Hydrogen Demand Research Articles

Estimation-based model predictive control of an electrically-heated steam methane reforming process

The surge in demand for hydrogen (H2) across diverse sectors, including clean energy transportation and chemical synthesis, underscores the need for a thorough investigation into H2 production dynamics and the development of effective controllers for industrial applications. This paper focuses on an electrically heated steam methane reforming (SMR) process for H2 production, offering advantages such as enhanced environmental sustainability, compactness, efficiency, and controllability compared to conventional reforming methods. Electric heating of the entire system allows for adjustments in current to control reactor temperature, thereby impacting hydrogen production rates. However, accurately modeling hydrogen production dynamics presents a formidable challenge, as complex models with high precision are computationally unsuitable for real-time control integration. Considering these factors, an accurate and efficient first-principles-based lumped-parameter model is developed to provide a dependable estimation of hydrogen production in an electrically-heated steam methane reformer. This model is validated experimentally and then utilized in a model predictive controller (MPC). To obtain the necessary state estimate information for the MPC, an extended Luenberger observer (ELO) method is employed to estimate state variables from limited, infrequent and delayed measurements of gas-phase reactor outlet stream and frequent measurements of the reactor temperature. Simulation comparisons with a proportional-integral (PI) controller reveal a much faster response in achieving the desired H2 production rate under the estimation-based MPC. Additionally, the simulations demonstrate the robustness of the controller to process variability such as a decrease in catalyst activation energy, commonly encountered in the SMR process, highlighting its effectiveness in maintaining stable operation under varying process conditions.

Optimal Scheduling of Integrated Energy System Considering Hydrogen Blending Gas and Demand Response

In the context of carbon neutrality and carbon peaking, in order to achieve low carbon emissions and promote the efficient utilization of wind energy, hydrogen energy as an important energy carrier is proposed to mix hydrogen and natural gas to form hydrogen-enriched compressed natural gas (HCNG). It is also injected into the natural gas pipeline network to achieve the transmission and utilization of hydrogen energy. At the same time, the participation of demand response is considered, the load’s peak and trough periods are adjusted, and the large-scale consumption of renewable energy and the reduction in carbon emissions are achieved. First of all, a fine model of hydrogen production and hydrogen use equipment is established to analyze the impact of adding hydrogen mixing on the economy and the low-carbon property of the system. With green certificates and demand response, the utilization rate of hydrogen energy is improved to further explore the energy utilization rate and emission reduction capacity of the system. Secondly, on the basis of modeling, the optimal scheduling strategy is proposed with the sum of energy purchase cost, equipment operation cost, carbon emission cost, wind curtailment cost, and green certificate income as the lowest objective function. Considering the constraints such as hydrogen blending ratio and flexible load ratio of the pipeline network, a low-carbon economic scheduling model of hydrogen mixed natural gas was established. The model was linearized and solved by using MATLAB 2021a and CPLEX solver. By comparing different scenarios, the superiority of the model and the effectiveness of the strategy are verified.

Assessing Hydrogen–Ammonia Ratios to Achieve Rapid Kernel Inception in Spark-Ignition Engines

Abstract In the quest for decarbonizing internal combustion engines, ammonia (NH3) is recognized as a viable alternative fuel due to its zero-carbon emission profile, positioning it as a potential substitute for conventional petroleum fuels. However, the suboptimal combustion characteristics of ammonia pose challenges for its direct application in engines. The introduction of hydrogen (H2) as a combustion enhancer shows promise in improving ammonia viability for engine use. While previous studies have confirmed the benefits of hydrogen addition to ammonia for enhanced engine performance, comprehensive analysis of the precise ammonia-to-hydrogen ratio for optimal efficacy remains scarce. This research aims to bridge this gap by evaluating hydrogen–ammonia mixtures for achieving methane-equivalent laminar flame speeds under typical engine conditions, with a focus on the kernel inception process primarily driven by laminar flames. The findings indicate that a minimum of 20% hydrogen mixed with ammonia is necessary to facilitate rapid spark inception, although it does not reach the laminar flame speed of methane. Additionally, employing a high compression ratio and operating near stoichiometry could lower the required hydrogen–ammonia ratio. Considering the challenges in generating ample hydrogen with NH3 dissociators and the need for operational conditions like full-load and low-speed to lessen hydrogen demand, ammonia–hydrogen fuel blends are deemed most suitable for stationary engine applications in the near term.

