Ammonia as a hydrogen energy carrier

The gravimetric H₂ densities and the heats of combustion of tanks stored ammonia (ammonia storage tanks) were similar to those of the liquid H₂ tanks at the weight of 20–30ton, although the gravimetric H₂ density of liquid H₂ is 100 wt%. The volumetric H₂ densities and the heats of combustion of ammonia storage tanks were about 2 times higher than those of liquid H₂ tanks at 1–4 × 10⁴ m³. Gray ammonia is synthesized from hydrogen through process known as steam methane reforming, nitrogen separated from air and Haber-Bosch process. Blue ammonia is the same as gray ammonia, but with CO₂ emissions captured and stored. Green ammonia is produced by reacting hydrogen produced by electrolysis of water and nitrogen separated from air with Haber-Bosch process using renewable energies. The energy efficiencies of gray, blue and green ammonia were better than those of liquid hydrogen and methylcyclohexane (MCH) with high H₂ density and similar to the efficiency of H₂ gas. The energy efficiencies of ammonia decreased in the order, gray ammonia > blue ammonia > green ammonia. The production costs of green hydrogen energy carried increased in the order, ammonia < liquid H₂<MCH. The amounts of energy consumption by N₂ production and Haber-Bosch process were below 10% compared with the value of H₂ production from water electrolysis.     

Transition to renewable energy systems with hydrogen as an energy carrier

Unlike the present energy system based on fossil fuels, an energy system based on renewable energy sources with hydrogen and electricity as energy carriers would be sustainable. However, the renewable energy sources in general have less emergy than the fossil fuels, and their carriers have lower net emergy. Because of that they would not be able to support continuous economic growth, and would eventually result in some kind of a steady-state economy. An early transition to renewable energy sources may prove to be beneficial in the long term, i.e., it may result in a steady state at a higher level than in the case of a transition that starts later. Once the economy starts declining it will not be able to afford transition to a more expensive energy system, and transition would only accelerate the decline. Similarly, if a transition is too fast it may weaken and drain economy too much and may result in a lower steady state. If a transition is too slow, global economy may be weakened by the problems related to utilization of fossil fuels (such as global warming and its consequences) before transition is completed and the result again would be a lower steady state. Therefore, there must be an optimal transition rate; however, its determination would require very complex models and constant monitoring and adjustment of parameters.     

Perspective on hydrogen energy carrier and its automotive applications

The paper outlines the concept of energy carrier with a particular reference to hydrogen, in view of a more disseminated employment in the field of automotive applications. In particular hydrogen production is analyzed considering the actual state of the art and recent technologies applied in production from the primary sources (fossil fuels, renewable energies, and water electrolysis). Then the problem of hydrogen storage is considered both from technical and economical point of views. In particular, differences between physical and chemical storage are here considered with a particular glance to the most innovative technologies including carbon nanostructures. A review on the main problems in storage and transportation is then shown with a particular attention given to infrastructures costs that perhaps will address particular choices for the technologies of the next future. Automotive applications are called out, accounting the main current technologies and notes on fueling station for hydrogen fed vehicle. The discussion of hydrogen safety in automotive put in evidence the needs for sophisticated sensors, but a comparison with the safety of gasoline and fire risks, evidences that some common incertitudes on hydrogen usage should be overcome. Some other safety issues are introduced in the section of hydrogen transportation. An overview of costs related hydrogen production, storage and transportation is finally given. This aspect is of a capital importance for the future dissemination of the hydrogen energy carrier.     

Economics of secondary renewable energy sources with hydrogen generation

Against the background of diminishing traditional energy sources, increasing negative impact on the environment, also due to some energy sectors, as well as the growing threat of extreme increase in the waste on a global scale, SRES have a serious potential to play the role of one of the key methods to achieve a sustainable balance, without any harm to the economic development. In practice, if assumed that the total population of the Earth is 7 billion people, at least 5 million tons of waste is generated on a daily basis (not counting the industrial ones). Of them, circa 2 million tons are non-recyclable, but these could be transformed into energy. Modern technologies offer up to 50% conversion of the source materials into useable free energy––i.e. there is a potential for the generation of approximately 1 million МW/h per day, or at least 300–350 TW/h per annum. This amounts to the whole electricity consumption of 5–10 small developed countries like Bulgaria, Slovenia, etc. The improvement and implementation of the SRES technologies will require significant expenses for scientific research and development. A part of these expenses can be covered by the general provision of incentives for alternative energy sources, another part should be provided by external sources, including funding from the central budgets, grants, as part of public-private partnerships, etc. The offered article examines the economics of the SRES, and all related factors, including their role and place in the energy sector, significance for the protection of the environment and for the achievement of the sustainable development goals (SDGs), adopted within the UN. An attempt is made to develop the existing and to offer new criteria for a more accurate and universal definition of the SRES. The objective of the article is not to claim to be an universal and exhaustive study of all aspects, related to the nature and use of the SRES, but it is rather an attempt to systematize and carry out a comparative analysis of the main problems, related to the SRES, as well as to draw the attention and stir a wider discussion on a topic, which––according to the authors––undeservedly fails to be sufficiently incorporated into the studies and research, related to the alternative energy development. Special attention is drawn to the opportunities provided by waste-to-hydrogen solutions alongside with other waste-to-energy approaches. Authors are also introducing for the first time the notion of “double-green-solution” as a specific feature of the waste-to-energy solutions. The article may be of interest to economists, investors and practitioners.     

