Design, performance, and cost characteristics of high temperaturesuperconducting magnetic energy storage

A conceptual design for superconducting magnetic energy storage (SMES) using oxide superconductors with higher critical temperature than metallic superconductors has been analyzed for design features, refrigeration requirements, and estimated costs of major components. The study covered the energy storage range from 2 to 200 MWh at power levels from 4 to 400 MW. A SMES that uses high temperature superconductors (HTS) and operates at high magnetic field (e.g. 10 T), can be more compact than a comparable, conventional low-temperature device at lower field. The refrigeration power required for a higher temperature unit (20 to 77 K) will be less by 60% to 90%. The improvement in energy efficiency is significant for small units, but less important for large ones. The material cost for HTS units is dominated by the cost of superconductor, so that the total cost of an HTS system will be comparable to a low temperature system only if the superconductor price in $/ampere-meter is made comparable by increasing current density or decreasing wire cost     

Research and development for steam and gas turbines in low-carbon future

Abstract

Future energy requirements for the UK will need to be met with reduced CO₂ emissions. There is a requirement for 2050 CO₂ emissions to be at 20% of 1990 levels. To achieve this there will need to be considerable investment into the research and development, and construction of renewables technologies. Despite this emphasis on renewable power, fossil fuelled power generation technologies, and in particular turbines, will still have a major role to play in the future. However, the way in which the turbines will be used may change significantly. There will therefore need to be research and development investment for turbines at all levels of technology readiness. The arguments for future R&D investment for steam and gas turbines are reviewed and some directions the R&D may need to take examined.     

HTS transformers

The paper elucidates on some of the potential systems benefits and provides an update of progress in major high-temperature superconductor (HTS) transformer development programs worldwide. It begins with background sections on earlier low-temperature-superconductor (LTS) transformer developments and on transformer losses and efficiencies and their influence on total owning costs (TOC) as one of the major drivers that may determine the success and broad acceptance of HTS transformers for power applications     

中国中长期碳减排战略目标初探(Ⅱ)——中国煤炭消费过程的碳排放及减排措施

中国能源领域排放的二氧化碳主要来自煤炭,因此煤炭消费过程中的碳减排措施尤为重要。煤炭的主要用户是发电部门,基于应对气候变化的需要,煤电行业的低碳途径不得不考虑采用CCS技术。不论是新建燃煤电厂,还是今后在传统电厂改建过程中增设CCS设施已是大势所趋,预计多数仍将采用MEA法脱除烟气中二氧化碳这一成熟技术。由于MEA法技术经济指标不够先进,估计10~20年内必将出现更先进的脱二氧化碳工艺技术。传统的燃煤锅炉增加CCS的经济效益已经逊于IGCC-CCS,预计2020年后IGCC电厂将成为新建煤电厂的首选方案。20年后采用临氢气化炉与燃料电池FC发电相结合、把高温的热能和甲烷的化学能直接转化为电力的IGFC高效燃煤电厂或将成功应用,IGFC综合能量转化效率比IGCC相对高出1/2~3/4,发展前景不可低估。钢铁、水泥和化工等高耗煤工业部门可通过节能和采用CCS技术降低碳排放,其余用煤的工业部门和分散用户则应考虑节能或用天然气等低碳燃料替代,间接起到减排效果。预计2050年燃煤发电和高耗煤工业总计将排放二氧化碳4.6Gt,如果二氧化碳捕集量是2.9Gt,则净排放量为1.7Gt。加上其他难以捕集二氧化碳的工业、部门及民用煤排放二氧化碳1.0Gt,合计二氧化碳净排放量为2.7Gt(情景A)。如果采用更先进的技术和严格的节能减排措施,可减少煤炭消耗0.31Gt标煤,减少二氧化碳排放0.5Gt,使煤源二氧化碳净排放量减少到2.2Gt(情景B)。无论哪种情景,实施CCS的任务都十分艰巨。     

Fireside issues in advanced power generation systems

Abstract

The requirements to supply increasing quantities of electricity and simultaneously to reduce the environmental impact of its production are currently major issues for the power generation industry. Routes to meeting these challenges include the development and use of power plants with ever increasing efficiencies coupled with the use of both a wider range of fuels and technologies designed to minimise CO₂ emissions. For fireside hot gas path components, issues of concern include deposition, erosion and corrosion in novel operating environments and increased operating temperatures. The novel operating environments will be produced both by the use of new fuel mixes and by the development of more complex gas pathways (e.g. in various oxyfired or gasification systems). Higher rates of deposition could significantly reduce heat transfer and increase the need for component cleaning. However, degradation of component surfaces has the potential to be life limiting, and so such effects need to be minimised. Materials and operational issues related to these objectives are reviewed.     

