Hydrogen engine systems for land vehicles

Based on the research results at Musashi Institute of Technology since 1970, the next two systems are to be proposed for hydrogen fuel engine for land vehicles are: (1) A substitute for gasoline engine; LH₂ tank is pressurized by evaporated H₂-gas with its inner pressure at 1 MPa, and LH₂ is delivered from bottom of the tank. Cold hydrogen (about −30°C) is injected at 1 MPa into the cylinder during the first half of the compression stroke, then it is ignited by a spark. Its maximum power to be attained is 10–20% more than that of the gasoline engine, and its thermal efficiency under the partial load becomes higher than the gasoline engine because of lean combustion. (2) A substitute for diesel engine; The system consists of a LH₂-tank at low pressure, LH₂-pump for high pressure injection and spark igniter. Its maximum power is attainable to the same as gasoline engine. A high pressure hydrogen gas expander will be developed in the future for obtaining useful power and cold hydrogen.     

A novel cryogenic insulation system of hollow glass microspheres and self-evaporation vapor-cooled shield for liquid hydrogen storage

Liquid hydrogen (LH₂) attracts widespread attention because of its highest energy storage density. However, evaporation loss is a serious problem in LH₂ storage due to the low boiling point (20 K). Efficient insulation technology is an important issue in the study of LH₂ storage. Hollow glass microspheres (HGMs) is a potential promising thermal insulation material because of its low apparent thermal conductivity, fast installation (Compared with multi-layer insulation, it can be injected in a short time.), and easy maintenance. A novel cryogenic insulation system consisting of HGMs and a self-evaporating vapor-cooled shield (VCS) is proposed for storage of LH₂. A thermodynamic model has been established to analyze the coupled heat transfer characteristics of HGMs and VCS in the composite insulation system. The results show that the combination of HGMs and VCS can effectively reduce heat flux into the LH₂ tank. With the increase of VCS number from 1 to 3, the minimum heat flux through HGMs decreases by 57.36%, 65.29%, and 68.21%, respectively. Another significant advantage of HGMs is that their thermal insulation properties are not sensitive to ambient vacuum change. When ambient vacuum rises from 10⁻³ Pa to 1 Pa, the heat flux into the LH₂ tank increases by approximately 20%. When the vacuum rises from 10⁻³ Pa to 100 Pa, the combination of VCS and HGMs reduces the heat flux into the tank by 58.08%–69.84% compared with pure HGMs.     

Control analysis of renewable energy system with hydrogen storage for residential applications

The combination of an electrolyzer and a fuel cell can provide peak power control in a decentralized/distributed power system. The electrolyzer produces hydrogen and oxygen from off-peak electricity generated by the renewable energy sources (wind turbine and photovoltaic array), for later use in the fuel cell to produce on-peak electricity. An issue related to this system is the control of the hydrogen loop (electrolyzer, tank, fuel cell). A number of control algorithms were developed to decide when to produce hydrogen and when to convert it back to electricity, most of them assuming that the electrolyzer and the fuel cell run alternatively to provide nominal power (full power). This paper presents a complete model of a stand-alone renewable energy system with hydrogen storage controlled by a dynamic fuzzy logic controller (FLC). In this system, batteries are used as energy buffers and for short time storage. To study the behavior of such a system, a complete model is developed by integrating the individual sub-models of the fuel cell, the electrolyzer, the power conditioning units, the hydrogen storage system, and the batteries. An analysis of the performances of the dynamic fuzzy logic controller is then presented. This model is useful for building efficient peak power control.     

