Assessment the hydrogen-electric coupled energy storage system based on hydrogen-fueled CAES and power-to-gas-to-power device considering multiple time-scale effect and actual operation constraints

Energy storage technology provides efficient energy management in renewable driven power system. The long duration time-scale fluctuation in unbalance power becomes more obvious and prominent with the elevated renewable penetration level. However, this issue is not widely considered in current energy storage system. In this paper, a green hydrogen-electric coupled energy storage system based on hydrogen-fueled compressed air energy storage (CAES) and power-to-gas-to-power (PtGtP) device is proposed. The hydrogen-based PtGtP device, including proton exchange membrane fuel cell (PEMFC) and PEM electrolzyer, is employed to smooth out the long duration time-scale fluctuation. Whereas, the hydrogen-fueled CAES is used to settle the remaining time-scale fluctuations. Moreover, the coupled feature is reflected by the hydrogen medium. The hydrogen only generates in PtGtP device, but consumes in both PtGtP device and hydrogen-fueled CAES. The performance assessment by considering the actual operation constraints is conducted based on historical data from real world. The simulated results show that the proposed system can provide an effective and flexible power management in the high share renewable power system. The loss of power supply probability (LPSP) is 5.40%, which is higher than that of any single energy storage system. However, the wind curtailment ratio (WCR) is 8.81%, illustrating an insufficient energy storage capacity. Furthermore, the energy shifting occurs in both several days scale and seasonal scale. This is obvious evidence for function of long duration energy storage (LDES) for the proposed coupled energy storage.     

Techno-economic analysis of hydrogen energy for renewable energy power smoothing

With the increasing proportion of renewable energy (mainly wind power and photovoltaic) connected to the grid, the fluctuation of renewable energy power brings great challenges to the safe and reliable operation of power grid. As a clean, low-carbon secondary energy, hydrogen energy is applied in renewable energy (mainly wind power and photovoltaic) grid-connected power smoothing, which opens up a new way of coupling hydrogen storage energy with renewable energy. This paper focuses on the optimization of capacity of electrolyzers and fuel cells and the analysis of system economy in the process of power output smoothing of wind/photovoltaic coupled hydrogen energy grid-connected system. Based on the complementary characteristics of particle swarm optimization (PSO) and chemical reaction optimization algorithm (CROA), a particle swarm optimization-chemical reaction optimization algorithm (PSO-CROA) are proposed. Aiming at maximizing system profit, the capacity of electrolyzers and fuel cells are constrained by wind power fluctuation, and considering environmental benefits, government subsidies and time value of funds, the objective function and its constraints are established. According to the simulation analysis, by comparing the calculated results with PSO and CROA, it shows that PSO-CROA effectively evaluates the economy of the system, and optimizes the optimal capacity of the electrolyzers and fuel cells. The conclusion of this paper is of great significance for the application of hydrogen energy storage in the evaluation of power smoothness and economy of renewable energy grid connection and the calculation of economic allocation of hydrogen energy storage capacity.     

A metal hydride system for a forklift: Feasibility study on on-board chemical storage of hydrogen using numerical simulation

This paper describes a technical feasibility study of on-board metal hydride storage systems. The main advantages of these systems would be that of being able to replace counterweights with the weight of the storage system and using the heat emissions of fuel cells for energy, making forklifts a perfect use case. The main challenge is designing a system that supplies the required energy for a sufficiently long period. A first draft was set up and analyzed to provide a forklift based on a fuel cell with hydrogen from HydralloyC5 or FeTiMn. The primary design parameter was the required amount of stored hydrogen, which should provide energy equal to the energy capacity of a battery in an electric vehicle. To account for highly dynamic system requirements, the reactor design was optimized such that the storage was charged in a short time. Additionally, we investigated a system in which a fixed amount of hydrogen energy was required. For this purpose, we used a validated simulation model for the design concepts of metal hydride storage systems. The model includes all relevant terms and parameters to describe processes inside the system's particular reactions and the thermal conduction due to heat exchangers. We introduce an embedded fuel cell model to calculate the demand for hydrogen for a given power level. The resulting calculations provide the required time for charging or a full charge depending on the tank's diameter and, therefore, the necessary number of tanks. We conclude that the desired hydrogen supply times are given for some of the use cases. Accordingly, the simulated results suggest that using a metal hydride system could be highly practical in forklifts.     

