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Biohythane, the promising gaseous biofuel, can be produced by the recirculated two-phase anaerobic digestion (R-TPAD). The effect of hydraulic retention time (HRT) as 30, 20 and 10 days on biohythane production via R-TPAD (recirculation ratio = 0.4) was investigated with co-digestion of food waste and paper waste. The results showed that HRTs of 30 and 20 days maintained stable performance for R-TPAD but HRT of 10 days led to the final decrease in biogas production. The failure in the end was attributed to the wash-out of microbes. The removal efficiencies for COD and carbohydrates were decreased by short HRTs while for VS it remained relatively stable at about 75.7 ± 4.0%. All through the operation, acidogenic phase and methanogenic phase were separated stably and butyrate pathway was the dominant pathway for hydrogen fermentation in the first stage. The microbial community in the first stage reached the highest diversity when total HRT was 20 days, where the hydrogen production rate was the highest. The genera Lactobacillus and Caproiciproducens kept dominating the dark fermentation in the acidogenic phase, and Ruminococcus and Methanosarcina were decreasing in the methanogenic phase. The biohythane yields were 411 mL/g-VS fed , 332 mL/g-VS fed and 253 mL/g-VS fed , respectively, where the H 2 contents were 18.4%, 14.7% and 8.8%, respectively. [Display omitted] • The R-TPAD system (R = 0.4) was operated for biohythane production. • R-TPAD operated under HRTs of 30 and 20 maintained stable performance. • Organic removals and biohythane yields were lowered by short HRTs. • Different microbial communities were identified by co-occurrence network. • Biohythane yields affected by different parameters were discussed. [ABSTRACT FROM AUTHOR]

The study presents a novel integrated three-compartment electrochemical continuous electrodeionization reactor that was constructed in a laboratory environment. In order to extract large amounts of carbon dioxide from naturally occurring oceanwater in the form of bicarbonate and carbonate, it develops a innovative electrolytic cation exchange process. At the same time, it produces hydrogen gas for possible hydrocarbon synthesis. The study employs the Box-Behnken experimental design approach implemented through the Design Expert software to investigate and optimize the performance of electrochemical hydrogen extraction from Ocean water from an integrated reactor. The integrated electrochemical continuous-type electrodeionization reactor comprises two cation-permeable membranes that operate as boundaries between three compartments: a central compartment and electrode compartments that house the cathode and anode, each of which may reverse polarity. These membranes are made of gel polystyrene cross-linked with divinylbenzene, which has acidic properties that allow cation transport while inhibiting anions. The integrated reactor's electrode chambers are enclosed in plexiglass end plates and contain distinct Plexiglass electrode compartments. These compartments have mesh and solid steel anode and cathode electrodes, with an electrode active area of 176.71 cm2. The influence of various factors, such as voltage and electrolyte amount, on the production of hydrogen synthesis is examined. The study results demonstrate a maximum hydrogen production rate of 2.2 mg/min and a hydrogen production efficiency of 7.82%. The lab testing was carried out using experimental equipment to determine viability. The tests included 35-min runs that measured hydrogen generation under various parameters, such as applied voltage, electrolyte concentration, and pH levels. The ocean salt solutions of 0.5M, 1M, and 2M were initially prepared and evaluated for hydrogen generation. Each concentration is assessed at a voltage range of 4–15V, with matching solution pH values ranging from 2 to 7. Optimization studies were conducted to enhance the hydrogen production rate. The results indicate that hydrogen production rises proportionally with applied voltage and electrolyte concentration but falls with pH growth. Within the Design Expert software, the statistical methods for response surface analysis and optimization are utilized accordingly. • The paper develops an integrated three-compartment system for hydrogen production. • The paper investigates the system overall efficiencies for assessment. • It discusses how varying voltage and concentration affects hydrogen production. [ABSTRACT FROM AUTHOR]

The defossilization of industry has far-reaching implications regarding the future demand for hydrogen and other forms of energy. This paper presents and applies a fundamental bottom-up model that relies on techno-economic data of industrial production processes. Its aim is to identify, across a range of scenarios, the most cost-effective low-carbon options considering a variety of production systems. Subsequently, it derives the hydrogen and electricity demand that would result from the implementation of these least-cost low-carbon options in process industries in Germany. Aligning with the German government's target year for achieving climate neutrality, this study's reference year is 2045. The primary contribution lies in analyzing which hydrogen-based and direct electrification solutions would be cost-effective for a range of energy price levels under climate-neutral industrial production and what the resulting hydrogen and electricity demand would be. To this end, the methodology of this paper comprises the following steps: selection of the relevant industries (I), definition of conventional reference production systems and their low-carbon options (II), investigation and processing of the techno-economic data of the standardized production systems (III), establishment of a scenario framework (IV), determination of the least-cost low-carbon solution of a conventional reference production system under the scenario assumptions made (V), and estimation of the resulting hydrogen and electricity demand (VI). According to the results, the expected industrial hydrogen consumption in 2045 ranges from 265 TWh for higher hydrogen prices in or above the range of onshore wind-based green hydrogen supply costs, to up to 473 TWh for very low hydrogen prices corresponding to typical blue hydrogen production costs. Meanwhile, the direct electricity consumption of the process industries in the results ranges from 147 TWh for these rather low hydrogen prices to 338 TWh for the higher hydrogen prices in the region of or above the hydrogen supply costs from the electrolysis of energy from an onshore wind farm. Most of the break-even hydrogen prices that are relevant to the choice of low-carbon options are in the range of the benchmark purchase costs for blue hydrogen and green hydrogen produced from offshore wind power, which span between €40 per MWh and €97 per MWh. [Display omitted] • Derivation of the future hydrogen and power demand of the process industry in Germany. • Bottom-up, process-level model to find the least-cost low-carbon production method. • Reference year is 2045, and the achievement of climate-neutral production is assumed. • Model determines the hydrogen and power demand under varying hydrogen prices. • Expected hydrogen use between 265 TWh and 473 TWh, depending on scenario assumptions. [ABSTRACT FROM AUTHOR]

The large-scale integration of renewable energy sources leads to daily and seasonal mismatches between supply and demand and the curtailment of wind power. Hydrogen produced from surplus wind power offers an attractive solution to these challenges. In this paper, we consider a large offshore wind park and analyze the need for hydrogen storage at the onshore and offshore sides of a large transportation pipeline that connects the wind park to the mainland. The results show that the pipeline with line pack storage, though important for day-to-day fluctuations, will not offer sufficient storage capacity to bridge seasonal differences. Furthermore, the results show that if the pipeline is sufficiently sized, additional storage is only needed on one side of the pipeline, which would limit the needed investments. Results show that the policy which determines what part of the wind power is fed into the electricity grid and what part is converted into hydrogen has a significant influence on these seasonal storage needs. Therefore, investment decisions for hydrogen systems should be made by considering both the onshore and offshore storage requirements in combination with electricity transport to the mainland. • Introducing hydrogen to electricity systems reduces peak capacity requirements. • We investigate the seasonal role of hydrogen storage for offshore wind parks. • Volume and capacity requirements were identified for many supply and demand scenarios. • For sufficient pipeline sizes, only onshore storage is required. • Hydrogen and electricity infrastructural decisions should not be made in isolation. [ABSTRACT FROM AUTHOR]

The changing climate poses unprecedented risks and challenges to agricultural production and energy systems worldwide, necessitating innovative technology and policy solutions that transcend traditional boundaries. This paper highlights the critical intersection of energy and agricultural systems and identifies low-carbon intensity ammonia (LCIA) as a pivotal element in reducing the carbon footprint of US agricultural production, particularly in fertilizer use. It presents a comprehensive analysis of the ammonia market and value chain, emphasizing its potential to decarbonize agricultural fertilizers and serve as an alternative clean energy source. The technical review covers various ammonia production methods, from natural gas-based processes with carbon capture and storage to electrolysis using renewable energy. These methods' economic and environmental implications are examined to provide insights into the levelized costs and emissions of LCIA applications across various scenarios. A case study focusing on the Permian Basin and Southern High Plains regions is conducted to illustrate the regional synergy between the agriculture and energy sectors, proposing a framework for integrating LCIA into the US agricultural sector. The proposed framework, Sustainable Ammonia for Resilient Agriculture, outlines policy recommendations and strategic investments to overcome market and infrastructure barriers, aiming to develop a resillient and sustainable LCIA value chain. Future research direction should emphasize the need for local value chain development plans encompassing agriculture, energy, infrastructure, and workforce development under a unified policy framework. [Display omitted] • This study shows how low-carbon intensity ammonia links agriculture and energy sectors, enhancing sustainability. • Explores ammonia production methods and their economic and environmental benefits. • Provides actionable recommendations for integrated policies to support low-carbon intensity ammonia. • Features Permian Basin and Southern High Plains case study, highlighting regional synergies and local impacts. [ABSTRACT FROM AUTHOR]

