Hydrogen Utilization Research Articles

(Invited) Targeted Research to Develop Next Generation PEM Water Electrolyzers

The utilization of low-carbon intensity hydrogen as an energy carrier promises a path to the decarbonization of sectors including electricity, heavy-duty transportation, and industry at scale. The United States Department of Energy is investing into this opportunity by heavily supporting research and development efforts for hydrogen production at scale. In recent years, the DOE has established the H2NEW consortium which consists of nine national labs and additional partners to focus on the advancement of water electrolysis. It also launched the Hydrogen Energy Earthshot in 2021, targeting the reduction of clean hydrogen production cost by 80% from $5 to $1 per 1 kg H2 produced in 1 decade. For these efforts to be successful, techno-economic analyses are used to identify the research and development areas with the greatest impact, supporting targeted studies on scalable manufacturing and materials that lower capital costs, produce hydrogen efficiently, and enable durable operation over the system lifetime.In this presentation the challenges and trade-offs of electrolyzer operation for renewable hydrogen generation will be reviewed, and results from targeted NREL studies on components, materials and interfaces will be discussed in detail, including for example PTL morphology, PTL coatings, and PTL/catalyst layer interactions and their effect on operation with thin membrane materials, hydrogen crossover and voltage loss contributions. The presentation also touches on any advanced in-situ diagnostic development that was required for the studies, such as high pressure operation, hydrogen crossover quantification, high throughput testing, and spatial diagnostics.

Utilization of coal for hydrogen generation

ABSTRACT The utilization of coal for hydrogen generation presents a multifaceted approach employing processes like coal gasification, pyrolysis, or high-temperature steam reforming. These methodologies entail reacting coal with steam or oxygen under elevated temperatures, yielding a gas mixture comprising hydrogen, carbon monoxide, and various byproducts. This paper delves into the exploration of hydrogen generation from coal, highlighting techniques such as gasification, pyrolysis, and other emerging methods. Notably, hydrogen discoveries within coal basins have garnered significant attention due to their implications for energy production and environmental sustainability. Certain coal basins harbor deposits rich in hydrogen, surpassing conventional coal reserves in their hydrogen content. These hydrogen-rich coals, including select sub-bituminous and lignite varieties, offer promising avenues for hydrogen production and utilization. However, the utilization of coal for hydrogen generation is not without its challenges. Technical hurdles, such as process efficiency and environmental concerns, demand rigorous investigation and innovative solutions. This paper addresses the challenges faced in coal-based hydrogen generation while elucidating the potential future prospects. It explores avenues for enhancing process efficiency, mitigating environmental impacts, and integrating coal-based hydrogen generation into broader energy strategies. Moreover, it underscores the importance of interdisciplinary research and collaboration in unlocking the full potential of coal for sustainable hydrogen production.

Limitations and Opportunities of Self-Supported Co-Based Anodes for Pure Water-Fed Anion Exchange Membrane Water Electrolyzers

