dan derajat putih sebesar 112,27% ISO. The Comparison of Sodium Percarbonate, Hydrogen Peroxide, Hypochlorite, and Xylanaseon Optical Properties of Deinked PulpAbstract The use of raw materials from SWL (sorted white ledger) paper originating from mechanical processes as well as used paper types that contain a lot of ink has a negative impact because it causes no optimal value for the optical properties of deinked pulp. The cause of these problems is the high content of metals and lignin. To overcome this problem, it is necessary to add DTPA (Diethylene Triamine Pentaacetic Acid) as a remover for metals and bleaching agents to remove lignin. The bleaching agents used in this study were sodium percarbonate, hydrogen peroxide, hypochlorite, and xylanase. Variation of bleach dose (1%, 1,5%, and 2%) and temperature (50°C, 70°C, and 90°C) is performed to determine the optimal point. The results showed that the whitening material used was able to increase the bright and white degrees of deinked pulp. The most optimal optical properties values obtained in the whitening process using 2% sodium percarbonate at 70°C, with a bright degree value of 85.30% ISO and a degree of white of 112.27% ISO. Keywords: SWL, waste paper, sodium percarbonate, hydrogen peroxide, hypochlorite, xylanase.

Over the last decade there has been a growing interest in the research of feasibility to use high altitude long endurance (HALE) aircrafts in order to provide mobile communications. The use of HALEs for telecommunication networks has the potential to deliver a wide range of communication services (from high-quality voice to high-definition videos, as well as high-data-rate wireless channels) cost effectively. One of the main challenges of this technology is to design its power supply system, which must provide the enough energy for long time flights in a reliable way. In this paper a photovoltaic/hydrogen system is proposed as power system for a HALE aircraft due its high power density characteristic. In order to obtain the optimal sizing for photovoltaic/hydrogen system a particle swarm optimizer (PSO) is used. As a case study, theoretical design of the photovoltaic/hydrogen power system for three different HALE aircrafts located at 18° latitude is presented. At this latitude, the range of solar radiation intensity was from 310 to 450 Wh/sq·m/day. The results obtained show that the photovoltaic/hydrogen systems calculated by PSO can operate during one year with efficacies ranging between 45.82% and 47.81%. The obtained sizing result ensures that the photovoltaic/hydrogen system supplies adequate energy for HALE aircrafts.

When extracting natural uranium from hydrogenic deposits, one of the problems of development efficiency is the low rate of conversion of a useful component into a productive solution during underground well leaching, which significantly lengthens the life of the field and increases the total cost of obtaining finished products [1; 2]. The object of the research is technological installations for in-situ borehole leaching of hydrogenous ores. The purpose of the research is to consolidate the knowledge obtained in laboratory studies under industrial operating conditions and to develop modes of application of this technology in the development of reserves of hydrogenous ores of Khiagda type. Research objective is to establish the most effective modes of hydrogen peroxide application as an oxidizer. Research methodology is presented by the collection of accumulated information, its mathematical and statistical processing, and development of regulations of the leaching process with hydrogen peroxide; conducting research work and establishing the relationship between the mining, geological, hydrogeological and technological Research methods: mathematical and statistical analysis, semi-industrial tests. The reasons for the low intensity of leaching are both complex mining, geological and hydrogeological conditions for the localization of hydrogenic ores and low groundwater temperature. One of the effective technological techniques for increasing leaching efficiency is the use of chemical activators of the uranium extraction process from ore minerals [10‒14]. Laboratory studies [7] of the use of chemical oxidizers in the ores of the Khiagdinsky ore field deposits have shown that hydrogen peroxide is the most effective activator of leaching. To verify the results of laboratory tests in situ at one of the ore deposits of the Khiagdinskoye deposit, pilot tests of the results of these studies were carried out. As a result of the work performed, it has become possible to establish the optimal modes of sulfuric acid leaching of chiagdin ores using hydrogen peroxide as an activator.

Steelmaking is responsible for approximately one third of total industrial carbon dioxide (CO2) emissions. Hydrogen (H2) direct reduction (H-DR) may be a feasible route towards the decarbonization of primary steelmaking if H2 is produced via electrolysis using fossil-free electricity. However, electrolysis is an electricity-intensive process. Therefore, it is preferable that H2 is predominantly produced during times of low electricity prices, which is enabled by the storage of H2. This work compares the integration of H2 storage in four liquid carriers, methanol (MeOH), formic acid (FA), ammonia (NH3) and perhydro-dibenzyltoluene (H18-DBT), in H-DR processes. In contrast to conventional H2 storage methods, these carriers allow for H2 storage in liquid form at moderate overpressures, reducing the storage capacity cost. The main downside to liquid H2 carriers is that thermochemical processes are necessary for both the storage and release processes, often with significant investment and operational costs. The carriers are compared using thermodynamic and economic data to estimate operational and capital costs in the H-DR context considering process integration options. It is concluded that the use of MeOH is promising compared to the other considered carriers. For large storage volumes, MeOH-based H2 storage may also be an attractive option to the underground storage of compressed H2. The other considered liquid H2 carriers suffer from large thermodynamic barriers for hydrogenation (FA) or dehydrogenation (NH3, H18-DBT) and higher investment costs. However, for the use of MeOH in an H-DR process to be practically feasible, questions regarding process flexibility and the optimal sourcing of CO2 and heat must be answered.

