Hydrogen energy,economy and storage: Review and recommendation

The hydrogen economy is a proposed system where hydrogen is produced and used extensively as the primary energy carrier. Successful development of hydrogen economy means innumerable advantages for the environment, energy security, economy, and final users. One major key to wholly develop hydrogen economy is safe, compact, light and cost-efficient hydrogen storage. The conventional gaseous state storage system as pressurized hydrogen gas and liquid state storage system pose safety and cost problems to onboard applications; therefore, they do not satisfy the future goals for a hydrogen economy. Fortunately, solid-state storage systems based on metal hydrides have demonstrated great potentials to store hydrogen in large quantities in a quite secure, compact, and repeatedly reversible manner and thus, becoming increasingly attractive option for hydrogen applications. However, techno-economic feasibility of hydrogen storage systems is yet to be realized as none of the current metal hydrides fulfill all the essential criteria for a practical hydrogen economy, mainly because of low hydrogen storage capacity, sluggish kinetics and unacceptable temperatures of hydrogen absorption/desorption. This article gives a brief review of hydrogen as an ideal sustainable energy carrier for the future economy, its storage as the stumbling block as well as the current position of solid-state hydrogen storage in metal hydrides and makes a recommendation based on the most promising novel discoveries made in the field in recent times which suggests a prospective breakthrough towards a hydrogen economy.     

Current situation and prospect of hydrogen storage technology with new organic liquid

This paper starts with the brief introduction to various methods of hydrogen storage, such as pressurized gaseous hydrogen storage, cryogenic liquefaction hydrogen storage, carbonaceous materials hydrogen storage, metal alloy hydrogen storage, complexation hydride hydrogen storage, glass microspheres hydrogen storage, liquid organic hydrogen storage, and so on. The corresponding principles of hydrogen storage were summarized with the analysis on advantages and disadvantages. Additionally, the characteristics of hydrogen storage with N-ethylcarbazole were profoundly discussed. The conditions and catalysts for hydrogenation and dehydrogenation (N-ethylcarbazole) were also analyzed at some length as well. According to the present situation of hydrogen storage with organic liquids, some ideas were put forward to get higher content and speed of absorbing and releasing hydrogen.     

Review of hydrogen economy in Malaysia and its way forward

Heavy fossil fuels consumption has raised concerns over the energy security and climate change while hydrogen is regarded as the fuel of future to decarbonize global energy use. Hydrogen is commonly used as feedstocks in chemical industries and has a wide range of energy applications such as vehicle fuel, boiler fuel, and energy storage. However, the development of hydrogen energy in Malaysia is sluggish despite the predefined targets in hydrogen roadmap. This paper aims to study the future directions of hydrogen economy in Malaysia considering a variety of hydrogen applications. The potential approaches for hydrogen production, storage, distribution and application in Malaysia have been reviewed and the challenges of hydrogen economy are discussed. A conceptual framework for the accomplishment of hydrogen economy has been proposed where renewable hydrogen could penetrate Malaysia market in three phases. In the first phase, the market should aim to utilize the hydrogen as feedstock for chemical industries. Once the hydrogen production side is matured in the second phase, hydrogen should be used as fuel in internal combustion engines or burners. In the final phase hydrogen should be used as fuel for automobiles (using fuel cell), fuel-cell combined heat and power (CHP) and as energy storage.     

安庆石化用氢优化分析与建议

在对氢气需求量统计和各种加工方案分析的基础上,提出安庆石化用氢方案:新建装置制氢工艺应采用轻烃蒸汽转化法,制氢规模宜定为4.0×104t/a;顶出炼厂气作制氢原料;确定分级用氢原则,全厂设置高、低两个氢气管网,氢气提纯装置PSA-1出口供低压氢气管网,PSA-2和PSA-3出口供高压氢气管网,低压氢气管网压力按1.5～1.7MPa设置,高压氢气管网压力按2.0MPa设置,重整氢气进PSA-2。低压氢气管网满足蜡油加氢、柴油加氢Ⅲ和丁辛醇装置用氢需要,高压氢气管网供氢满足重油加氢装置需要,PSA-2重整尾气送制氢装置作原料。制氢装置原料选择和运转模式为:煤气化装置正常供氢期间,PSA-2重整尾气全部进制氢装置制氢;煤气化装置停工时,停苯乙烯装置,顶出焦化干气经原焦化干气制氢预处理设施加氢处理后,与PSA-2重整尾气共同作为制氢原料,以保证全厂氢气供应;制氢装置原料紧缺时,使用石脑油(或重整拔头油)作为补充原料。     