深海风力发电技术的发展现状与前景分析

海上风电从潮间带和近海走向深海远岸将是必然趋势。现有的机组基础型式及安装技术势必不能满足新的环境要求。漂浮式基础、整体安装及自航自升式施工平台极有可能成为未来海上风力发电的主流技术。北半球中纬度附近海域在发展深海风电方面具有独特优势及迫切需求,我国需尽早进行规划和部署相关技术及产业。     

中国燃煤发电节能技术的发展及前景

我国一次能源结构决定了发电以煤电为主的基本格局,当前国内火力发电行业需要解决的两大突出问题是高能耗和严重的环境污染。2009年全国发电机组平均供电煤耗341g/(kW.h),高于330g/(kW.h)的国际平均水平。大力发展新型高效节能性火力发电技术,对进一步提高我国火力发电机组的发电效率,减少燃煤大气污染物排放具有十分重要的意义。发达国家正积极发展更高参数的超超临界火力发电技术(600℃/700℃),我国也把"超(超)临界燃煤发电技术"列入"863计划"。可以预见,在我国近中期电力事业的发展中,会把发展更高参数的超临界技术作为火电建设的主要方向。IGCC发电技术是未来煤炭能源系统的基础,被公认为是世界上最清洁的燃煤发电技术。随着煤气化技术和燃气轮机技术的不断发展和进步,IGCC将朝着大容量、高效率、低排放的方向发展。大型直接空冷发电技术是解决我国西北部富煤贫水地区火力发电的有效手段,以2×600MW机组为例,空冷机组比湿冷机组节水约80%左右。通过对火力发电机组各系统的集成与优化,可在现有超超临界机组技术不变的情况下,最大限度地利用余热回收,提高整个机组的发电效率,从而降低煤耗,实现机组在运行过程中的节能。     

Shedding light on solar technologies—A techno-economic assessment and its policy implications

Solar power technologies will have to become a major pillar in the world's future energy system to combat climate change and resource depletion. However, it is unclear which solar technology is and will prove most viable. Therefore, a comprehensive comparative assessment of solar technologies along the key quantitative and qualitative competitiveness criteria is needed. Based on a literature review and detailed techno-economic modeling for 2010 and 2020 in five locations, we provide such an assessment for the three currently leading large-scale solar technologies. We show that today these technologies cannot yet compete with conventional forms of power generation but approach competitiveness around 2020 in favorable locations. Furthermore, from a global perspective we find that none of the solar technologies emerges as a clear winner and that cost of storing energy differs by technology and can change the order of competitiveness in some instances. Importantly, the competitiveness of the different technologies varies considerably across locations due to differences in, e.g., solar resource and discount rates. Based on this analysis, we discuss policy implications with regard to fostering the diffusion of solar technologies while increasing the efficiency of policy support through an adequate geographical allocation of solar technologies.     

Electricity's future

Economic development will continue to be dependent on the avalability of electric power and environmental concerns will play a major role in the choice of new generation technologies required to alleviate the forecasted shortages for most nations before the end of this century. Advanced technologies for the combustion of fossil fuels and splitting the atom, the predominant existing global resources for the production of power, will have to meet increasingly more stringent standards for public acceptance.     

Making carbon dioxide sequestration feasible: Toward federal regulation of CO2 sequestration pipelines

As the United States moves closer to a national climate change policy, it will have to focus on a variety of factors affecting the manner in which the country moves toward a future with a substantially lower carbon footprint. In addition to encouraging renewable energy, smart grid, clean fuels and other technologies, the United States will need to make substantial infrastructure investments in a variety of industries. Among the significant contributors to the current carbon footprint in the United States is the use of coal as a major fuel for the generation of electricity. One of the most important technologies that the United States can employ to reduce its carbon footprint is to sequester the carbon dioxide (“CO₂”) from coal-fired power plants. This article focuses on the legal and policy issues surrounding a critical piece of the necessary sequestration infrastructure: CO₂ pipelines that will carry CO₂ from where it is removed from fuel or waste gas streams to where it will be sequestered. Ultimately, this article recommends developing a federally regulated CO₂ pipeline program to foster the implementation of carbon sequestration technology.     