The continuous growth of anthropogenic carbon emissions from the aviation industry has emphasized the urgent request to substitute traditional aviation fuels with Sustainable Aviation Fuels (SAFs) because SAFs can potentially reduce carbon emissions by around 50–90% as compared to traditional kerosene-based fuels. In this paper, a novel SAF production pathway is developed which is based on biomass processing, nuclear energy, and thermochemical reactions of the vanadium chloride cycle for SAF, clean power, and hydrogen production. The entire system is assessed thermodynamically in terms of energy and exergy performances. Various sensitivity analyses are computed to determine the reliable operating parameters. The study concludes that biomass-to-SAF energetic and exergetic performance is achieved to be 76.72% and 74.35%. The energetic and exergetic performance values, through efficiencies, of the V–Cl cycle are calculated to be 68.08% and 53.50%, respectively. For hydrogen production and storage, an energy penalty of around 16.83 kJ/kg H 2 is calculated, which results in an efficiency penalty of 6.18%. The overall energetic and exergetic efficiencies of the proposed integrated system are found to be around 59.79% and 23.78%, respectively. • This study develops a nuclear and biomass-based integrated energy system for cleaner community applications. • A vanadium chloride thermochemical cycle is incorporated into the integrated system to produce clean hydrogen. • A fluidized bed pyrolysis reactor is simulated in the Aspen Plus. • An optimization study of the chemical process is undertaken. • Both energy and exergy efficiencies are considered for system performance evaluation. [ABSTRACT FROM AUTHOR]

This paper utilizes a Structural Time Series Model (STM) with an underlying component to estimate the global hydrogen demand function. This approach allows for the discernment of the ongoing impact of technology and the dynamic changes in consumer behavior that affect hydrogen demand over time. To estimate the hydrogen demand function, the analysis incorporates key variables, including hydrogen price, natural gas price, oil price, and GDP (Gross Domestic Product) per capita. The study utilizes quarterly global data from the first quarter of 2009 to the fourth quarter of 2021. In comparing the underlying components influencing hydrogen demand, the study suggests that advancements in production technology, organizational technology, and changes in consumer behavior collectively contribute to a gradual leftward shift in the global hydrogen demand curve over time. The study uncovered that, in the short term, global hydrogen demand demonstrates high inelasticity. Furthermore, the results reveal. a complementary relationship between natural gas and hydrogen, although this complementarity diminishes significantly over time. Additionally, the findings suggest that oil. can function as a substitute for hydrogen, with the substitution effect intensifying in the long term. Interestingly, hydrogen is initially perceived as a luxury commodity, yet over the long term, it transitions to behaving as a normal commodity. [Display omitted] • Global hydrogen demand considers underlying factors. • Demand is inelastic, complements natural gas, and substitutes oil. • Technology minimally impacts demand. • Hydrogen remains a luxury commodity. [ABSTRACT FROM AUTHOR]

Abstract The concept of the levelized cost of energy or respectively hydrogen (LCH) is frequently chosen for techno-economic analyses of energy technologies. However, the results of the LCH very much depend on the assessment perspective, which may be either private (or synonymously business) or social. The paper identifies three points as being basically responsible for differences: (1) tax deductibility of cost components, (2) external environmental costs, and (3) discounting. The objectives of the paper are to present the levelized cost of hydrogen for improved alkaline water electrolysis (AWE) and to highlight the different results from private and social perspectives. Accordingly, the methodology comprises the different LCH calculation schemes, an energy scenario focusing on electricity, a Life Cycle Assessment for environmental impacts of AWE technology, and the monetary valuation of these impacts. As a case study, we chose the production of hydrogen from advanced alkaline water electrolysis at three different sites in Europe (Germany, Austria, and Spain). The paper shows that the private and social LCH differ strongly. Inclusion of all cost components and comparatively low discount rates provoke highest LCH from social perspective. The main differences in the case study presented here are due to full accounting for environmental costs – with the global warming potential resulting from electricity generation as the main environmental cost source – and due to electricity price projections. Finally, the paper also discusses the sensitivity of LCHs with respect to parameters such as plant lifetime, monetary values of CO2, and tax rates. [ABSTRACT FROM AUTHOR]

Green hydrogen production by water electrolysis is sustainable and carbon-free for energy storage. This paper introduces recent development in integrated green hydrogen polygeneration. Throughout this review, theoretical concepts, design types, and recent developments related to the integration of Alkaline Electrolysis (AE), Proton Exchange Membrane Electrolysis (PEME), and the Solid Oxide Electrolysis Cell (SOEC) are summarised. This review evaluates the thermodynamic efficiency and economic impact of green hydrogen production integrated with different energy sources, energy storage and power cycles. Compared with two kinds of commercially applied methods (AE and PEME), SOEC is the state-of-the-art method to produce hydrogen, which can be integrated with external heat to reduce energy consumption. SOEC avoids the inevitable energy loss in AE and PEME, which leads to low-temperature waste heat evaluated as exergy destruction rather than utilized. The overall efficiency improvement of SOEC systems is over 10%. In most cases, the efficiency is always over 70%, and over 80% in some cases, which exceeds the typical values of 20%–60% from AE and PEME systems. The produced hydrogen can be stored and transported, as well as being used as a feedstock for chemical production, forming a polygeneration system with multiple energy sources, desalination, and fuel production. The latest lifetime of SOEC was predicted at 50,000 h or more, which is the minimum requirement to be commercially competitive. In the literature review, 80.4% of papers chose exergy efficiency as assessment index, compared with 67.9% of energy efficiency. And 58.9% of them chose genetic algorithm to complete multi-objective optimization. • The recent developments in green hydrogen polygeneration is accessed. • Compare the thermodynamic and economic impact of various polygenerations with multiple energy sources. • The competitiveness of SOEC in plant is compared with AE and PEME via 4 E analysis. • 80.4% of papers chose exergy efficiency as assessment index and 58.9% chose GA for optimization. [ABSTRACT FROM AUTHOR]

With industrial informatization, rich data frameworks provide the possibility of efficient design and global optimization of methane to hydrogen processes. However, the high coupling between mixed variables leads to the difficulty of first-principles modeling (FPM) to capture the optimal Pareto front in infeasible domains. In this paper, a machine learning proxy (MLP) method is proposed to minimize economic, exergy destruction, CO 2 emissions, and maximize hydrogen production. First, process simulation as FPM is built using physical properties, energy balance, and reaction kinetics to analyze single variable effects and objective trade-offs. Then, datasets consisting of feed, heat transfer, and design variables are built by sampling the FPM in design and extended spaces. The eXtreme Gradient Boosting (XGBoost) with hyperparameter optimization is built as a proxy FPM, capturing the complex mapping between variables and objectives. Finally, the Pareto front is searched in design and extended spaces by combining the proxy model and genetic algorithm. The proposed method benefits 20.2%, 37.2%, 46.7%, and 2.3% in economic, exergy destruction, CO 2 emissions and hydrogen production respectively compared to the heuristic design. XGBoost not only can effectively proxy FPM to capture the complex behavior of reforming techniques, but also can perform better in infeasible domains that are difficult to explore with FPM. [Display omitted] • A MLP optimization method is proposed to explore the trade-offs for four objectives. • The R2 score of XGBoost is above 98.4% for four objective values. • Proxy model exhibits effective exploration of the space far beyond the FPM boundaries. • TAC, exergy destruction, CO 2 emissions, and H 2 production benefits 20.2%, 37.2%, 46.7% and 2.3%. [ABSTRACT FROM AUTHOR]

The iron and steel industry accounts for one third of global industrial CO 2 emissions, putting pressure on the industry to shift towards more sustainable modes of production. However, for an industry characterised by path dependency and technological lock-ins, sustainability transitions are not straightforward. In this study, we aim to explore the potential pathways for sustainability transitions in the iron and steel industry. To do so, we have conducted a case study in Sweden where there are policy and industry commitments towards fossil-free steel production. Our theoretical points of departure are the technological innovation system (TIS) approach and the multi-level perspective (MLP), and our paper presents the dynamics behind an emerging case of transition towards a hydrogen-based future. The paper has two major contributions to the literature on sustainability transitions. First, it attempts to borrow some concepts from the MLP and integrate them with the TIS approach. Second, it empirically presents an in-depth case study of the iron and steel industry – an understudied context in the field of sustainability transitions. By doing so, it sheds some light on the dynamics between an emerging TIS and potential transition pathways of a regime. [ABSTRACT FROM AUTHOR]