The economics and the environmental benignity of different colors of hydrogen

Due to the increasing greenhouse gas emissions, as well as due to the rapidly increasing use of renewable energy sources in the electricity generation over the last years, interest in hydrogen is rising again. Hydrogen can be used as a storage for renewable energy balancing the whole energy systems, and contributing to the decarbonization of the energy system, especially of the industry and the transport sector.The major objective of this paper is to discuss various ways of hydrogen production depending on the primary energy sources used. Moreover, the economic and environmental performance of three major hydrogen colors, as well as major barriers for faster deployment in fuel cell vehicles, are analyzed.The major conclusion is that the full environmental benefits of hydrogen use are highly dependent on the hydrogen production methods and primary sources used. Only green hydrogen with electricity from wind, PV and hydro has truly low emissions. All other sources like blue hydrogen with CCUS or electrolysis using the electricity grid have substantially higher emissions, coming close to grey hydrogen production. Another conclusion is that it is important to introduce an international market for hydrogen to lower costs and to produce hydrogen where conditions are best.Finally, the major open question remaining is whether – including all external costs of all energy carriers, hydrogen of any color may become economically competitive in any sector of the energy system. The future success of hydrogen is very dependent on technological development and resulting cost reductions, as well as on future priorities and the corresponding policy framework. The policy framework should support the shift from grey to green hydrogen.     

A green hydrogen credit framework for international green hydrogen trading towards a carbon neutral future

Hydrogen as a low-carbon clean energy source is experiencing a global resurgence and has been recognized as an alternative energy carrier that can help bring the world to a carbon neutral future. However, getting to scale is one of the main challenges limiting the growth of the hydrogen economy. In particular, the high cost of transporting green hydrogen is bottlenecking the international trading and wider adoption of hydrogen for global carbon natural objectives. In order to explore incentives for the global hydrogen economy and develop new pathways towards the carbon neutral future, the concept of hydrogen credit is proposed by this research and a framework of trading hydrogen credits similar to carbon credits in the international market is established. This research aims to contribute to the overall uptake of green hydrogen financially rather than relying on the physical production, transportation, and storage of hydrogen. Case studies are presented to demonstrate the feasibility and efficiency of the proposed hydrogen credit framework, as well as the great potential of a global hydrogen credit market.     

Effect of nitrogen-addition on the absorption and diffusivity of hydrogen in a stable austenitic stainless steel

An austenitic stainless steel (SUS316L) was prepared with and without addition of solute nitrogen. The effect of cold-working and nitrogen addition on hydrogen solubility and hydrogen diffusion were investigated. High-pressure hydrogen gas and thermal desorption techniques were used. Increasing dislocation densities were related to a higher hydrogen content and higher nitrogen content related to a lower hydrogen content. Both dislocations and nitrogen had a negligible effect on hydrogen diffusion. The different hydrogen contents in the dislocations and the metal lattice, as well as trapping and diffusion activation energies explained the lack of effect of dislocations on hydrogen solubility.     

Investigation of concentration measurement for hydrogen leakage with a new calibration visual approach

Hydrogen leakage concentration rapid measurement is the key issue for hydrogen application as hydrogen leakage is easy to cause hydrogen safety issues such as hydrogen explosions. Non-invasive visual measurement method such as the schlieren measurement technique is the prospective solution. However, the specific relationship between the hydrogen leakage concentration and schlieren image gray remains unclear, which leads that the schlieren technique procedure is developed for visualization and acquiring qualitative information only. This paper aims to decouple the hydrogen leakage concentration from the complicated schlieren image information, and find the mapping relationship between the hydrogen leakage concentration and schlieren image gray, hence realizing a quantitative hydrogen leakage concentration analysis. Therefore, a hydrogen leakage visualization experimental bench is established to simulate and measure hydrogen leakage by a series of experiments under different leakage concentrations. The mapping relationship between the hydrogen leakage concentration and schlieren image gray is obtained by the experiments using the schlieren technique. Then, a new calibration schlieren technique with the function of visually measuring hydrogen leakage concentration is developed and verified under 80% hydrogen leakage concentration. Results of the trials demonstrated the ability of the proposed technique successfully measure concentration distributions with satisfactory accuracy.     