Oxidized starch, an additive used in paper manufacturing and products for construction industry, is usually produced using harmful oxidant, such as hypochlorites or periodates. In this study, a simple and efficient eco-friendly laboratory and industrial procedures for starch oxidation were developed. The procedure involves application of small amounts of more environmentally friendly oxidant, hydrogen peroxide, a novel special metal complex catalyst such as copper(II) citrate and copper(II) ricinoleate and biobased plasticizers. Optimization procedure, with respect to the quantity of hydrogen peroxide and temperature in the presence of iron(II) sulphate catalyst, was performed by using the response surface methodology. Compa-rative analysis of the use of the other catalysts that is copper(II) sulphate, copper(II) citrate and copper(II) ricinoleate, indicated copper(II) citrate as the catalyst of choice. Improvement of starch is achieved using three plasticizers: ricinoleic acid (RA), diisopropyl tartarate, as well as epoxidized soybean, linseed and sunflower oils. The effects of hydrogen peroxide and catalyst concentrations, as well as the reaction temperature in the presence of naturally based plasticizers on the physicochemical, thermal and morphological properties of oxidized starch are presented. According to the results obtained in initial experiments, the optimal industrial process is based on the use of copper(II) citrate (0.1 %) as a catalyst and RA (3 %) as a plasticizer.

In this work, hydrogel polymer electrolytes (HPEs) were obtained by the photopolymerization of a mixture of two monomers: Exothane 8 (Ex8) and 2-hydroxyethylmethacrylate acid phosphate (HEMA-P) in an organic solvent N-methyl-2-pyrrolidone (NMP), which was replaced after polymerization with water, and then with the electrolyte. The ratio of monomers as well as the concentration of NMP was changed in the composition to study its influence on the properties of the HPE: conductivity (electrochemical impedance spectroscopy, EIS) and mechanical properties (puncture resistance). Properties were optimized using a mathematical model to obtain a hydrogel with both good mechanical and conductive properties. To the best of our knowledge, it is the first publication that demonstrates the application of optimization methods for the preparation of HPE. Then, the hydrogel with optimal properties was tested as a separator in a two-electrode symmetric AC/AC pouch-cell. The cells were investigated by cyclic voltammetry galvanostatic charge/discharge with potential limitation and EIS. Good mechanical properties of HPE allowed for obtaining samples of smaller thickness while maintaining very good dimensional stability. Thus, the electrochemical capacitor (EC) resistance was reduced and their electrochemical properties improved. Moreover, photopolymerization kinetics in the solvent and in bulk by photo-DSC (differential scanning calorimetry) were performed. The great impact on the polymerization of HEMA-P and its mixtures (with Ex8 and NMP) have strong intermolecular interactions between reagents molecules (i.e., hydrogen bonds).

Biomass production is spatially distributed resulting in high transportation costs when moving dedicated biomass crops and crop residues. A multifaceted approach was taken to address this issue as the low bulk and energy density of biomass limits transportation efficiency. Two systems were analyzed for the conversion of biomass into a denser feedstock applicable to on-farm use. Pelletization was able to densify the material into a solid fuel. Using a pilot scale flat ring pellet mill, the density of the material was able to be increased to at least 4.4 times that of uncompressed material. Pellet durability was found to be strongly related to the moisture content of the material entering the mill. Unlike with ring roller pellet mills, a higher durability was typically seen forbiomass materials with a preconditioned moisture content of 20% (w.b.). From a liquid fuel standpoint, the conversion of lignocellulosic material into biobutanol on-farm was the second method investigated. For the pretreatment of biomass, alkaline hydrogen peroxide spray was demonstrated to be an effective enhancer of saccharification. The viability of on-farm biobutanol preprocessing bunker facilities within Kentucky was analyzed using Geographic Information systems (GIS) to specifically address transportation related factors. The spatial variability of corn field production, size, and location were resolved by utilizing ModelBuilder to combine the various forms of data and their attributes. Centralized and Distributed preprocessing with Centralized refining (DC) transportation systems were compared. Centralized was defined as transport of corn stover directly from the field to a refinery. Distributed-Centralized was specified as going from the field to the biobutanol bunker with corn stover and from the bunker to the refinery with a dewatered crude biobutanol solution. For the DC design, the location of the field and refinery were fixed with the biobutanol bunker location being variable and dependent upon differing maximum transportation (8-80 km) cutoffs for biomass transport from the field to biobutanol bunkers. The DC designs demonstrated a lower (38 - 59%) total transportation cost with a reduced fuel use and CO2 emissions compared to the centralized system.

As inorganic materials are put to more and more practical uses--mainly in electric, magnetic, and optical devices--materials scientists must have an increasingly sophisticated understanding of the chemical and physical properties of inorganic compounds. This volume--the first of its kind in twenty years--provides a unified presentation of the chemistry of non-stoichiometric compounds based on statistical thermodynamics and structural inorganic chemistry. Four modern examples of non-stoichiometric compounds--ionic conducting compounds, hydrogen absorbing alloys, magnetic materials, and electrical materials--are discussed in detail. Students and researchers in structural inorganic chemistry, crystallography, materials science, and solid state physics will find this much-needed book both practical and informative.