Photocatalytic Hydrogen-Future Energy

The rapid increase in energy consumption, driven by the rising vehicle population and travel demand, has led to a surge in greenhouse gas (GHG) emissions. This necessitates the development of sustainable and eco-friendly technologies and fuels to mitigate global and local environmental impacts. Four primary justifications support transitioning to alternative fuels and technologies: dwindling oil reserves worldwide, adverse environmental effects of vehicle pollution, escalating oil production costs, and the complex challenges of maintaining energy security in international markets. To address these concerns, there is a growing global demand for hydrogen as a sustainable energy source. Utilizing photocatalytic and photoelectrochemical (PEC) water-splitting reactions, particularly with graphene quantum dots-based composites, offers promising avenues for efficient and eco-friendly hydrogen generation. The selection of these systems is based on their unique physical and chemical properties, with graphene providing strong support and efficient electron transport, while components like cadmium sulfide (CdS) and zinc oxide (ZnO) enhance light absorption and charge separation. This integrated approach shows potential for efficient and sustainable hydrogen production, further bolstered by advances in metal-containing photocatalysts and collaborative efforts across energy markets.

Reduction of greenhouse gases emissions by use of hydrogen produced in a refinery by water electrolysis

The study considers production of hydrogen in a local oil refinery by electrolysis of water using exclusively electricity from renewable energy sources. Produced hydrogen is to be used as fuel for cars and buses. However, in case when the demand for hydrogen is less than production, which is expected in the beginning, as currently there are no hydrogen vehicles in Croatia, excess of produced green hydrogen would be used in the refinery production process, partially substituting hydrogen currently being produced from natural gas. The carbon footprint of hydrogen currently being produced in the refinery is calculated taking into account direct and indirect (upstream) CO2 emissions as well as methane fugitive emissions, along with the NOx emissions, converted to the amount of equivalent CO2 emissions. Each kg of green hydrogen used to power city buses instead of diesel would reduce well-to-wheels CO2 emissions by 33.39 kg, and when used to power cars instead of gasoline it would reduce them by 28.99 kg. If green hydrogen is used as a replacement for gray hydrogen produced from natural gas in the refinery, it would reduce the CO2 emissions by 21.74 kg per each kg of hydrogen substituted.

Hydrogen refueling stations powered by hybrid PV/wind renewable energy systems: Techno-socio-economic assessment

Hydrogen is considered as an attractive alternative to fossil fuels in the transportation sector. However, the penetration of Fuel Cell Electric Vehicles (FCEV) is hindered by the lack of hydrogen refueling station infrastructures. In this study, the feasibility of a hybrid PV/wind system for hydrogen refueling station is investigated. Refueling events data is collected in different locations including industrial, residential, highway, and tourist areas. Station Occupancy Fractions (SOF) and Social-to-Solar Fraction (STSF) indicators are developed to assess the level of synchronization between the hydrogen demand and solar potential. Then, a validated computer code is used to optimize the renewable system components for off/on-grid cases based on minimizing the Net Present Cost (NPC) and the Loss of Hydrogen Supply Probability (LHSP). For off grid cases, the results show that STSF attains maximum value in the industrial area where 0.62 fraction of refueling events occur during the sunshine hours and minimum NPC is achieved. It is observed that when STSF attains lower values of 0.52, 0.41 and 0.38 for residential, highway, and tourist areas, NPC increases by 8, 16 and 31%, respectively. This is associated with lower level of coordination between the hydrogen demand and solar potential. The same conclusion can be stated for the on-grid cases. Therefore, for green hydrogen production via solar energy utilization, it is recommended that a tariff should be applied to encourage refueling hydrogen vehicles during the availability of solar radiation while reducing the environmental impact, storage requirements, and eventually the cost of hydrogen production.