Hydrogen production for energy: An overview

Power to hydrogen is a promising solution for storing variable Renewable Energy (RE) to achieve a 100% renewable and sustainable hydrogen economy. The hydrogen-based energy system (energy to hydrogen to energy) comprises four main stages; production, storage, safety and utilisation. The hydrogen-based energy system is presented as four corners (stages) of a square shaped integrated whole to demonstrate the interconnection and interdependency of these main stages. The hydrogen production pathway and specific technology selection are dependent on the type of energy and feedstock available as well as the end-use purity required. Hence, purification technologies are included in the production pathways for system integration, energy storage, utilisation or RE export. Hydrogen production pathways and associated technologies are reviewed in this paper for their interconnection and interdependence on the other corners of the hydrogen square.Despite hydrogen being zero-carbon-emission energy at the end-use point, it depends on the cleanness of the production pathway and the energy used to produce it. Thus, the guarantee of hydrogen origin is essential to consider hydrogen as clean energy. An innovative model is introduced as a hydrogen cleanness index coding for further investigation and development.     

Design concepts of hydrogen supply chain to bring consumers offshore green hydrogen

This study presents design concepts for hydrogen supply chains as a way to investigate how to transport green hydrogen from offshore sites to onshore sites where it would be available to consumers. The six concepts suggested are based on compressed hydrogen, a pipeline, liquefied hydrogen, liquid organic hydrogen carriers (LOHC), ammonia, and a subsea cable. Most of the concepts transported the hydrogen from production to consumption sites, but in the case of the subsea cable transferred electricity from the offshore wind farm. All the design concept were created to satisfy the same specific case study. For this case study, the East Sea was selected as the hydrogen production site, Busan port was chosen as the hydrogen consumption site. The six concepts were applied to the suggested case study before being compared from the viewpoint of each system's complexity. The results show that the pipeline- and subsea cable-based hydrogen supply chains are relatively simple relative to the other concepts, the LOHC- and ammonia-based hydrogen supply chains are inherently more complex because they require de-hydrogenation and cracking processes to extract hydrogen from the LOHC and ammonia. On the other hand, ammonia and liquefied hydrogen have advantages in terms of ship transportation because they both provide high volumetric densities. In the case of ammonia, the infrastructure required would be significantly reduced if it could be directly used as a fuel without the cracking and purification processes. This study proposes and compares various hydrogen supply chain concepts with the goal that the results will prove helpful to those attempting to create an offshore hydrogen supply chain by providing fundamental data to decision-makers in the early design stages.     

Constructing a new business model for fermentative hydrogen production from wastewater treatment

The development of hydrogen energy as a sustainable energy resource is essential for mitigating climate change. The primary challenge to the commercialization of hydrogen energy, relative to that of petrochemical fuels, is cost. Therefore, an innovative business model that converts the costs of procuring biomass into revenue via the production of hydrogen was developed. Profitable hydrogen production can typically be realized by lowering costs through continuous technological development and increasing scale. Feedstock procurement costs, however, limit the cost/benefit reduction flexibility. This study employs biowaste material as feedstock for biological fermentative hydrogen production. This model extends the hydrogen production value chain to include the income from biomass hydrogen production as well as the revenue from processing biowaste and reduced fuel source costs. This study investigates the costs involved in the commercialization of the hydrogen fermentation process, develops an innovative business model, and presents a case study to describe this model.     

The possibilities of cooperation between a hydrogen generator and a wind farm

In this paper, a hydrogen generator and a wind farm were taken as the research objects. The H₂ generator consisted characteristics of laboratory-tested electrolyzers were determined as a function of the hydrogen mass flow. Determining the auxiliary power index of the device allowed the efficiency of the hydrogen generator to be determined as a function of hydrogen mass flow as well as the hydrogen generator relative power. The dynamic characteristics of a generator were also presented. The possibility of a given wind farm cooperating with hydrogen generators that are characterized by different powers and various efficiencies was simulated. Algorithm enables determination of hydrogen generators efficiency for devices with various performance in nominal operation point is shown. It has been shown that proper selection of the power of the hydrogen generator in relation to the power of the wind farm can ensure a high efficiency for the device.     