Economic impacts of hydrogen as an energy carrier in European countries

The two objectives of this paper are to identify possible sectoral shifts and employment effects due to the application of hydrogen in the energy system for selected European countries till 2030. This is based on assumptions about the market penetration of hydrogen as an energy carrier, an analysis of the competitiveness of EU countries in this technology field and input–output model calculations.     

Thermophysical properties of the energy carrier methanol under the influence of dissolved hydrogen

The present experimental work focuses on revealing the influence of hydrogen (H₂) on the interfacial tension, viscosity, density, and thermal diffusivity of the liquid phase of the energy carrier methanol under saturation conditions, which has been only fragmentarily investigated so far, and on providing corresponding H₂ solubility and Fick diffusion coefficient data. For this, conventional methods, dynamic light scattering from the liquid bulk and from the liquid-gas interface as well as Raman spectroscopy were used at temperatures up to 393 K and pressures up to 8 MPa. The results show that with H₂ under saturation conditions, the viscosity and density of liquid methanol are nearly pressure-independent, whereas the interfacial tension is reduced by about 6% at 8 MPa. The latter effect is temperature-independent despite the increasing H₂ concentration with increasing temperature, which may be associated with a counteracting influence of temperature on a presumed surface enrichment of H₂.     

非化石能源制氢技术综述

在现今的经济社会和未来的低碳经济中H2将发挥重要作用.非化石能源制氢是化石能源短缺和温室气体排放等约束下的可持续制氢路径.综述了可再生电力电解制氢、核能制氢、太阳能制氢和生物质能制氢等四种非化石能源制氢技术的工作原理、流程设备和技术特点,最后对我国未来非化石能源制氢的路线选择进行了评论.     

Multi carrier energy systems and energy hubs: Comprehensive review,survey and recommendations

In this paper, the multi carrier energy (MCE) systems are reviewed from different point of views including mathematical models, integrated components and technologies, uncertainty management, planning objectives, environmental pollution, resilience, and robustness. The basic of MCE systems is formed by combination of cooling, heating and power (CCHP). The natural gas and electricity are the main inputs to MCE systems and the cooling, heating, and electricity are the common outputs. The regular energy converters in the MCE systems are combined heat and power (CHP), gas boiler, absorption-electrical chillers, power to gas (P2G) and fuel-cell. The generic energy storages are electrical, heating, cooling, hydrogen, carbon dioxide (CO₂) and hydro systems.     

Explaining hydrogen energy technology acceptance: A critical review

The use of hydrogen energy and the associated technologies is expected to increase in the coming years. The success of hydrogen energy technology (HET) is, however, dependent on public acceptance of the technology. Developing this new industry in a socially responsible way will require an understanding of the psychology factors that may facilitate or impede its public acceptance. This paper reviews 27 quantitative studies that have explored the relationship between psychological factors and HET acceptance. The findings from the review suggest that the perceived effects of the technology (i.e., the perceived benefits, costs and risks), and the associated emotions, are strong drivers of HET acceptance. This paper does, though, highlight some limitations with past research that make it difficult to make strong conclusions about the factors that influence HET acceptance. The review also reveals that few studies have investigated acceptance of different types of HET beyond a couple of applications. The paper ends with a discussion about directions for future research and highlights some practical implications for messaging and policy.     