Hydrogen has been regarded as an energy source with a potential to be used in various sectors, including transportation, power generation and industrial processes1-3. Producing hydrogen via water electrolysis using green electricity will be necessary for a sustainable future. Proton exchange membrane water electrolysis (PEMWE) is one of mature and leading electrolysis technologies, while anion exchange membrane water electrolysis (AEMWE) is regarded as a new, emerging technology4. However, PEMWE system suffers from their expensive cost and scarcity of iridium-based oxygen evolution reaction (OER) catalysts, having no alternative OER catalysts. Compared to PEMWE, AEMWE can be pursued with non-platinum group metal (non-PGM) thanks to its alkaline environment4,5.Here, non-PGM Co-based catalyst coated anodes were prepared using a simple hydrothermal reaction followed by heat treatment. Different phases and crystallinity of cobalt-based anodes were prepared and tested in pure water-fed AEMWE devices. To investigate the catalyst-ionomer/membrane interfaces at the anodes, the loadings of Co3O4 catalyst and ionomer topcoats were controlled. The cell performance in polarization curves was correlated with electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) measurements. The comparison of anodes operated with pure water feed and with supporting electrolyte was made to highlight the importance of catalyst-ionomer interface in pure water-fed AEMWE. Lastly, our self-supported Co3O4 anode outperformed a commercial Co3O4 NP ink-based anode, projecting a potential of direct growth of catalyst materials on PTLs in pure water-fed AEMWE.Reference(1) Agyekum, E. B.; Nutakor, C.; Agwa, A. M.; Kamel, S. A Critical Review of Renewable Hydrogen Production Methods: Factors Affecting Their Scale-Up and Its Role in Future Energy Generation. Membranes 2022, 12 (2).(2) Qusay, H.; Sameer, A.; Aws Zuhair, S.; Hayder, M. S.; Marek, J. Green hydrogen: A pathway to a sustainable energy future. Int. J. Hydrogen Energy 2024, 50, 310-333.(3) Joonsik, H.; Krisha, M.; HeeJin, C. A review of hydrogen utilization in power generation and transportation sectors: Achievements and future challenges. Int. J. Hydrogen Energy 2023, 48 (74), 28629-28648.(4) Lee, S. A.; Kim, J.; Kwon, K. C.; Park, S. H.; Jang, H. W. Anion exchange membrane water electrolysis for sustainable large-scale hydrogen production. Carbon Neutralization 2022, 1 (1), 26-48.(5) Juchan, Y.; Myeong Je, J.; Xiaojun, Z.; Yoo Sei, P.; Jooyoung, L.; Sung Mook, C.; Yadong, Y. Non-precious electrocatalysts for oxygen evolution reaction in anion exchange membrane water electrolysis: A mini review. Electrochem. Commun. 2021, 131, 107118.

Enhancing Anode Reversal Tolerance by Low-Carbon and Carbon-Free Anode Catalyst Layers for Proton Exchange Membrane Fuel Cells

Proton exchange membrane fuel cells (PEMFCs), as the main hydrogen utilization device, are considered a powerful tool for accelerating a carbon-neutral society. However, durability and cost are the two main obstacles to the commercialization of PEMFCs. Specifically, the anode reversal has been extensively studied as a severe issue that deteriorates the performance and durability of PEMFCs and leads to cell failure. Commercially, iridium oxide (IrOx) or iridium black is intensively utilized as oxygen evolution reaction catalysts to fabricate reversal tolerant anodes (RTAs) despite the slight performance loss. However, previous studies concentrated on investigating the origin or phenomena during the cell-reversal, the key factors and mechanisms affecting the anti-reversal performance, and the interaction among the anode catalyst layer components are still yet to be explored.Hence, we systematically studied the performance using three typical carbon supports with three metal contents and different metal deposition orders by experiments and model calculations. First, we synthesized Ir outside Ir/Pt/C and Pt outside Pt/It/C with uniform nanoparticle size and distribution and characterized them comprehensively. A new parameter, “relative metal coverage”, is put forward to evaluate and predict the anti-reversal ability, showing that higher relative metal coverage results in a longer reversal time and lower polarization performance degradation rate. In addition, Ir outside Ir/Pt/C shows better reversal tolerance than Pt outside Pt/It/C, which has been rarely mentioned in previous studies. Further, the experimental results show that even though the metal coverage is high, the performance degradation caused by carbon corrosion is still inevitable. On this basis, we synthesized a high specific surface area conductive oxide Ti4O7 as the anode catalyst support to eliminate the adverse effects of carbon corrosion. Previously, the initial performance of Ti4O7-supported catalyst was obstructed by the disadvantaged electrical conductivity of Ti4O7. We obtain a comparable polarization performance after optimizing the Ti4O7-supported anode catalyst layer parameters by shortening the electron transfer pathway and increasing metal coverage. Typically, the Ir@IrOx/Pt/Ti4O7-fabricated RTA with low Ir loading displays approximately ten times longer reversal time (6 hours) and two orders of magnitude lower degradation rate than a conventional carbon-supported counterpart. The degradation origin of the Ti4O7-supported anodes is also studied by postmortem characterizations, pointing to the Pt oxidation caused by the formation of TiOx thin layers on the Pt surface. These two works aim to promote the development of highly durable and reversal tolerance anode and provide a bright perspective for practical high-performance, low-degradation, and cost-friendly RTA fabrication.

Product Selection Toward High-Value Hydrogen and Bamboo-Shaped Carbon Nanotubes from Plastic Waste by Catalytic Microwave Processing.

