Publications

Hydrogen is an ideal energy carrier in future applications due to clean byproducts and high efciency. However many challenges remain in the application of hydrogen including hydrogen production delivery storage and conversion. In terms of hydrogen storage two compression modes (mechanical and non-mechanical compressors) are generally used to increase volume density in which mechanical compressors with several classifcations including reciprocating piston compressors hydrogen diaphragm compressors and ionic liquid compressors produce signifcant noise and vibration and are expensive and inefcient. Alternatively non-mechanical compressors are faced with issues involving large-volume requirements slow reaction kinetics and the need for special thermal control systems all of which limit large-scale development. As a result modular safe inexpensive and efcient methods for hydrogen storage are urgently needed. And because electrochemical hydrogen compressors (EHCs) are modular highly efcient and possess hydrogen purifcation functions with no moving parts they are becoming increasingly prominent. Based on all of this and for the frst time this review will provide an overview of various hydrogen compression technologies and discuss corresponding structures principles advantages and limitations. This review will also comprehensively present the recent progress and existing issues of EHCs and future hydrogen compression techniques as well as corresponding containment membranes catalysts gas difusion layers and fow felds. Furthermore engineering perspectives are discussed to further enhance the performance of EHCs in terms of the thermal management water management and the testing protocol of EHC stacks. Overall the deeper understanding of potential relationships between performance and component design in EHCs as presented in this review can guide the future development of anticipated EHCs.

With the deepening electrification of transportation hydrogen fuel cell electric vehicles (FCEVs) are emerging as a vital component of clean and electrified transportation systems. Nonetheless renewable-based hydrogen production–refueling stations (HPRSs) for FCEVs still need solid models for accurate simulations and a practical capacity optimization method for cost reduction. To address this gap this study leverages real operation data from China’s largest HPRS to establish and validate a comprehensive model integrating hydrogen production storage renewables FCEVs and the power grid. Building on this validated model a novel capacity optimization framework is proposed incorporating an improved Jellyfish Search Algorithm (JSA) to minimize the initial investment cost operating cost and levelized cost of hydrogen (LCOH). The results demonstrate the framework’s significant innovations and effectiveness: It achieves the maximum reductions of 29.31% in the initial investment 100% in the annual operational cost and 44.19% in LCOH while meeting FCEV demand. Simultaneously it reduces peak grid load by up to 43.80% and enables renewable energy to cover up to 89.30% of transportation hydrogen demand. This study contributes to enhancing economic performance and optimizing the design and planning of HPRS for FCEVs as well as promoting sustainable transportation electrification.

In response to the global climate change and the need for green and low-carbon development hydrogen energy has been recognized as a clean energy source that can achieve carbon neutrality unlike fossil fuels. As a country with a shortage of energy resources the development of hydrogen energy is of significant importance for China to adjust its energy structure and accelerate the new era of energy transformation. Based on the development of China’s hydrogen energy industry this paper elaborates on the current status and development trends of key technologies in the entire industrial chain of hydrogen energy in various stages including production storage transportation and application and identifies the problems and challenges of hydrogen energy development. The paper focuses on the analysis of hydrogen storage and transportation application scenarios and clarifies the selection of hydrogen storage and transportation technologies in different scenarios. To achieve healthy devel opment of China’s hydrogen energy industry it is necessary to strengthen top-level design make strategic planning encourage large-scale state-owned energy enterprises to play a leading role promote the development of the entire industry chain increase technological research and development efforts prevent the risk of core technology constraints and vigorously promote the application of hydrogen energy to realize the construction of a hydrogen energy society.

Civil aviation provides an essential transportation network that connects the world and supports global economic growth. To maintain these benefits while meeting environmental goals next-generation aircraft must have drastically reduced climate impacts. Hydrogen-powered aircraft have the potential to fly existing routes with no carbon emissions and reduce or eliminate other emissions. This paper is a comprehensive guide to hydrogen-powered aircraft that explains the fundamental physics and reviews current technologies. We discuss the impact of these technologies on aircraft design cost certification and environment. In the long term hydrogen aircraft appear to be the most compelling alternative to today’s kerosene-powered aircraft. Using hydrogen also enables novel technologies such as fuel cells and superconducting electronics which could lead to aircraft concepts that are not feasible with kerosene. Hydrogen-powered aircraft are technologically feasible but require significant research and development. Lightweight liquid hydrogen tanks and their integration with the airframe is one of the critical technologies. Fuel cells can eliminate in-flight emissions but must become lighter more powerful and more durable to make large fuel cell-powered transport aircraft feasible. Hydrogen turbofans already have these desirable characteristics but produce some emissions albeit much less damaging than kerosene turbofans. Beyond airframe and propulsion technologies the viability of hydrogen aircraft hinges on low-cost green hydrogen production which requires massive investments in the energy infrastructure.

