Distributed generation: Semantic hype or the dawn of a new era?

As the electric utility industry continues to restructure, driven both by rapidly evolving regulatory environments and by market forces, the emergence of a number of new generation technologies also profoundly influences the industry's outlook. While it is certainly true that government public policies and regulations have played a major role in the rapidly growing rate at which distributed generation is penetrating the market, it is also the case that a number of technologies have reached a development stage allowing for large-scale implementation within existing electric utility systems. At the onset of any discussion related to distributed generation, one question begs to be answered: is the fact that electric power producing facilities are distributed actually a new and revolutionary concept? Have power plants not always been located across broad expanses of land? The answer to these questions clearly is that electric power plants have always been sited all across the service territories of the utilities owning them. Hence, the opening question: as with many so-called innovations that have been put forward during the recent past, is the entire concept of distributed generation a simple semantic marketing hype or are we actually at the dawn of a new electric power generation era? We believe that a new electric power production industry is emerging, and that it will rely on a broad array of new technologies. This article sets the stage for distributed generation covering such topics as: the present power production situation; what distributed generation is; capability ratings and system interfaces; market penetration of internal combustion engine generators, fuel cells and microturbines; potential generation mix issues, network considerations including power quality, reactive power coordination, reliability and reserve margin, reliability, network redundancy, safety and accountability; public policy and regulatory impact; and standards.     

Investors’ reaction to the government credibility problem: A real option analysis of emission permit policy risk

In relation to creating a CO₂ emission permit market, there are two types of climate change policy risks: (1) It is uncertain whether and when a cap-and-trade system will be implemented; and (2) once a policy is in place, there may be government credibility issues. This paper examines the effect of these policy risks on real option decisions of electric power plant investment. To model both an investment decision and generation flexibility, this study evaluates an exotic compound American option on multiple strips of European spread options through the implementation of least squares Monte Carlo simulation. Government credibility risk leads to more investment in “less green” resources and induces additional cash flow variation, which increases the average time to investment (value of waiting). However, in an extreme case, government credibility can actually hasten investment because the risk may be more favorable to electric power companies. Furthermore, if emission trading is planned to be implemented in the future (e.g., 2020), and the market believes that the probability of successful implementation is low, firms will build a “less green” plant early to benefit from the period before the green rule is applied.     

Evacuation infrastructure for new generating station: Options available in Indian context

Facing a deficit of 9% in power generation, India needs to harness all forms of generation including renewable energy (RE) which presently contributes less than 8% to total generation capacity. To increase the same, concerns of RE developers are being addressed by the government and regulatory bodies. One such concern is availability of transmission grid for evacuation of power. Transmission lines required for power evacuation from RE generators are typically not included in their network plan by the transmission utility. Considering the financial health and underperformance of these utilities, even if the required transmission lines are included in the network plan, RE developers are uncertain and unsure of the timely execution of the plan. Ministry of Power has earlier notified guidelines [Government of India, Ministry of Power, 2006a. Resolution on tariff based competitive-bidding guidelines for transmission service; Government of India, Ministry of Power, 2006b. Resolution on guidelines for encouraging competition in development of transmission projects] for enabling private sector participation in transmission to enable the private developers to build the required evacuation infrastructure. This paper evaluates the options available as per the legislative and regulatory framework in India through which the evacuation infrastructure for the RE projects can be built by the transmission utility or the potential investors. The key concept of “dedicated transmission line”, which has been a keenly debated and often a misunderstood issue, is also discussed in great detail.     

