Self-control system in storage unit of PV plants

A new system for self-controlling of storage batteries being charged by PV plants has been developed. This provides enhanced system reliability, lower system cost, and simpler operation for the user. In this system, the only requirement is to design and select PV panels so that their voltage-sensitive region (on the I–V curve) coincides with that required for a simple remote PV plant and for long periods.     

微网孤网经济运行研究

建立了含冷热电联产系统的微网经济性数学模型,并将环保因素考虑在内,采用改进的遗传算法对微网孤网的经济调度进行了仿真计算。结合含多种微源的微网案例,给出了微网孤网运行时的具体调度方案,研究结果表明,该模型可有效应用于微网孤网的经济运行特性研究,同时结果显示蓄电池组的优化调度可减少系统的综合运行成本。     

Performance and development of PV - plant for water pumping and desalination for remote area in Saudi Arabia

PV plant for water pumping and desalination in remote area has been implemented; the plant was the first of its kind in Saudi Arabia. The design of PV plant was based on the specification of the site, the depth and quality of water, the daily water quantity produced and the autonomy period of the plant during cloudy conditions as well as other local climatic conditions. The plant has two main PV separate systems, first, PV water pumping system which is characterized by storing the water in two storage tanks and without electric energy storage, second, PV system for the operation of the reverse osmosis unit (water desalination), this system is characterized by the storage of electric energy (batteries). The storage batteries are used to supply the required electric power to the equipment in the plant, during night and cloudy weather. The batteries capacity is designed to be sufficient for 5 days autonomy. In order to make the operation and maintenance of the PV plant highly reliable, the design is based on the selection of equipment which are commonly available in the local market. The head of the submersible pump is 50 m from surface level, and the amount of water production from Reverse Osmosis Unit is about 600 liters per hour. The total installed PV capacity for pumping system is 980 Wp, and for desalination system is 10. 89 kWp.     

Simulations of economical and technical feasibility of battery and flywheel hybrid energy storage systems in autonomous projects

This paper deals with the feasibility of a Renewable Energy Sources (RES)-based stand-alone system for electricity supply based on a Flywheel Energy Storage System (FESS) located on the Greek Island of Naxos. The innovative use of flywheels in parallel connection with electrochemical batteries, as an integrated storage device in the same power plant, was selected to be simulated as it is a necessary buffer covering the load of a typical house. The optimal configuration for the electromechanical connection between the electrochemical batteries and flywheels is also considered in this study. Operational characteristics of the new storage systems were estimated and used in the simulations, while the financial aspects of the projects finalized using hand-made calculations and the HOMER software was used only for the energy calculations. It was found that an off-grid project using advanced and totally “green” technologies is possible and comparable to more conventional RES-based systems, in terms of energy and economical feasibility. Finally, it can be concluded that systems with low price flywheels are equivalent to those with electrochemical batteries.     

15 Years of R&D in central solar heating in Denmark

Danish R&D activities during the last two decades in the field of Central Solar Heating Plants and Thermal Energy Storage Technologies are presented. The most relevant central solar heating plants (CSHPs), with and without seasonal storage, are examined and essential experiences highlighted. The Saltum and Ry plants represent the type of CSHPs with preheating the return stream of a district heating net and no storage involved. The Marstal plant represents an alternative approach, connecting the CSHP to the delivery pipe for summer operation. Here the plant involves short-term storage and the application of variable flow that lead to novelties in the control strategy. The plant is described and experiences are analysed. The presented cases show that the technology, under special conditions, can be economically competitive with other heating technologies. Under normal conditions, public funding and acceptance of higher energy price are necessary. Further technical development and push towards a market is required. Especially the development of economical storage technologies is decisive. Work with steel tanks, concrete tanks, aquifer storage, bore hole storage and most importantly, from a Danish view, pit water storage is presented and conclusions are drawn. R&D in the field of CSHPs call for international co-operation, knowledge transfer and not least financing. The structural and political climate that shapes the boundaries of the R&D activities and also makes up the dominant barrier for the dissemination of CSHPs is discussed. Conclusions are drawn and future work outlined.     