Intra-day control and scheduling of energy systems require high-speed computation and strong robustness. Conventional mathematical driven approaches usually require high computation resources and have difficulty handling system uncertainties. This paper proposes two data-driven scheduling approaches for hydrogen penetrated energy system (HPES) operational scheduling. The two data-driven approaches learn the historical optimization results calculated out using the mixed integer linear programing (MILP) and conditional value at risk (CVaR) respectively. The intra-day rolling optimization mechanism is introduced to evaluate the proposed data-driven scheduling approaches MILP data-driven approach and CVaR data-driven approach along with the forecasted renewable generation and load demands. Results show that the two data-driven approaches have lower intra-day operational costs compared with the MILP based method by 1.17% and 0.93%. In addition the combined cooling and heating plant (CCHP) has a lower frequency of changing the operational states and power output when using the MILP data-driven approach compared with the mathematical driven approaches.

This study presents a new three-step Cu-Cl cycle that can operate with heat input without electrolysis. While the sensitivity analyses of the system are performed to evaluate the system performance through the Aspen Plus thermodynamic analyses of the system are performed with energetic and exergetic approaches. The highest exergy destruction among the components in the system was the decomposition reactor with a rate of 50.6%. Furthermore the energy and exergy values for the simulated system to produce 1 mol of hydrogen were determined by calculating the energy requirements of all components in the system. The total energy required for the system to generate 1 mol of hydrogen is calculated to be 997.81 kJ/mol H2. It was found that the component that required the most energy 504.76 kJ/mol H2 in the system was the decomposition reactor. Moreover the overall energy and exergy efficiencies are calculated to be 72.50% and 46.70% respectively.

Electrifying ammonia production using renewable energy (RE) and water electrolysis is a critical step in the worldwide transition from fossil fuels to alternative energy sources. However the common requirement that the ammonia reactor operate at a steady production level harms the system’s economic feasibility due to the large hydrogen and battery storage required to overcome RE variability. In this study we examine the sensitivity of the plant storage capacity requirement to the flexibility of the ammonia reactor. We examine two aspects of ammonia reactor flexibility: ramping rate flexibility and the range of operation (turndown flexibility). We develop a storage dispatch and ammonia reactor scheduling optimization which computes the minimum storage requirement given a RE generation profile and set of reactor flexibility parameters. We optimize across a sweep of flexibility parameters for two locations in the United States. We find that turndown flexibility is the most important while ramping flexibility has little effect on the overall storage requirement. Further we see that seasonal variability in the RE generation profile is the primary driver of high storage capacity requirement. We find that with a turndown flexibility of 60% of the ammonia plants rated capacity which is understood to be achievable with existing ammonia reactor technology the storage capacity was reduced by 84 % in one of the locations we examined which resulted in a 22% decrease in the levelized cost of ammonia with pipe-based hydrogen storage.