考虑低谷调峰限制和环境成本的发电容量规划

提出一种考虑低谷调峰限制的含可再生能源电力系统发电容量规划模型,该模型能确保通过运行调度最优发电容量组合满足规划年中每一天的低谷调峰限制,然后结合筛选曲线法和拉格朗日松弛法进行求解。而且,为了研究环境成本对发电容量规划和系统调峰性能的影响,在发电成本中增加CO₂排放成本。最后,算例分析验证所提方法的合理性和有效性,结果表明了在高渗透率可再生能源电力系统发电容量规划中综合考虑低谷调峰限制和环境成本的必要性。     

Prediction of cost and emission from Indian coal-fired power plants with CO2 capture and storage using artificial intelligence techniques

Coal-fired power plants are one of the most important targets with respect to reduction of CO₂ emissions. The reasons for this are that coal-fired power plants offer localized large point sources (LPS) of CO₂ and that the Indian power sector contributes to roughly half of all-India CO₂ emissions. CO₂ capture and storage (CCS) can be implemented in these power plants for long-term decarbonisation of the Indian economy. In this paper, two artificial intelligence (AI) techniques—adaptive network based fuzzy inference system (ANFIS) and multi gene genetic programming (MGGP) are used to model Indian coal-fired power plants with CO₂ capture. The data set of 75 power plants take the plant size, the capture type, the load and the CO₂ emission as the input and the COE and annual CO₂ emissions as the output. It is found that MGGP is more suited to these applications with an R² value of more than 99% between the predicted and actual values, as against the ~96% correlation for the ANFIS approach. MGGP also gives the traditionally expected results in sensitivity analysis, which ANFIS fails to give. Several other parameters in the base plant and CO₂ capture unit may be included in similar studies to give a more accurate result. This is because MGGP gives a better perspective toward qualitative data, such as capture type, as compared to ANFIS.     

Solar-powered regenerative PEM electrolyzer/fuel cell system

An electrolyzer/fuel cell energy storage system is a promising alternative to batteries for storing energy from solar electric power systems. Such a system was designed, including a proton-exchange membrane (PEM) electrolyzer, high-pressure hydrogen and oxygen storage, and a PEM fuel cell. The system operates in a closed water loop. A prototype system was constructed, including an experimental PEM electrolyzer and combined gas/water storage tanks. Testing goals included general system feasibility, characterization of the electrolyzer performance (target was sustainable 1.0 A/cm² at 2.0 V per cell), performance of the electrolyzer as a compressor, and evaluation of the system for direct-coupled use with a PV array. When integrated with a photovoltaic array, this type of system is expected to provide reliable, environmentally benign power to remote installations. If grid-coupled, this system (without PV array) would provide high-quality backup power to critical systems such as telecommunications and medical facilities.     

A coal-fired power plant integrated with biomass co-firing and CO2 capture for zero carbon emission

A promising scheme for coal-fired power plants in which biomass co-firing and carbon dioxide capture technologies are adopted and the low-temperature waste heat from the CO₂ capture process is recycled to heat the condensed water to achieve zero carbon emission is proposed in this paper. Based on a 660 MW supercritical coal-fired power plant, the thermal performance, emission performance, and economic performance of the proposed scheme are evaluated. In addition, a sensitivity analysis is conducted to show the effects of several key parameters on the performance of the proposed system. The results show that when the biomass mass mixing ratio is 15.40% and the CO₂ capture rate is 90%, the CO₂ emission of the coal-fired power plant can reach zero, indicating that the technical route proposed in this paper can indeed achieve zero carbon emission in coal-fired power plants. The net thermal efficiency decreases by 10.31%, due to the huge energy consumption of the CO₂ capture unit. Besides, the cost of electricity (COE) and the cost of CO₂ avoided (COA) of the proposed system are 80.37 $/MWh and 41.63 $/tCO₂, respectively. The sensitivity analysis demonstrates that with the energy consumption of the reboiler decreasing from 3.22 GJ/tCO₂ to 2.40 GJ/ tCO₂, the efficiency penalty is reduced to 8.67%. This paper may provide reference for promoting the early realization of carbon neutrality in the power generation industry.     

