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1.
Hydrogen sulfide (H2S) methane (CH4) reformation (H2SMR) (2H2S + CH4 = CS2 + 4H2) is a potentially viable process for the removal of H2S from sour natural gas resources or other methane containing gases. Unlike steam methane reformation that generates carbon dioxide as a by-product, H2SMR produces carbon disulfide (CS2), a liquid under ambient temperature and pressure—a commodity chemical that is also a feedstock for the synthesis of sulfuric acid. Pinch point analyses for H2SMR were conducted to determine the reaction conditions necessary for no carbon lay down to occur. Calculations showed that to prevent solid carbon formation, low inlet CH4 to H2S ratios are needed. In this paper, we analyze H2SMR with either a cryogenic process or a membrane separation operation for production of either liquid or gaseous hydrogen. Of the three H2SMR hydrogen production flowsheets analyzed, direct liquid hydrogen generation has higher first and second law efficiencies of exceeding 80% and 50%, respectively.  相似文献   

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3.
This paper presents a review of the development of large-scale hydrogen liquefaction processes throughout the world from 1898 to 2009. First, there is a concise literature review including numerous past, present, and future designs given such as the first hydrogen liquefaction device, long time ago simple theoretical processes, today's actual plants with efficiencies 20–30%, a list of the capacity and location of every hydrogen liquefaction plant in the world, and some modern more efficient proposed conceptual plants with efficiencies 40–50%. After that, further information about the development and improvement potential of future large-scale liquid hydrogen liquefaction plants is given. It is found that every current plant is based on the pre-cooled Claude system, which is still the same as was 50 years ago with little improvement. Methods to resolve the challenges of the future plants include proposing completely new configurations and efficient systems coupled with improved efficiencies of the main system components such as compressors, expanders, and heat exchangers. Finally, a summary and comparison of the process efficiencies are described, including a newly proposed Multi-component Refrigerant (MR) system being developed by NTNU and SINTEF Energy Research AS.  相似文献   

4.
A proposed liquid hydrogen plant using a multi-component refrigerant (MR) refrigeration system is explained in this paper. A cycle that is capable of producing 100 tons of liquid hydrogen per day is simulated. The MR system can be used to cool feed normal hydrogen gas from 25 °C to the equilibrium temperature of −193 °C with a high efficiency. In addition, for the transition from the equilibrium temperature of the hydrogen gas from −193 °C to −253 °C, the new proposed four H2 Joule–Brayton cascade refrigeration system is recommended. The overall power consumption of the proposed plant is 5.35 kWh/kgLH2, with an ideal minimum of 2.89 kWh/kgLH2. The current plant in Ingolstadt is used as a reference, which has an energy consumption of 13.58 kWh/kgLH2 and an efficiency of 21.28%: the efficiency of the proposed system is 54.02% or more, where this depends on the assumed efficiency values for the compressors and expanders. Moreover, the proposed system has some smaller-size heat exchangers, much smaller compressor motors, and smaller crankcase compressors. Thus, it could represent a plant with the lowest construction cost with respect to the amount of liquid hydrogen produced in comparison to today’s plants, e.g., in Ingolstadt and Leuna. Therefore, the proposed system has many improvements that serve as an example for future hydrogen liquefaction plants.  相似文献   

5.
A large-scale point to point hydrogen transport is one strategy for a prospective energy import scenario for certain countries. The case for a hydrogen transport from Australia to Japan has been addressed in several studies. However, most studies lack transparency and detailed insights into the made assumptions thus a fair evaluation of different transport pathways is challenging. To address this issue, we developed a model where a large-scale point to point hydrogen transport of liquid hydrogen is compared with the transport via liquid organic hydrogen carrier (LOHC), namely via methyl cyclohexane and hydrogenated dibenzyl toluene. We analyzed, where energy is required along the different pathways, where hydrogen losses do occur and how the costs are put together. Furthermore, the influence of hydrogen feed costs is also considered. For hydrogen production costs of 5 €2018/kgH2 the total delivery costs are in the range of 6.40– 8.10 €2018/kgH2.  相似文献   