Assessment of the potential future market in Sweden for hydrogen as an energy carrier

This study was performed as a Swedish contribution to the program of the International Energy Agency (IEA) concerning research and development on the production of hydrogen from water. A common framework of the joint IEA-group was applied throughout the work. A survey of the study is given in the report.The study projects future hydrogen markets during the period 1980–2025 in the investigated sectors, estimates the probable range of hydrogen production costs for various manufacturing methods, and evaluates the expected market shares in competition with alternative energy carriers.A general scenario for the economic and industrial development in Sweden during the period was evaluated. The average increase in gross national product was assumed to become 1.6% per year and equal over all society sectors except for residential housing construction and the total energy supply, which are assumed to increase with 0.81 and 0.90% per year, respectively.Three different energy scenarios based on the economic scenario were developed with the following characteristics: an alternative based on nuclear energy; an alternative based on renewable indigenous energy sources; and an alternative based on the present energy picture with free access to imported natural or synthetic fuels. Within each of the three scenarios, an analysis was made of the competitiveness of hydrogen on both the demand and the supply sides of the agreed sectors: chemical industry; steel industry; peak power production; residential and commercial heating; and transportation. Costs were calculated for the production, storage and transmission of hydrogen according to technically feasible methods and were compared to those of alternative energy carriers. Health, environmental and societal implications were also taken into consideration. The results have been used to estimate the market penetration of hydrogen in the regarded sectors.     

Integration of hydrogenation and dehydrogenation based on dibenzyltoluene as liquid organic hydrogen energy carrier

The heat transfer oil dibenzyltoluene (DBT) offered an intriguing approach for the scattered storage of renewable excess energy as a novel Liquid Organic Hydrogen Carrier (LOHC). The integration of hydrogenation and dehydrogenation in H0-DBT/H18-DBT pairs demonstrated that the feasibility of hydrogenation and dehydrogenation reaction conducted in one reactor with the same catalyst, which would be proposed to simplify the hydrogen storage process. The optimal reaction temperature based on the inhibition of ring opening and cracking was investigated combined with the ¹H NMR analysis. Meanwhile, the ideal catalyst 3 wt% Pt/Al₂O₃ for high hydrogen storage efficiency was screened out. Cycle tests of hydrogenation and dehydrogenation integration reaction had shown that the hydrogen storage efficiency was 84.6% after five cycle tests. The integration of hydrogenation and dehydrogenation reaction based on DBT exhibited the ideal thermal stability, which demonstrated its potential as a reversible H₂ carrier.     

A systemic review of hydrogen supply chain in energy transition

Targeting the net-zero emission (NZE) by 2050, the hydrogen industry is drastically developing in recent years. However, the technologies of hydrogen upstream production, midstream transportation and storage, and downstream utilization are facing obstacles. In this paper, the development of hydrogen industry from the production, transportation and storage, and sustainable economic development perspectives were reviewed. The current challenges and future outlooks were summarized consequently. In the upstream, blue hydrogen is dominating the current hydrogen supply, and an implementation of carbon capture and sequestration (CCS) can raise its cost by 30%. To achieve an economic feasibility, green hydrogen needs to reduce its cost by 75% to approximately 2 $/kg at the large scale. The research progress in the midterm sector is still in a preliminary stage, where experimental and theoretical investigations need to be conducted in addressing the impact of embrittlement, contamination, and flammability so that they could provide a solid support for material selection and large-scale feasibility studies. In the downstream utilization, blue hydrogen will be used in producing value-added chemicals in the short-term. Over the long-term, green hydrogen will dominate the market owing to its high energy intensity and zero carbon intensity which provides a promising option for energy storage. Technologies in the hydrogen industry require a comprehensive understanding of their economic and environmental benefits over the whole life cycle in supporting operators and policymakers.     

An integrated impact assessment of hydrogen as a future energy carrier in Nigeria's transportation,energy and power sectors

A hydrogen economy, the long-term goal of visionary nations, has the potential to provide energy security, along with environmental and economic benefits. The concept of a hydrogen energy economy was first conceived at The Hydrogen Economy Miami Energy (THEME) Conference, held in March 1974 in Miami, Florida, where the International Association for Hydrogen Energy was established. Forty years later, advances in hydrogen technologies have led the world's most developed countries to invest extensively in preparation for a future hydrogen-based economy. However, the transition from a conventional petroleum-based energy economy to a hydrogen economy involves many uncertainties regarding concerns such as the development of efficient fuel cell technologies, problems in hydrogen production and distribution infrastructure, hydrogen safety issues, and the response of carbon-based fuel markets. This paper presents an assessment of the economic impact of hydrogen energy on the transportation and energy use sectors of Nigeria, along with implications for Greenhouse Gas (GHG) emissions. The analysis uses the Long range Energy Alternatives Planning (LEAP) technology database and model to simultaneously consider the impact of alternative and conventional technologies and fuels on these sectors.     