Design analysis and tri-objective optimization of a novel integrated energy system based on two methods for hydrogen production: By using power or waste heat

Hydrogen is rapidly turning into one of the essential energy carriers for future sustainable energy systems. The main reason for this is the possibility of off-peak excess power production and storage of renewable stations such as wind farms, photovoltaic plants, etc. For hydrogen (itself) or its sub-productions methanol, ammonia, etc. Such energy systems are so-called power2X technologies. For hydrogen and other biogases, using a fuel cell is a promising method for returning the fuel to the power grid or electric cars in the form of electricity. In this paper, a novel hybrid energy system consisting of a molten carbonate fuel cell (MCFC) and different options to generate hydrogen from the waste heat of the MCFC is investigated. The system consists of two scenarios of weather using proton exchange membrane electrolyzer (PEME) of vanadium chloride (VCL) cycle. The article presents a comprehensive thermodynamic, economic, and environmental analysis of the system optimized by tri-objective optimization (as an innovative optimization) methods. The aim of the optimization task here is to minimize the costs and emissions while maximizing efficiency. A parametric study is conducted to see the effect of different design parameters on the system's performance. Results demonstrate that fuel utilization factor, stack temperature, and current density have the most critical effect on the system performance. In addition, the system coupled with the VCL cycle exhibits better performance than the system with PEME. In addition, at the optimized point, the efficiency, cost rate, and emission become 69.28%, 3.73 ($/GJ), and 1.16 kg/kWh, respectively. In addition, the produced hydrogen in VCL and PEME are 585 kg/day and 293 kg/day respectively.     

Environmental assessment and extended exergy analysis of a “zero CO2 emission”, high-efficiency steam power plant

Aim of this paper is to analyze the performance of an innovative high-efficiency steam power plant by means of two “life cycle approach” methodologies, the life cycle assessment (LCA) and the “extended exergy analysis” (EEA).

The plant object of the analysis is a hydrogen-fed steam power plant in which the H₂ is produced by a “zero CO₂ emission” coal gasification process (the ZECOTECH^© cycle). The CO₂ capture system is a standard humid-CaO absorbing process and produces CaCO₃ as a by-product, which is then regenerated to CaO releasing the CO₂ for a downstream mineral sequestration process.

The steam power plant is based on an innovative combined-cycle process: the hydrogen is used as a fuel to produce high-temperature, medium-pressure steam that powers the steam turbine in the topping section, whose exhaust is used in a heat recovery boiler to feed a traditional steam power plant.

The environmental performance of the ZECOTECH^© cycle is assessed by comparison with four different processes: power plant fed by H₂ from natural gas steam reforming, two conventional coal- and natural gas power plants and a wind power plant.     

AC Impedance of Li(Ni1/3Co1/3Mn1/3)O2/graphite cell as UPS

以Li（Ni_1/3Co_1/3Mn_1/3）O₂/graphite动力电池为研究对象,在模拟备用电源工况下对动力电池进行交流阻抗测试。通过建立等效电路来研究欧姆阻抗R_s、电荷传递阻抗R_ct和扩散阻抗CPE_W随不同搁置时间、荷电状态（state of charge,SOC）的变化规律,研究Li（Ni_1/3Co_1/3Mn_1/3）O₂/graphite动力电池在备用电源工况下,容量和阻抗的变化趋势。结果表明：随着搁置时间的增加,电池容量衰减1.7%左右。随着搁置时间的增加,不同SOC下的欧姆阻抗R_s具有相同的变化趋势,电荷传递阻抗明显增加。随着SOC的降低,由双电层产生的电荷传递阻抗在逐渐增加。在SOC=0%时,扩散阻抗随搁置时间的增加而增加,在SOC=100%、50%的扩散阻抗有细微的增加。容量衰退和阻抗结果显示出Li（Ni_1/3Co_1/3Mn_1/3）O₂/graphite动力电池可以很好地在备用电源工况上使用。     

Assessment of hydrogen production from waste heat using hybrid systems of Rankine cycle with proton exchange membrane/solid oxide electrolyzer