Anatomically the kidney consists of the cortex, medulla, and renal pelvis. The kidneys have approximately 2 million nephrons and receive 20% of the resting cardiac output making the kidneys the richest blood flow per gram of tissue in the body. A high blood and plasma flow to the kidneys is essential for the generation of a large amount of glomerular filtrate, up to 125 ml min−1, to regulate the fluid and electrolyte balance of the body. The kidneys also have many other important physiological functions, including excretion of metabolic wastes or toxins, regulation of blood volume and pressure, and also production and metabolism of many hormones. Although plasma creatinine concentration has been frequently used to estimate glomerular filtration rate by the Modification of Diet in Renal Disease (MDRD) equation in stable chronic kidney diseases, the MDRD equation has limitations and does not reflect glomerular filtration rate accurately in healthy individuals or patients with acute kidney injury. An optimal acid–base environment is essential for many body functions, including haemoglobin–oxygen dissociation, transcellular shift of electrolytes, membrane excitability, function of many enzymes, and energy production. Based on the concepts of electrochemical neutrality, law of conservation of mass, and law of mass action, according to Stewart’s approach, hydrogen ion concentration is determined by three independent variables: (1) carbon dioxide tension, (2) total concentrations of weak acids such as albumin and phosphate, and (3) strong ion difference, also known as SID. It is important to understand that the main advantage of Stewart over the bicarbonate-centred approach is in the interpretation of metabolic acidosis.

The main objective of this book is to acquaint the reader with the main modern problems of the multisensor data analysis and opportunities of the hyperspectral shooting being carried out in the wide range of wavelengths from ultraviolet to the infrared range, visualization of the fast combustion processes of flame propagation and flame acceleration, the limit phenomena at flame ignition and propagation. The book can be useful to students of the high courses and scientists dealing with problems of optical spectroscopy, vizualisation, digital recognizing images and gaseous combustion. The main goal of this book is to bring to the attention of the reader the main modern problems of multisensory data analysis and the possibilities of hyperspectral imaging, carried out in a broad wave-length range from ultraviolet to infrared by methods of visualizing fast combustion processes, propagation and flames acceleration, and limiting phenomena during ignition and flame propagation. The book can be useful for students of higher courses and experimental scientists dealing with problems of optical spectroscopy, visualization, pattern recognition and gas combustion.

Decontamination is often necessary in facilities with sensitive spaces where pathogen elimination is critical. Historically, high concentration vaporized hydrogen peroxide technologies have been applied in these areas for pathogen disinfection. While effective, these high concentration solutions come with inherent risks to human health and safety. Alternatively, one recent innovation is a hybrid hydrogen peroxide system which combines a 7% hydrogen peroxide solution with a calibrated fogging device that delivers a mixture of vaporous and micro aerosolized particles, significantly lowering the risk of exposure to high-concentration hazardous chemicals. Studies performed with this technology demonstrate high level pathogen decontamination across a variety of tested pathogens and substrates. This chapter will cover a brief history of hydrogen peroxide technologies and their application processes; examine the correlations between viral inactivation, viral disinfection, and biological indicators for validation; demonstrate the necessity of dwell time for optimal efficacy; discuss the effects of viral disinfectant use on laboratory surfaces; and examine various studies, including virologic work performed in Biosafety Level 3 facilities and good laboratory practice (GLP) data performed by EPA-approved laboratories. This chapter will provide readers a deeper understanding of essential components and considerations when implementing hydrogen peroxide systems for viral decontamination.

This chapter will provide an overview of antiseptic agents used to irrigate wounds for the prevention or treatment of orthopaedic infections, including their mechanism of action, spectrum of microbicidal activity, safety including potential adverse effects, efficacy in eliminating infective pathogens, and efficacy against established biofilm. Some of the common irrigation solutions include acetic acid, bacitracin and polymyxin, chlorhexidine, dilute povidone-iodine (PI), sodium hypochlorite, and hydrogen peroxide. The current guidelines for prevention of surgical site infection (SSI) from the Centers for Disease Control and Prevention (CDC), World Health Organization (WHO), and International Consensus Meeting (ICM) on orthopaedic infections only recognize sterile dilute PI as the most optimal irrigation solution. PI, sodium hypochlorite, and hydrogen peroxide provide the broadest range of antimicrobial coverage. Chlorhexidine, PI, and hydrogen peroxide may be useful in eradicating biofilm. The addition of antibiotics to irrigation solutions is not recommended as it does not confer any benefit and may further contribute to emergence of antibiotic resistant pathogens. While severe adverse effects are uncommon, cases of anaphylaxis with chlorhexidine and oxygen emboli with the use of hydrogen peroxide have been reported.

Multifunctional biomedical materials capable of integrating optical functions open up promising new possibilities for the application of photosensitive materials. For example, they are highly desirable for advanced intraocular lens (IOL) implants. For this purpose, we propose hydrogels, based on poly(ethylene glycol) (PEG) prepolymers, which are photochemically crosslinkable and thereby patternable. Various photoinitiators are used and investigated spectroscopically; those with high sensitivity in the optical region of the spectrum are advantageous. Hydrogel films have been obtained, which are applicable for light-based patterning and, hence, for functionalization of both surface and volume: It is shown that a local change in optical properties can be induced in special hydrogel films by photochemical crosslinking. Such a local light-induced material response forms the basis for volume holographic patterning. Cytocompatibility of hydrogels and compositions is evaluated via cytotoxicity tests. Exploiting the interrelationship between structure and function is highly relevant for biomedical materials with multifunctionality.