Economic prospects for the application of new electric energy storage devices

The technical and economic properties of new storage devices for electric energy such as batteries, hydrogen storage systems, flywheels, steam storage plants and compressed air storage facilities are compared with conventional peak power plants such as gas turbines and hydroelectric storage systems. The analysis shows that batteries, steam storage plants and compressed air storage facilities may be economically competitive with conventional peak power devices. Batteries are especially appropriate for dispersed energy storage systems.Utilization of storage devices instead of gas turbines results in substitution of oil or natural gas by coal or nuclear fuel.     

基于加速寿命试验的锂离子电池可靠性分析方法

为了有效地提高锂离子电池寿命评估的准确性,延长储能系统在配电网中运行年限,文章提出了基于加速寿命试验的锂离子电池可靠性分析方法。综合考虑不同放电深度对锂离子电池寿命影响,建立了锂离子电池的寿命衰退模型;确定了荷电状态(SOC)与健康度(SOH)的关联特性关系;提出了基于逆幂率方程的储能系统加速寿命试验方法;基于情景分析法对锂离子电池的可靠性进行了分析。研究结果表明,文章所提出的试验方法能够准确地对不同运行状态下的锂离子电池储能系统进行可靠性评估,保证储能系统并网运行过程中的调控准确性。     

An ultracapacitor circuit for reducing sulfation in lead acid batteries for Mild Hybrid Electric Vehicles

The nickel metal hydride (NiMH) batteries used in most hybrid electric vehicles (HEVs) provide satisfactory performance, but are quite expensive. In spite of their lower energy density, lead acid batteries would be much more economical except they are prone to sulfation in HEV applications. However, sulfation can be greatly reduced by a circuit that uses an ultracapacitor in conjunction with the battery. The resulting system will provide much cheaper energy storage if ultracapacitor prices can be reduced to levels predicted by some manufacturers.     

Research progress on fre protection technology of LFP lithium-ion battery used in energy storage power station

随着电化学储能市场的蓬勃发展,电化学储能电池本身的安全性越来越受到关注,如何最大程度地降低储能电池组火灾风险是电化学储能大规模应用时亟需解决的问题。本文综述目前国内外针对锂离子电池热失控已有的研究成果,包括磷酸铁锂电池的燃烧特性、火灾危险等级以及在储能电站预警系统中应用的锂离子电池热失控及热扩散参数;梳理不同灭火剂对电池火灾的灭火效率;同时总结电化学储能电站的灭火系统选择,为电网储能工程应用提供参考,有效支持锂离子储能电池的大规模工程需求。     

Using next generation nuclear power reactors for development of a techno‐economic model for hydrogen production

Nuclear and hydrogen are considered to be the most promising alternatives energy sources in terms of meeting future demand and providing a CO?‐free environment, and interest in the development of more cost‐effective hydrogen production plants is increasing—and nuclear‐powered hydrogen generation plants may be a viable alternative. This paper is a report on investigating the application of new generation nuclear power plants to hydrogen production and development of an associated techno‐economic model. In this paper, theoretical and computational assessments of generations II, III+, and IV nuclear power plants for hydrogen generation scenarios have been reported. Technical analyses were conducted on each reactor type—in terms of the design standard, fuel specification, overnight capital cost, and hydrogen generation. In addition, a theoretical model was developed for calculating various hydrogen generation parameters, and it was then extended to include an economic assessment of nuclear power plant‐based hydrogen generation. The Hydrogen Economic Evaluation Program originally developed by the International Atomic Energy Agency was used for calculating various parameters, including hydrogen production and storage costs, as well as equity, operation and maintenance (O&M), and capital costs. The results from each nuclear reactor type were compared against reactor parameters, and the ideal candidate reactor was identified. The simulation results also verified theoretically proven results. The main objective of the research was to conduct a prequalification assessment for a cogeneration plant, by developing a model that could be used for technical and economic analysis of nuclear hydrogen plant options. It was assessed that high‐temperature gas‐cooled reactors (HTGR‐PM and PBR200) represented the most economical and viable plant options for hydrogen production. This research has helped identify the way forward for the development of a commercially viable, nuclear power‐driven, hydrogen generation plant.     

