东北地区县域秸秆热电联产技术经济性分析

30 MW秸秆发电汽轮机是适宜于东北玉米主产区的最佳县域秸秆发电厂的投资规模,本文以实际运行的30MW秸秆发电厂为例,开展秸秆发电项目的技术经济分析.研究结论表明,秸秆热电联产在能源利用率及经济收益等方面具有优越性.     

Valuing distributed energy resources: Combined heat and power and the modern grid

In this paper we examine how decision makers can more precisely assess the costs of disruptive weather events and the value of resilient distributed energy systems such as combined heat and power (CHP). CHP makes up a small percentage of the energy infrastructure in the United States despite its substantial efficiency and resilience benefits. In part this is because the resilience value of CHP is not fully accounted for in energy infrastructure project cost screenings. To capture this benefit in investment decisions, we propose a framework for a metric called the Distributed Energy Resource Resiliency Value (DERRV) and discuss how such a metric might be applied to CHP.     

计及需求响应的光热电站热电联供型微网的优化运行

光热电站利用新型太阳能发电装置实现光—热—电之间的能量转化,可以输出比较稳定的电功率,为解决太阳能发电的消纳问题提供了有效途径。在此背景下,提出在热电联供型微网中引入光热电站以辅助系统运行,并结合风电站、电储能装置、电加热器等能量转换设备构建一种新的微网架构。之后,以零售电价和零售热价为信号引导微网内用户参与需求响应,并基于价格弹性矩阵建立了电负荷和热负荷的需求响应模型。在此基础上,考虑风电和光电出力的不确定性,以最大化微网运行效益为目标建立了模糊机会约束规划模型。然后,对模型进行了简化,最终形成混合整数线性规划问题,并用高效的商业求解器CPLEX求解。最后,以某微网系统在冬季和夏季的典型日为例对所提模型和方法进行了说明。     

Supply security for domestic fuels at Finnish combined heat and power plants

The focus of the study was on examining the preparations of Finnish CHP plants for a domestic fuel crisis. National supply security has become topical as the use of domestic fuels, especially peat and wood fuels, has increased over the past decade and temporary regional shortages of domestic fuels have occurred. The study utilised a questionnaire targeting the largest domestic fuel users producing district heating and electricity. The response rate was high, reflecting the importance attached to the subject. The most significant challenges in peat fuel and wood fuel supply security were found to be the time-consuming environmental permit processes for peatlands entering energy use, lack of wood fuel terminals, and the currently unpredictable taxation and subsidy policy. General operation conditions should be improved for domestic fuels' use, and continuity of domestic labour and fuel production must be guaranteed.     

Free piston Stirling engines: A review

This paper presents a detailed review on free piston Stirling engines (FPSEs) technology. Generally, the Stirling engines can be categorized into two broad classes comprising kinematic and dynamic converters among which FPSEs are known as the dynamic type. Other well-known dynamic Stirling converters are Fluidyne and thermosacoustic engines among which the thermosacoustic ones are the most advanced Stirling converters recently presented. In this research, the dynamic Stirling engines are first introduced and reviewed. Then, the review work is directed toward the FPSEs, one of the most reliable dynamic Stirling converters utilized in different applications such as combined heat and power systems (CHPs). Subsequently, the working principles of different types of FPSEs and their performance are summarized. Next, several manufactured FPSEs, as well as their corresponding features and applications, are discussed. Finally, the article is conducted to analysis and modeling approaches of FPSEs. Accordingly, linear and nonlinear analytical techniques of FPSEs are introduced, and some comparative data are provided to verify the modeling schemes. Then, various design parameters affecting the engine performance are introduced and studied. The outcomes of this review work demonstrate the potential of FPSEs for different applications and reveal that the perturbation-based model is likely the most comprehensive nonlinear method for modeling and design of the FPSEs.     

New optimization method based on energy management in microgrids based on energy storage systems and combined heat and power

Microgrids can be assumed as a solution model for green energy sources, energy storage systems, and combined heat and power (CHP) systems. In this work, the cost and emission minimization based on a demand response (DR) program is considered an optimization problem. To solve the mentioned problem a new multiobjective optimization algorithm (improved particle swarm optimization) is proposed based on a fuzzy mechanism to select the optimal value. The microgrid system includes two CHP units, fuel cell and battery systems, and the heat buffer tank. In this problem, two different feasible operating regions have been assumed in CHPs. Accordingly, to decrease the operational cost, time-of-use, and real-time pricing DR programs have been simulated, and the impacts of the mentioned models are evaluated overload profiles. The effectiveness of proposed models has been applied on different cases studies by different scenarios. The proposed model solved the DR program, time of use-DR and real-time pricing-DR problems. The proposed model could reduce the cost about 10%.     