Efficiencies of hydrogen storage systems onboard fuel cell vehicles

Energy efficiency, vehicle weight, driving range, and fuel economy are compared among fuel cell vehicles (FCV) with different types of fuel storage and battery-powered electric vehicles. Three options for onboard fuel storage are examined and compared in order to evaluate the most energy efficient option of storing fuel in fuel cell vehicles: compressed hydrogen gas storage, metal hydride storage, and onboard reformer of methanol. Solar energy is considered the primary source for fair comparison of efficiencies for true zero emission vehicles. Component efficiencies are from the literature. The battery powered electric vehicle has the highest efficiency of conversion from solar energy for a driving range of 300 miles. Among the fuel cell vehicles, the most efficient is the vehicle with onboard compressed hydrogen storage. The compressed gas FCV is also the leader in four other categories: vehicle weight for a given range, driving range for a given weight, efficiency starting with fossil fuels, and miles per gallon equivalent (about equal to a hybrid electric) on urban and highway driving cycles.     

Hydrogen energy storage system in a Multi‒Technology Microgrid:technical features and performance

The features and performance of a hydrogen energy storage system included in the microgrid powering a plant for advanced green technologies is presented. The microgrid is powered by a 730–kW photovoltaic source and four energy storage systems. The hydrogen storage system consists of a water demineralizer, a 22.3–kW alkaline electrolyzer generating hydrogen, its AC–DC power supply, 99.9998% hydrogen purifier, 200-bar compressor, 200–L gas storage cylinders, a 31.5–kW proton–exchange–membrane fuel cell running on hydrogen, its DC–AC power conditioning system. The whole system is housed in three containers provided with anti–salt filters to remove brine. The whole system is controlled by the microgrid system supervisor. Operative tests at nominal power show that the round-trip efficiency of the hydrogen energy storage system at full power is ca. 10% in a pure electric operation and ca. 24% in a heat cogeneration operation. At half power these values reduce to 9.5% and 18%, respectively.     

Role of hydrogen in future North European power system in 2060

The Balmorel model has been used to calculate the economic optimal energy system configuration for the Scandinavian countries and Germany in 2060 assuming a nearly 100% coverage of the energy demands in the power, heat and transport sector with renewable energy sources. Different assumptions about the future success of fuel cell technologies have been investigated as well as different electricity and heat demand assumptions. The variability of wind power production was handled by varying the hydropower production and the production on CHP plants using biomass, by power transmission, by varying the heat production in heat pumps and electric heat boilers, and by varying the production of hydrogen in electrolysis plants in combination with hydrogen storage. Investment in hydrogen storage capacity corresponded to 1.2% of annual wind power production in the scenarios without a hydrogen demand from the transport sector, and approximately 4% in the scenarios with a hydrogen demand from the transport sector. Even the scenarios without a demand for hydrogen from the transport sector saw investments in hydrogen storage due to the need for flexibility provided by the ability to store hydrogen. The storage capacities of the electricity storages provided by plug-in hybrid electric vehicles were too small to make hydrogen storage superfluous.     

Cogeneration of power and substitute of natural gas using biomass and electrolytic hydrogen

Storing renewable energy sources is becoming a very important issue to allow a further reduction of greenhouse gas emissions. Most of such energy sources generate electric power which not always can be conveniently transferred to the grid and also its conversion to hydrogen presents some critical aspects connected mainly to hydrogen distribution and storage.Electrolysis generates not only hydrogen, but also oxygen which could be used to burn biomass or waste products (oxycombustion) in power plants with the result to obtain an exhaust gas containing mainly water and CO₂. This last can be converted into a mixture of methane and hydrogen by reacting with electrolytic hydrogen, so that the power used for electrolysis is stored into a fuel which can be distributed and stored just like natural gas.In this paper, an innovative biomass fuelled plant has been designed and simulated for different layouts with an internal combustion engine as a main power system. Utilizing hydrogen and oxygen produced through electrolysis and applying a hydrogasification process, the plant produces electricity and a substitute of natural gas. The result of such simulations is that the electricity can be stored in a useful and versatile fuel with a marginal efficiency up to 60%.     