The dismantling of the spent alkaline zinc manganese dioxide batteries and the recovery of the zinc from the anodic material

The existing plants for the recovery of exhausted alkaline zinc manganese dioxide batteries adopt an initial heat treatment and then a grinding. The last operation intermixtures the components of the batteries and consequently the successive recovery process proves to be rather complicate and needs a large scale plant. An initial dismantling and separation of the anodic, cathodic and packing components allow a successively easier recovery process and a small scale plant. This possibility has been assumed in this work and a simple recovery process has been proposed for the anodic material, consisting of an initial leaching step to separate and recover the unconverted metallic zinc and a successive step of cathodic deposition to recover the converted ionic zinc. A highly efficient zinc recovery has been obtained at the cathodic deposition step by adopting a heat treatment of the anodic material before its leaching process.     

Optimal flow of regional forest biomass to a district heating system

There has been a growing interest in utilizing forest biomass for energy generation in district heating systems to reduce dependence on fossil fuels. However, variability in forest biomass availability and quality over time and its complex and costly supply chain have made investments in forest biomass energy generation projects less attractive. In this paper, a linear programming model is developed to minimize the delivery cost of forest biomass to the gate of heating plants and determine the optimal monthly flow of biomass to the plants. The model has a 1‐year planning horizon with monthly time steps. It determines (1) the amount of woodchips that should be transported to the plants from supply sources directly and through the terminal storages, (2) the amount of biomass that should be stored at supply sources and at terminal storages, and (3) the amount of biomass that should be chipped at supply sources and at terminal storages. The model was applied to a potential district heating system in Williams Lake, BC, Canada. The results of the optimization model indicated that it would not be economical to carry out the chipping process at the terminal storage. Biomass should be chipped at supply sources, and woodchips should be sent to the terminal storage and/or directly to the plant. Of the total optimum annual flow of woodchips to the plant, 90% is transported directly, while 10% is transported to the plant via the terminal storage. It would cost $43.38 Odt^?1 to deliver forest biomass to the plant. Copyright © 2013 John Wiley & Sons, Ltd.     

聚变发电站总平面布置优化

  目的  在中国聚变工程试验堆(CFETR)的概念设计过程中，厂区总平面布置意义重大，通过对厂区总平面布置面临的储能系统和布置进行比较，初步探索聚变发电厂厂区总平面的布置方案。  方法  根据聚变发电厂工艺流程、储能技术路线及储热介质的分析、研究，通过组合储能方式和布置形成了四种方案，进行了技术经济对比。  结果  熔融盐储能经济优势突出，但高温腐蚀问题对核电站安全运行影响较大，导热油方案则刚好相反。提出的储能区与核岛、常规岛的三角形布置或串联布置方案均符合总平面布置要求，并且能很好地满足全厂热力系统及储能系统热力运行流向。  结论  储能技术路线及储能区的布置是影响聚变发电厂布置的关键因素，提出的布置方案均能很好地适应新增加的储能系统热力运行，为后续聚变发电厂总平面布置提供参考。     

电站锅炉运行参数对经济性的影响

本文针对某电站锅炉,进行了燃烧调整试验,分析了运行参数对锅炉效率的影响,提出了合理的运行工况。为电站锅炉经济运行提供参考。     

Dynamic simulation of air storage–based gas turbine plants

Cavern storage is a proven energy storage technology, capable of storing energy in the form of compressed air inside a cavern. The Huntorf plant and the Alabama plants use this technology to store electrical energy during the off‐peak load hours by compressing the air inside a cavern and then using this compressed air during gas turbine operation to generate electricity during peak load demand hours. The advantage of doing this is that it increases the efficiency of gas turbine operation while meeting the grid generation and the load balance. The operation of a typical compressed air energy storage (CAES)–based gas turbine plant involves the operation of several components, including the compressor, the cavern storage, the combustor, the turbine, and so on. The dynamics of the plant as a whole depends on the performance of the individual components. The focus of this article is to develop a Simulink‐based models for each of the individual components, which can then be assembled appropriately to design an entire CAES plant. As an illustration, a case study for the Huntorf CAES plant is presented with the developed models. A typical daily operation of the Huntorf plant is simulated and compared with the reported Huntorf plant data. The model accurately captures the reported dynamics of the cavern storage. In addition, the reported quantities like the compressor power consumption, the turbine power generation, and the temperature at different junctions of the CAES plant match well with the simulated results. Copyright © 2011 John Wiley & Sons, Ltd.     