The properties of aluminum including: light weight, high strength, and resistance to corrosion make it an ideal material for use in applications such as: transportation, food and beverage packaging, construction, defense and aerospace, machinery and tools and consumer products. In addition to reviewing various grades of aluminum, this article will provide an overview of important properties including: crystal structure, density, thermal expansion, thermal and electrical conductivity, Debye temperature, magnetic susceptibility, electrical properties, compressibility, optical properties, solidification and melting, corrosion, mechanical properties and hydrogen solubility.

In this paper, an estimation model of fuel cell life degradation and lithium battery life degradation is defined based on experimental data. A dynamic programming algorithm based on global optimization is proposed, which takes the total equivalent hydrogen consumption cost of power system and the cost of fuel cell power degradation as the target function, and weights the power degradation term of fuel cell with a penalty coefficient, so that the designed energy management strategy can take into account the economy and durability of the vehicle. Considering that the control strategy based on global optimization is sensitive to operating conditions, i.e. the reduction of hydrogen consumption and fuel cell degradation costs by dynamic programming algorithm is based on operating conditions. Once the input condition of operating conditions is changed, the control strategy will not guarantee the optimum. Therefore, this paper uses the optimal results of dynamic programming algorithm to provide the data set of off-line training. Transformer is applied to make time series prediction, which will help to solve the problem of balancing power distribution considering economy and durability under various conditions. The input characteristics of the transformer network are the current bus demand power, the battery state of charge and the fuel cell power of the previous time, and the output is the fuel cell power predicted at the current time. The results of Transformer model are compared with those of dynamic programming, and they are very close. The Transformer model was trained using standard UDDS and NEDC operating conditions and tested on HWFET. The test shows that the developed Transformer model has good generalization ability for different operating conditions.

The present study focuses on the porosity formation in three Al-Si cast alloys widely used in automotive industries viz. A319.0, A356.0, and A413.0 alloys under various conditions: stirring, degassing. Sr level, amount of grain refining, combined modification and grain refining, as well as hydrogen level. The solidification rate was the same for all alloys in terms of the mold used and its temperature. The microstructural investigations were carried out quantitatively using an optical microscope-image analyzer system scanning systematically over a polished sample area of 25 mm × 25 mm and qualitatively using an electron probe microanalzer equipped with EDS and WDS systems. The results were coupled with hardness measurements.

Distinctive characteristics of titanium dioxide such as high refractive index, overwhelmingly high melting and boiling point, high toughness, and hardness, photocatalytic nature, ability to absorb or reflect UV-rays, DeNox catalyst, nontoxicity, inert behavior, etc., have brought about the massive use of TiO2 in a variety of conventional as well as advanced engineering applications. Broad commercial utilization of titanium dioxide in products including paints, anti-air pollutants, cosmetics, skincare and sunblock, pharmaceuticals, surface protection, building energy-saving, etc., accounts for its multibillion dollars market worldwide. Titanium dioxide carries unique thermal and optical characteristics and therefore has gained significance as a potential candidate for advanced applications such as clean hydrogen fuel harvesting, photoelectric solar panels, photothermal conversion, treatment of exhaust gases from combustion engines and power plants, thermal energy storage, thermal management of electronic devices and photovoltaics, and nano-thermofluids. This chapter presents a brief insight into some of the noteworthy characteristics and a comprehensive overview of advanced thermal applications of TiO2.

Soil reaction is the amount of acids (acidity) or bases (alkalinity) present in a soil and is indicated by a term called “pH”. By definition, pH is the logarithm of the reciprocal of the hydrogen ion (H+) concentration, or When a number has a smaller superscript number with it, the number is raised to that power which is called the “logarithm.” Raising a number to a power means multiplying that number by itself the number of times indicated by the superscript. . . . Examples: 102 means 10 x 10 = 100; 103 means 10 x 10 x 10 = 1,000. The logarithm (log) is 2 for the first example and 3 for the second. . . . Logarithms are used as these are more convenient in expressing the amount of hydrogen ions present. Under neutral solutions the pH is 7.0. Any pH that is less than 7 is acid and any pH above is alkaline. When changing from a pH of 7 to a pH of 6, the H ion concentration increases ten times, and when going from a pH of 7 to a pH of 5, the H ion concentration increases 100 times because pH uses a geometric scale and not an arithmetic scale. Thus, pH changes by steps of ten times the next adjacent number. The logarithmic scale used for pH is the same type, but opposite in direction, as that used to measure earthquakes. For each larger number of earthquake, the severity increases ten times; for each smaller number of pH, the acidity increases ten times. Some plants can tolerate very low pH (4.5) and others can withstand a pH of 8.3, but the optimum range for growth of most plants and microbes is between 6 and 7. Availability of most nutrients is affected by pH changes. Charts have been constructed to show this relationship. On these charts the pH at which most nutrients are readily available is from 6 to 7. At extremes of pH, availability of nutrients to plants often is reduced considerably.

Silver nanoparticles (AgNPs) are one of the most vital and fascinating nanomaterials among several metallic nanoparticles that are involved in biomedical applications. But their stabilization towards agglomeration is a serious concern. Synthesized silver nanoparticles can be dispersed in polymeric hydrogel for stabilization and can be efficiently used in heterogeneous catalysis. Polystyrene crosslinked with 1, 6-hexanediol diacrylate can be suitably functionalized for catalytic activities. The nature of the support has a profound influence on the reactivity of the polymeric resin. A flexible support with optimum hydrophilic and hydrophobic balance enhanced the reactivity of the supporting system. Using this supported AgNPs catalytic reduction of Para-nitro phenol can be easily accomplished comparing to conventional method.