The objective of the paper is to simulate the whole steelmaking process cycle based on Direct Reduced Iron and Electric Arc Furnace technologies, by modeling for the first time the reduction furnace based on kinetic approach, to be used as a basis for the environmental and techno-economic plant analysis by adopting different reducing gases. In addition, the impact of carbon capture section is discussed. A complete profitability analysis has been conducted for the first time, adopting a Monte Carlo simulation approach. In detail, the use of syngas from methane reforming, syngas and hydrogen from gasification of municipal solid waste, and green hydrogen from water electrolysis are analyzed. The results show that the Direct Reduced Iron process with methane can reduce CO 2 emissions by more than half compared to the blast furnace based-cycle, and with the adoption of carbon capture, greenhouse gas emissions can be reduced by an additional 40%. The use of carbon capture by amine scrubbing has a limited economic disadvantage compared to the scenario without it, becoming profitable once carbon tax is included in the analysis. However, it is with the use of green hydrogen from electrolyzer that greenhouse gas emissions can be cut down almost completely. To have an environmental benefit compared with the methane-based Direct Reduced Iron process, the green hydrogen plant must operate for at least 5136 h per year (64.2% of the plant's annual operating hours) on renewable energy. In addition, the use of syngas and separated hydrogen from municipal solid waste gasification is evaluated, demonstrating its possible use with no negative effects on the quality of produced steel. The results show that hydrogen use from waste gasification is more economic with respect to green hydrogen from electrolysis, but from the environmental viewpoint the latter results the best alternative. Comparing the use of hydrogen and syngas from waste gasification, it can be stated that the use of the former reducing gas results preferable, from both the economic and environmental viewpoint. [Display omitted] • CCS plant has higher profitability in the presence of carbon tax than the base plant. • Green H 2 plant needs 5136 annual hours of renewable energy for enviro benefit. • H 2 over syngas, from waste gasification, improves economic and enviro outcomes. [ABSTRACT FROM AUTHOR]

Blending hydrogen into the natural gas network can help decarbonize the energy sector by supporting the penetration of renewables. Italy is an importer of natural gas whose composition and properties depend on its origin. Previous literature simulates gas networks using a set of hydrogen molar fractions regardless of the natural gas composition variability. Instead, this paper defines the maximum mixable percentage of hydrogen as a function of the gas composition underlining the importance of not adopting a single hydrogen limit. Furthermore, the paper investigates whether guaranteeing gas quality also guarantees compliance with fluid dynamic constraints on a real network. The test case consists of seven gases imported in Italy in 2019 and an urban distribution network, meshed and consisting of more than 2000 elements with medium and several low-pressure levels. A steady-state simulation of the network is performed using each of the seven gases for a winter day in the case of pure natural gas and natural gas blended with hydrogen. The results show that the highest hydrogen molar fraction mixable in these gases can range between 5.3% and 14.8% and considering the lowest percentage can reduce the decarbonization potential of the network by 1463 kg of CO 2 ,eq. The simulations show that fluid-dynamic standards are not always met in the low-pressure networks and safety limits on pressure and velocity are exceeded at peak demand. The results also lead the authors to suggest that a modulation of pressure setpoints as a function of gas composition should be investigated. [Display omitted] • Hydrogen blending with natural gases of various origins imported into Italy. • Hydrogen maximum blend depends on natural gas origin. • Steady-state analysis of a real gas distribution grid during a winter day in Italy. • Compliance with quality limits does not ensure compliance with fluid dynamic limits. • Low pressure network overcomes fluid-dynamic limits. [ABSTRACT FROM AUTHOR]

Abstract This paper provides an extensive analysis of the literature on technological, economic, and environmental aspects for clean-hydrogen production. Hydrogen production routes that are compatible with renewable and nuclear sources are introduced, highlighting the recent advances and developments found in the literature on this topic. Discussions on recent and future expectations on cost aspects of clean-hydrogen economy are introduced in generic cost-based comparisons. In addition, recent literature on environmental aspects of common clean-hydrogen production technologies is investigated and their results are analyzed. Among clean energy sources, lower electricity prices from nuclear and geothermal energy make these sources feasible for low-cost hydrogen generation that has the potential to compete with fossil-based hydrogen production. Solar and wind conversion technologies and their intermittent nature are strongly affecting hydrogen production cost. However, mature technologies provide competitive hydrogen cost values, especially when integrated to electrolysis-based technologies. Ongoing research shows promotive and encouraging results for a clean and carbon-free energization of hydrogen production in the near future. [ABSTRACT FROM AUTHOR]

Abstract Climate policy objectives require zero emissions across all sectors including steelmaking. The fundamental process changes needed for reaching this target are yet relatively unexplored. In this paper, we propose and assess a potential design for a fossil-free steelmaking process based on direct reduction of iron ore with hydrogen. We show that hydrogen direct reduction steelmaking needs 3.48 MWh of electricity per tonne of liquid steel, mainly for the electrolyser hydrogen production. If renewable electricity is used the process will have essentially zero emissions. Total production costs are in the range of 361–640 EUR per tonne of steel, and are highly sensitive to the electricity price and the amount of scrap used. Hydrogen direct reduction becomes cost competitive with an integrated steel plant at a carbon price of 34–68 EUR per tonne CO2 and electricity costs of 40 EUR/MWh. A key feature of the process is flexibility in production and electricity demand, which allows for grid balancing through storage of hydrogen and hot-briquetted iron, or variations in the share of scrap used. Highlights • A process design for hydrogen direct reduction (H-DR) steelmaking is proposed. • 3.48 MWh electricity are consumed per ton of steel product. • H-DR emits only 2.8% of blast furnace CO 2. • Competitive production cost at low electricity and moderate carbon prices. • High flexibility due to hydrogen and HBI storage, and varying scrap charge. [ABSTRACT FROM AUTHOR]

Thermo-catalytic reforming (TCR) is defined as intermediate pyrolysis at moderate temperatures and heating rates with subsequent reforming at elevated temperatures using biochar as a catalyst. TCR experiments were carried out to pyrolyze and subsequently reform Solid Grade Laminate (SGL) waste. SGL is a Kraft paper-derived product and as it is widely used in many applications, high volumes of waste laminate must be disposed of at end of life. To assess TCR for SGL waste treatment, the characterisation of the initial feedstock was accomplished, and it concluded that SGL is suitable to be processed via TCR. The main energy carrier products (char, oil and syngas) were generated by TCR in a 2 kg/h pilot-scale reactor under a pyrolysis temperature of 500 °C and reforming temperature of 650 °C, respectively. The mass balance analysis demonstrated that 50 wt% of the initial feedstock was comprehensively converted to syngas, 28 wt% to char and 22 wt% to a liquid fraction containing both water (17 wt%) and organics (5 wt%). The oil showed good properties as its HHV reached a value of 32.72 MJ/kg, with low oxygen and sulphur contents. However further processing is required for the fuels to be within suitable limits for use as drop-in fuels for vehicles. The syngas was found to be rich in hydrogen especially when pyrolysis temperature reaches its maximum. Lastly, char revealed a calorific value of 25.94 MJ/kg and was of a stable form of carbon, exhibiting potential as a feedstock for gasification or as a carbon capture and storage medium. TCR of SGL represents novelty as this feedstock has not been tested before in a pyrolysis/reforming system and it is a promising route in an optic of circularity. In waste valorisation, TCR oil has a great opportunity to be used as a fuel or blended with other conventional fuels, thus supporting the shift towards more sustainable mobility. [Display omitted] • Thermo-catalytic reforming (TCR) represents a promising technology for solid grade laminate waste valorisation and biofuel production. • 50 wt% of the initial feedstock was converted to syngas, 28 wt% to char and 22 wt% to a liquid fraction containing both water (17 wt%) and organics (5 wt%). • The syngas deriving from solid grade laminate contained almost 50 vol% hydrogen. [ABSTRACT FROM AUTHOR]

In this paper, a detailed analysis of the impact of hydrogen blending in the natural gas grid in terms of potential increase of Intermittent Renewable Energy Source (IRES) penetration, increase of electrolyzer power installed, reduction of CO 2 emission and environmental footprint, is provided formulating models in EnergyPLAN and OpenLCA software. The Italian energy system is taken as case-study. Three scenarios have been analysed: BASELINE scenario represents the current energy system; MID-SCENARIO foresees a total IRES capacity of 158.17 GW (x5 compared to 2019 capacity) derived from the capability to convert intermittent electricity surplus in hydrogen and inject it in the natural gas grid; in the END-SCENARIO, the IRES capacity is pushed up to 272.1 GW. The main outcomes of the study attest that blending of hydrogen in the natural gas grid leads to beneficial impacts in terms of environmental footprint. Considering the global energy system, hydrogen production and blending in the natural gas grid leads to a maximum decrease of 15% in CO 2 emissions compared to 2019. The impact is significant but limited by a threshold in the maximum hydrogen amount that the gas distribution infrastructure can currently accept (hydrogen molar fraction <20%). Focusing the study on the electricity generation sector, the reduction of CO 2 emissions reaches −66% in the END-SCENARIO. The LCA index "Fossil resource scarcity" is reduced by up to −77% due to the replacement of fossil fuels, starting from coal. On the other hand, the LCA category "Mineral scarcity" undergoes an increase (x3.03 in MID-SCENARIO, ×2.73 in END-SCENARIO) due to the large amounts of materials needed to manufacture the photovoltaic plants, wind farms and electrolyzers, such as copper, aluminum, platinum, nickel, titanium and silicon, exacerbating the critical materials issue. [ABSTRACT FROM AUTHOR]