Research on optimization layout of hydrogen refueling facility network based on renewable energy hydrogen production mode

Within the transportation sector, hydrogen fuel cell vehicles represent the most efficient method of harnessing hydrogen energy. The establishment of a hydrogen refueling facility network that encompasses the entire cycle of hydrogen energy production, transportation, and application contributes to the effective promotion of hydrogen fuel cell vehicles. However, existing research predominantly focuses on hydrogen production and the conversion of refueling stations, neglecting the economic and stability considerations of the full-cycle use of hydrogen energy. This study proposes a hydrogen refueling facility network planning model that utilizes hydrogen energy throughout its full cycle. Firstly, a hydrogen demand estimation model based on the application scenarios of hydrogen fuel cell vehicles which clarifies the hydrogen requirements in each scenario is proposed. Regional hydrogen energy needs and the costs of building hydrogen refueling stations are then considered, using a set cover model to optimize the overall layout of existing and new refueling stations. Finally, taking into account the supply costs of renewable energy hydrogen production points and regional supply stability, a hydrogen refueling facility network planning model is constructed. The Beijing-Tianjin-Hebei region is selected as a case study, establishing a large-scale hydrogen supply network based on renewable energy hydrogen production, transportation, and usage.

A scenario analysis of the energy transition in Japan’s road transportation sector based on the LEAP model

Japan has lagged behind other developed nations in transitioning its transportation sector to sustainable energy sources. This study employs the Low Emissions Analysis Platform model to examine six scenarios, assessing energy consumption and emissions associated with four major energy sources and pollutants. Our findings reveal an overall decline in total energy consumption across all scenarios. Notably, the Combined scenario where multiple policies are integrated demonstrates the most significant reduction, with a 56% decrease compared to the Business as usual scenario by 2050. The analysis also indicates that the electricity and hydrogen demand for electric vehicles and fuel cell vehicles remains economically viable within future strategic plans. Emissions, including CO2, Carbon Monoxide (CO), Methane (CH4), and Nitrous Oxide (N2O), exhibit substantial reductions, particularly under the Active Promotion Scenario, where a high EV adoption rate is achieved. Moreover, the Combined scenario resulting in a comprehensive and integrated approach, leads to a remarkable 66% decrease in emissions. These results serve as valuable reference points for the Japanese government, aiding in the formulation of future targets for widespread EV adoption and emission standards for pollutants.

Hydrogen in aviation: A simulation of demand, price dynamics, and CO2 emission reduction potentials

Aviation contributes to anthropogenic climate change by emitting both carbon dioxide (CO2) and non-CO2 emissions through the combustion of fossil fuels. One approach to reduce the climate impact of aviation is the use of hydrogen as an alternative fuel. Two distinct technological options are presently under consideration for the implementation of hydrogen in aviation: hydrogen fuel cell architectures and the direct combustion of hydrogen. In this study, a hydrogen demand model is developed that considers anticipated advancements in liquid hydrogen aircraft technologies, forecasted aviation demand, and aircraft startup and retirement cycles. The analysis indicates that global demand for liquid hydrogen in aviation could potentially reach 17 million tons by 2050, leading to a 9% reduction in CO2 emissions from global aviation. Thus, the total potential of hydrogen in aviation extends beyond this, considering that the total market share of hydrogen aircraft on suitable routes in the model is projected to be only 27% in 2050 due to aircraft retirement cycles. Additionally, it is shown, that achieving the potential demand for hydrogen in aviation depends on specific market prices. With anticipated declines in current production costs, hydrogen fuel costs would need to reach about 70 EUR/MWh by 2050 to fulfill full demand in aviation, assuming biofuels provide the cheapest option for decarbonization alongside hydrogen. If e-fuels are the sole option for decarbonization alongside hydrogen, which is the more probable scenario, the entire hydrogen demand potential in aviation would be satisfied according to this study's estimates at significantly higher hydrogen prices, approximately 180 EUR/MWh.