Design of hybrid power-to-power systems for continuous clean PV-based energy supply

The increasing penetration of intermittent renewable sources, fostering power sector decarbonization, calls for the adoption of energy storage systems as an essential mean to improve local electricity exploitation, reducing the impact of distributed power generation on the electric grid. This work compares the use of hydrogen-based Power-to-Power systems, battery systems and hybrid hydrogen-battery systems to supply a constant 1 MW_el load with electricity locally generated by a photovoltaic plant. A techno-economic optimization model is set up that optimizes the size and annual operation of the system components (photovoltaic field, electrolyzer, hydrogen storage tanks, fuel cell and batteries) with the objective of minimizing the annual average cost of electricity, while guaranteeing an imposed share of local renewable self-generation. Results show that, with the present values of investment costs and grid electricity prices, the installation of an energy storage system is not economically attractive by itself, whereas the installation of PV panels is beneficial in terms of costs, so that the baseline optimal solution consists of a 4.2 MW_p solar field capable to self-generate 33% of the load annually. For imposed shares of self-generation above 40%, decoupling generation and consumption becomes necessary. The use of batteries is slightly less expensive than the use of hydrogen storage systems up to a 92% self-generation rate. Above this threshold, seasonal storage becomes predominant and hybrid storage becomes cheaper than batteries. The sale of excess electricity is always important to support the plant economics, and a sale price reduction sensibly impacts the results. Hydrogen storage becomes more competitive when the need for medium and long terms energy shift increases, e.g. in case of having a cap on the available PV capacity.     

Potential for flexible operation of pulverised coal power plants with CO2 capture

Abstract

Fossil-fired plants play an important role in electricity networks as mid-merit plants that can respond relatively quickly to changes in supply and demand. As a consequence, they are required to operate over a wide output range and play an important role in maintaining the quality and security of electricity supply by providing response and reserve capacity. Carbon dioxide capture and storage (CCS) has been identified as a critical technology for future electricity generation from coal in the UK. Although the performance of CCS schemes where CO₂ capture plants are operated at full load has been considered in detail, part load performance is less well understood. Developing a better understanding of part load performance of plants operating with CO₂ capture is crucial in determining their suitability to operate as mid-merit plants. This paper presents an assessment of the potential impact of adding post-combustion CO₂ capture at pulverised-coal power plants. Estimated performance of steam cycles working with post-combustion CO₂ capture plant are presented at full and part load, leading to performance predictions for pulverised-coal power plants operated over a range of loads and with varying levels of CO₂ capture. By adjusting the operation of the capture plant, as well as the boiler/steam cycle, an extended range of operation can be achieved including lower minimum stable generation levels and additional 'pumped storage like' capacity for times of high demand. For example, plant operators can alter the energy penalty for the CO₂ capture plant with an associated change in plant output by reducing the level of CO₂ capture. This can allow extra electricity to be generated and sold when electricity prices are high. With solvent storage it should also be possible to increase power plant output for a number of hours, but without associated increases in CO₂ emissions.     

Independent thermal storage power station with molten salt:Technology and evaluation

储能电站可解决可再生能源间歇性和不稳定性的问题,满足常规电力系统和区域能源系统效率,安全性和经济性的迫切需要.本文提出了一种新的蓄热电站技术----独立熔盐蓄热电站,进行了独立熔盐蓄热电站原理的介绍,概念设计和技术经济评价.结果表明:独立熔盐蓄热电站初期投资很低,仅为6152.88元/kW,投资回收期短,在3年以内.独立熔盐蓄热电站占地面积小,可建在城市中实现热电联供,总能效率可由单纯发电的30%提高到80%以上.     

电站锅炉直吹式制粉系统的节能实践

针对珠啤热电厂锅炉制粉系统进行的改造和调整试验,对制约制粉系统经济性的因素进行了分析,并提出了改进措施,可为配有E型中速磨煤机直吹式制粉系统的电站锅炉经济运行提供参考。     

Advancements in the Field of Direct Steam Generation in Linear Solar Concentrators—A Review

Direct steam generation in parabolic trough or linear Fresnel collectors represents one interesting technological option for concentrating solar electricity production. Today's state of the art characterized by the first commercial plants in operation is a result of more than 20 years of intensive research on this topic. This article provides a review on the key results from research that includes physical effects like heat transfer and pressure drop in horizontal boiler tubes, plant layout considerations, and thermal storage options. An overview on test and demonstration facilities as well as on commercial plants is given, leading to an outlook on the next generation of direct steam generation systems.