Given the rapidly increasing concern of the climate change, this paper is aimed to answer whether hydrogen fuel cells can truly be a green solution in the shipping sector from a life cycle perspective. To achieve this goal, the parametric trend life cycle assessment which is LCA-based methodology was applied for around 2000 ships presently engaged in international and domestic services. The lifecycle environmental impacts of various hydrogen production methods were evaluated, including steam methane reforming, coal gasification, methanol cracking, and electrolysis via wind energy. The performance of three representative types of fuel cell systems, proton exchange membrane fuel, molten carbonate fuel cell, and solid oxide fuel cell were taken into account. The steam methane reforming and coal gasification processes were found to have the greatest environmental potentials across their lifetime. However, this paper points out that steam methane reforming could make better lifecycle merits than conventional diesel or LNG products, if production pathways are properly proposed. Additionally, when using LNG as the primary fuel source for fuel cells, it was found that the LNG upstream phase would produce about 100 times more emissions than the downstream phase. The research findings were summarized and condensed into a form of lifetime environmental indicators which enable us to understand/evaluate the quantified correlations between holistic environmental impacts of fuel cells and ship characteristics. The research findings are expected to assist stakeholders in making informed decisions, while also providing an insight into near-future regulatory frameworks and policy making for a green hydrogen maritime economy. • Parametric Trend lifecycle assessment (PT-LCA) was applied for thousands of ships. • General relations between emissions and ship characteristics were presented. • Lifecycle benefits/harms of hydrogen were quantified/demystified. • Corrective actions were proposed for proper use of hydrogen as marine fuel. [ABSTRACT FROM AUTHOR]

Renewably produced hydrogen offers a solution for mobility via fuel cell electric vehicles without emissions during driving. However, the hydrogen supply chain, from hydrogen production to the fueling station – incorporating seasonal storage and transport – varies in economic and environmental aspects depending on the technology used, as well as individual conditions, such as the distance between production and demand. Previous studies have focused on the economic aspects of varying technologies and elaborated application areas of each technology, while environmental issues were not specifically considered. To address this shortcoming, this paper presents a life cycle assessment of three supply chain architectures: (a) Liquid Organic Hydrogen Carriers (LOHCs hereinafter) for transport and storage; as well as (b) compressed hydrogen storage in salt caverns, together with pipelines; and (c) pressurized gas truck transport. The results of this study show that the pipeline solution has the least environmental impact with respect to most of the impact categories for all analyzed cases. Only for short distances, i.e., 100 km, is truck transport better in a few impact categories. When considering truck transport scenarios, LOHCs have higher environmental impacts than pressurized gas in seven out of 14 impact categories. Nevertheless, for longer distances, the difference is decreasing. The seasonal storage of hydrogen has almost no environmental influence, independent of the impact category, transport distance or hydrogen demand. In particular, strong scaling effects underlie the good performance of pipeline networks. [ABSTRACT FROM AUTHOR]

Hydrogen could be used as a ‘cleaner’ cooking fuel, particularly in communities that rely on biomass and fossil fuels, to reduce local pollution and related health effects. However, hydrogen must be produced using sustainable feedstocks and energy sources to ensure that local impacts are not reduced at the expense of other impacts generated elsewhere in the life cycle. To this end, this paper evaluates life cycle environmental impacts of renewable hydrogen produced in a proton-exchange membrane electrolyser using solar energy. The aim of the study is to find out if hydrogen produced in this system and used as a cooking fuel is environmentally sustainable in comparison with conventional cooking fuels typically used in developing countries, such as liquefied petroleum gas (LPG), charcoal and firewood. The results suggest that hydrogen would reduce the climate change impact by 2.5–14 times to 0.04 kg CO 2 eq./MJ compared to firewood (0.10 kg CO 2 eq./MJ) and LPG (0.57 kg CO 2 eq./MJ). Some other impacts would also be lower by 6%–35 times, including depletion of fossil fuels, summer smog and health effects from emissions of particulates, both locally and across the rest of the life cycle. However, some other impacts would increase by 6%–6.7 times, such as depletion of metals and freshwater and marine ecotoxicity. These are mainly due to the solar photovoltaic panels used to generate power for the electrolyser. In terms of the local impacts, the study suggests that hydrogen would reduce local pollution and related health impacts by 8%–35 times. However, LPG is still environmentally a better option than hydrogen for most of the impacts, both at the point of use and on a life cycle basis. [ABSTRACT FROM AUTHOR]

Researchers have aimed to find sustainable solutions for future mobility because of climate and energy demand issues, making the shift toward sustainable-powered traction essential. However, high costs and the need for partnerships between public and private entities affect hydrogen mobility in its early-stage development. This study examines 233 papers from the Scopus database to shed light on a systematic road to this theme's main features and recurrent issues by adopting bibliometric and coding analyses. The main results show an expansion of publications from 1999 to 2022, which is related to the increased publications and scientific productivity of researchers on this topic and factors such as energy crises and restrictive oil price policies. Furthermore, the expansion of interest is also due to multiple initiatives by supranational entities. The study uncovers the most relevant journals, authors, countries of collaboration, and co-occurrences of keywords. Using a topic dendrogram, we discovered four search clusters: (1) hydrogen for sustainable development, (2) hydrogen as an alternative fuel for mobility: challenges, (3) hydrogen and policy implications, and (4) hydrogen and mobility reshaped. Based on the knowledge gained, our study confirms the challenges of hydrogen mobility and the difficulties associated with higher costs, mainly in sectors where the energy used for transformation is derived from sources other than renewable ones. Further implications show that an alternative to traditional engines requires substantial investment from public and private companies and proper business models. We provide a scientific roadmap of the most relevant issues for managers and policymakers to extend the use of hydrogen in the transportation sector. [ABSTRACT FROM AUTHOR]

This paper investigates the least-cost greenhouse gas (GHG) abatement pathway for a coupled energy system. We consider the roles of diverse abatement technologies, such as renewable electricity generation, biomass and carbon capture and storage (CCS), as well as sources of operational flexibility, such as peaking generators, electricity storage, transmission and electrolysis. Scenario and sensitivity analyses are applied to explore plausible pathways to energy system decarbonization. All modelled pathways to a zero-emissions energy system feature an accelerating transition from fossil fuels to renewable energy with diverse technologies playing a role. This includes variable renewable generators (VRG), CCS, and sources of operational flexibility on different timescales. Specifically, synchronous condensers appear to be a cost-effective option to control system frequency, inter-seasonal hydrogen storage in engineered caverns can play a significant and complementary role to that of pumped hydro and battery storage, and technologies that capture and sequester atmospheric carbon, including biomass-to-CCS and direct air capture (DAC), can also play a significant role in the transition to net-zero emissions. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes various solar thermochemical processes for the production of hydrogen, carbon nano particles, industrial grade carbon black, and metals with substantially reduced CO2 emission footprint. The paper introduces an innovative approach of a three-dimensional volumetric production of carbon nano particles via thermal cracking of methane gained by carbon seeding as an alternative to the existing two dimensional modes. The paper also describes an alternative pathway for hydrogen production via three consecutive solar thermochemical processes, namely, solar cracking of methane, solar carbo-reduction of ZnO and CO reduction of CdO, providing long term storage of solar energy. Finally, the paper provides an example solar windowed reactor for clean production of hydrogen, and it presents numerical analysis of the solar reactor based on computational fluid dynamics results, simulating one of the major problems with natural gas cracking in solar reactors, namely, carbon contamination of the transparent window and clogging of the reactor. [Copyright &y& Elsevier]