The spectrum of power from wind turbines

The power spectral density of the output of wind turbines provides information on the character of fluctuations in turbine output. Here both 1-second and 1-hour samples are used to estimate the power spectrum of several wind farms. The measured output power is found to follow a Kolmogorov spectrum over more than four orders of magnitude, from 30 s to 2.6 days. This result is in sharp contrast to the only previous study covering long time periods, published 50 years ago. The spectrum defines the character of fill-in power that must be provided to compensate for wind's fluctuations when wind is deployed at large scale. Installing enough linear ramp rate generation (such as a gas generator) to fill in fast fluctuations with amplitudes of 1% of the maximum fluctuation would oversize the fill-in generation capacity by a factor of two for slower fluctuations, greatly increasing capital costs. A wind system that incorporates batteries, fuel cells, supercapacitors, or other fast-ramp-rate energy storage systems would match fluctuations much better, and can provide an economic route for deployment of energy storage systems when renewable portfolio standards require large amounts of intermittent renewable generating sources.     

Reducing cycling costs in coal fired power plants through power to hydrogen

The increase of renewable share in the energy generation mix makes necessary to increase the flexibility of the electricity market. Thus, fossil fuel thermal power plants have to adapt their electricity production to compensate these fluctuations. Operation at partial load means a significant loss of efficiency and important reduction of incomes from electricity sales in the fossil power plant. Among the energy storage technologies proposed to overcome these problems, Power to Gas (PtG) allows for the massive storage of surplus electricity in form of hydrogen or synthetic natural gas. In this work, the integration of a Power to Gas system (50 MWe) with fossil fuel thermal power plants (500 MWe) is proposed to reduce the minimum complaint load and avoid shutdowns. This concept allows a continuous operation of power plants during periods with low demand, avoiding the penalty cost of shutdown. The operation of the hybrid system has been modelled to calculate efficiencies, hydrogen and electricity production as a function of the load of the fossil fuel power plant. Results show that the utilisation of PtG diminishes the specific cost of producing electricity between a 20% and 50%, depending on the framework considered (hot, warm and cold start-up). The main contribution is the reduction of the shutdown penalties rather than the incomes from the sale of the hydrogen. At the light of the obtained results, the hybrid system may be implemented to increase the cost-effectiveness of existing fossil fuel power plants while adapting the energy mix to high shares of variable renewable electricity sources.     

System design and control strategy of the vehicles using hydrogen energy

This paper presented a system design review of fuel cell hybrid vehicle. Fuel supply, hydrogen storage, DC/DC converters, fuel cell system and fuel cell hybrid electric vehicle configurations were also reviewed. We explained the difference of fuel supply requirement between hydrogen vehicle and conventional vehicles. Three different types of hydrogen storage system for fuel supply are briefly introduced: high pressure, liquid storage and metal oxides storage. Considering of the potential risk of explosion, a security hydrogen storage system is designed to restrict gas pressure in the safe range. Due to the poor dynamic performance of fuel cells, DC/DC converters were added in hybrid vehicle system to improve response to the changes of power demand. Requirements that in order to select a suitable DC/DC converter for fuel-cell vehicles design were listed. We also discussed three different configurations of fuel-cell hybrid vehicles: “FC + B”, “FC + C”, and “FC + B + C”, describing both disadvantages and advantages. “FC + B + C” structure has a better performance among three structures because it could provide or absorb peak current during acceleration and emergency braking. Finally, the energy management strategies of fuel cell and were proposed and the automotive energy power requirement of an application example was calculated.     

Generation of typical operation curves for hydrogen storage applied to the wind power fluctuation smoothing mode

In this paper, a typical-operation-curve generation method of a hydrogen energy storage system operating under the mode of stabilizing wind power fluctuations is proposed. This method is used to optimize the power and capacity configuration of the energy storage system. The time series curves of the charging and discharging powers of the hydrogen energy storage are obtained by EMD decomposition, and the curves are classified according to the similarities and differences of the characteristic par...     