Capacity payment impact on gas-fired generation investments under rising renewable feed-in — A real options analysis

We assess the effect of capacity payments on investments in gas-fired power plants in the presence of different degrees of renewable energy technology (RET) penetration. Low variable cost renewables increasingly make investments in gas-fired generation unprofitable. At the same time, growing feed-in from intermittent RETs amplifies fluctuations in power generation, thus entailing the need for flexible buffer capacity—currently mostly gas-fired power plants. A real options approach is applied to evaluate investment decisions and timing of a single investor in gas-fired power generation. We investigate the necessity and effectiveness of capacity payments. Our model incorporates multiple uncertainties and assesses the effect of capacity payments under different degrees of RET penetration. In a numerical study, we implement stochastic processes for peak-load electricity prices and natural gas prices. We find that capacity payments are an effective measure to promote new gas-fired generation projects. Especially in times of high renewable feed-in, capacity payments are required to incentivize peak-load investments.     

燃料电池发电的电站应用

燃料电池作为一种高效稳定的分布式清洁能源,其发电技术在电站领域的应用备受关注,而国内燃料电池电站尚在起步阶段,因此对这一领域的研究和实践经验具有重要意义。基于韩国燃气轮机联合循环电站中燃料电池发电项目的实施,介绍了燃料电池的选型,并通过模拟运行确定了最佳余热回收方案。MCFC燃料电池额定发电效率为47%,余热回收后效率提高3.5%。这些经验将对国内未来燃料电池电站的建设起到参考和借鉴意义。     

Investment risks under uncertain climate change policy

This paper describes results from a model of decision-making under uncertainty using a real options methodology, developed by the International Energy Agency (IEA). The model represents investment decisions in power generation from the perspective of a private company. The investments are subject to uncertain future climate policy, which is treated as an external risk factor over which the company has no control. The aims of this paper are to (i) quantify these regulatory risks in order to improve understanding of how policy uncertainty may affect investment behaviour by private companies and (ii) illustrate the effectiveness of the real options approach as a policy analysis tool. The study analysed firms’ investment options of coal- and gas-fired power plants and carbon capture and storage (CCS) technologies. Policy uncertainty is represented as an exogenous event that creates uncertainty in the carbon price. Our findings indicate that climate policy uncertainty creates a risk premium for power generation investments. In the case of gas- and coal-fired power generation, the risk premium would lead to an increase in electricity prices of 5–10% in order to stimulate investment. In the case of CCS, the risk premium would increase the carbon price required to stimulate investment by 16–37% compared to a situation of perfect certainty. The option to retrofit CCS acts as a hedge against high future carbon prices, and could accelerate investment in coal plant. This paper concludes that to minimise investment risks in low carbon technologies, policy-makers should aim to provide some long-term regulatory certainty.     

保障安全、优化结构,促进上海市电力发展

对《上海市电力发展"十二五"规划》进行了解读,总结了"十一五"期间上海市电力发展的成果和存在的问题,分析了"十二五"期间上海电力产业面临的严峻形势,即电力格局调整,保电压力大,调峰压力将进一步增加,受资源环境约束新建电厂困难,电价上涨压力增加。因此,创新驱动、转型发展,将是‘十二五’时期上海电力发展的必然选择,保障电力供应安全、推进电源结构低碳化和实现城市电网智能化,将成为"十二五"上海市电力转型发展的工作重心。     

地热发电的投资经济分析

地热能是一种清洁的可再生能源,越来越多的国家宣布支持地热开发。地热发电必须考虑到影响成本的各种因素,地热发电的成本主要由初始投资和电力生产运行及维护成本两部分组成。地热项目具体的投资成本与资源特征和现场条件有着非常密切的关系,资源的温度、深度、化学特性和渗透性是影响发电成本的主要因素。与传统化石燃料发电相比,地热发电已具有相当的竞争力,在生命周期内地热发电厂的平均成本大大低于传统燃料发电厂。另外,地热发电还有抵消化石燃料价格波动对电力市场影响的作用,有利于促进农村和偏远地区经济发展,有利于能源供应多元化。当然,地热能发展也面临着一些障碍,包括钻井的成功率、地热技术尚不够完善以及项目启动成本高等。建议今后地热资源的利用不再仅局限于极少数高温地热项目中,而是尽可能发掘地热资源的所有潜力。     