Within this paper, new findings of the potential of four considered intermediate solutions towards a primary climate-neutral steel production are reported. (1) Injection of natural gas into a blast furnace, (2) injection of hydrogen into a blast furnace, (3) natural gas-based direct reduction with subsequent input of the hot briquetted iron (HBI) in a blast furnace, and (4) hydrogen-based direct reduction with subsequent input of the hot briquetted iron in a blast furnace. The current study is a carbon footprint assessment applied to the product hot-rolled coil (HRC) according to the ISO norm 14067:2019. A cradle to gate approach is used including the production of raw materials to the production of hot-rolled coil. To define a reference point, a carbon footprint of hot-rolled coil produced via a typical blast furnace – basic oxygen furnace (BF-BOF) route is presented. The basic data set is based on primary data from the integrated site of thyssenkrupp Steel Europe AG (tkSE) , year 2018. Within a novel approach, this base line is enhanced by integrating metallurgical models from the literature. Thereby all changes of the complex material and energy supply chain of an integrated site and of the upstream chain are reported. The carbon footprint of each process unit is presented in detail so that optimization potentials are identified, which impacts are analysed within a sensitivity analysis. A holistic comparison of using hydrogen in a blast furnace to using hydrogen in a direct reduction plant is presented and delivers important findings. This can help steel producers to maximize the efficiency of hydrogen use. Since the focus of this paper lies on the comparison of steel production routes and the assessments for all considered scenarios are based on the same methodologies and databases the sensitivity of made assumptions on the deltas between these scenarios is much weakened than the sensitivity of absolute values. That's one of the reasons why, the conclusions of this paper, which are referred to the plant of tkSE, can be transferred to other production sites, as well. The presented results can help decision-makers to know the potentials of possible intermediate solutions towards a climate-neutral steel production and how the potentials can be maximized. The carbon footprint of the product hot-rolled coil is 2.1 t CO 2 eq/t HRC following the recycled content approach and 0.82 t CO 2 eq/t HRC following the end-of-life recycling approach. The reduction potential for the carbon footprint is about 4 % for injecting natural gas into a blast furnace and about 9 % for injecting hydrogen into a blast furnace. The hydrogen is produced via electrolysis driven by a renewable German energy mix, year 2018. Using hot briquetted iron (HBI) within a blast furnace leads to a reduction potential between 5 % and 12 % for natural gas based-HBI and between 10 % and 17 % for H 2 -based HBI. The reduction potential strongly depends on the iron feedstock, which is replaced by the hot briquetted iron. Between 4.5 and 7.0 kg CO 2 eq/kg H 2 are avoided by injecting hydrogen into a blast furnace, and about 5.4 kg CO 2 eq/kg H 2 are prevented if the hydrogen is injected into a direct reduction plant. [Display omitted] • The carbon footprint of hot-rolled coil is 2.1 t CO 2 eq/t, based on primary data. • Injection of natural gas and hydrogen into a blast furnace. • Input of hydrogen and natural gas-based HBI in a blast furnace. • Comparison of using hydrogen in a blast furnace and a direct reduction plant. • The interim scenarios enable a reduction potential of up to 17 %. [ABSTRACT FROM AUTHOR]

The year 2022 is the seventh year since the Paris Agreement was signed. In the context of the same goals of achieving carbon neutrality and transforming the energy structure, hydrogen has become one of the most appealing options for realizing a better vision. This paper reviews the status and challenges of hydrogen application paths in high carbon emission sectors, especially in the electricity and heating, transportation, and steel industries. The discussions focus on the potential contribution from the replacement of primary energy and the reduction in carbon emission by switching to a hydrogen economy. In the case of China in 2030, the application of hydrogen in a single sector is expected to save up to $27.8 billion in carbon tax. Additionally, the key technologies for hydrogen production, storage, and carbon footprint in the industry chain are discussed. In contrast, the cost-effective blue hydrogen is still the best choice. The hydrogen storage technologies suitable for large-scale and low energy consumption need to be broken through. The study of carbon footprint in the industry chain will promote the development of hydrogen in the designated sectors and provide insights for the policy decision on hydrogen development at the regional or industrial level. • The hydrogen application paths for decarbonization are thoroughly compared. • Hydrogen production paths are reviewed in aspects of cost and carbon intensity. • Hydrogen production from fossil energy with CCS is a positive choice. • The LCA method of the industry chain is conducive to the hydrogen promotion. • Specific suggestions for the sustainable development of hydrogen are proposed. [ABSTRACT FROM AUTHOR]

Both solar and wind are considered leading renewables, and coupling them uniquely for solving the energy solutions in the remote communities is strongly needed to meet the demands of electricity, heat, cooling and hydrogen, which is the main goal of this study. In this regard, the present paper investigates a newly designed stand-alone onshore wind and concentrated solar-based hydrogen energy system where an anion exchange membrane electrolyzer, proton exchange membrane fuel cell, a heat pump, and absorption refrigeration chiller are considered as the other system components. The proposed system is then analyzed from the energy and exergy points of view of thermodynamics. Each hour in a typical meteorological year is considered in a time-dependent analysis to evaluate the feasibility as well as to better understand the phenomena and the effects of the varying parameters on the system performance. To perform a realistic analysis, the actual meteorological data and commercially available products' data are used based on the availability. The main contributions of this study to the state of the art of the current literature may be listed as the system originality, system integration for multigeneration, and time-dependent system analysis and performance assessment with the selected hourly parameters. A unique case study is performed for an indigenous community where a community load is generated for each hour by considering the meteorological characteristic of Cochrane, Ontario. The system capacities are designed according to the community in the case study where a 23 MWp wind farm, 3.17 MWp PT-CSP, 14.3 MW PEM fuel cell, and 19 MW AEM electrolyzer are required to fully meet the commodity requirements. The present wind and solar-based system brings synergetic advantages, such as lowering the energy storage capacity needed and providing a more synchronized operation. The overall integrated system's energy and exergy efficiencies are calculated as 20% and 19.5%, respectively. The cost assessment shows that the total operational expenses of the proposed integrated system result in $3.7 M each year while the total capital cost is $95 M. The hydrogen's unit cost is calculated as $4.38/kg, and the levelized cost of electricity is found to be $0.141/kWh. Finally, the synergetic advantages and disadvantages of using a wind and solar-based hydrogen energy system are discussed from the energetic, exergetic and economic perspectives. [ABSTRACT FROM AUTHOR]

Due to increasing concerns about global warming and climate change, renewable energy-based systems have gained importance for power generation, and hydrogen and alternative fuels production. This paper concerns the development of a new hybrid biomass and wind energy-based system for production of green methanol with electricity, heat and freshwater and its assessment thermodynamically through energy and exergy methods. The proposed system further consists of compressed air energy storage (CAES) to store excess power generated by wind turbines during the charging period, which is combined with a multi effect desalination (MED) unit. During the peak hours, biogas is produced through anaerobic digestion and upgraded into biomethane via water scrubbing. The compressed air is discharged and combusted with the biomethane to generate electricity and heating. Moreover, hydrogen is produced via an alkaline electrolyzer to synthesize green methanol. During the charging period, the output rates for electricity and freshwater are 2684 kW and 7.9 kg/s, respectively. The electricity, heating, and methanol production rates during the discharging period are 11,979 kW, 5186 kW, and 0.03 kg/s, respectively. The overall energy and exergy efficiencies of the present system are determined to be 40.96% to 46.31%, respectively. [ABSTRACT FROM AUTHOR]

As the offshore energy landscape transitions to renewable energy useful decommissioned or abandoned oil and gas infrastructure can be repurposed in the context of the circular economy. Oil and gas platforms, for example, offer opportunity for hydrogen (H 2) production by desalination and electrolysis of sea water using offshore wind power. However, as H 2 storage and transport may prove challenging this study proposes to react this H 2 with the carbon dioxide (CO 2) stored in depleted reservoirs. Thus, producing a more transportable energy carriers like methane or methanol in the reservoir. This paper presents a novel thermodynamic analysis of the Goldeneye reservoir in the North Sea in Aspen Plus. For Goldeneye, which can store 30 Mt of CO 2 at full capacity, if connected to a 4.45 GW wind farm, it has the potential to produce 2.10 Mt of methane annually and abate 4.51 Mt of CO 2 from wind energy in the grid. • Opportunity for overlap of wind and oil and gas in North Sea to make green hydrogen. • Green hydrogen can be combined with carbon dioxide in depleted reservoirs. • Methane production favoured at conditions of Goldeneye reservoir in North Sea. • Thermodynamic model shows more hydrogen in feed increases methane production. • Associated carbon and financial savings increase feasibility. [ABSTRACT FROM AUTHOR]

In this paper we present the optimal year round production of synthetic methane from water electrolysis and CO2 comparing the use of solar PV systems and wind turbines on a monthly basis. The process starts obtaining electricity in a wind farm or a solar field, which is then used to produce oxygen and hydrogen in a system of electrolyzers. The oxygen is purified and stored, and the hydrogen, after being purified using a deoxygenating reactor, reacts with CO2 to synthesize methane. We study the operation of the plant for a year considering the wind or solar availability. The use of wind or solar energy depends on the region and the area available for the installation of solar panels or wind turbines. Europe and the US have been screened for the use of both sources of energy, being solar preferable in most regions. We present a detailed case of study in the South of Europe, Gulf of Cádiz. Solar is cheaper than wind in terms of inversion (240 M€ vs. 363 M€) and production costs (0.33 €/m3 vs. 0.49 €/m3), while the monthly operation differs due to the availability of renewable energy. [ABSTRACT FROM AUTHOR]