A techno-economic assessment of hydrogen production from waste heat using a proton exchange membrane (PEM) electrolyzer and solid oxide electrolyzer cell (SOEC) integrated separately with the Rankine cycle via two different hybrid systems is investigated. The two systems run via three available cement waste heats of temperatures 360 °C, 432 °C, and 780 °C with the same energy input. The waste heat is used to run the Rankine cycle for the power production required for the PEM electrolyzer system, while in the case of SOEC, a portion of waste heat energy is used to supply the electrolyzer with the necessary steam. Firstly, the best parameters; Rankine working fluid for the two systems and inlet water flow rate and bleeding ratio for the SOEC system are selected. Then, the performance of the two systems (Rankine efficiency, total system efficiency, hydrogen production rate, and economic and CO₂ reduction) is investigated and compared. The results reveal that the two systems' performance is higher in the case of steam Rankine than organic, while a bleeding ratio of 1% is the best condition for the SOEC system. Rankine output power, total system efficiency, and hydrogen production rate rose with increasing waste heat temperature having the same energy. SOEC system produces higher hydrogen production and efficiency than the PEM system for all input waste heat conditions. SOEC can produce 36.9 kg/h of hydrogen with a total system efficiency of 23.8% at 780 °C compared with 27.4 kg/h and 14.45%, respectively, for the PEM system. The minimum hydrogen production cost of SOEC and PEM systems is 0.88 $/kg and 1.55 $/kg, respectively. The introduced systems reduce CO₂ emissions annually by about 3077 tons.     

Concentrating solar power:Current status and perspective

太阳能热发电是将太阳能转化为热能,通过热功转化过程发电的技术.太阳能热发电站具有发电功率相对平稳可控,运行方式灵活,可进行热电并供等优势,同时具有非常好的环境效益.太阳能热发电规模化发展后,近期能够作为调峰电源为风力发电,光伏发电等间歇性电源提供辅助服务.随着未来技术的优化提升,由大型太阳能热发电站组成的太阳能热发电厂有可能承担电力系统基础负荷.目前,全球太阳能热发电产业正在兴起,装机容量逐年增加,然而,我国在太阳能热发电关键技术研究上明显落后于先进国家,太阳能热发电产业发展速度明显滞后;另外,我国也没有发布明确的太阳能热发电产业激励政策,这直接导致了一批项目迟迟不能落地.     

Comparative analysis of thermophysical properties of mixed nitrates

熔融盐作为传蓄热介质已经广泛应用于太阳能光热发电中,硝酸盐以其熔点低、成本和腐蚀性小等优点成功应用于商业电站。采用差示扫描量热法、热重法、DIN法、激光闪射法、阿基米德原理和旋转法对Solar salt（60% NaNO₃+40% KNO₃）、Hitec（7% NaNO₃+53% KNO₃+40% NaNO₂）、Hitec XL[7% NaNO₃+45% KNO₃+48% Ca（NO₃）₂]以及本课题组自主研制的四元混合硝酸盐[16.67% Ca（NO₃）₂·4H₂O+44.17% KNO₃+5.83% NaNO₃+33.33% NaNO₂]的熔点、分解温度、比热容、热导率、密度及黏度进行测量和对比研究,分析4种混合硝酸盐热物性优缺点,为工程应用提供基础性数据。结果显示,在四种混合硝酸盐中,四元盐熔点最低、分解温度最高、平均比热容和热导率均高于其他三种混合硝酸盐,Hitec XL密度最大,Solar salt黏度最低。     

Geologic feasibility of underground hydrogen storage in Canada

Electricity production in the majority of Canada's regions is characterized by high proportions of nuclear and renewable sources such as hydroelectricity. Future plans to phase out coal-fired power plants by 2030 and decrease fossil fuel use in favor of increased integration of renewables highlight the need to develop strategies which can match intermittent and base-load electricity output with market demand. The use of hydrogen gas generated through off-peak electrolysis has been highlighted by the Canadian government as a potential avenue forward in managing electrical grids with surplus and intermittent electricity generation. This technology can be supported in a safe and cost-effective manner by underground hydrogen storage in geological formations. In this article, an overview of Canadian geology, as well as an assessment of the potential application of underground storage methods and associated safety concerns in Canada is presented. Favorable locations for pilot projects are found in the sedimentary basins of western and Atlantic Canada as well as southern Ontario, or the crystalline rocks of the Canadian Shield.     