Abstract The growing attention to environmental issues has led to an increase in renewable source exploitation. These resources, in addition to their characteristic of zero emissions, can be employed where there is no connection to the electricity grid or to produce synthetic fuels (e.g. hydrogen or synthetic natural gas) via power-to-gas technologies. In the context of the ERA-Net Project ZEHTC (Zero Emission Hydrogen Turbine Center), the aim of this paper is the development of a design calculation model for the ZEHTC pilot plant, consisting in the first gas turbine test facility making use of the power produced during tests — along with renewables — for hydrogen production, integrated with batteries. The hydrogen is locally used — mixed with natural gas — to run the gas turbine, reducing its environmental impact. The developed code aims at maximizing the conversion of the renewable source into hydrogen and guaranteeing its availability for the planned tests. It includes physical-mathematical models for each component and has been used to perform a parametric analysis varying the main components size, thus estimating the total produced hydrogen. The main innovation of the ZEHTC micro-grid project consists in the use of a gas turbine — instead of a fuel cell — as system to reconvert the stored hydrogen.

Abstract The hydrogen production by means of renewable energy exploitation has the potential to address issues that arise when an increasing share of power is generated from sources that have a highly variable output. Although these systems have been widely studied, one of the key aspects to be considered is the choice of the energy management strategy. The aim of this paper is to define and present an optimal strategy for the energy flow management of a pilot plant consisting of a turbine gas facility making use of power produced during turbine tests — along with solar — for hydrogen production integrated with batteries storage. Key results from the analyses are: i) increasing the hydrogen production target, the hydrogen production ratio increases up to a maximum value equal to about 100%; ii) optimizing the management strategy, the system is always able to meet the demand of hydrogen; iii) with a larger hydrogen storage capacity, the microgrid is able to exploit a higher amount of renewable production, achieving the total renewable energy exploitation.

Abstract The purpose of this paper is to present the various technological solutions optimized for the use of hydrogen, in transport, distribution, storage and utilization, analyzing their criticalities and advantages. Hydrogen compression is a fundamental step in the transportation and storage segments and continuous improvement are required. The greatest technological challenges are certainly the high pressures required for the various fields of use, the need to maintain a clean gas and to use materials that are not subject to embrittlement. The choice between the different compression technologies is based on the need for pressures and flow rates; in the case of high flow rates and low compression ratios a centrifugal compressor is preferable, while for low flow rates and high compression ratios the choice goes to piston compressors. To prevent gas contamination, dry reciprocating compressor are preferred because they allow to avoid an oil separator filter on the discharge. Current technology of reciprocating compressors allows to compress hydrogen up to 300 bar with lubricated machines, while with dry technology it is possible to reach up to 250 bar. A second criticality on reciprocating compressors is maintenance: the parts subject to wear need to be serviced every 8000 hour of operation. The use of innovative materials will increase the maintenance intervals reaching higher pressures without lubrication. To increase the pressure ratio with centrifugal compressor, it's needed to increase the rotating speed, therefore the peripheral speed, with materials suitable for H2, stages get high compression to reduce the number of compressor bodies. If the process conditions require high delivery pressures combined with large flow rates, a solution of centrifugal compressors alone would be able to manage the flow rate but not the required delivery pressure. On the other hand, the use of reciprocating compressors would require a considerable number of units. In this case, therefore, the optimal solution is to combine the two technologies, centrifugal and pistons, using the best features. A case study in which the superior performances of the hybrid solution in terms of total cost of ownership will be described and compared with traditional single technology compression train

This study investigates the effects of introducing electronically excited oxygen on trends in exergy destruction during hydrogen combustion. Electronically excited oxygen enhances many properties of combustion. By understanding how it alters the chemical kinetics, and hence the destruction of exergy, it may be possible to improve the overall exergetic efficiency of combustion thereby reducing fuel use to achieve desired energy conversion. A numerical model was developed of an adiabatic plug flow reactor using CHEMKIN-PRO; in conjunction with a hydrogen oxidation mechanism that includes explicit reaction pathways for various electronically excited species. Exergy destruction was calculated for cases where singlet oxygen composed 0%–100% of the oxidizer while maintaining a stoichiometric oxidizer-fuel ratio; all other inlet conditions were held fixed. Results show that an optimal range of exergetic combustion efficiency exists between 0%–20%, with the maximum occurring at approximately 10%. A detailed assessment of the total exergy destruction reveals that, for the optimal range of exergetic combustion efficiencies, as much as 60% of the total exergy destruction occurs prior to ignition. For inlet percentages of singlet oxygen greater than 20%, the majority of the total exergy destruction occurs after ignition. This paper examines the phenomenological events taking place in the reaction mechanism that give rise to the destruction of exergy during combustion. Understanding these mechanisms and the effects of introducing excited oxygen into the combustion process, sheds light on how we might use excited oxygen to increase the exergetic efficiency of combustion.