Hydrogen refueling station location optimization under uncertainty

Hydrogen refueling stations (HRS) are essential for the growth of the hydrogen energy and fuel cell vehicle industry, making the strategic decision of their location and scale critical. This study advances the HRS location optimization problem by integrating network planning and hydrogen scheduling optimization, a novel approach that addresses both where and how big HRSs should be, alongside managing supply relations and hydrogen transportation scheduling. Uniquely, it incorporates uncertainty factors in hydrogen demand, using a two-stage multi-period stochastic programming model designed to minimize both construction and operational costs under variable demand scenarios, while also ensuring customer satisfaction. Our main contributions include the development of this comprehensive model and the introduction of an efficient metaheuristic algorithm to solve it, significantly enhancing computational efficiency. The effectiveness of our approach is demonstrated through numerical experiments, and a sensitivity analysis provides crucial insights, underlining the practical implications for HRS infrastructure development. The findings not only offer a methodological advancement in HRS location selection but also deliver tangible results that can guide industry stakeholders in strategic decision-making, marking a significant step forward in the sustainable development of hydrogen energy infrastructure.

Low-Carbon Economic Dispatch of Integrated Energy Systems in Industrial Parks Considering Comprehensive Demand Response and Multi-Hydrogen Supply

To address the increasing hydrogen demand and carbon emissions of industrial parks, this paper proposes an integrated energy system dispatch strategy considering multi-hydrogen supply and comprehensive demand response. This model adopts power-to-gas technology to produce green hydrogen, replacing a portion of gray hydrogen and incorporates a carbon capture system to effectively reduce the overall carbon emissions of the industrial park. Meanwhile, incentive-based and price-based demand response strategies are implemented to optimize the load curve. A scheduling model is established targeting the minimization of procurement, operation, carbon emission, and wind curtailment costs. The case study of a northern industrial park in China demonstrates that the joint supply of green and gray hydrogen reduces carbon emissions by 40.98% and costs by 17.93% compared to solely using gray hydrogen. The proposed approach successfully coordinates the economic and environmental performance of the integrated energy system. This study provides an effective scheduling strategy for industrial parks to accommodate high shares of renewables while meeting hydrogen needs and carbon reduction targets.

Future of hydrogen in the U.S. energy sector: MARKAL modeling results

Hydrogen is an attractive energy carrier which could play a role in decarbonizing process heat, power or transport applications. Though the U.S. already produces about 10 million metric tons of H2 (over 1 quadrillion BTUs or 1 % of the U.S. primary energy consumption), production technologies primarily use fossil fuels that release CO2, and the deployment of other, cleaner H2 production technologies is still in the very early stages in the U.S. This study explores (1) the level of current U.S. hydrogen production and demand, (2) the importance of hydrogen to accelerate a net-zero CO2 future, and (3) the challenges that must be overcome to make hydrogen an important part of the U.S. energy system. The study discusses four scenarios and hydrogen production has been shown to increase in the future, but this growth is not enough to establish a hydrogen economy. In this study, the characteristics of hydrogen technologies and their deployments in the long-term future are investigated using energy system model MARKAL. The effects of strong carbon constraints do not cause higher hydrogen demand but show a decrease in comparison to the business-as-usual scenario. Further, according to our modeling results, hydrogen grows only as a fuel for hard-to-decarbonize heavy-duty vehicles and is less competitive than other decarbonization solutions in the U.S. Without improvements in reducing the cost of electrolysis and increasing the performance of near-zero carbon technologies for hydrogen production, hydrogen will remain a niche player in the U.S. energy system in the long-term future. This article provides the reader with a comprehensive understanding of the role of hydrogen in the U.S. energy system, thereby explaining the long-term future projections.

Policy Implementation Roadmap, Diverse Perspectives, Challenges, Solutions Towards Low-Carbon Hydrogen Economy

Hydrogen is a nearly emission-free energy carrier with many enticing qualities, including wide availability, environmental friendliness, and a high calorific value. There have constantly been a lot of challenges to establish an entire fledge low carbon hydrogen economy in the past century. This study aims to critically analyse the economic, environmental, technological, and policy implementation and division of low-carbon hydrogen to find novel solutions, bridging the gaps and giving a perspective approach to the study. Differentiation of various low carbon hydrogen (LCH) components, including green and blue hydrogen, was also proposed based on the life cycle assessment emissions (LCAE). Current policy perspectives and Promised Pledged Perspectives are considered to project hydrogen demand in 2030. A thorough economic analysis of low-carbon hydrogen system technologies is also conducted from both hydrogen production and storage perspectives by comparing various production and storage systems. Current Policies towards LCH were critically viewed from policymakers, consumers, and R & D perspectives, through which several challenges, gaps, and keynote necessities were also stated.