Natural liquid organic hydrogen carrier with low dehydrogenation energy: A first principles study

Liquid organic hydrogen carriers (LOHCs) represent a promising approach for hydrogen storage due to their favorable properties including stability and compatibility with the existing infrastructure. However, fossil-based LOHC molecules are not green or sustainable. Here we examined the possibility of using norbelladine and trisphaeridine, two representative structures of Amaryllidaceae alkaloids, as the LOHCs from the sustainable and renewable sources of natural products. Our first principles thermodynamics calculations reveal low reversibility for the reaction of norbelladine to/from perhydro-norbelladine because of the existence of stabler isomers of perhydro-norbelladine. On the other hand, trisphaeridine is found promising due to its high hydrogen storage capacity (~5.9 wt%) and favorable energetics. Dehydrogenation of perhydro-trisphaeridine has an average standard enthalpy change of ~54 kJ/mol-H₂, similar to that of perhydro-N-ethylcarbazole, a typical LOHC known for its low dehydrogenation enthalpy. This work is a first exploration of Amaryllidaceae alkaloids for hydrogen storage and the results demonstrate, more generally, the potential of bio-based molecules as a new sustainable resource for future large-scale hydrogen storage.     

Utilization of green ammonia as a hydrogen energy carrier for decarbonization in spark ignition engines

Rising concerns about the dependence of modern energy systems on fossil fuels have raised the requirement for green alternate fuels to pave the roadmap for a sustainable energy future with a carbon-free economy. Massive expectations of hydrogen as an enabler for decarbonization of the energy sector are limited by the lack of required infrastructure, whose implementation is affected by the issues related to the storage and distribution of hydrogen energy. Ammonia is an effective hydrogen energy carrier with a well-established and mature infrastructure for long-distance transportation and distribution. The possibility for green ammonia production from renewable energy sources has made it a suitable green alternate fuel for the decarbonization of the automotive and power generation sectors. In this work, engine characteristics for ammonia combustion in spark ignition engines have been reported with a detailed note on engines fuelled with pure ammonia as well as blends of ammonia with gasoline, hydrogen, and methane. Higher auto-ignition temperature, low flammability, and lower flame speed of ammonia have a detrimental effect on engine characteristics, and it could be addressed either by incorporating engine modifications or by enhancing the fuel quality. Literature shows that the increase in compression ratio from 9.4:1 to 11.5:1 improved the maximum power by 59% and the addition of 10% hydrogen in supercharged conditions improved the indicated efficiency by 37%. Challenges and strategies for the utilization of ammonia as combustible fuel in engines are discussed by considering the need for technical advancements as well as social acceptance. Energy efficiency for green ammonia production is also discussed with a due note on techniques for direct synthesis of ammonia from air and water.     

The impact of large-scale energy storage requirements on the choice between electricity and hydrogen as the major energy carrier in a non-fossil renewables-only scenario

The need for large-scale storage, when the energy source is subject to periods of low-energy generation, as it would be in a direct solar or wind energy system, could be the factor which justifies the choice of hydrogen, rather than electricity, as the principal energy carrier. It could also be the ‘Achilles heel’ of a solar-based sustainable energy system, tipping the choice to a nuclear breeder system.     

The Black Sea and hydrogen energy

The Black Sea is a unique sea. Its water contains hydrogen sulphide. The author suggests the idea for using it for production of hydrogen and sulphur in the electrolytic stage of the Solar-Wind-Hydrogen Energy Systems (SWHES).     

The hydrogen/hydride energy concept

With technology at its present stage, hydrogen is a very convenient secondary energy source (fuel, propellant) at the end of the oil era, as hydrogen (given the necessary primary energy, e.g. coal, nuclear energy for hydrogen production) is available in water in practically inexhaustible quantities and its distribution in the form of pure hydrogen or part-hydrogen gas mixtures (town gas) presents no fundamental technical problems.

Hydrogen technology brought about as a result of the dwindling reserves of mineral oil offers particularly favourable advantages in that hydrogen, like oil, can be applied universally as an energy source not only for domestic and industrial use, but also for motor vehicles.

The storage of hydrogen for mobile (vehicle) and stationary (domestic) applications is best undertaken by the aid of suitable metal hydrides. Hydride research at Daimler-Benz not only produced the world's first combination hydride vehicles, it also led to the discovery and further development of a series of possible applications for hydrides.

This work shows, that hydrogen out of metal hydrides is not only environmentally acceptable and offers independence of petroleum supplies, metal hydrides also permit optimum primary energy utilization by means of waste heat recovery from all combustion processes, heating and cooling of houses and cars without consuming primary energy and a reduction in energy consumption during the production of inexpensive D₂O for natural uranium reactors.     

氢能知识系列讲座(12)前景日益重要的氢能

一使用氢能是CO_2减排的最终方案2007年11月27日,联合国开发计划署(UNDP)在其发布的《2007～2008人类发展报告》中,以极其严厉的措辞警告气候变化会带来双重灾难:首先是贫困人口的发展倒退,接着是全人类长期遭受威