In order to predict and prevent cold cracking in welds in structural materials used in pressure vessels, the hydrogen distribution in the welds used to join stainless steel clad Cr-Mo steels, stainless steel overlay Cr-Mo steels and A533B steel was calculated in this study. In the calculation methods employed in this study, the diffusion and concentration of hydrogen in the welds was calculated using the diffusion equation based on activity considering the hardness and stress distributions, as well as the dependence on temperature for hydrogen diffusion coefficient. The diffusion and concentration behavior of hydrogen during welding, post weld heat treatment (PWHT) processing can be simulated using the calculation methods applied in this study. From the comparison between calculated and the experimental results of cold cracking tests such as the y-shape cold cracking test, cracking was prominently observed in the heat affected zone (HAZ), when the hydrogen content and residual stresses were over certain critical values. Based on the results of this analysis, it was suggested that it is possible to use this simulation method to predict the optimal hydrogen removal heat treatment conditions for these materials.

In previous work the authors have demonstrated that when hydrogen is combusted in stoichiometric proportions at 1 atm and 1200 K, and singlet oxygen comprises 0–20% of the oxidizer, an optimal range of exergetic efficiency exists. The maximum exergetic efficiency occurs at approximately 10%. Over this range, roughly 60% of the total exergy destruction occurs prior to ignition. This is a significant result because it suggests that the exergetic efficiency of combustion might be improved at a fundamental level by chemical means, thereby inherently increasing the efficiency of fuel use for a desired energy application. The objective of the study presented in this paper is to analyze the reaction mechanisms for combustion with varying percentages of singlet oxygen, to determine which reaction pathways most influence the observed trends in exergy destruction and exergetic efficiency. This was accomplished by performing both sensitivity and rate-of-production analyses of the hydrogen-oxygen combustion mechanism. The results of the analysis show that the presence of singlet oxygen governs the rate of production of hydroxyl and other key radicals. These key radicals directly affect the phenomenological processes associated with chemical induction and thermal induction during ignition. Therefore, the observed optimum exergetic efficiency correlates to the quantity of singlet oxygen in the inlet charge that minimizes exergy destruction by fostering chemical reactions due to radical formation to a greater extent than thermal heat release. The results of this analysis are noteworthy and provide new insight regarding how the exergetic efficiency of combustion may be optimized by introducing singlet oxygen, thereby altering the reaction pathways to enhance energy conversion in a fundamental way that could have important implications for improved fuel use.

Hydrogen as a next generation energy carrier, is a clear and zero emission fuel with growing application in various fields. Intermodal transportation is an important issue for the safety and economic use of hydrogen fuel in distributed sites. Hydrogen is usually transported in high-pressure cylinders on trucks with bounded space. In this paper, we investigated different cylinder designs, packing strategies and their impact on the storage density, which is defined as the weight of hydrogen divided by the storage space, and then found out the optimal design and packing strategy. The high-pressure hydrogen gas was considered as real gas, and the stress distribution was analyzed for the 4130 steel cylinders based on the thick-wall cylinder model. Two different head designs of sphere and elliptical head were considered and discussed. A high storage density strategy with cylinder geometric parameter design, hydrogen gas pressure and cylinder packing methods were proposed. An exploration of the carbon fiber cylinder showed the potential of the composite material as a storage cylinder in high-pressure storage situations.

Abstract It is now universally established that the use of fossil fuels is responsible for environmental issues such as global warming. Among the different renewable energy sources, solar energy is considered one of the most affordable resources for meeting current energy demands and mitigating environmental problems. However, the exploitation of solar energy is challenging because of both diurnal and seasonal variations. Power-to-Hydrogen technologies can play a key role to counterbalance the variation of solar irradiance. Moreover, hydrogen-fueled gas turbines are considered promising technologies to decarbonize the electricity sector. To tackle these concerns, this paper presents a multi-generation energy system operated in island mode in which a hydrogen-fueled gas turbine is coupled with a solar photovoltaic plant, an electrolyzer, an absorption chiller, electric and thermal energy storage, as well as a hydrogen storage. Therefore, the energy system is 100% based on renewable energy. The sizes of the components and the respective energy management strategy are optimized by maximizing the exploitation of renewable energy sources, while the supply of electricity from the national grid must be null. Moreover, the effect of ambient conditions on the optimal sizing is also investigated by considering the thermal, cooling and electrical energy demands of two case studies located in two different climatic zones. The paper demonstrates that the adoption of hydrogen-fueled gas turbines coupled with Power-to-Hydrogen technologies can effectively support the transition towards a clean energy supply. Moreover, this study provides a procedure for the optimal sizing of a multi-generation energy system fully based on solar energy, by also demonstrating that both PV panel area and hydrogen storage volume are feasible, if compared to the considered district layout.