Abstract: The integration of hydrogen technologies in the automotive industry as an option to cope with environmental issues has typically attracted significant attention among politicians, academics, and the media. After the recent “hydrogen hype” this interest in hydrogen technologies highlights the need to fully understand to what extent this sector is being pushed by new inventions. This paper presents a worldwide patent analysis of hydrogen technologies in the automotive sector. The study has been performed using a novel methodology by assessing trends of patents between 1990 and 2010 and their citations. As a result, we emphasize that the interest in hydrogen technologies has not declined over time and is mainly focusing on a small number of niches, although competing alternatives, such as electric vehicles, capture greater interest. Moreover, citation trends provide further insight into the development prospects of fuel cell and storage technologies as a point of convergence of multi-sectorial investments and, consequently, of potential R&D strategies in the automotive sector. [Copyright &y& Elsevier]

Hydrogen is having a worldwide momentum as a clean versatile energy solution and this is the time for nuclear hydrogen production technologies to play its role in securing a clean and affordable energy future. For over four decades, several nations have been investigating the potential of tens of thermochemical cycles for efficient and sustainable hydrogen production. These cycles require high quality heat (i.e. heat at high temperatures) solely or along with electric power (i.e. hybrid thermochemical cycles) both of which can be provided by nuclear energy. This paper delivers a highlight on the potential of nuclear energy for hydrogen production. It also discusses the main features of five of the promising thermochemical cycles that are considered for integration with nuclear power plants. Furthermore, the paper highlights the current status and advances of R&D in these thermochemical cycles as well as cost estimation and the main safety consideration for large-scale nuclear hydrogen production using different nuclear-driver technologies. [ABSTRACT FROM AUTHOR]

This paper examines the decarbonization of three coupled energy sectors: electricity, transport and heating/industry. The sector coupling includes the production of hydrogen from each of electricity via electrolysis, the gasification of coal and the reforming of natural gas; the displacement of gasoline/diesel and natural gas by any of these forms of hydrogen; the generation of electricity by gas turbines and reciprocating engines fuelled by either natural gas or any of these forms of hydrogen; and the electrification of the transport fleet. Plausible sensitivities to technological learning, energy efficiency measures, natural gas prices and subsidies for renewables are examined systematically as the coupled system's total greenhouse gas emissions are reduced to zero. The observed transition to zero emissions finds significant uses for hydrogen from both electrolysis and fossil fuels with carbon capture and storage (CCS). Plausible rates of technological learning from today to 2050 dramatically reduce the total costs and the land area required for achieving deep abatement mainly due to the projected fall in the costs of wind, solar PV and electrolysis. The combination of hydrogen fuelled reciprocating engines, electrolysis and hydrogen gas storage is also observed to provide lower cost, long term electricity storage than batteries and pumped hydropower. Nonetheless, the marginal costs of reducing emissions beyond approximately 90% abatement relative to today are always more than 100 $/t CO2e and land use can increase dramatically. This suggests that negative emission technologies will likely have a role in achieving net-zero emissions in combination with widespread renewable deployment, technological learning and some continued fossil fuel use with CCS. [ABSTRACT FROM AUTHOR]

Abstract: In the oil refining and petrochemical industry, hydrogen flows in so-called hydrogen networks are a common feature. A practical problem in hydrogen network analysis is to identify the minimum fresh hydrogen input flowrate to ensure that the hydrogen streams produced by combining the flows of internal sources satisfy certain concentration specifications of sinks for hydrogen and impurities such as H2S. To tackle this problem, this paper presents a novel graphical procedure, much inspired by the pioneering work of that makes use of the unique features of ternary composition diagram for three-component systems. In addition, accounting for constraints on flowrates inside a ternary visualization diagram is another novel aspect of this graphical method. Two literature case studies based on hydrogen systems with multiple impurities are solved to illustrate the effectiveness and elegance of the proposed method. [Copyright &y& Elsevier]

Abstract: Hydrogen production, via Dark Anaerobic Fermentation, leads to a negative net energy balance because of the difference between the energy produced as hydrogen and the direct ones (heat and electricity) consumed to produce it. The residual metabolites (Volatile Fatty Acids and alcohols) at the end of hydrogen production are oxidized compounds with a high-energy value. This paper deals with experimental tests that were conducted to recovery the energy embedded in these metabolites. Two proofs of the tests have been realized following two strategies: i) production of biogas containing methane by methanogen microorganisms from liquid metabolites; ii) production of additional H2 from acetate as main constituted of Volatile Fatty acids (VFAs) by Microbial Electrolysis Cell (MEC) with a cation exchange membrane (CEM). Both technologies have shown to be feasible and offer a double positive effect: the total produced energy increased and a beneficial effect, due to the achievement of a greater abatement of the organic wastewater load in the effluent, was obtained. A detailed energy analysis has showed that the second methanogenic stage increases the overall energy efficiency of the two-stage process to a great extent compared to the H2 stage on its own. The introduction of a second step leads to a positive net energy production for the methanogenic step, while additional research is necessary for the case of hydrogen production by MEC, as this technology is still at the infancy stage. [Copyright &y& Elsevier]

Abstract: Hydrogenation units are often operated at high pressure, requiring the use of compressors which are one of the most expensive chemical processing equipment. Optimizing a hydrogen network should therefore take into consideration not only purity and flowrate constraints but also pressure requirements. In this paper, based on the hydrogen surplus diagram approach, the average pressure profiles of hydrogen sources and sinks are proposed through the introduction of a system’s minimum pressure drop Δp. Combined with the traditional purity profiles, whether a source can meet a sink either for hydrogen concentration or for pressure requirements can be determined intuitively. In cases where the pressure of a source is not sufficient for a sink, installing a hydrogen compressor or using another source with higher purity and pressure could be potential solutions. A cost equation is established to determine which of the two solutions is economically more viable. For different matching situations between sources and sinks, strategies for optimum placement of compression equipment within a given hydrogen network are proposed. A case study is used to illustrate the application and effectiveness of the proposed method. [Copyright &y& Elsevier]

Abstract: Hydrogen is an important utility in the production of clean fuels such as low-sulfur gasoline and diesel. The shortage of hydrogen resource motivates the integrated management of hydrogen networks with purifiers. In this paper, we propose a systematic approach for the retrofit design of these hydrogen networks. By establishing a state-space superstructure, all possible placements of existing compressors and purifiers are incorporated in the proposed MINLP model. Total annual cost (TAC) is employed as the optimizing object to understand the trade-offs between operating cost and capital cost. A real refinery system near Shanghai of China city is used to illustrate the applicability of the approach. [Copyright &y& Elsevier]

Hydrogen technologies are rapidly spreading, with significant attention to the mobility sector requiring a robust and widespread fueling infrastructure. Hydrogen stations are indeed fundamental to transitioning from pilot projects towards large-scale implementation in many countries. Operating under extreme conditions, the new stations need more informed designs and equipment to meet the growing demand and their more frequent utilization. Via a set of experimental research activities and investigated scenarios carried out at the Cal State LA Hydrogen Research and Fueling Facility, this paper shares a novel and comprehensive set of data collected over a period of one year on fueling events frequency and refueling process station behaviors. A performance evaluation of the station is presented under different load scenarios in severe conditions during "back-to-back fuelings", with monitoring of fundamental parameters for infrastructure sizing, including dynamic cooling response, pressure levels, thermodynamics, and the state of charge of the vehicle. The presented data analysis could surely contribute as closer-to-reality inputs for a variety of station performance modeling tools. • Analysis of monthly data frequency and multiple daily refueling processes. • Novel and comprehensive data sharing collected over a period of one year. • Investigation on station increased demand and hydrogen shared mobility program. • Storage pressure levels during the several refueling processes. • Evaluation of dynamic cooling response, temperature, and vehicle state of charge. [ABSTRACT FROM AUTHOR]

Abstract: One of the most critical issues in the production of low-sulphur fuels is managing the impact of the new environmental requirements on the hydrogen balance of the refinery. The combination of low-sulphur fuel specifications and reduced production of hydrogen in catalytic reformers make hydrogen management a critical issue. More efficient use of hydrogen thus becomes unavoidable. This paper addresses the problem of the actual hydrogen distribution at the Porto Refinery of the GALP ENERGIA network, and uses a new tool based on the concept of hydrogen surplus. By means of different methodologies and resorting to linear programming, an efficient network design has been achieved that reduces the hydrogen utilities usage by 30% (achieving 30% more gas to the fuel system), while also dealing with the complexity and need for flexibility so characteristic of a refinery as well as the reduction of operating costs related to the pneumatic system. In terms of hydrogen manufacturing reduction in the platformings, it is possible to reduce by 6%. [Copyright &y& Elsevier]