Hidden biases in Australian energy policy

The challenges in developing technology for the capture and storage of CO₂ from coal, oil and gas power generation, as well as those associated with the storage of nuclear waste, are widely regarded as solvable. According to proponents of clean coal, oil and gas technologies, as well as the proponents of nuclear technology, it is only a matter of time and resources to find a solution to their waste problems. Similarly, the Australian Government argues that our main efforts need to be concentrated on clean coal technologies, as well as considering the nuclear option. However, when it comes to the challenges associated with renewable energy technologies, like intermittency of wind generated grid power, storage of electricity from renewable energy and so on, there seems to be an attitude amongst Australian energy planners that these challenges represent insurmountable technical and financial problems, and will, at least in the short to medium term, prevent them from becoming a viable alternative to coal, oil, gas and uranium based energy technologies.     

Development status of superconducting motors

The article gives a brief history of the development of superconducting motors with emphasis on the use of high temperature superconductors. At present, effort is directed toward the demonstration of a 1000 hp HTS motor, the test of which will mark another significant milestone in HTS motor development. For the first time, a closed-loop refrigeration system will be used to maintain an operating temperature near 30 K for the HTS field winding. Following the conclusion of the 1000 hp HTS motor project, a 5000 hp HTS motor will be constructed and tested to demonstrate its economical viability. The progress in developing HTS motors to date is shown. The rotor for the 1000 hp motor was designed to accommodate other coils and can provide a test bed for wire developed in the future     

与景观结合的奥运森林公园并网光伏发电系统

并网光伏发电系统与奥运森林公园景观相结合,体现了"绿色奥运、科技奥运、人文奥运"三大理念,是清洁能源技术在奥运会中的应用。并网光伏发电系统设计中采用了MPPT技术、防孤岛效应技术、逆功率反送保护技术和完善的并网光伏发电系统监控技术,提高了并网光伏发电系统运行的可靠性和电网的安全性。奥运期间奥运区域供电等级提升为特级,为满足供电可靠性,示范电站采用带功率流向检测的并网模式,当并网光伏发电系统的有功功率超过指定负载的有功功率时,切断并网光伏发电系统,防止电能馈入电网。     

富氧燃烧技术研究现状及发展

富氧燃烧技术的优越性使其近年来在国内外迅速发展,为燃煤发电提供了一条切实可行的出路.就近年来国内外研究机构及其所进行的相应研究进行归纳概括,总结富氧燃烧过程中热质传输、煤粉反应和灰的生成特性.与传统空气燃烧条件作比较,提出富氧燃烧改造过程面临的问题和挑战,对亟待予以解决的技术问题做出展望.     

Impact of hydrogen energy storage on California electric power system: Towards 100% renewable electricity

Decarbonization of the power sector is a key step towards greenhouse gas emissions reduction. Due to the intermittent nature of major renewable sources like wind and solar, storage technologies will be critical in the future power grid to accommodate fluctuating generation. The storage systems will need to decouple supply and demand by shifting electrical energy on many different time scales (hourly, daily, and seasonally). Power-to-Gas can contribute on all of these time scales by producing hydrogen via electrolysis during times of excess electrical generation, and generating power with high-efficiency systems like fuel cells when wind and solar are not sufficiently available. Despite lower immediate round-trip efficiency compared to most battery storage systems, the combination of devices used in Power-to-Gas allows independent scaling of power and energy capacities to enable massive and long duration storage. This study develops and applies a model to simulate the power system balance at very high penetration of renewables. Novelty of the study is the assessment of hydrogen as the primary storage means for balancing energy supply and demand on a large scale: the California power system is analyzed to estimate the needs for electrolyzer and fuel cell systems in 100% renewable scenarios driven by large additions of wind and solar capacities. Results show that the transition requires a massive increase in both generation and storage installations, e.g., a combination of 94 GW of solar PV, 40 GW of wind, and 77 GW of electrolysis systems. A mix of generation technologies appears to reduce the total required capacities with respect to wind-dominated or solar-dominated cases. Hydrogen storage capacity needs are also evaluated and possible alternatives are discussed, including a comparison with battery storage systems.     