Abstract Equations of state and transport property models for hydrogen and hydrogen mixed with natural gas components relevant for pipeline transport have been evaluated by comparing to experimental data and reference equations of state. The evaluated properties are density, speed of sound, Joule-Thompson coefficient, the isobaric and isochoric heat capacity, viscosity, and thermal conductivity. A temperature span of −10 to 50 °C and a pressure span of 1-300 bara has been set as the target range for pipeline transport. Viscosity and thermal conductivity models have been evaluated for binaries where experimental data are available. The goal of this work was to determine if models already available in commercial simulators can predict fluid properties accurate enough for engineering purposes. The classical cubic equations of state of Soave-Redich-Kwong (SRK) and Peng-Robinson (PR) with van der Waals mixing rules have been tested with parameters extracted from the common commercial simulations tools Hysys, Unisim, PVTsim Nova and Multifash. In general, the different parameter sets give similar performance. One exception is the H2-CH4 binary, where both Unisim and Multifash use a non-optimal kij interaction parameter. Neither the SRK, nor PR can describe the Joule-Thompson coefficient of hydrogen, and the error lies in the range 50%-100%. The Joule-Thompson coefficient is however small, and the effect of this misprediction on pipeline simulations might not be significant. For viscosity and thermal conductivity predictions, the SuperTRAPP model in REFPROP 10 as well as simpler viscosity models LGE, LBC and a corresponding-state-principle model of PVTsim Nova have been evaluated. The SuperTRAPP model in REFPROP 10 was found to predict viscosity and thermal conductivity within a reasonable accuracy for pure hydrogen. The simpler viscosity models LGE and LBC overestimate the viscosity of hydrogen by 65% to 90% in the transport domain of interest. For the hydrogen binary systems studied, the SuperTRAPP model for the thermal conductivity and viscosity had errors around 20% at high pressures. Comparing corresponding-state-principle viscosity models with the SuperTRAPP model gave relative deviations in the range 3.9% to 13%. The SRK equation of state is found to perform better than the PR equation of state, with a relative density error below 1% for hydrogen rich systems. A TIBCO Spotfire® visualization dashboard has been developed for easy access to the evaluation results of the large amount of data and thermodynamic models. A steady-state thermohydraulic analysis for Europipe (Norway to Europe) has been performed to evaluate the effect that using different equations of state and viscosity models have on the thermohydraulic estimations. After a review of the thermodynamic model's performance, clear guidance on model selection for hydrogen transportation is provided.

Increased research into the chemistry, physics and material science of hydrogen cycling compounds has led to the rapid growth of solid-phase hydrogen-storage options. The operating conditions of these new options span a wide range: system temperature can be as low as 70K or over 600K, system pressure varies from less than 100kPa to 35MPa, and heat loads can be moderate or can be measured in megawatts. While the intense focus placed on storage materials has been appropriate, there is also a need for research in engineering, specifically in containment, heat transfer, and controls. The DOE’s recently proposed engineering center of expertise underscores the growing understanding that engineering research will play a role in the success of advanced hydrogen storage systems. Engineering a hydrogen system will minimally require containment of the storage media and control of the hydrogenation and dehydrogenation processes, but an elegant system design will compensate for the storage media’s weaker aspects and capitalize on its strengths. To achieve such a complete solution, the storage tank must be designed to work with the media, the vehicle packaging, the power-plant, and the power-plant’s control system. In some cases there are synergies available that increase the efficiency of both subsystems simultaneously. In addition, system designers will need to make the hard choices needed to convert a technically feasible concept into a commercially successful product. Materials cost, assembly cost, and end of life costs will all shape the final design of a viable hydrogen storage system. Once again there is a critical role for engineering research, in this case into lower cost and higher performance engineering materials. Each form of hydrogen storage has its own, unique, challenges and opportunities for the system designer. These differing requirements stem directly from the properties of the storage media. Aside from physical containment of compressed or liquefied hydrogen, most storage media can be assigned to one of four major categories, chemical storage, metal hydrides, complex hydrides, or physisorption. Specific needs of each technology are discussed below. Physisorption systems currently operate at 77K with very fast kinetics and good gravimetric capacity; and as such, special engineering challenges center on controlling heat transfer. Excellent MLVSI is available, its cost is high and it is not readily applied to complex shape in a mass manufacture setting. Additionally, while the heat of adsorption on most physisorbents is a relatively modest 6–10kJ/mol H2, this heat must be moved up a 200K gradient. Physisorpion systems are also challenged on density. Consequently, methods for reducing the cost of producing and assembling compact, high-quality insulation, tank design to minimize heat transfer while maintaining manufacturability, improved methods of heat transfer to and from the storage media, and controls to optimize filling are areas of profitable research. It may be noted that the first two areas would also contribute to improvement of liquid hydrogen tanks. Metal hydrides are currently nearest application in the form of high pressure metal hydride tanks because of their reduced volume relative to compressed gas tanks of the same capacity and pressure. These systems typically use simple pressure controls, and have enthalpies of roughly 20kJ/mol H2 and plateau pressures of at most a few MPa. During filling, temperatures must be high enough to ensure fast kinetics, but kept low enough that the thermodynamically set plateau pressure is well below the filling pressure. To accomplish this balance the heat transfer system must handle on the order of 300kW during the 5 minute fill of a 10kg tank. These systems are also challenged on mass and the cost of the media. High value areas for research include: heat transfer inside a 35MPa rated pressure vessel, light and strong tank construction materials with reduced cost, and metals or other materials that do not embrittle in the presence of high pressure hydrogen when operated below ∼400K. The latter two topics would also have a beneficial impact on compressed gas hydrogen storage systems, the current “system to beat”. Complex hydrides frequently have high hydrogen capacity but also an enthalpy of adsorption >30kJ/mol H2, a hydrogen release temperature >370K, and in many cases multiple steps of adsorption/desorption with slow kinetics in at least one of the steps. Most complex hydrides are thermal insulators in the hydrided form. From an engineering perspective, improved methods and designs for cost effective heat transfer to the storage media in a 5 to 10MPa vessel is of significant interest, as are materials that resist embrittlement at pressures below 10MPa and temperatures below 500K. Chemical hydrides produce heat when releasing hydrogen; in some systems this can be managed with air cooling of the reactor, but in other systems that may not be possible. In general, chemical hydrides must be removed from the vehicle and regenerated off-board. They are challenged on durability and recycling energy. Engineering research of interest in these systems centers around maintaining the spent fuel in a state suitable for rapid removal while minimizing system mass, and on developing highly efficient recycling plant designs that make the most of heat from exothermic steps. While the designs of each category of storage tank will differ with the material properties, two common engineering research thrusts stand out, heat transfer and structural materials. In addition, control strategies are important to all advanced storage systems, though they will vary significantly from system to system. Chemical systems need controls primarily to match hydrogen supply to power-plant demand, including shut down. High pressure metal hydride systems will need control during filling to maintain an appropriately low plateau pressure. Complex hydrides will need control for optimal filling and release of hydrogen from materials with multi-step reactions. Even the relatively simple compressed-gas tanks require control strategies during refill. Heat transfer systems will modulate performance and directly impact cost. While issues such as thermal conductivity may not be as great as anticipated, the heat transfer system still impacts gravimetric efficiency, volumetric efficiency and cost. These are three key factors to commercial viability, so any research that improves performance or reduces cost is important. Recent work in the DOE FreedomCAR program indicates that some 14% of the system mass may be attributed to heat transfer in complex hydride systems. If this system is made to withstand 100 bar at 450K the material cost will be a meaningful portion of the total tank cost. Improvements to the basic shell and tube structures that can reduce the total mass of heat transfer equipment while maintaining good global and local temperature control are needed. Reducing the mass and cost of the materials of construction would also benefit all systems. Much has been made of the need to reduce the cost of carbon fiber in compressed tanks and new processes are being investigated. Further progress is likely to benefit any composite tank, not just compressed gas tanks. In a like fashion, all tanks have metal parts. Today those parts are made from expensive alloys, such as A286. If other structural materials could be proven suitable for tank construction there would be a direct cost benefit to all tank systems. Finally there is a need to match the system to the storage material and the power-plant. Recent work has shown there are strong effects of material properties on system performance, not only because of the material, but also because the material properties drive the tank design to be more or less efficient. Filling of a hydride tank provides an excellent example. A five minute or less fill time is desirable. Hydrogen will be supplied as a gas, perhaps at a fixed pressure and temperature. The kinetics of the hydride will dictate how fast hydrogen can be absorbed, and the thermodynamics will determine if hydrogen can be absorbed at all; both properties are temperature dependent. The temperature will depend on how fast heat is generated by absorption and how fast heat can be added or removed by the system. If the design system and material properties are not both well suited to this filling scenario the actual amount of hydrogen stored could be significantly less than the capacity of the system. Controls may play an important role as well, by altering the coolant temperature and flow, and the gas temperature and pressure, a better fill is likely. Similar strategies have already been demonstrated for compressed gas systems. Matching system capabilities to power-plant needs is also important. Supplying the demanded fuel in transients and start up are obvious requirements that both the tank system and material must be design to meet. But there are opportunities too. If the power-plant heat can be used to release hydrogen, then the efficiency of vehicle increases greatly. This efficiency comes not only from preventing hydrogen losses from supplying heat to the media, but also from the power-plant cooling that occurs. To reap this benefit, it will be important to have elegant control strategies that avoid unwanted feedback between the power-plant and the fuel system. Hydrogen fueled vehicles are making tremendous strides, as can be seen by the number and increasing market readiness of vehicles in technology validation programs. Research that improves the effectiveness and reduces the costs of heat transfer systems, tank construction materials, and control systems will play a key role in preparing advanced hydrogen storage systems to be a part of this transportation revolution.