Abstract: Fuel cells in combination with hydrogen are expected to play an important role in a future sustainable transport system. Recent studies have provided insight into how technological transitions may come about and may be managed. However, there is a lack of methodologies aimed at starting off transitions or system innovations, in practice. This paper addresses this issue by presenting a methodology characterized by a bottom–up approach to generate a roadmap for short-term projects within a long-term perspective. The methodology is applied in a Rotterdam case study of the transition to a fuel cell transport system. The outcome of this case study leads to recommendations for setting up a framework to facilitate and stimulate kicking off system innovation. [Copyright &y& Elsevier]

Access to affordable renewable energy and clean water are among the most prominent challenges humankind faces to ensure a non-discriminatory comfort of living. Innovation in system engineering meets with new energy carriers, enabling synergistic effects defined as "sector-coupling". For instance, hydrogen and Reversible Solid Oxide Cells (rSOCs) are innovative technologies that yield multiple valuable effects. This paper evaluates the impact of such technology in novel PV-hybrid storage mini-grids with close access to seawater, achieving simultaneous renewable energy storage and seawater desalination thereby. The novel mini-grid operation is simulated in archetypal rural communities from developing countries (Sub-Saharan Africa) for 365 days of operation. The study encompasses three development scenarios in agreement with sustainability policies in force. The analysis of results allows finding the fittest mini-grid asset to achieve techno-economic optimization. A trade-off solution is identified with a critical reading of results in a future perspective: the Levelized Cost Of Electricity (LCOE) for a system with at least 70% renewables penetration is in the range of 0.29–0.43 €/kWh, while the rSOC runs with the only energy storage task. Moreover, the availability of seawater pushes LCOE below 0.20 €/kWh since it is also possible to benefit from the desalination function. This result aligns with the most economic mini-grid asset that can be implemented while embedding a significant energy performance increase. • A brand-new technology is proposed to tackle the critical water-energy nexus. • Heterogeneous metrics are introduced to quantify cross-sectoral integration effects. • Tanzania's development scenarios are analyzed. • Sector coupling produces positive leverage on the unitary cost of electricity. • Optimal mini-grid asset forecasts LCOE<0.200 €/kWh and water availability up to 0.4 L/day/p. [ABSTRACT FROM AUTHOR]

For the sustainable communities, there is a strong need to address the United Nations' sustainable development goals for communities, cities and countries. In this paper, we develop a unique hybrid energy system for cleaner productions of energy, fuel, food and water for an indigenous community by addressing the following goals, namely: zero hunger; clean water; affordable and clean energy; industry, innovation and infrastructure; sustainable cities and communities; and climate action. Also, the present sustainable system is investigated thermodynamically by considering energy and exergy criteria and evaluated through energy and exergy efficiencies. As a case study, the Saugeen First Nation indigenous community in the Bruce Peninsula in Ontario, Canada, is selected for meeting the demands of useful commodities where an integration of a newly developed multigenerational system with an existing nuclear reactor is achieved in order to provide food security, supply the freshwater for drinking purposes, and meet the community's electricity and heat demands. Moreover, to exploit the existing thermophysical properties of fluids in the nuclear system, a hydrogen generation unit is proposed. The novel integration is enhanced the current nuclear system and increased the variety of useful outputs. The overall system is analyzed according to the first and second laws of thermodynamics. A transient (time-dependent) analysis is carried out via hourly simulations with software packages and hourly sensitive meteorological data. The overall system performance results are obtained as 65.8% for energy efficiency and 40.1% exergy efficiency at average ambient conditions for a 126.04 mol/s hydrogen production rate. [ABSTRACT FROM AUTHOR]

Hydrogen energy storage through Metal Hydride (MH) reactors has various applications in concentrated solar powers and fuel cells for stationary applications in renewable energy systems. Hydrogen storage performance and consumption of these systems are strongly dependent on heat and mass transfer characteristics. Incorporating Phase Change Materials (PCMs) and spiral tube heat exchangers into metal hydride reactors improves storage performance significantly. The present paper includes a numerical investigation on the storage performance of a novel Porous Metal Hydride Tank (PMHT) integrated with PCM as a passive heat transfer system. Moreover, a heat exchanger with newly-offered Flat Spiral Tube Planes (FSTPs) is mounted into a reactor for heat transfer enhancement. The air as Heat Transfer Fluid (HTF) flows into the metal reactor through a spiral tube to enhance the heat and mass transfer. The effects of various spiral configurations, different shapes, and thicknesses of PCM jackets on the absorption/desorption process of hydrogen are investigated in detail. Also, various inlet temperatures are applied to the system to examine its impact on the absorption/desorption process. According to the results, increasing the number of FSTPs along the PMHT reduces the absorption duration by 8%. Moreover, compared with PMHT without PCM, the absorption and desorption performance of PCM-based PMHT is improved by 44% and 20%, respectively. Furthermore, increasing and decreasing the air inlet temperature leads to a 43% and 47% reduction in total desorption and absorption duration, respectively. Finally, conical-shaped PCM-jackets are found to be capable of demonstrating better absorption and desorption performances. They offer the advantage of less PCM usage to provide even a higher performance than annulus PCM-jackets. In this regard, the conical-shaped PCM provides the means for the PMHT to reach its maximum hydrogen absorption by only 85% usage of its PCM volume. In comparison, annulus-shaped PCM uses 98% of its PCM volume to help the PMHT reach its maximum hydrogen absorption capability. • A 3D numerical study is carried out for a Novel Mg-based metal hydride tank. • The reactor is equipped with a spiral tube heat exchanger and phase change material. • Phase change materials can store and supply the reaction heat to the reactor. • Secondary circulation of spiral tube has notable effect on heat transfer enhancement. • Metal tank with conical-shaped phase change material has desirable performance. [ABSTRACT FROM AUTHOR]

Hydrogen management is very important for the production of clean fuels such as low-sulfur gasoline and diesel. As a key contaminant in the hydrogen network, hydrogen sulfide not only deactivates catalysts but also corrodes equipments. Hence, it is necessary to integrate hydrogen sulfide removal process model into the optimization of hydrogen allocation network. However, a desulfurization process model with simplifications and assumptions may yield suboptimal results and a model based on rigorous process mechanism may require high computational cost. To solve this problem, this paper proposes a novel approach for simultaneous optimization of refinery hydrogen allocation network and hydrogen sulfide removal processes. The optimization is realized in two steps. First, surrogate models are developed as approximations to the rigorous process and thermodynamic model for the desulfurization processes. Second, the surrogate model is embedded into the mathematical programming model for hydrogen network optimization. The effectiveness of the proposed approach is illustrated by its application to a case study taken from a real refinery. Result comparison between the proposed method and a literature model based on simplified desulfurization models is carried out, proving that, with the proposed method, more practical optimization result can be obtained with much less computational effort. • Surrogate model is applied to approximate the rigorous desulfurization process. • State-space superstructure is used to capture coupling relations of the subsystems. • Hydrogen distribution and desulfurization are optimized simultaneously. • More practical network configuration is obtained with less computational cost. [ABSTRACT FROM AUTHOR]

Hydrogen network integration is an effective way to reduce the cost of refineries, and a number of graphical and mathematical methods have been proposed. Parameters of reactors, separators and purifier have a great effect on hydrogen consumption, while only simple models of these equipment are considered. This paper proposed a method to optimize the hydrogen network of a refinery with multiple components and detailed reactor, separator, purifier modeling considered. For all hydrotreating units, models of reactor are built and considered, as well as separators and purifier. The effect of their operation parameters (temperature, pressure et al.) on hydrogen flowrate and concentration is analyzed. An integration model is built with hydrogen network, all reactors and separators, and purifier interconnected. It performs a simultaneous optimization for hydrogen related equipment according to the requirement of refinery, and can minimize the fresh hydrogen consumption with multiple components considered. Based on the developed optimization framework, the hydrogen network of a refinery is optimized and its utility consumption is reduced by 17.70%. The optimal temperatures of reactors and separators, and the pressure in purifier are determined, as well as the corresponding optimal hydrogen distribution network. • Method is proposed for optimizing hydrogen network, reactors, separator and purifier. • Models of equipment are built and their interconnection with hydrogen network is considered. • The effect of operating parameters on streams and hydrogen network is analyzed. • Optimal hydrogen network and operating parameters are identified. • The hydrogen consumption of a refinery is reduced by 17.70% after optimization. [ABSTRACT FROM AUTHOR]