Large-scale long-distance land-based hydrogen transportation systems: A comparative techno-economic and greenhouse gas emission assessment

Interest in hydrogen as an energy carrier is growing as countries look to reduce greenhouse gas (GHG) emissions in hard-to-abate sectors. Previous works have focused on hydrogen production, well-to-wheel analysis of fuel cell vehicles, and vehicle refuelling costs and emissions. These studies use high-level estimates for the hydrogen transportation systems that lack sufficient granularity for techno-economic and GHG emissions analysis. In this work, we assess and compare the unit costs and emission footprints (direct and indirect) of 32 systems for hydrogen transportation. Process-based models were used to examine the transportation of pure hydrogen (hydrogen pipeline and truck transport of gaseous and liquified hydrogen), hydrogen-natural gas blends (pipeline), ammonia (pipeline), and liquid organic hydrogen carriers (pipeline and rail). We used sensitivity and uncertainty analyses to determine the parameters impacting the cost and emission estimates. At 1000 km, the pure hydrogen pipelines have a levelized cost of $0.66/kg H₂ and a GHG footprint of 595 gCO₂eq/kg H₂. At 1000 km, ammonia, liquid organic hydrogen carrier, and truck transport scenarios are more than twice as expensive as pure hydrogen pipeline and hythane, and more than 1.5 times as expensive at 3000 km. The GHG emission footprints of pure hydrogen pipeline transport and ammonia transport are comparable, whereas all other transport systems are more than twice as high. These results may be informative for government agencies developing policies around clean hydrogen internationally.     

Suppression of hydrogen embrittlement of gear steel 20CrMnTiH with pulsed electric current

When steel is smelted and used, hydrogen penetration will lead to hydrogen embrittlement, reduce the service life of materials, and even cause safety accidents. Various defects in steel can trap hydrogen atoms as hydrogen traps, resulting in high hydrogen content in materials. In this study, 20CrMnTiH gear steel billets with high hydrogen content were treated by electric pulse. It was found that the elongation and tensile strength of the samples treated by electric pulse were improved, which is attributed to the reduction of diffusible hydrogen content in the sample. Meanwhile, as an irreversible hydrogen trap, FeO's reduction makes it easier for hydrogen atoms to diffuse and escape under the electric field. Pulse current not only promotes the diffusion of hydrogen atoms, but also eliminates some hydrogen traps. The hydrogen control method under pulse current provides another alternative for solid state dehydrogenation and repair of hydrogen embrittlement fracture.     

Refuelling scenarios of a light urban fuel cell vehicle with metal hydride hydrogen storage. Comparison with compressed hydrogen storage counterpart

The high price of hydrogen fuel in the fuel cell vehicle refuelling market is highly dependent on the one hand from the production costs of hydrogen and on the other from the capital cost of a hydrogen refuelling station's components to support a safe and adequate refuelling process of contemporary fuel cell vehicles. The hydrogen storage technology dominated in the vehicle sector is currently based on high-pressure compressed hydrogen tanks to extend as much as possible the driving range of the vehicles. However, this technology mandates the use of large hydrogen compression and cooling systems as part of the refuelling infrastructure that consequently increase the final cost of the fuel. This study investigated the prospects of lowering the refuelling cost of small urban hydrogen vehicles through the utilisation of metal hydride hydrogen storage. The results showed that for low compression hydrogen storage, metal hydride storage is in favour in terms of the dispensed hydrogen fuel price, while its weight is highly comparable to the one of a compressed hydrogen tank. The final refuelling cost from the consumer's perspective however was found to be higher than the compressed gas due to the increased hydrogen quantity required to be stored in fully empty metal hydride tanks to meet the same demand.     

Total Site Hydrogen Integration with fresh hydrogen of multiple quality and waste hydrogen recovery in refineries

This paper proposes a novel method combining Pinch Methodology and waste hydrogen recovery, aiming to minimise fresh hydrogen consumption and waste hydrogen discharge. The method of multiple-level resource Pinch Analysis is extended to the level of Total Site Hydrogen Integration by considering fresh hydrogen sources with various quality. Waste hydrogen after Total Site Integration is further regenerated. The technical feasibility and economy of the various purification approaches are considered, demonstrated with a case study of a refinery hydrogen network in a petrochemical industrial park. The results showed that fresh hydrogen usage and waste hydrogen discharge could be reduced by 21.3% and 67.6%. The hydrogen recovery ratio is 95.2%. It has significant economic benefits and a short payback period for Total Site Hydrogen Integration with waste hydrogen purification. The proposed method facilitates the reuse of waste hydrogen before the purification process that incurs an additional environmental footprint. In line with the Circular Economy principles, hydrogen resource is retained in the system as long as possible before discharge.     