6.
Pakistan's energy crisis can be diminished through the use of Renewable and alternative sources of energy. Hydrogen as an energy vector is likely to replace the fossil fuels in the future owing to the political, financial and environmental factors associated with the latter. In this regard it is imperative that conscious effort is directed towards the production of hydrogen from Renewable resources. Renewable energy resources are abundantly available in Pakistan. The need to produce Hydrogen from Renewable resources in Pakistan (or any developing economy) is investigated because it is possible to store vast amount of intermittent renewable energy for later use. Thus the introduction of Hydrogen in the energy supply chain implies the start of a Pakistan Hydrogen Economy. Many nations have developed the Hydrogen Energy Roadmap, and if Pakistan has to follow suite it is only possible through the employment of Renewable energy resources. This study estimates the potential of different Renewable resources available in Pakistan i.e. Solar, Wind, Geothermal, Biomass and Municipal Solid waste. An estimate is then made for the potential of producing hydrogen from various established technologies from each of these Renewable resources. A number of reviews have been published stating the availability and usage of Renewable energy in Pakistan; however no specific study has been focused on the use of Renewable resources for developing a Hydrogen economy or a power-to-gas system in Pakistan. This study concludes that that Biomass is the most feasible feedstock for developing a Hydrogen supply chain in Pakistan with a potential to generate 6.6 million tons of Hydrogen annually, followed by Solar PV that has a generation potential of 2.8 million tons and then Municipal solid waste with a capacity of 1 million ton per annum.  相似文献   

7.
In a hydrogen liquefier the pre-compression of feed gas has generally higher stand-alone exergy efficiency than the cooling and liquefaction sub-process. Direct comparison of liquefiers based on overall exergy efficiency and specific power consumption will favour those with a higher portion of pre-compression. A methodology for comparing hydrogen liquefaction processes that compensates for non-uniformity in feed specifications has been developed and applied to three different hydrogen liquefiers. The processes in consideration have been modified to have equal hydrogen feed pressure, resulting in a more consistent comparison. Decreased feed pressure results in generally higher power consumption but also higher exergy efficiency, and vice versa. This approach can be adapted to the boundary conditions that the liquefaction process will be subject to in a real energy system.  相似文献   

8.
A large-scale hydrogen production system is proposed using solid fuels and designed to increase the sustainability of alternative energy forms in Canada, and the technical and economic aspects of the system within the Canadian energy market are examined. The work investigates the feasibility and constraints in implementing such a system within the energy infrastructure of Canada. The proposed multi-conversion and single-function system produces hydrogen in large quantities using energy from solid fuels such as coal, tar sands, biomass, municipal solid waste (MSW) and agricultural/forest/industrial residue. The proposed system involves significant technology integration, with various energy conversion processes (such as gasification, chemical looping combustion, anaerobic digestion, combustion power cycles-electrolysis and solar–thermal converters) interconnected to increase the utilization of solid fuels as much as feasible within cost, environmental and other constraints. The analysis involves quantitative and qualitative assessments based on (i) energy resources availability and demand for hydrogen, (ii) commercial viability of primary energy conversion technologies, (iii) academia, industry and government participation, (iv) sustainability and (v) economics. An illustrative example provides an initial road map for implementing such a system.  相似文献   