Grandfathering and coal plant emissions: the cost of cleaning up the Clean Air Act

The Clean Air Act imposes much stricter emission limits on new coal-burning power plants than on older ones — a practice that has no obvious theoretical justification. Elimination of “grandfather rules”, i.e., applying new plant standards to the US electric industry as a whole, would eliminate 40% of nationwide SO₂ emissions and 15% of NO_X emissions, while raising average retail electricity rates by only 4%. Under this scenario, 94% or more of existing coal plants would remain economically competitive with new gas-fired power plants. Policy options for elimination of grandfathering include: an explicit requirement that each existing plant meet new-plant standards; a “cap and trade” system of emission allowances similar to the current SO₂ trading system; and a generation performance standard, an interesting new variant on emissions trading which incorporates a more equitable and flexible allocation of allowances.     

Economics of electric power generation options and sulfur oxide emission control

By the use of spreadsheet techniques, a simple but versatile program has been developed for analyzing the economics of electric power generation for all types of plants. The incentives for various power-generation options are quantified.The impact of SO_x, emission control using flue-gas desulfurization (FGD) on power cost is about $0.013/kWhr for plants with a load factor of 0.7 and represents 20% of the power cost. It is shown that use of an aged plant is more economical than of a new plant equipped with FGD to meet the SO_x emission regulations, even though continued use of old plants defeats measures for environmental improvement. With the current price structures, continued use of an aged, oil-fired, steam-electric plant is economically attractive, and a natural gas combined-cycle electric plant may now be economically viable.     

Future security of power supply in Germany—The role of stochastic power plant outages and intermittent generation

Many power plants in Germany and Europe are approaching the end of their technical lifetime. Moreover, the increasing wind and solar power generation reduces the operation times of thermal power plants, making future investments in new generation capacity uncertain under current market conditions. Consequently, the future development of security of power supply is unclear. In this paper, we assess the impact of stochastic fluctuations in power plant availability, renewable generation, and grid load on the future security of supply in Germany. We model variations in power plant availability by application of a combined Mean‐reversion Jump‐diffusion approach. On the basis of that and using Monte‐Carlo methods, we simulate 300 different time series of availability. These profiles are fed into the fundamental power system model REMix, applied to evaluate the appearance of supply shortfalls in hourly resolution. We assess 6 scenarios for the year 2025, differing in renewable generation and demand profiles, as well as grid infrastructure. Geographical focus of the analysis is Germany, but the electricity exchange with its European neighbours is modelled as well. Our results show that the choice of the power plant availability profile can change the loss of load expectation and loss of load hours by up to 50%. However, the influence of load and renewable generation profiles is found to be significantly higher. Assuming that no new conventional power plants are built and existing plants are decommissioned at the end of their empirical lifetime, we identify supply gaps of up to 2.7 GW in Germany.     

Introducing OTEC to mainland utilities

The adoption of advanced technology by a large electric utility must be preceded by a lengthy assessment process involving cost, performance, reliability, technology availability, environmental impact, legal, institutional, and other factors. Over the past 25 years, the most important technological development to take place in the electric utility business has been that of nuclear power generation. This technology, though proven technically, has encountered significant problems. The time to site and construct a nuclear plant has grown because of environmental and regulatory restrictions. The absence of a national policy with respect to nuclear waste disposal and fuel recycling has created what appears to utility planners to be a very unfavorable political environment. For these and other reasons, the capital cost of nuclear plants has been steadily increasing and utility managements have begun to look to other fuel technologies such as coal.In this paper, we examine the major factors which a large utility considers in evaluating any potentially important new energy system. Briefly, we review U.S. electric utility experience with technological innovation and identify the major problem areas facing industry from one utility's point of view. We then discuss the feasibility and appeal of ocean thermal energy conversion (OTEC) technology and describe the steps which one utility executes in determining the need for new capacity and the planning process which results in the construction and operation of a new plant. These steps are then applied to OTEC.Tentatively, we have concluded that the current U.S. Government OTEC program leaves OTEC an unlikely candidate for meaningful U.S. mainland applications within the century. We recommend a specific development strategy which will produce performance and cost data needed by potential investors in, and by operators of, electric utilities.     