The escalating levels of plastic waste and energy crises underscore the urgent need for effective waste-to-energy strategies. This study focused on converting polypropylene wastes into high-value products employing various iron-based catalysts and microwave radiative thermal processing. The Al-Fe catalysts exhibited exceptional performance, achieving a hydrogen utilization efficiency of 97.65% and a yield of 44.07 mmol/g PP. The gas yields increased from 19.99 to 94.21 wt % compared to noncatalytic experiments. Furthermore, this catalytic system produced high-value bamboo-shaped carbon nanotubes that were absent in other catalysts. The mechanism analysis on catalytic properties and product yields highlighted the significance of oxygen vacancies in selecting high-value products through two adsorption pathways. Moreover, the investigation examined the variations in product distribution mechanisms between conventional and microwave pyrolysis, in which microwave conditions resulted in 4 times higher hydrogen yields. The technoeconomic assessment and Monte Carlo risk analysis further compared the disparity. The microwave technique had a remarkable internal rate of return (IRR) of 39%, leading to an income of $577/t of plastic with a short payback period of 2.5 years. This research offered sustainable solutions for the plastic crisis, validating the potential applicability of commercializing the research outcomes in real-world scenarios.

Comprehensive evaluation and optimization strategy of solar-driven methanol steam reforming for hydrogen production

In the current era of green energy transformation and hydrogen utilization, there is a pervasive interest in thermochemical hydrogen production using solar energy. This study proposes an innovative strategy for the comprehensive evaluation and optimization of a novel solar-driven methanol steam reforming hydrogen production system. The solar-to-chemical conversion and utilization process were simulated via a comprehensive model, incorporating a kinetic model to calculate the reaction process within the photothermal reactor. Furthermore, an integrated evaluation system based on Taguchi's design, ANOVA, and gray relational analysis was constructed to optimize the objectives of methanol conversion, hydrogen yield, and CO selectivity. The results revealed that the catalyst weight to inlet methanol molar rate operating parameter significantly influenced system performance compared to the inlet temperature and steam-methanol ratio. The multi-objective optimized operating factors resulted in the highest methanol conversion (99.99 %), the highest hydrogen yield (3.196), and the lowest CO selectivity (1.71E-3). Additionally, a interaction factor analysis model is introduced to evaluate the interaction effects between each factor. The results indicate consistent optimal values and corresponding operating conditions across these methods for the system proposed in this study. This study offers valuable insights and guidance for the practical operation of solar-driven thermochemical hydrogen production reactions.

Review of Hydrogen-Related Accidents: Root Causes, Mitigation Strategies, and Recommendations for secure utilization.

Abstract Hydrogen, acknowledged as a versatile and sustainable energy carrier, is gaining significant attention across industries, becoming a focal point in the pursuit of cleaner energy solutions. However, Ensuring the safe utilization of hydrogen presents inherent challenges, giving rise to a spectrum of related accidents. This study delves into the intricate landscape of hydrogen utilization, acknowledging both its significance and inherent challenges associated with its safety. This comprehensive review examines hydrogen-related accidents from the Hydrogen Incident and Accident Database (HIAD) within a defined timeframe, analyzing causes and evaluating the effectiveness of current mitigation strategies through categorization and assessment of the root causes of hydrogen-related incidents, this review aspired to provide an in-depth understanding of safety issues and also reviewed the effectiveness of current mitigating strategies, employing risk assessment models. A thorough analysis of these incidents uncovered crucial insights, The findings of the review paper illustrate that human factor and management factors were possibly greater causes of hydrogen accidents than other factors, and management factors to be more hazardous than other factors. Through comprehensive literature review, the study aims to offer practical recommendations for refining safety protocols in hydrogen utilization like the implementation of Human Error Assessment and Reduction Technique (HEART) and Human Factor Analysis and Classification System (HFACS) for human factor induced incidents and process safety management (PSM) program for management factor induced incidents. Additionally, specific recommendation for reoccurring incidents based on severity are made to enhance safety protocols, thereby fostering its secure application across diverse industries.