9.
Leading physical and materials-based hydrogen storage options are evaluated for their potential to meet the vehicular targets for gravimetric and volumetric capacity, cost, efficiency, durability and operability, fuel purity, and environmental health and safety. Our analyses show that hydrogen stored as a compressed gas at 350–700 bar in Type III or Type IV tanks cannot meet the near-term volumetric target of 28 g/L. The problems of dormancy and hydrogen loss with conventional liquid H2 storage can be mitigated by deploying pressure-bearing insulated tanks. Alane (AlH3) is an attractive hydrogen carrier if it can be prepared and used as a slurry with >50% solids loading and an appropriate volume-exchange tank is developed. Regenerating AlH3 is a major problem, however, since it is metastable and it cannot be directly formed by reacting the spent Al with H2. We have evaluated two sorption-based hydrogen storage systems, one using AX-21, a high surface-area superactivated carbon, and the other using MOF-177, a metal-organic framework material. Releasing hydrogen by hydrolysis of sodium borohydride presents difficult chemical, thermal and water management issues, and regenerating NaBH4 by converting B–O bonds is energy intensive. We have evaluated the option of using organic liquid carriers, such as n-ethylcarbazole, which can be dehydrogenated thermolytically on-board a vehicle and rehydrogenated efficiently in a central plant by established methods and processes. While ammonia borane has a high hydrogen content, a solvent that keeps it in a liquid state needs to be found, and developing an AB regeneration scheme that is practical, economical and efficient remains a major challenge.  相似文献   

10.
On-board and off-board performance and cost of cryo-compressed hydrogen storage are assessed and compared to the targets for automotive applications. The on-board performance of the system and high-volume manufacturing cost were determined for liquid hydrogen refueling with a single-flow nozzle and a pump that delivers liquid H2 to the insulated cryogenic tank capable of being pressurized to 272 atm. The off-board performance and cost of delivering liquid hydrogen were determined for two scenarios in which hydrogen is produced by central steam methane reforming (SMR) or by central electrolysis. The main conclusions are that the cryo-compressed storage system has the potential of meeting the ultimate target for system gravimetric capacity, mid-term target for system volumetric capacity, and the target for hydrogen loss during dormancy under certain conditions of minimum daily driving. However, the high-volume manufacturing cost and the fuel cost for the SMR hydrogen production scenario are, respectively, 2–4 and 1.6–2.4 times the current targets, and the well-to-tank efficiency is well short of the 60% target specified for off-board regenerable materials.  相似文献   

11.
To improve safety regulations for fuel cell vehicles and hydrogen infrastructures, experiments on cryo-compressed hydrogen leakage diffusion were conducted. The experimental apparatus can supply 90 MPa hydrogen at various temperature conditions (50 K–300 K) at a maximum flow rate of 100 kg/h. The hydrogen leakage flow rate was measured using pinhole nozzles with different outlet diameters (0.2 mm, 0.4 mm, 0.7 mm, and 1 mm). It was confirmed that the hydrogen leakage flow rate increases as the supply temperature decreases. To evaluate the hydrogen flow rate including the cryogenic condition, the orifice equation for liquid was found to be appropriate. The orifice flow coefficient converged to a constant value of 0.6 on the high-density condition side. The hydrogen concentration distribution was measured by injecting high-pressure hydrogen from the 0.2-mm pinhole for 10 min under a constant pressure/temperature condition. The axial hydrogen concentration distribution obtained by the ambient temperature (~300 K) hydrogen injection test well agreed with the experimental formula based on previous research studies. In addition, as the hydrogen injection temperature decreased, it was found that the hydrogen concentration increased, and an empirical formula of the 1% concentration distance for the cryogenic hydrogen system was newly presented. Additional tests were conducted using pinholes of different diameters, and a 1% concentration distance was confirmed to be proportional to the hydrogen leakage flow rate to the 0.5th power.  相似文献   