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.     

我国电力用煤效率分析及改进措施

电力工业一直是我国主要的耗煤大户,煤炭消费量超过总消费量的50%。本文分析了我国煤炭消费状况、电力用煤的趋势、电力用煤的效率等,重点讨论的是电力用煤效率的改进措施问题,包括机组容量优化、电源结构调整、风电开发、水电开发、核电开发等。     

国标《塔式太阳能光热发电站设计标准》关键共性技术

      目的     塔式光热发电是我国首批太阳能热发电示范项目的主流型式。为了促进科技进步,推动产业发展,有必要对塔式光热发电站的设计进行规范。      方法     在总结分析塔式光热发电站设计经验的基础上,对光热发电设计的共性原则和关键技术进行了研究,给出了适用范围、规模划分、设计寿命等共性原则,重点研究了太阳能资源评估、集热系统与设备、储热系统与设备、自动化系统等关键技术方案。      结果     确定了塔式光热发电站的主要设计方案,给出了发电量估算方法,制定了世界首部太阳能光热发电设计标准《塔式太阳能光热发电站设计标准》。标准为国内塔式光热发电项目的开发、建设和运行提供了技术支撑,其主要内容已经上升为国际标准IEC62862-4-1《塔式太阳能光热发电站设计总体要求》。      结论     标准可对塔式光热发电站的设计提供指导。     

Changing Sunshine: Analyzing the dynamics of solar electricity policies in the global context

Although solar costs have been dropping in recent years, solar power is still more expensive than conventional and other renewable energy options, and in most applications solar power still needs continuing government policy support. However, the need to achieve multiple objectives and ensure sufficient political support for solar power makes it difficult for policy makers to design an optimal solar power policy. The dynamic and uncertain nature of the solar industry, combined with the constraints imposed by broader economic, political and social conditions further complicates the task of policy making. In this paper, we present a framework to critically analyze the objectives behind different country policies, how factors such as macro-economic conditions and development paradigms affect the policy outcomes and finally, how these outcomes affect the overall cost reduction of solar energy. We find that while the extent of cost reduction through creation of large demand remains to be seen, it is essential for governments to provide adequate support for leapfrog RD&D, and exploit real comparative advantages across countries for effective solar cost reduction. Policy makers need to optimally design their policies by balancing national objectives and paying capacity with the global objective of solar power cost reduction in order to realize its full potential.     

新型负荷接入环境下的配电网分布式电源规划

随着电动汽车以及储能技术的不断成熟,电动汽车及储能设备等新型负荷的不确定性给分布式电源接入配电网的规划工作带来了新的挑战。基于机会约束,建立了一种考虑新型负荷特性的配电网分布式电源规划模型,该模型既包括电动汽车与储能设备等新型负荷,也包括分布式风电、光伏发电等典型分布式电源,并应用概率潮流和遗传算法对模型进行求解。对IEEE33节点测试系统的测试结果表明,接入新型负荷后系统不确定性增强、总体收益有所下降,验证了所建立的电源规划模型处理负荷及分布式电源不确定性问题的可行性。     