Exergoenvironmental analysis and optimization of a cogeneration plant system using Multimodal Genetic Algorithm (MGA)

In the present work, a combined heat and power plant for cogeneration purposes that produces 50 MW of electricity and 33.3 kg/s of saturated steam at 13 bar is optimized using genetic algorithm. The design parameters of the plant considered are compressor pressure ratio (r_AC), compressor isentropic efficiency (η_comp), gas turbine isentropic efficiency (η_GT), combustion chamber inlet temperature (T₃), and turbine inlet temperature (TIT). In addition, to optimally find the optimum design parameters, an exergoeconomic approach is employed. A new objective function, representing total cost rate of the system product including cost rate of each equipment (sum of the operating cost, related to the fuel consumption) and cost rate of environmental impact (NO_x and CO) is considered. Finally, the optimal values of decision variables are obtained by minimizing the objective function using evolutionary genetic algorithm. Moreover, the influence of changes in the demanded power on various design parameters are parametrically studied for 50, 60, 70 MW of net power output. The results show that for a specific unit cost of fuel, the values of design parameters increase, as the required, with net power output increases. Also, the variations of the optimal decision variables versus unit cost of fuel reveal that by increasing the fuel cost, the pressure ratio, r_AC, compressor isentropic efficiency, η_AC, turbine isentropic efficiency, η_GT, and turbine inlet temperature (TIT) increase.     

Ensuring emergency power for critical municipal services with natural gas-fired combined heat and power (CHP) systems: A cost–benefit analysis of a preemptive strategy

Electric power failures in the aftermath of disasters cripple the delivery of critical emergency services. While emergency generators are available in some facilities, these systems are designed for short-term use and support limited functions. The substantial investment required to ensure emergency power for all critical services is difficult to justify because of the uncertainty associated with the likelihood and magnitude of future disasters. Investment evaluations change when a new source of emergency power is considered. This study evaluates the costs and benefits of a program to preemptively install new building-sited electric combined heat and power (CHP) generation technologies to ensure reliable long-term power for critical municipal services in hurricane-prone regions of the US. Three municipalities are selected for this analysis: Houston, Texas; Miami, Florida; and Charleston, South Carolina. Analysis indicates that costs of such a program can, in some cases, provide net energy bill savings regardless of the occurrence of a disaster.     

Manure's allure: Variation of the financial, environmental, and economic benefits from combined heat and power systems integrated with anaerobic digesters at hog farms across geographic and economic regions

Several studies have shown that anaerobic digesters integrated with combined heat and power systems (CHP/AD) are a financially attractive way to generate electricity, reduce odor, and improve nutrient management on hog farms; yet only very few systems have been installed to date. Employing published financial, economic, and environmental indicators, this study tests whether the benefits from CHP/AD identified in these studies can be replicated across all major hog-farming regions in the US. The study finds that a modest support of 1 cent per kWh is needed to assure that CHP/AD generated electricity is competitive with current utility rates in many hog-farming states. However, the study also shows that once CHP/AD systems are promoted hog-farming states stand to reap large benefits from CHP/AD, particularly environmental benefits (such as odor control and emissions reductions), economic benefits (in form of job creation), and added generating capacity.     

Selection of typical demand days for CHP optimization

Optimizing the configuration and operation of a CHP system for a whole year becomes a computationally demanding task when, for example, integer variables are used to model the status (on/off) of different pieces of equipment. The reason is that a discrete optimization problem is fundamentally an enumerative problem, featuring that the number of possible solutions grows exponentially with the number of integer variables. This computational difficulty is known as the curse of dimensionality, and severely limits the chances to use mixed integer programming methods to design CHP systems. To work out this problem, this paper presents a new and unambiguous method to reduce a full year of demand data to a few representative days that adequately preserve significant characteristics such as the peak demands, the demand duration curves, and the temporal inter-relationship between the different types of demands (power, heating, and cooling). Days are selected using a partitional clustering method known as the k-medoids method, and their ability to resemble the original data is tested by means of two quality indexes and a calendar visual inspection. Two case studies are discussed for the completeness of the paper, showing how the method and the quality indexes can be used in practice.