The path of the smart grid

Exciting yet challenging times lie ahead. The electrical power industry is undergoing rapid change. The rising cost of energy, the mass electrification of everyday life, and climate change are the major drivers that will determine the speed at which such transformations will occur. Regardless of how quickly various utilities embrace smart grid concepts, technologies, and systems, they all agree onthe inevitability of this massive transformation. It is a move that will not only affect their business processes but also their organization and technologies.     

The production of electricity,heat and hydrogen with the thermal power plant in combination with alternative technologies

Alternative technologies in combination with thermal power plant allow the production of heat, electricity and hydrogen using renewable energy sources in combination with gas or coal, as a very important energy source in traditional energy engineering in Slovenia. The technologies aim, inter alia, to reduce greenhouse gas emissions, increase the use of renewable energy sources and take a step forward to the production of hydrogen as an alternative energy source in numerous applications. In view of the estimated demand for heat, electricity and hydrogen in the Savinja-?alek region, Slovenia, the technologies to meet such demand are proposed in this article from a technical perspective. An energy and economic analysis of the operation of the Thermal Power Plant (TPP) will be done. The TPP is operating in a variable operating regime. The possibility of stationary operation of the power plant will be analysed, the surplus of produced electricity will be used for the hydrogen production. The process is based on the Rankine-Clausius cycle (RC) with dual superheating using water or steam as the working media. The idea in this article, is to generate in the above mentioned facility as much hydrogen, heat, cold and electricity as needed by the Savinja-?alek region in industry, transport, etc. Thus, the power plant could operate optimally, constantly at 100% of power, which would allow simultaneous production of electricity, heat and hydrogen. Hydrogen could be used for sale on the market or for the electricity production or for heating. Hydrogen could be produced via electrolysis or thermochemical process. In the second part of article, the analysis of RC with concentrated solar energy and wood chips was analysed.     

Optimized thermal coupling of micro thermoelectric generators for improved output performance

There is a significant push to increase the output power of thermoelectric generators (TEGs) in order to make them more competitive energy harvesters. The thermal coupling of TEGs has a major impact on the effective temperature gradient across the generator and therefore the power output achieved. The application of micro fluidic heat transfer systems (μHTS) can significantly reduce the thermal contact resistance and thus enhance the TEG's performance. This paper reports on the characterization and optimization of a μTEG integrated with a two layer μHTS. The main advantage of the presented system is the combination of very low heat transfer resistances with small pumping powers in a compact volume. The influence of the most relevant system parameters, i.e. microchannel width, applied flow rate and the μTEG thickness on the system's net output performance are investigated. The dimensions of the μHTS/μTEG system can be optimized for specific temperature application ranges, and the maximum net power can be tracked by adjusting the heat transfer resistance during operation. A system net output power of 126 mW/cm² was achieved with a module ZT of 0.1 at a fluid flow rate of 0.07 l/min and an applied temperature difference of 95K.It was concluded that for systems with good thermal coupling, the thermoelectric material optimization should focus more on the power factor than on the figure of merit ZT itself, since the influence of the thermal resistance of the TE material is negligible.     

Progress in beam-down solar concentrating systems

Concentrating solar technologies are promising renewable energy systems for exploiting incident beam solar irradiation with high exergy efficiency values. These systems provide the possibility for producing useful heat at high temperatures that can be utilized by highly efficient power cycles or producing directly solar fuels with receiver reactor technology. In the last years, the concept of beam-down concentrating solar technology gains more and more attention due to a series of advantages associated with this idea. This concept is based on the use of two-stage reflectors for concentrating solar irradiation close to the ground, something that leads to a more compact system with reduced height. Furthermore, the high-temperature heat production and the chemical processes take place on the ground and not at a great height, increasing the safety levels of the system. Moreover, this design leads to compact configurations with lower materials use, lower wind loads and without the need to move the receiver for tracking the sun.The objective of this review is to present the recent progress on beam-down solar concentrating technology and to highlight the need for giving attention to this direction. Critical advantages of this technology are demonstrated and the associated limitations are discussed. The emphasis is on the presentation of the different technologies that can be coupled with the beam-down technology. Thermodynamic power cycles (Brayton, Rankine and Stirling), photovoltaics, thermochemical processes, as well as other applications are included and discussed. Practically, power production and solar fuels are the major useful outputs that can be generated by beam-down solar concentrating configurations. The reviewed technologies are critically discussed and compared in terms of energy, economic and environmental aspects. Future steps in the field are suggested based on the existing literature.     

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.