Review of energy management systems and optimization methods for hydrogen‐based hybrid building microgrids

AbstractRenewable energy‐based microgrids (MGs) strongly depend on the implementation of energy storage technologies to optimize their functionality. Traditionally, electrochemical batteries have been the predominant means of energy storage. However, technological advancements have led to the recognition of hydrogen as a promising solution to address the long‐term energy requirements of microgrid systems. This study conducted a comprehensive literature review aimed at analysing and synthesizing the principal optimization and control methodologies employed in hydrogen‐based microgrids within the context of building microgrid infrastructures. A comparative assessment was conducted to evaluate the merits and disadvantages of the different approaches. The optimization techniques for energy management are categorized based on their predictability, deployment feasibility, and computational complexity. In addition, the proposed ranking system facilitates an understanding of its suitability for diverse applications. This review encompasses deterministic, stochastic, and cutting‐edge methodologies, such as machine learning‐based approaches, and compares and discusses their respective merits. The key outcome of this research is the classification of various energy management strategy (EMS) methodologies for hydrogen‐based MG, along with a mechanism to identify which methodologies will be suitable under what conditions. Finally, a detailed examination of the advantages and disadvantages of various strategies for controlling and optimizing hybrid microgrid systems with an emphasis on hydrogen utilization is provided.

Modification of the hydrogen compression properties of Zr–Fe–Cr–V-based alloys through Ti doping

Hydrogen refueling stations typically rely on compressors to increase the pressure of hydrogen received from long-tube trailers, enabling efficient refill of hydrogen storage tanks. However, mechanical hydrogen compressors are unable to effectively harness residual hydrogen below 6 MPa in long-tube trailers. Herein, we developed a ZrFe2-based hydrogen compression alloy to enhance the hydrogen pressure that meets the input pressure requirement of mechanical hydrogen compressors. Specifically, the co-substitution of Cr and V for Fe was conducted to reduce the plateau slope and hysteresis, and Ti was introduced to partially substitute Zr to regulate the plateau pressure. The effects of Ti on the structure and hydrogen storage properties of Zr–Fe–Cr-based alloys have been investigated by first-principles calculations, wherein Zr1-xTixFe1.7Cr0.2V0.1 (x = 0, 0.1, 0.2, 0.3, 0.4) alloys were designed and synthesized. The optimized Zr0.8Ti0.2Fe1.7Cr0.2V0.1 alloy provided a hydrogen absorption capacity of 1.22 wt% under 3.88 MPa H2 pressure at 300 K and achieved an effective hydrogen compression capacity of 1.07 wt% at 355 K at an H2 desorption pressure of 6.36 MPa. This advancement holds great promise for the efficient utilization of residual hydrogen at approximately 6 MPa in long-tube trailers, thus leading to a significant improvement in hydrogen transportation efficiency.

Analysis of hydrogen supply and demand in China's energy transition towards carbon neutrality

The role of hydrogen in the transition to carbon-neutral energy systems will be influenced by key factors such as carbon neutrality pathways, hydrogen production technology costs, and hydrogen transportation costs. Existing studies have not comprehensively analyzed and compared the impact of these key factors on the development of hydrogen supply and demand under China's carbon neutrality pathways. This study uses the Global Change Assessment Model (GCAM) with an upgraded hydrogen module to evaluate the development potential of China's hydrogen industry, considering various carbon neutrality pathways as well as hydrogen production and transportation costs. The findings indicate that, by 2050, hydrogen could account for 8%–14% of final energy, averting 1.0–1.7 Bt of carbon emissions annually at an average mitigation cost of 85–183 USD t−1CO2. The total hydrogen production is projected to reach 75–135 Mt, with 34%–56% from renewable energy electrolysis and about 15%–29% from fossil fuel-based CCS. On a sectoral level, by 2050, the hydrogen demand in the industrial and transportation sectors is expected to reach 37–63 Mt and 30–42 Mt, with a potential reduction of about 0.6–0.9 BtCO2 and 0.5–0.6 BtCO2. The share of hydrogen in the final energy of the steel and chemical sectors is estimated to be 9%–19% and 17%–25%, collectively accounting for 36%–42% of total hydrogen demand and 46%–50% of total emission reduction potential. Realizing hydrogen's emission reduction potential relies on the rapid development of hydrogen production, transportation, and utilization technologies. Firstly, the development of on-site electrolysis for hydrogen production and early deployment of industrial hydrogen applications should be prioritized to stimulate overall growth of hydrogen industry and cost reduction. Secondly, vigorous development of renewable energy electrolysis and hydrogen end-use technologies like fuel cells should be pursued, along with the demonstration and promotion of hydrogen transportation technologies. Lastly, further advancement of carbon market mechanisms is essential to support the widespread adoption of hydrogen technologies.