Possible optimal configurations for the ZECOMIX high efficiency zero emission hydrogen and power plant

Coal use for electricity generation will continue growing in importance. In the present work the optimization of a high efficiency and zero emissions coal-fired plant, which produces both hydrogen and electricity, has been developed. The majority of this paper concerns an integration of gasification unit, which is characterized by coal hydrogasification and carbon dioxide (CO₂) separation, with a power island, where a high-hydrogen content syngas is burnt with pure oxygen stream. Another issue is the high temperature CO₂ desorption. Because of the elevated temperature heat supply, the regeneration process affects the overall performance of ZECOMIX plant. An advanced steam cycle characterized by a medium pressure steam compressor and expander has been considered for power generation. A preliminary study of different components leads to analyze possible routes for optimization of the whole plant. The plant equipped with a CO₂ capture unit could reach efficiency close to 50%. The simulations of a thermodynamic model were carried out using the software ChemCAD.

This study is a part of a larger research project, named ZECOMIX, led by ENEA (Italian Research Agency for New technologies, Energy and Environment), other partners being ANSALDO and different Italian Universities. It is aimed at analyzing an integrated hydrogen and power production plant.     

Synthetic carbonaceous fuel and feedstock using nuclear power,air and water

Development of synthetic carbonaceous fuels and feedstocks (SCFF) is imperative if the U.S. is to maintain its world leadership. Nuclear power can provide not only the stationary thermal and electrical power backbone in the country but can also be of great assistance in supplying SCFF. All forms of carbonaceous materials can serve as sources of raw material for SCFF, however, here we consider the ultimate renewable resource of carbon which is CO₂ from the atmosphere or the oceans. A number of methods for the recovery of CO₂ have been examined. An absorption-stripping system utilizing dilute carbonate solvent appears most economical for atmospheric recovery while distillation appears of interest for sea-water recovery. An alternative isothermal process utilizing chlor-alkali cells is also described. Electrolytic hydrogen is thermocatalytically combined with the CO₂ to form methanol which can then be dehydrated to gasoline. Production cost is dominated by the energy for hydrogen and the plant capital investment. Base loaded nuclear power plants supplying peaking load and generating SCFF in an off-peak mode is proposed for reducing costs. Under 1974/5 conditions, incremental power costs would have been a minimum. Under 1985 escalated conditions, incremental costs indicate 6 mills/kWh(e) for power which yields 33.9 c/gallon methanol or 77.1 c/gallon of equivalent gasoline which takes credit for oxygen would break even with $23/bb1 of oil. The capital investment for producing the equivalent of one million barrels/day of gasoline in 142 nuclear reactors of 100 MW(e) capacity, operating in an off-peak mode, amounts to slightly more than the investment in new oil exploration and production facilities and considerable less than the projected outflow of capital to foreign OPEC countries. The nuclear synthesis-route using atmospheric and aquatic CO₂, simulates the solar photosynthetic process and provides a long-term renewable and environmentally acceptable alternate source of SCFF.     

Factors regulating nitrogenase activity and hydrogen evolution in Azolla-anabaena symbiosis

Nitrogenase activity and H₂ production capacity have been studied in intact Azolla plants. Under aerobic conditions the plants showed a C₂H₂ reduction rate of 6.65 nmoles C₂H₄ mg⁻¹ fresh weight in light at 48h. Considerable activity was also present in the dark. Though H₂ evolution was detected under aerobic conditions there was multifold stimulation under anaerobic conditions. There was no significant change in nitrogenase activity under anaerobic conditions. Increasing concentrations of O₂ inhibited nitrogenase activity but 5% O₂ proved stimulatory for H₂ evolution in light. In the dark, there was a gradual stimulation in H₂ evolution even up to 20% O₂. Addition of combined nitrogen sources, namely NH₄Cl or KNO₃ (10 mM) resulted in complete inhibition of C₂H₂-reduction activity within 48 h, but H₂ evolution was not inhibited. Indeed these combined nitrogen sources stimulated H₂ evolution. Though nitrogenase activity was affected, the heterocyst frequency remained unaltered. Phosphate addition resulted in significant stimulation of nitrogenase and H₂ evolution activity. These results suggest that on nitrogenase and H₂ evolution activity in Azolla are affected by a number of factors which show a differential effect on nitrogenase and H₂ evolution. Furthermore, our results indicate the presence of a soluble reversible hydrogenase in Azolla.     