Two electrolysis technologies fed with renewable energy sources are promising for the production of CO 2 -free hydrogen and enabling the transition to a hydrogen society: Alkaline Electrolyte (AE) and Polymer Electrolyte Membrane (PEM). However, limited information exists on the potential environmental impacts of these promising sustainable innovations when operating on a large-scale. To fill this gap, the performance of AE and PEM systems is compared, using ex-ante Life Cycle Assessment (LCA), technology analysis and exploratory scenarios for which a refined methodology has been developed to study the effects of implementing large-scale sustainable hydrogen production systems. Ex-ante LCA allows modelling the environmental impacts of hydrogen production, exploratory scenario analysis allows modelling possible upscaling effects at potential future states of hydrogen production and use in vehicles in the Netherlands in 2050. A bridging tool for mapping the technological field has been created enabling the combination of quantitative LCAs with qualitative scenarios. This tool also enables diversity for exploring multiple sets of visions. The main results from the paper show, with an exception for the "ozone depletion" impact category, (1) that large-scale AE and PEM systems have similar environmental impacts with variations lower than 7% in all impact categories, (2) that the contribution of the electrolyser is limited to 10% of all impact categories results, and (3) that the origin of the electricity is the largest contributor to the environmental impact contributing to more than 90% in all impact categories, even when renewable energy sources are used. It is concluded that the methodology was applied successfully and provides a solid basis for an ex-ante assessment framework that can be applied to emerging technological systems. • We compare the LCA impacts of alkaline and PEM electrolysers. • LCA is combined innovatively with futures scenarios. • The influence of electrolysers is negligible when compared to other stages of the life cycle per functional unit. • The orginin of the electricity remains the largest environmental contributor to the impact scores. [ABSTRACT FROM AUTHOR]

The transportation sector has been the largest contributor to emissions and pollution in Canada. Climate and public health have been negatively affected by the consumption of fossil fuels by conventional vehicles. The rollout of fuel cell electric vehicles (FCEVs) has not yet occurred due to a conundrum. Specifically, a refueling infrastructure is required for the mass deployment of FCEVs, but the commercialization of FCEVs is required for investments, thus leading to the question of which will be required first, vehicle commercialization or hydrogen refueling stations. This paper develops a multi-objective model to determine the optimal sizes and locations of the hydrogen infrastructure needed to generate and distribute hydrogen for the key Highway Corridor (HWY 401) in Ontario. The model is used to aid the early-stage transition plan for the conversion of conventional vehicles to FCEVs in Ontario by proposing a feasible solution to the infrastructure dilemma posed by the initial adoption of hydrogen as fuel in the general market. The health benefit from the pollution reduction is also determined to show the potential social and economic incentives of using FCEVs. The results show that hydrogen production and delivery cost can reduce from $22.7/kg H 2 in a 0.1% market share scenario to $14.7/kg H 2 in a 1% market share scenario. The environmental and health benefit of developing hydrogen refueling infrastructure for heavy-duty vehicles is 1.63 million dollar per year and 1.45 million dollars per year, respectively. Also, every kilogram of H 2 can avoid 11.09 kg CO 2 from entering the atmosphere. In a 1% market share scenario, proposed hydrogen network avoids more than 37,000 tonnes CO 2 per year. Image 1 • Designed an optimal hydrogen infrastructure network along the Windsor-Montreal corridor. • Considered different market share targets to find the optimal allocation. • The production and distribution costs were calculated using HDSAM and H2A. • The air pollution reduction was calculated for different market share targets. • The health benefits of different hydrogen development scenarios were calculated. [ABSTRACT FROM AUTHOR]

Scrap containing NdFeB is a valuable resource for the production of NdFeB magnets as the demand for these materials grows. One of the challenges is to recover the rare earths or the NdFeB alloy powder in a clean and cost effective manner so that it can be re-processed into new magnets rather than becoming lost to landfill. Work on using hydrogen to process scrap magnets (HPMS) has been shown to be successful when targeting hard disk drives. Currently, there is a lack of information on reliable methods to separate out NdFeB from other scrap sources such as automotive drives. In the near future, with increasing sales and electrification of cars, the automotive sector could be an important source for Dy containing magnets. In this paper, the hydrogen processing of scrap magnets has been demonstrated as an extraction method for NdFeB from automotive rotors for the first time, with the aim to examine the viability of this recycling process and learn lessons for design for recycling. Thus leading to the sustainable production of these components. Significant challenges were outlined when applying the hydrogen process to rotors with embedded magnets. After the extraction, further process steps may also be needed to separate epoxy coatings, as sieving could only reduce the carbon content to 1420 ppm, compared to 770 ppm in the base alloy. The gravimetric measurements also confirmed that Dy additions increase both the initiation and absorption time for hydrogen decrepitation. Hence, a higher hydrogen pressure will be required to speed up the process. • H 2 can be used to extract NdFeB magnets from the automotive scrap, however, many challenges in the recycling are presented. • The importance of design choices, having negative impact on the recycling, are investigated in this work, so can be avoided. • Higher Dy additions slow down the kinetics of the hydrogen decrepitation reaction by 75% at RT & 1.2 bar hydrogen pressure. • Scrap magnet with 8.5 wt% Dy took longer to initiate and a higher H 2 pressure is required for quick processing of the scrap. • The carbon content could only be reduced to 1420 ppm by sieving because the coating was breaking at similar rate to powder. [ABSTRACT FROM AUTHOR]

Nowadays, to address the different demands of consumers, i.e., electricity, heat and gas, the concept of energy hub (EH) is emerged. Integrating multiple energy sources under the concept of energy hub can improve the efficiency and reliability of the system; moreover, efficiency increasing cause to decrease in environmental emission. Environmental emission is a very important issue from the global warming point of view that should be considered in the researches. In this regard, green hydrogen can be used as a clean energy carrier that can be stored for a long time without degradation. To this end, this paper focuses on the concept of hydrogen-based smart micro energy hub (SMEH) considering integrated demand response (IDR) and fuel cell-based hydrogen storage system (HSS). IDR is introduced to control consumers' electrical and heat demand patterns. Additionally, HSS not only can convert power from renewable energy sources (RESs) to hydrogen (P2H) in a low electricity price period and vice versa (H2P) in a high electricity price period but also can supply the hydrogen-based industry. The aim of the proposed model is to minimize the total energy cost of hydrogen-based energy hub integrated with IDR and HSS under a robust optimization (RO) approach considering the uncertainty of electricity price. The proposed optimization model provides day-ahead scheduling for SMEH, which would improve the operation of the energy system. Finally, simulation and numerical results are provided to confirm the effectiveness of the proposed model. According to the obtained results, considered technologies cause to decrease in operation cost up to 7.8% and improve the system robustness against electricity market uncertainty up to 30%. [ABSTRACT FROM AUTHOR]

This paper provides a comprehensive review on the various techniques and routes of solar hydrogen production. The solar energy options considered are thermal energy, electrical energy, photonic energy, and hybrid options. The hybrid option includes thermal and electrical, electrical and photonic, biochemical and thermal, and biochemical and photonic energies. Some relevant literature review with their key findings, conclusions, and suggestions is presented. Various methods of solar energy-based hydrogen production are explained and briefly discussed. The technologies available for realizing these methods are also presented. Some recent advances in solar hydrogen generation is also presented in which some novel techniques are discussed. Some plant configurations are also discussed and compared to consider the factors which influence the cost of hydrogen. This review article also aims to comparatively assess and evaluate the several routes of producing hydrogen using solar energy. The comparative evaluation is performed using two sets of criteria. Criteria set 1 consists of environmental impact and cost of hydrogen production. Criteria set 2 comprises energy and exergy efficiencies, sustainability indices and hydrogen production rates. High-temperature energy methods show much better efficiencies and hydrogen yield while at the same time are more environmentally harmful. Photonic and biochemical energy routes are more environmentally friendly and sustainable, but have low efficiencies. • Identifying potential solar hydrogen production methods for application in various sectors. • Categorizing the potential methods for various applications and possibilities under various conditions. • Discussing the challenges and opportunities as well as future directions of the considered methods. • Comparatively evaluating the considered methods. [ABSTRACT FROM AUTHOR]

The Swedish steel industry stands before a potential transition to drastically lower its CO 2 emissions using direct hydrogen reduction instead of continuing with coke-based blast furnaces. Previous studies have identified hydrogen direct reduction as a promising option. We build upon earlier efforts by performing a technological innovation system study to systematically examine the barriers to a transition to hydrogen direct reduction and by providing deepened quantitative empirics to support the analysis. We also add extended paper and patent analysis methodology which is particularly useful for identifying actors and their interactions in a technological system. We conclude that while the innovation system is currently focused on such a transition, notable barriers remain, particularly in coordination of the surrounding technical infrastructure and the issue of maintaining legitimacy for such a transition in the likely event that policies to address cost pressures will be required to support this development. [ABSTRACT FROM AUTHOR]