Decentralised optimisation of cogeneration in virtual power plants

Within several projects we investigated grid structures and management strategies for active grids with high penetration of renewable energy resources and distributed generation (RES & DG). Those ”smart grids” should be designed and managed by model based methods, which are elaborated within these projects. Cogeneration plants (CHP) can reduce the greenhouse gas emissions by locally producing heat and electricity. The integration of thermal storage devices is suitable to get more flexibility for the cogeneration operation. If several power plants are bound to centrally managed clusters, it is called “virtual power plant”. To operate smart grids optimally, new optimisation and model reduction techniques are necessary to get rid with the complexity.There is a great potential for the optimised management of CHPs, which is not yet used. Due to the fact that electrical and thermal demands do not occur simultaneously, a thermally driven CHP cannot supply electrical peak loads when needed. With the usage of thermal storage systems it is possible to decouple electric and thermal production. We developed an optimisation method based on mixed integer linear programming (MILP) for the management of local heat supply systems with CHPs, heating boilers and thermal storages. The algorithm allows the production of thermal and electric energy with a maximal benefit. In addition to fuel and maintenance costs it is assumed that the produced electricity of the CHP is sold at dynamic prices. This developed optimisation algorithm was used for an existing local heat system with 5 CHP units of the same type. An analysis of the potential showed that about 10% increase in benefit is possible compared to a typical thermally driven CHP system under current German boundary conditions. The quality of the optimisation result depends on an accurate prognosis of the thermal load which is realised with an empiric formula fitted with measured data by a multiple regression method.The key functionality of a virtual power plant is to increase the value of the produced power by clustering different plants. The first step of the optimisation concerns the local operation of the individual power generator, the second step is to calculate the contribution to the virtual power plant. With small extensions the suggested MILP algorithm can be used for an overall EEX (European Energy Exchange) optimised management of clustered CHP systems in form of the virtual power plant. This algorithm has been used to control cogeneration plants within a distribution grid.     

Critical success factors for BOT electric power projects in China: Thermal power versus wind power

Chinese electric power industry has adopted Build–Operate–Transfer (BOT) approach in a number of projects to alleviate the pressure of sole state-owned investment. The Chinese government has taken enormous efforts to create an environment to facilitate the application of BOT approach in electric power projects. Moreover, the growing attention on the sustainability issues puts the traditional major source of electricity – thermal power project under more strict scrutiny. As a result, various renewable energy projects, particularly the wind power projects have involved private sector funds. Both thermal power and wind power projects via BOT approach have met with a varying degree of success. Therefore, it is imperative to understand the factors contributing towards the success of both types of BOT power projects. Using an extensive literature survey, this paper identifies 31 success factors under 5 categories for Chinese BOT electric power projects. This is followed by a questionnaire survey to exam relative significance of these factors. The results reveal the different levels of significance of success factors for BOT thermal power projects versus wind power projects. Finally, survey results were analyzed to explore the underlying construction and distributions among the identified success factors. This study provides a valuable reference for all involved parties that are interested in developing BOT electric power projects in China.     

Village electrification technologies—an evaluation of photovoltaic cells and compact fluorescent lamps and their applicability in rural villages based on a Tanzanian case study

Electrification of remote sites in developing countries is often realised trough diesel generator sets and an electric distribution network. This was also the technology used in the village Urambo, where the first rural electrification co-operative in Tanzania was started in 1994. Climate change however calls for decreased fossil fuel combustion worldwide and new technologies have been further developed since the erection of the diesel generator sets in Urambo. It is therefore not obvious that electrification of other rural areas shall follow the Urambo example.In this article, the situation for 250 electricity consumers in Urambo will be demonstrated and the implications for them of introducing new technologies will be evaluated. Technology options regarded in the study are individual photovoltaic (PV) power systems and either incandescent lamps, tube lights or compact fluorescent lights (CFLs) supplied by diesel generation. The different options have been evaluated with respect to consumer costs and environmental impact.The results of the comparison show that PV generation is able to compete with diesel generation if combined with incandescent lamps, but not when tube lights or CFLs are used in the conventional supply system. It should be noted, however, that while the diesel option offer financially more attractive solutions, individual PV systems do not result in any CO₂ emissions. Furthermore, PV systems normally have a higher reliability. However, since the diesel option is not only cheaper but also offers a wider range of energy services and facilitates, future connection to the national electric grid, the conclusion is that this is preferable before individual PV systems for communities similar to Urambo, if the consumers shall pay the full cost of the service.