Strategies to promote nuclear energy utilization in hydrogen production

The significant increase in harmful GHG emissions has led to dramatic global climatic changes. Thus, a need arises for clean, sustainable, economically viable energy sources. Prink hydrogen is the production of hydrogen using a nuclear energy source. No clear legislation regulates the utilization and operation of hydrogen in general and pink hydrogen in particular. This study analyzes nuclear energy regulations in various countries and regions and introduces a gap analysis in the nuclear field, comparing the under-established to the well-established regulatory bodies. This study utilized a harmonious blend of analytical tools utilizing both a gap analysis and an integrated decision-making methodology. Gap analysis showed a weak regulatory infrastructure, which hinders the adoption of pink hydrogen in some regions. Strategies were suggested in this study to address the identified weaknesses and threats linked to pink hydrogen technology to enhance energy security.

Recent Advances in Revealing the Electrocatalytic Mechanism for Hydrogen Energy Conversion System.

In light of the intensifying global energy crisis and the mounting demand for environmental protection, it is of vital importance to develop advanced hydrogen energy conversion systems. Electrolysis cells for hydrogen production and fuel cell devices for hydrogen utilization are indispensable in hydrogen energy conversion. As one of the electrolysis cells, water splitting involves two electrochemical reactions, hydrogen evolution reaction and oxygen evolution reaction. And oxygen reduction reaction coupled with hydrogen oxidation reaction, represent the core electrocatalytic reactions in fuel cell devices. However, the inherent complexity and the lack of a clear understanding of the structure-performance relationship of these electrocatalytic reactions, have posed significant challenges to the advancement of research in this field. In this work, the recent development in revealing the mechanism of electrocatalytic reactions in hydrogen energy conversion systems is reviewed, including in situ characterization and theoretical calculation. First, the working principles and applications of operando measurements in unveiling the reaction mechanism are systematically introduced. Then the application of theoretical calculations in the design of catalysts and the investigation of the reaction mechanism are discussed. Furthermore, the challenges and opportunities are also summarized and discussed for paving the development of hydrogen energy conversion systems.

Low-Carbon Distributed Optimal Operation of Integrated Energy System Considering Wind and Solar Uncertainty

To ensure the supply and demand balance of integrated energy systems (IES) in the electric-carbon market and solve the complicated interest relationship among participants in the system, a distributed optimal scheduling model based on the extended carbon emission flow theory of integrated energy systems was proposed. Firstly, hydrogen energy production and utilization devices are introduced into the energy supply side to establish an expanded carbon emission flow model of the hydrogen-energy coupling integrated energy system based on carbon emission flow theory. Then, the fuzzy membership function is used to characterize the uncertainty of wind and light output. The distributed optimization algorithm based on goal cascade analysis realizes the decoupling of the integrated energy service provider and the user. This achieves the independent solution of the integrated energy service provider. A numerical example is given to verify that the proposed strategy can realize the stable and optimal operation of the integrated energy system in an uncertain environment.

A novel development of an unmanned surface vehicle directly powered by an air-cooled proton exchange membrane fuel cell stack

Most compact Unmanned Surface Vehicles (USVs) used in water quality monitoring and maritime surveillance rely on lithium batteries. However, they're only ideal for short missions. This paper first fabricates a novel lightweight, air-cooled, high-power-density Proton Exchange Membrane Fuel Cell (PEMFC) stack with ultrathin steel bipolar plates as the primary power source for a self-made compact USV. This stack consists of 40 single cells and integrates a reliable air-cooled system, operating in parallel with a supercapacitor to enhance its performance. Experimental results show that this PEMFC-powered USV outperforms the main lithium battery-powered counterpart, offering an extended cruising range and better power stability and significantly increasing the cruising range from 8 km to 38 km when the PEMFC stack and the main lithium battery are of similar volume and weight. Integrating a low voltage purging logic with a 0.4 V threshold in the dead-end anode (DEA) mode results in a remarkable hydrogen utilization rate of up to 98%. Moreover, the average voltage of the PEMFC stack with the supercapacitor consistently exceeds that of the stack without the supercapacitor by approximately 0.125 V, mitigating the impact of rapid load changes. The results verify the feasibility of the proposed air-cooled PEMFC-powered USV.