A role for ammonia in the hydrogen economy

Ammonia (NH₃) is a non-polluting fuel which produces only water and nitrogen as products of combustion. Therefore, it could be an alternative to hydrogen for vehicle motive power in the hydrogen economy. For this role ‘electrolytic ammonia’ would be prepared by catalytic combination of electrolytic hydrogen and atmospheric nitrogen. The background and developmental status of hydrogen and ammonia as motor-vehicle fuels are reviewed. Engine tests have demonstrated that ammonia can replace gasoline or diesel fuel for motor vehicles, giving near-theoretical values of engine power and efficiency. Ammonia is superior to hydrogen as a vehicle fuel for several reasons: it can be stored and transported as a liquid at ambient temperatures in low-pressure containers; per unit volume ammonia has 1.3 times the heating value of liquid hydrogen; ammonia is distributed internationally in quantities of over 100 million tons per year, and procedures and facilities are established world-wide for its safe handling and distribution. These factors would greatly facilitate the commercial adoption of ammonia as a practical replacement for carbonaceous fuels. The projected cost of supplying ‘electrolytic ammonia’ to motor vehicle filling stations is estimated to be roughly half the cost of supplying electrolytic liquid hydrogen for the same purpose, i.e. $10.5–12.5 GJ⁻¹ for ammonia vs $25–30 GJ⁻¹ for LH₂ (1988$). A summary is presented of the physical and thermo-chemical characteristics and estimated costs of ammonia in comparison with hydrogen, as liquid, compressed gas or stored as metal hydride. Properties of gasoline, methanol, ethanol and liquified methane are also listed.     

Modeling of a hybrid marine current-hydrogen active power generation system

This paper presents the modeling and the simulation of a hybrid marine current-hydrogen power generation system. The marine current power generation system consists of a fixed pitch marine current turbine directly coupled to a permanent magnet synchronous generator (PMSG). The generator is connected to a DC link capacitor via a controlled rectifier, which has two modes of operation. The first mode is the maximum power point tracking (MPPT) by using torque control when the generator runs below the rated speed. The second mode is the power limitation (at the rated value) when the generator runs above the nominal speed. The generated power is transferred from the DC-link to the load via an inverter to run the system in a stand-alone operation mode. An energy storage system must cover the difference between the generation and the consumption for this scheme. The hydrogen, compared with the different energy storage systems, exhibits characteristics more applicable for marine current power generation systems. When the generated power is higher than the load requirements, a Megawatt-scale proton exchange membrane (PEM) electrolyzer consumes the surplus energy for hydrogen generation. The generated hydrogen is stored in tanks to feed a PEM fuel cell system to generate power in case of shortage. Based on this topology and operation procedure, the overall system is called an active power generation system. The MW scale PEM electrolyzer model is presented based on state of the art and the literature of different scales PEM electrolyzer system modeling.     

A green hydrogen energy storage concept based on parabolic trough collector and proton exchange membrane electrolyzer/fuel cell: Thermodynamic and exergoeconomic analyses with multi-objective optimization

With the continuous penetration of renewable energy plants into energy markets and their surplus power generation during off-peak periods, the need for utility-scale energy storage technologies is globally prioritized. Among the existing large-scale energy storage technologies, hydrogen storage has appeared as a powerful alternative due to its environmental benefits and the ability to store a large amount of energy for several hours to months. The major objective of the proposed research is to introduce a novel configuration of green hydrogen production for power generation during peak demand periods. In this regard, an innovative hybridization of a solar unit based on a parabolic trough collector with a proton-exchange membrane electrolyzer and a fuel cell is introduced and analyzed from the thermodynamic and exergoeconomic perspectives. Moreover, a sensitivity analysis and a multi-objective optimization based on the combination of neural network and grey wolf optimization algorithms are conducted to select the best working fluid of the solar unit and ideal operating conditions according to the minimum cost rate and the maximum exergy efficiency. The results indicate that Dowtherm? A synthetic oil is the best working fluid, and the proposed system can generate 9, 14.9, and 20.1 MW of power during off-, mid-, and on-peak times, respectively. The results also show that the proposed system operates with an exergy efficiency of 17.6% and a cost rate of 492.4 $/hr under the optimal conditions.