Wind energy–hydrogen storage hybrid power generation

In this theoretical investigation, a hybrid power generation system utilizing wind energy and hydrogen storage is presented. Firstly, the available wind energy is determined, which is followed by evaluating the efficiency of the wind energy conversion system. A revised model of windmill is proposed from which wind power density and electric power output are determined. When the load demand is less than the output of the generation, the excess electric power is relayed to the electrolytic cell where it is used to electrolyze the de‐ionized water. Hydrogen thus produced can be stored as hydrogen compressed gas or liquid. Once the hydrogen is stored in an appropriate high‐pressure vessel, it can be used in a combustion engine, fuel cell, or burned in a water‐cooled burner to produce a very high‐quality steam for space heating, or to drive a turbine to generate electric power. It can also be combined with organic materials to produce synthetic fuels. The conclusion is that the system produces no harmful waste and depletes no resources. Note that this system also works well with a solar collector instead of a windmill. Copyright © 2001 John Wiley & Sons, Ltd.     

Review on key technologies and applications of hydrogen energy storage system

随着国内以风电,太阳能为主的可再生能源快速增长,可再生能源消纳能力不足和并网困难等问题愈发突出,大规模储能系统被证实是解决该问题的有效方法.本文回顾了现有成熟储能系统的不足与限制,分析氢储能的优势特点,构建了电能链和氢产业链融合的氢储能系统,为可再生能源的进一步发展提供良策.随后对氢储能系统三个环节(制氢,储运氢,氢发电)关键技术进行了梳理,对电解槽技术,燃料电池技术和储氢材料中的关键性能进行了比较和评估.在氢储能领域,部分发达国家已经初步形成了从基础研究,应用研究到示范演示的全方位格局,本文对德国和法国的重点示范工程进行了调研,为我国未来发展氢储能的提供参考.     

Integration of large-scale hydrogen storages in a low-carbon electricity generation system

This study investigates the overall feasibility of large energy storages with hydrogen as energy carrier onsite with a pre-combustion carbon capture and storage coal gasification plant and assesses the general impacts of such a backup installation on an electricity generation system with high wind power portion. The developed system plant configuration consists of four main units namely the gasification unit, main power unit, backup power unit including hydrogen storage and ancillary power unit. Findings show that integrating a backup storage in solid or gaseous hydrogen storage configuration allows to store excessive energy under high renewable power output or low demand and to make use of the stored energy to compensate low renewable output or high power demand. The study concludes that the developed system configuration reaches much higher load factors and efficiency levels than a plant configuration without backup storage, which simply increases its power unit capacity to meet the electricity demand. Also from an economical point of view, the suggested system configurations are capable to achieve lower electricity generation costs.     

Hydrogen the fuel for 21st century

Non-Conventional Energy Sources, such as solar and hydrogen energy will remain available for infinite period. One of the reasons of great worry for all of us is reducing sources of conventional energies. The rate of fossil fuel consumption is higher than the rate of the fossil fuel production by the nature. The results will be the scarcity of automobile fuel in the world which will create lot of problems in transport sector. The other aspect is pollution added by these sources in our environment which increases with more use of these sources, resulting in the poor quality of life on this planet. There is constant search of alternate fuel to solve energy shortage which can provide us energy without pollution.Hence most frequently discussed source is hydrogen which when burnt in air produces a clean form of energy. In the last one decade hydrogen has attracted worldwide interest as a secondary energy carrier. This has generated comprehensive investigations on the technology involved and how to solve the problems of production, storage and transportation of hydrogen. The interest in hydrogen as energy of the future is due to it being a clean energy, most abundant element in the universe, the lightest fuel, richest in energy per unit mass and unlike electricity, it can be easily stored. Hydrogen gas is now considered to be the most promising fuel of the future. In future it will be used in various applications, e.g. it can generate Electricity, useful in cooking food, fuel for automobiles, hydrogen powered industries, Jet Planes, Hydrogen Village and for all our domestic energy requirements.Hydrogen as a fuel has already found applications in experimental cars and all the major car companies are in competition to build a commercial car and most probably they may market hydrogen fuel automobiles in near future but at a higher cost compared to gasoline cars but it is expected that with time the cost of hydrogen run cars will decrease with time. Long lasting, light and clean metal hydride batteries are already commercial for lap top computers. Larger capacity batteries are being developed for electrical cars. Hydrogen is already being used as the fuel of choice for space programmes around the world. It will be used to power aerospace transports to build the international space station, as well as to provide electricity and portable water for its inhabitants. Present article deals with the storage and applications of hydrogen in the present energy scenario.     