Near-to-surface geothermal energy with heat pumps is state of the art and is already widespread in Switzerland. In the future energy system, medium-deep to deep geothermal energy (1 to 6 kilometres) will, in addition, play an important role. To the forefront is the supply of heat for buildings and industrial processes. This form of geothermal energy utilisation requires a highly permeable underground area that allows a fluid – usually water – to absorb the naturally existing rock heat and then transport it to the surface. Sedimentary rocks are usually permeable by nature, whereas for granites and gneisses permeability must be artificially induced by injecting water. The heat gained in this way increases in line with the drilling depth: at a depth of 1 kilometre, the underground temperature is approximately 40°C, while at a depth of 3 kilometres it is around 100°C. To drive a steam turbine for the production of electricity, temperatures of over 100°C are required. As this requires greater depths of 3 to 6 kilometres, the risk of seismicity induced by the drilling also increases. Underground zones are also suitable for storing heat and gases, such as hydrogen or methane, and for the definitive storage of CO2. For this purpose, such zones need to fulfil similar requirements to those applicable to heat generation. In addition, however, a dense top layer is required above the reservoir so that the gas cannot escape. The joint project “Hydropower and geo-energy” of the NRP “Energy” focused on the question of where suitable ground layers can be found in Switzerland that optimally meet the requirements for the various uses. A second research priority concerned measures to reduce seismicity induced by deep drilling and the resulting damage to buildings. Models and simulations were also developed which contribute to a better understanding of the underground processes involved in the development and use of geothermal resources. In summary, the research results show that there are good conditions in Switzerland for the use of medium-deep geothermal energy (1 to 3 kilometres) – both for the building stock and for industrial processes. There are also grounds for optimism concerning the seasonal storage of heat and gases. In contrast, the potential for the definitive storage of CO2 in relevant quantities is rather limited. With respect to electricity production using deep geothermal energy (> 3 kilometres), the extent to which there is potential to exploit the underground economically is still not absolutely certain. In this regard, industrially operated demonstration plants are urgently needed in order to boost acceptance among the population and investors.