12.
Nuclear energy can be used as the primary energy source in centralized hydrogen production through high-temperature thermochemical processes, water electrolysis, or high-temperature steam electrolysis. Energy efficiency is important in providing hydrogen economically and in a climate friendly manner. High operating temperatures are needed for more efficient thermochemical and electrochemical hydrogen production using nuclear energy. Therefore, high-temperature reactors, such as the gas-cooled, molten-salt-cooled and liquid-metal-cooled reactor technologies, are the candidates for use in hydrogen production. Several candidate technologies that span the range from well developed to conceptual are compared in our analysis. Among these alternatives, high-temperature steam electrolysis (HTSE) coupled to an advanced gas reactor cooled by supercritical CO2 (S-CO2) and equipped with a supercritical CO2 power conversion cycle has the potential to provide higher energy efficiency at a lower temperature range than the other alternatives.  相似文献   

13.
Hydrogen is recognized as one of the most promising alternative fuels to meet the energy demand for the future by providing a carbon-free solution. In regards to hydrogen production, there has been increasing interest to develop, innovate and commercialize more efficient, effective and economic methods, systems and applications. Nuclear based hydrogen production options through electrolysis and thermochemical cycles appear to be potentially attractive and sustainable for the expanding hydrogen sector. In the current study, two potential nuclear power plants, which are planned to be built in Akkuyu and Sinop in Turkey, are evaluated for hydrogen production scenarios and cost aspects. These two plants will employ the pressurized water reactors with the electricity production capacities of 4800 MW (consisting of 4 units of 1200 MW) for Akkuyu nuclear power plant and 4480 MW (consisting of 4 units of 1120 MW) for Sinop nuclear power plant. Each of these plants are expected to cost about 20 billion US dollars. In the present study, these two plants are considered for hydrogen production and their cost evaluations by employing the special software entitled “Hydrogen Economic Evaluation Program (HEEP)” developed by International Atomic Energy Agency (IAEA) which includes numerous options for hydrogen generation, storage and transportation. The costs of capital, fuel, electricity, decommissioning and consumables are calculated and evaluated in detail for hydrogen generation, storage and transportation in Turkey. The results show that the amount of hydrogen cost varies from 3.18 $/kg H2 to 6.17 $/kg H2.  相似文献   

14.
Energy storage using liquid organic hydrogen carrier (LOHC) is a long-term method to store renewable energy with high hydrogen energy density. This study investigated a simple and low-cost system to produce methylcyclohexane (MCH) from toluene and hydrogen using fluctuating electric power, and developed its control method. In the current system, hydrogen generated by an alkaline water electrolyzer was directly supplied to hydrogenation reactors, where hydrogen purification equipment such as PSA and TSA is not installed to decrease costs. Hydrogen buffer tanks and compressors are not equipped. In order to enable MCH production using fluctuating electricity, a feed-forward toluene supply control method was developed and introduced to the system. The electrolyzer was operated under triangular waves and power generation patterns of photovoltaic cells and produced hydrogen with fluctuating flow rates up to 7.5 Nm3/h. Consequently, relatively high purity of MCH (more than 90% of MCH mole fraction) was successfully produced. Therefore, the simplified system has enough potential to produce MCH using fluctuating renewable electricity.  相似文献   

15.
In contrast to conventional technologies of hydrogen production like water electrolysis or coal gasification we propose a method based on the atmospheric pressure microwave plasma. In this paper we present results of the experimental investigations of the hydrogen production from ethanol in the atmospheric pressure plasma generated in waveguide-supplied cylindrical type nozzleless microwave (915 MHz and 2.45 GHz) plasma source (MPS). Argon, nitrogen and carbon dioxide were used as a working gas. All experimental tests were performed with the working gas flow rate Q ranged from 1500 to 3900 NL/h and absorbed microwave power PA up to 6 kW. Ethanol was introduced into the plasma as vapours carried with the working gas. The process resulted in the ethanol conversion rate greater than 99%. The hydrogen production rate was up to 210 NL[H2]/h and the energy efficiency was 77 NL[H2] per kWh of absorbed microwave energy.  相似文献   