Simulation of hydrogen leak and explosion for the safety design of hydrogen fueling station in Korea

Hydrogen has been used as chemicals and fuels in industries for last decades. Recently, it has become attractive as one of promising green energy candidates in the era of facing with two critical energy issues such as accelerating deterioration of global environment (e.g. carbon dioxide emissions) as well as concerns on the depletion of limited fossil sources. A number of hydrogen fueling stations are under construction to fuel hydrogen-driven vehicles. It would be indispensable to ensure the safety of hydrogen station equipment and operating procedure in order to prevent any leak and explosions of hydrogen: safe design of facilities at hydrogen fueling stations e.g. pressurized hydrogen leak from storage tanks. Several researches have centered on the behaviors of hydrogen ejecting out of a set of holes of pressurized storage tanks or pipes. This work focuses on the 3D simulation of hydrogen leak scenario cases at a hydrogen fueling station, given conditions of a set of pressures, 100, 200, 300, 400 bar and a set of hydrogen ejecting hole sizes, 0.5, 0.7, 1.0 mm, using a commercial computational fluid dynamics (CFD) tool, FLACS. The simulation is based on real 3D geometrical configuration of a hydrogen fueling station that is being commercially operated in Korea. The simulation results are validated with hydrogen jet experimental data to examine the diffusion behavior of leak hydrogen jet stream. Finally, a set of marginal safe configurations of fueling facility system are presented, together with an analysis of distribution characteristics of blast pressure, directionality of explosion. This work can contribute to marginal hydrogen safety design for hydrogen fueling stations and a foundation on establishing a safety distance standard required to protect from hydrogen explosion in Korea being in the absence of such an official requirement.     

燃料电池车车载储氢系统的技术发展与应用现状

综述了燃料电池车车载储氢系统技术，包括高压氢、液氢、金属氢化物、低温吸附、纳米碳管高压吸附以及液体有机氢化物等的研究进展及其车载应用现状。参照燃料电池车对车载储氢系统单位重量储氢密度与体积储氢密度的目标要求，对目前已应用和处于研发阶段的一些储氢技术的性能指标和存在问题进行了分析讨论。同时对目前该领域的若干新的研究报道，如超高压轻质复合容器、混合储氢容器、b.c．c．储氢合金、超级活性碳和“浆液”双相储氢等，也作了简要介绍。     

Helio-hydro and helio-thermal production of hydrogen

Fossil fuels account for about 80% of the world annual energy demands. Renewables contribute 14% and nuclear some 6%. These numbers will soon change as the world's population grows, energy demand rises, cheap oil and gas deplete, global warming effects continue rising and city pollution worsens the living conditions. The development of energy sources and devices will emerge more aggressively to address the world's energy and environmental situation. A concept of using hydrogen as an energy carrier or storage as a fuel, a replacement of burning fluid fossil fuels is presented. Sources of energy from which hydrogen can be produced in a massive quantity and at a low cost are briefly surveyed. A short account of devices to be employed for hydrogen production is given. Primarily the sun, sea, runoff waters, winds and fissionable materials are to be utilized. The discussion on the inexhaustibility of naturally occurring sources utilized and/or harnessed in this process will lead to the low cost for hydrogen production. Some hydrogen rich products including hydrogen sulfide and methane accompany the oil, gas and brine, when they are pumped out of the ground. While methane is used sometimes as fuel; the hydrogen sulfide is disposed off invariably. In principle, hydrogen can be extracted from these waste products. We discuss here to produce hydrogen in economically feasible manner. The use of brine as a means of usable solar energy in the form of heat and electricity was discussed earlier. Here, we aim at discussing the production of hydrogen from the brine and hydrogen sulfide gas. The brine is proposed to be utilized for two purposes: one for salt gradient solar pond to produce usable heat and electricity, and the other as an electrolyte to produce hydrogen out of itself. The hydrogen from hydrogen sulfide can chemically be extracted.     

Hydrogen storage and demand to increase wind power onto electricity distribution networks

An optimal power flow (OPF) methodology is developed to investigate the provision of a demand hydrogen as a means to maximise wind power generation in relation to a constrained electricity network. The use of excess wind energy to generate hydrogen for use as a transport fuel is investigated. Hydrogen demand is included in the objective function of the OPF, and a techno-economic analysis is presented. We conclude that using this method to generate hydrogen increases the utilisation of wind energy and allows for a hydrogen demand to be met at or near to the point of use. The OPF algorithm that has been developed optimises the amount of wind energy utilised, as well as minimising the amount of hydrogen demand not met. The cost at which the hydrogen is produced was found to be dependent on the operating methodology, component capital investment costs, level of hydrogen demand, and storage constraint.