The design of long-life,high-efficiency PEM fuel cell power supplies for low power sensor networks

Field sensor networks have important applications in environmental monitoring, wildlife preservation, in disaster monitoring and in border security. The reduced cost of electronics, sensors and actuators make it possible to deploy hundreds if not thousands of these sensor modules. However, power technology has not kept pace. Current power supply technologies such as batteries limit many applications due to their low specific energy. Photovoltaics typically requires large bulky panels and is dependent on varying solar insolation and therefore requires backup power sources. Polymer Electrolyte Membrane (PEM) fuel cells are a promising alternative, because they are clean, quiet and operate at high efficiencies. However, challenges remain in achieving long lives due to factors such as degradation and hydrogen storage. In this work, we devise a framework for designing fuel cells power supplies for field sensor networks. This design framework utilize lithium hydride hydrogen storage technology that offers high energy density of up to 5000 Wh/kg. Using this design framework, we identify operating conditions to maximize the life of the power supply, meet the required power output and minimize fuel consumption. We devise a series of controllers to achieve this capability and demonstrate it using a bench-top experiment that operated for 5000 h. The laboratory experiments point towards a pathway to demonstrate these fuel cell power supplies in the field. Our studies show that the proposed PEM fuel cell hybrid system fueled using lithium hydride offers at least a 3 fold reduction in mass compared to state-of-the-art batteries and 3-5 fold reduction in mass compared to current fuel cell technologies.     

加快我国抽水蓄能工程建设

电力系统需要调峰调频和备用容量设备，抽水蓄能电站是最佳选择之一。我国电力系统容量越来越大，调峰调频、提高系统设备利用率、减少能耗以及提高供电质量和安全可靠性等问题非常突出，需要加快建设抽水蓄能电站。     

Distributed control of a user-on-demand renewable-energy power-source system using battery and hydrogen hybrid energy-storage devices

A user-on-demand power source based on renewable energy requires storage devices to balance power sources and power demands because of the fluctuation of power sources like solar cells or wind power generators. The role of the control system is defined as two different tasks: allowing a power-flow imbalance between demand and power sources; and balancing the power flow inside the system. Since this control is complicated, many control methods using precise calculation of the power balance have been proposed. An analogue-like distributed control method - named “modified DC-bus signalling” - for controlling a renewable-energy power source without the need for a central processing unit is proposed. The modified DC bus signalling method discussed in this paper is composed of a DC-bus line connected with a battery, water-splitting electrochemical cell, and a fuel cell for hydrogen-energy storage via converters. The proposed control method was demonstrated to be able to control step-like and random changes in input and output power. The battery compensated high-frequency fluctuations in power demand, and the electrochemical cell and fuel cell handled the remaining low-frequency ones, which were matched to their response speeds.     

All year power supply with off-grid photovoltaic system and clean seasonal power storage

The objective of the project is an all-year secure supply of alternating current based on a solar energy island grid consisting of serial components and seasonal energy storage. Photovoltaic modules, inverters, electrolysers, batteries, hydrogen stores and fuel cells form the basis of the independent power supply system. For this, selected load profiles were analysed and evaluated in theory and practice.The analysis is based on the results of the test runs of the system and the simulations, in which the combined hydrogen-battery-system is compared to the battery system.It was revealed that it is sensible to complement an island grid operating on lead batteries for shortterm energy supply with hydrogen as a long-term store. This ensures a year-round supply security based on solar energy and the extension of the life span of the batteries required for hydrogen-based power stores. The systems based purely on batteries can not provide perfect supply security during long periods of low solar radiation since they do not possess energy stores which allow long-term energy storage.Hence a seasonal energy store, such as hydrogen, is required to guarantee reliable power supply for every day of the year.Autonomous power supply systems with long-term energy stores operate independently from the public grid system and can be implemented without elaborate intelligent energy management. For this, however, the costs of the serial components must be reduced and the efficiency of the system must be improved.