This paper evaluates the potential impacts of introducing low-carbon intensity hydrogen technologies in two oil refineries with different complexity levels emphasizing the role of hydrogen production in reducing CO2 emissions. The novelty of this work lies in three key aspects: Comprehensive system analysis of refinery complexity using real site data integration of low-carbon Hydrogen technologies long-term and short-term strategies. Two Colombian refineries serve as case studies with technological solutions adapted to their complexity levels. The methodology involves evaluating different options for hydrogen production accounting for improvement in technological efficiency over time.<br/>The refinery systems were evaluated in a cost-optimization model built in Linny-r. Three different scenarios were considered Business-As-Usual (BAU) high and low-ambitions decarbonization scenarios focusing on the time horizons of 2030 and 2050.<br/>When comparing the two case studies the preferred decarbonization strategy for both facilities involves the substitution of SMR technology with water electrolyzers powered by renewable electricity. Post-2030 biomass-based hydrogen technology is still a costly alternative; however to achieve CO2 neutrality negative emissions storage of biogenic CO2 emerges as an achievable alternative.<br/>Our results indicate the achievability of CO2 reduction objectives in both refineries. Our results show that achieving long-term CO2 neutrality requires both refineries to increase renewable electricity production by 5 to 6 times for powering water electrolyzers steam production by 2 to 2.5 times for CO2 capture and supply of dry biomass by 2.6 to 4.5 kt/d.<br/>The two most significant factors influencing the refining net margin in the decarbonization scenarios are primarily the CO2 and the renewable electricity prices. The short-term horizon emerges as the pivotal period particularly within the high-ambition decarbonization scenarios. In this context the medium complexity refinery demonstrates economic viability until a CO2 price of 140 €/t CO2 while the high complexity refinery endures up to 205 €/t CO2.<br/>The high complexity refinery is better prepared to face the challenges of decarbonization and the impacts generated on the refining margin. Compared to the BAU scenario the high complexity refinery shows a negative impact on the net margin that corresponds to a 40% and 5% reduction in the short and long term respectively. Meanwhile for the medium complexity refinery the impact on net margin amounts to a 52% reduction in the short term and a 27% improvement in the long term.<br/>Furthermore our research highlights the significant potential for reducing CO2 emissions by fully eliminating the use of refinery gas as fuel providing alternative applications for it beyond combustion.

Electrofuels fuels produced from electricity water and carbon or nitrogen are of interest as substitutes for fossil fuels in all energy and chemical sectors. This paper focuses on electrofuels for transportation where some can be used in existing vehicle/vessel/aircraft fleets and fueling infrastructure. The aim of this study is to review publications on electrofuels and summarize costs and environmental performance. A special case denoted as bio-electrofuels involves hydrogen supplementing existing biomethane production (e.g. anaerobic digestion) to generate additional or different fuels. We use costs identified in the literature to calculate harmonized production costs for a range of electrofuels and bio-electrofuels. Results from the harmonized calculations show that bio-electrofuels generally have lower costs than electrofuels produced using captured carbon. Lowest costs are found for liquefied bio-electro-methane bio-electro-methanol and bio-electro-dimethyl ether. The highest cost is for electro-jet fuel. All analyzed fuels have the potential for long-term production costs in the range 90–160 € MWh−1 . Dominant factors impacting production costs are electrolyzer and electricity costs the latter connected to capacity factors (CFs) and cost for hydrogen storage. Electrofuel production costs also depend on regional conditions for renewable electricity generation which are analyzed in sensitivity analyses using corresponding CFs in four European regions. Results show a production cost range for electro-methanol of 76–118 € MWh−1 depending on scenario and region assuming an electrolyzer CAPEX of 300–450 € kWelec −1 and CFs of 45%–65%. Lowest production costs are found in regions with good conditions for renewable electricity such as Ireland and western Spain. The choice of system boundary has a large impact on the environmental assessments. The literature is not consistent regarding the environmental impact from different CO2 sources. The literature however points to the fact that renewable energy sources are required to achieve low global warming impact over the electrofuel life cycle.

Hydrogen is promoted as an alternative energy given the global energy shortage and environmental pollution. A scientific basiscan be provided for the safe use and emergency treatment of hydrogen based on hydrogen leakage and combustion behavior.This study examined the stagnation parameters of dynamic hydrogen leakage and flame propagation in turbulent jets undernormal temperatures and high pressure. Based on van der Waals’ equation of state for gas a theoretical model for completelypredicting stagnation parameters outlet gas velocity and flow rate changes in the process of high-pressure hydrogen leakagecould be proposed and the calculation result of this model was compared with the experimental result with an error within±10%. The progression and propagation of the flame in turbulent jets after ignition were recorded using the background-oriented schlieren image technology and the propagation speed of flame from the ignition position downward and upwardwas calculated. Moreover the influence of initial pressure nozzle diameter and ignition position on the flame propagationprocess and propagation speed was analyzed.