Dual-Intermetallic Heterostructure on Hierarchical Nanoporous Metal for Highly Efficient Alkaline Hydrogen Electrocatalysis.

Constructing well-defined active multisites is an effective strategy to break linear scaling relationships to develop high-efficiency catalysts toward multiple-intermediate reactions. Here, dual-intermetallic heterostructure composed of tungsten-bridged Co3W and WNi4 intermetallic compounds seamlessly integrated on hierarchical nanoporous nickel skeleton is reported as a high-performance nonprecious electrocatalyst for alkaline hydrogen evolution and oxidation reactions. By virtue of interfacial tungsten atoms configuring contiguous multisites with proper adsorptions of hydrogen and hydroxyl intermediates to accelerate water dissociation/combination and column-nanostructured nickel skeleton facilitating electron and ion/molecule transportations, nanoporous nickel-supported Co3W-WNi4 heterostructure exhibits exceptional hydrogen electrocatalysis in alkaline media, with outstanding durability and impressive catalytic activities for hydrogen oxidation reaction (geometric exchange current density of ≈6.62 mA cm-2) and hydrogen evolution reaction (current density of ≈1.45 A cm-2 at overpotential of 200 mV). Such atom-ordered intermetallic heterostructure alternative to platinum group metals shows genuine potential for hydrogen production and utilization in hydroxide-exchange-membrane water electrolyzers and fuel cells.

An experimental study on the hydrogen utilization in air-cooled proton exchange membrane fuel cell stack with a novel anode outlet design

In the realm of portable power system, air-cooled fuel cells stand out for their lightweight design and emission-free operation. Anode purging has emerged as an effective method to alleviate performance degradation in the dead-end anode stack. However, purging frequency can affect hydrogen utilization and output performance. This research aims to reduce the purging frequency and enhance hydrogen utilization of air-cooled fuel cell stacks by introducing a novel anodic outlet endplate. The novel outlet helps to remove liquid water and nitrogen from the stack, improve the output performance, and save the hydrogen usage in the air-cooled fuel cell stack. The peak power outputs of stacks equipped with the novel and conventional anodic outlets are recorded at 2313.95 W and 2213.35 W, respectively. Significantly, the novel anodic outlet configuration demonstrates a 4.54 % increase in peak power. Moreover, this configuration extends the purging interval, leading to a reduction in purging frequency. Under current load of 62 A, the novel anode outlet stack prolongs the purging interval of 134.73 s compare to its counterpart with a conventional anodic outlet than that of the conventional anode outlet. The findings presented in this study are poised to offer valuable insights into optimizing their efficiency and promoting sustainable solutions.

Multiple strategies regulating the d-band center of Ni2P/NiFe2O4 @N-GTs hierarchical nanoarchitecture as efficient electrocatalyst for overall water splitting

The rational design of highly active electrocatalysts for water electrolysis remains challenging for green hydrogen utilization. Herein, guided by the correlation between the electroactivity and the d-band center (Ed), a novel hierarchical nanoarchitecture (Ni2P/NiFe2O4-VO@N-GTs) was fabricated, in which, Ni2P nanoparticles are grown on the oxygen vacancy-rich NiFe2O4 nanosheet arrays anchoring on N-doping graphene tubes. The results reveal that the multiple strategies including the vacancies and heterogeneous interface construction effectively induce the charge redistribution, and further adjust the Ed to the appropriate energy level, which endows the optimal balance between the adsorption and desorption ability of the catalyst to reaction intermediates, thus leading to the conspicuous electrocatalytic activity. Additionally, the hierarchical nanoarchitecture contributes to the exposure of more active sites, the efficiency of electron transfer, and the release of generated gas. Hence, Ni2P/NiFe2O4-VO@N-GTs presents superior bifunctional activity, especially a low overpotential of 194 mV at 10 mA cm−2 for OER. The corresponding overall water electrolyzer owns a lower cell voltage and long-term durability with continuously operating over 330 h at 100 mA cm−2, outperforming the most reported bifunctional electrocatalysts. This work presents an effective pathway for regulating the Ed through multiple strategies to improve the catalytic performance of catalysts.