16.
The increasing demand for H2 for heavy oil upgrading, desulfurization and upgrading of conventional petroleum, and for production of ammonium, in addition to the projected demand for H2 as a transportation fuel and portable power, will require H2 production on a massive scale. Increased production of H2 by current technologies will consume greater amounts of conventional hydrocarbons (primarily natural gas), which in turn will generate greater greenhouse gas emissions. Production of H2 from renewable sources derived from agricultural or other waste streams offers the possibility to contribute to the production capacity with lower or no net greenhouse gas emissions (without carbon sequestration technologies), increasing the flexibility and improving the economics of distributed and semi-centralized reforming. Electrolysis, thermocatalytic, and biological production can be easily adapted to on-site decentralized production of H2, circumventing the need to establish a large and costly distribution infrastructure. Each of these H2 production technologies, however, faces technical challenges, including conversion efficiencies, feedstock type, and the need to safely integrate H2 production systems with H2 purification and storage technologies.  相似文献   

17.
In most current fossil-based hydrogen production methods, the thermal energy required by the endothermic processes of hydrogen production cycles is supplied by the combustion of a portion of the same fossil fuel feedstock. This increases the fossil fuel consumption and greenhouse gas emissions. This paper analyzes the thermodynamics of several typical fossil fuel-based hydrogen production methods such as steam methane reforming, coal gasification, methane dissociation, and off-gas reforming, to quantify the potential savings of fossil fuels and CO2 emissions associated with the thermal energy requirement. Then matching the heat quality and quantity by solar thermal energy for different processes is examined. It is concluded that steam generation and superheating by solar energy for the supply of gaseous reactants to the hydrogen production cycles is particularly attractive due to the engineering maturity and simplicity. It is also concluded that steam-methane reforming may have fewer engineering challenges because of its single-phase reaction, if the endothermic reaction enthalpy of syngas production step (CO and H2) of coal gasification and steam methane reforming is provided by solar thermal energy. Various solar thermal energy based reactors are discussed for different types of production cycles as well.  相似文献   

18.
One option to transport hydrogen over longer distances in the future is via Liquid Organic Hydrogen Carriers (LOHC). They can store 6.2 wt% hydrogen by hydrogenation. The most promising LOHCs are toluene and dibenzyltoluene. However, for the dehydrogenation of the LOHCs – to release the hydrogen again – temperatures above 300 °C are needed, leading to a high energy demand. Therefore, a Life Cycle Assessment (LCA) and Life Cycle Costing are conducted. Both assessments concentrate on the whole life cycle rather than just direct emissions and investments. In total five different systems are analysed with the major comparison between conventional transport of hydrogen in a liquefied state of matter and LOHCs. Variations include electricity supply for liquefaction, heat supply for dehydrogenation and the actual LOHC compound. The results show that from an economic point of view transport via LOHCs is favourable while from an environmental point of view transport of liquid hydrogen is favourable.  相似文献   

19.
The status of world oil reserves is a contentious issue, polarised between advocates of peak oil who believe production will soon decline, and major oil companies that say there is enough oil to last for decades.  相似文献   

20.
Hong Kong is highly vulnerable to energy and economic security due to the heavy dependence on imported fossil fuels. The combustion of fossil fuels also causes serious environmental pollution. Therefore, it is important to explore the opportunities for clean renewable energy for long-term energy supply. Hong Kong has the potential to develop clean renewable hydrogen energy to improve the environmental performance. This paper reviews the recent development of hydrogen production technologies, followed by an overview of the renewable energy sources and a discussion about potential applications for renewable hydrogen production in Hong Kong. The results show that although renewable energy resources cannot entirely satisfy the energy demand in Hong Kong, solar energy, wind power, and biomass are available renewable sources for significant hydrogen production. A system consisting of wind turbines and photovoltaic (PV) panels coupled with electrolyzers is a promising design to produce hydrogen. Biomass, especially organic waste, offers an economical, environmental-friendly way for renewable hydrogen production. The achievable hydrogen energy output would be as much as 40% of the total energy consumption in transportation.  相似文献   

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