Optimal design of a renewable hydrogen production system by coordinating multiple PV arrays and multiple electrolyzers

In the design of a renewable hydrogen production system (RHPS), it is of great significance to coordinate the power generation and electrolyzers for efficient and stable hydrogen production. To investigate the coordination and complementary characteristics of multiple PV arrays and multiple electrolyzers in the optimal design of RHPS, a coordinated design approach based on mathematical optimization for the optimal RHPS with multiple PV arrays and multiple electrolyzers was proposed, which features comprehensive considerations of different characteristics of power generation and economy of different types of PV arrays, and the dynamic operating characteristics and economy of various types and capacity of electrolyzers to adapt to fluctuating hydrogen demand. The optimal configuration of the RHPS with minimal total cost can be obtained by combining multiple PV arrays with multiple electrolyzers. Furthermore, the impacts of power generation on the economy of the system are systematically explored, and electrolyzer types are optimally deployed. The influence of different PV array types on the economics of the system is analyzed. An example of the RHPS was employed to demonstrate the feasibility and effectiveness of the proposed method. Results show that for the RHPS, the selection of the type of electrolyzers is mainly affected by the characteristics of power generation. In the system with only PV arrays for power supply, the total cost of the system with proton exchange membrane electrolyzers (PEMEL) is 11.2% lower than that of the system with alkaline electrolyzers (AEL). In the system with simple wind turbines for power generation, the total cost of the system with AEL is lower than that of the system with PEMEL. The selections of type and capacity of the electrolyzers in the system are affected by the minimal power limit of the AEL. The total cost of the system can be effectively reduced by coordinating the power generation and electrolyzers and combining AEL and PEMEL in the system. The selection of PV types is related to the unit cost and the seasonal changes in the capacity factor of different PV arrays, which is also influenced by the hydrogen demand and the curtailment rate. When the variations of power generation align with hydrogen demands, the total cost can be reduced by lowering seasonal energy storage capacity.

Influence of shunt currents in industrial-scale alkaline water electrolyzer plants

The aim of this paper is to analyze through simulation how the energy efficiency of a single electrolysis stack at various loads is affected by shunt currents and to determine the energy-optimal load distribution between lines in a multiline electrolysis system under various magnitudes of shunt current losses. A dynamic energy and mass balance model of an industrial 3MW, 16bar alkaline water electrolyzer (AWE) process was developed using MATLAB. The optimization goal is to determine the power supply for each AWE line so that it can meet any hydrogen demand while minimizing the global specific energy consumption (SEC). The Particle Swarm Optimization (PSO) algorithm is used to minimize the objective function. According to the results of the single stack investigation, shunt current reduction could significantly improve the energy efficiency of partial-load operation. In addition, the optimization study revealed that whenever two or more lines are required to run in order to satisfy the hydrogen demand, the global SEC is minimized when the lines operate at equal loads.

Methane catalytic cracking by solid materials and molten media for hydrogen production: A review

Excessive emission of carbon dioxide is the leading cause of global warming. Hydrogen has the advantages of high calorific value and zero carbon emissions. It is considered an ideal energy to solve the problem of global warming, so the demand for hydrogen is increasing yearly. Due to economic considerations, methane is the main raw material for hydrogen production. Currently, 48% of the world's hydrogen comes from steam methane reforming. However, this process needs to burn some methane for heating, generating carbon dioxide emissions simultaneously. In order to avoid carbon emissions from hydrogen production, there is an urgent need to develop new methods to produce hydrogen from methane. Because the carbon generated from direct methane cracking exists in solid form while not as carbon dioxide, the direct methane cracking process for hydrogen production has become a hot research topic in recent years. In this paper, a comprehensive review of the research related to catalytic methane cracking for hydrogen production is presented, especially the research on catalytic cracking of methane using solid materials or molten metal media as catalytic media is summarized in detail. Next, a brief overview of the mechanism of catalytic methane cracking for hydrogen production and the characteristics of the generated carbon as a by-product are presented. Finally, the catalytic cracking of methane in molten media or solid materials and the research trend were prospected.