Hydrogen reduction studies of low-grade multimetallic magnetite ore pellets

The hydrogen reducibility of pellets made from a low-grade multimetallic magnetite ore (Fe content ∼ 45 %) was investigated in the present study. Pellets were reduced in a horizontal tube furnace at temperatures ranging from 973 K to 1173 K for 1 to 60 min. Pure Hydrogen (H2) gas (99.9 %) at three flow rates of 0.25 L/min, 0.5 L/min, and 1 L/min were blown during the reduction process. A maximum reduction degree of 94.07 %, metallization ratio of 0.925, and H2 gas utilization of 9.01 % were obtained at a temperature and a reduction time of 1173 K and 60 min, respectively. In order to optimize the hydrogen utilization, a reduction temperature of 1173 K, a reduction time of 45 min, and a gas flow rate of 0.25 L/min were selected, resulting in a reduction degree and metallization ratio of 90 % and 0.89, respectively. The cold crushing strength (CCS) of the reduced pellets initially decreased and then increased slightly, exhibiting behavior similar to high-grade ores. Imputities like SiO2, Al2O3, and MgO, present in the low grade ores are found to control the porosity of the pellets, directly affecting the CCS and reducibility of the pellets.

An efficient data-driven approach for modeling and optimization of reactivity-controlled compression ignition engine fueled with polyoxymethylene dimethyl ethers and hydrogen

This paper presents an efficient data-driven approach for optimizing the utilization of PODEn and hydrogen in reactivity-controlled compression ignition (RCCI) engines. A novel high dimensional model representation (HDMR) technique is adopted to construct a highly accurate surrogate model for the RCCI engine based on the dataset generated by a detailed CFD model that has been calibrated against experimental data. The HDMR model is then coupled with Non-dominated Sorting Genetic Algorithm III (NSGA III), a multi-objective genetic algorithm, to search for the optimal operating conditions where the RCCI engine fueled by PODEn and H2 achieves the highest combustion performance. Results suggest that the constructed HDMR model is highly accurate, being able to predict the engine performance within milliseconds. The coupled HDMR-NSGA III approach successfully identifies the optimal engine operating condition, which significantly improves the combustion performance and reduces pollutant emissions compared with the base condition.

The effect of used cooking oil composition on the specific CO2e emissions embodied in HEFA‐SPK production

AbstractIn this study, the correlation between the composition, hydrogen/carbon (H/C) ratio, and hydrogen/oxygen (H/O) ratio of a used cooking oil (UCO) and the specific emissions embodied in the derived hydroprocessed esters and fatty acids synthetic paraffinic kerosene (HEFA‐SPK) is investigated. It is shown that HEFA‐SPK produced from UCOs with low concentrations of C18:1, high concentrations of C18:2, and low H/C ratios utilize less energy and more hydrogen during Fuel Production. Hence, HEFA‐SPK produced from such UCOs will embody higher gCO2e for fossil hydrogen utilization scenarios, and lower gCO2e for green hydrogen utilization scenarios compared with other UCOs. Conversely, it is shown that HEFA‐SPK produced from UCOs with high concentrations of C18:1, low concentrations of C18:2 and high H/C ratios utilize more energy and less hydrogen during Fuel Production. Hence, HEFA‐SPK derived from such UCOs will embody lower gCO2e for fossil hydrogen utilization scenarios, and higher gCO2e for green hydrogen utilization scenarios compared with other UCOs. Monte Carlo simulation gives the emissions embodied in Fuel Production a 95% confidence interval for all UCO‐derived HEFA‐SPK, showing a similar uncertainty for all compositions. A maximum of +1.1 gCO2e/MJSAF and −1.0 gCO2e/MJSAF is obtained for the upper and lower bounds respectively for the emissions embodied during HEFA‐SPK production from UCO. The application of the correlations founded in this study allows for the prediction of the specific emissions embodied in the feedstock‐to‐fuel conversion of any UCO, providing the C18:1 concentration, C18:2 concentration, H/C ratio and H/O ratio of the UCO is known.