An integrated alkali metal thermoelectric converter with sodium hydroxide thermoelectric water splitter and organic Rankine cycle for efficient power and hydrogen production

This study proposes the integration of the NaOH thermochemical water splitting cycle with both an alkali metal thermoelectric converter and an organic Rankine cycle. The objective of the proposed model is to enhance the overall efficiency by utilizing the waste heat generated by the NaOH thermochemical water splitting process and redirecting the heat from the alkali metal thermoelectric converter using bypass when hydrogen demand is low.Performance parameters such as system efficiency, system power, hydrogen production, AMTEC power production, and ORC power production were examined in the study. The results indicated an increase in power and hydrogen production with higher hot-end temperatures, along with an overall reduction in system efficiency for low values of load resistance. The system achieved a maximum efficiency of 53.37%.The system efficiency reached its peak at an AMTEC hot end temperature of 1173 °C, achieving 53.37 % efficiency at an RL value of 1.01 O. When the system operates at its maximum AMTEC power production, the AMTEC modules supply 12.81 kW, while the ORC generates 5.57 kW, and the hydrogen compressor consumes 0.13 kW. The total electrical power generation is 18.38 kW. The findings also indicate that the utilization of the bypass led to a reduction in hydrogen production while increasing the power output of the organic Rankine cycle.

Distributionally robust planning method for expressway hydrogen refueling station powered by a wind-PV system

Hydrogen fuel has received widespread attention as one of the critical solutions to global energy issues. The popularization of hydrogen fuel cell vehicles (HFCV) requires the deep integration of transportation and energy fields. Considering the complementarity of wind and PV power in remote areas, this paper proposes a planning model of an expressway hydrogen refueling station, including a hydrogen production system (HPS) powered by a wind-PV system and several hydrogen refueling systems (HRSs). The interaction and operation constraints of hydrogen production, storage, delivery, and demand are employed to complete hydrogen supply chain integration in the deterministic planning model. The spatiotemporal distribution of refueling demand at each HRS is obtained by Monte Carlo Simulation. Furthermore, we consider the impact of uncertainty related to renewable energy generation and refueling demand on planning and depict them by ambiguity sets based on Kullback Leibler divergence. The planning problem is transformed into a data-driven distributionally robust model and solved by Value-at-Risk and sample average approximation method. Results indicate that 1) The proposed model can simultaneously collaborate with the segments of the hydrogen supply chain. 2) The proposed method balances the planning reliability and economic efficiency and enhances solution robustness.

Multiperiod Modeling and Optimization of Hydrogen-Based Dense Energy Carrier Supply Chains

The production of hydrogen-based dense energy carriers (DECs) has been proposed as a combined solution for the storage and dispatch of power generated through intermittent renewables. Frameworks that model and optimize the production, storage, and dispatch of generated energy are important for data-driven decision making in the energy systems space. The proposed multiperiod framework considers the evolution of technology costs under different levels of promotion through research and targeted policies, using the year 2021 as a baseline. Furthermore, carbon credits are included as proposed by the 45Q tax amendment for the capture, sequestration, and utilization of carbon. The implementation of the mixed-integer linear programming (MILP) framework is illustrated through computational case studies to meet set hydrogen demands. The trade-offs between different technology pathways and contributions to system expenditure are elucidated, and promising configurations and technology niches are identified. It is found that while carbon credits can subsidize carbon capture, utilization, and sequestration (CCUS) pathways, substantial reductions in the cost of novel processes are needed to compete with extant technology pathways. Further, a research and policy push can reduce the levelized cost of hydrogen (LCOH) by upwards of 2 USD/kg.

Optimal Operation Planning to Achieve Both Hydrogen Demand and Multi-DR for Large-scale Hydrogen Plant

Optimal Operation Planning to Achieve Both Hydrogen Demand and Multi-DR for Large-scale Hydrogen Plant