The impact of the new investments in combined cycle gas turbine power plants on the Italian electricity price

The paper measures the variation of the electricity price in Italy within the next 10 years due to the recent investment flow in combined cycle gas turbine (CCGT) power plants. It starts by investigating the possibility of decoupling gas and oil prices on the basis of hypotheses about the amount of existing resources and plausible technical substitutability assumptions of the latter with the former. In particular, it is supposed that, in the Italian market, natural gas will play a crucial role which oil has had in power generation. The price of electricity stemming from natural gas is then calculated taking into account the role of the power mix restructuring that derives from the CCGT power plants investments. Under reasonable assumptions, it is shown that a net reduction of at least 17% on the electric price is likely to be expected.     

Families of optimal thermodynamic solutions for combined cycle gas turbine (CCGT) power plants

Optimal designs of a CCGT power plant characterized by maximum second law efficiency values are determined for a wide range of power demands and different values of the available heat transfer area. These thermodynamic optimal solutions are found within a feasible operation region by means of a non-linear mathematical programming (NLP) model, where decision variables (i.e. transfer areas, power production, mass flow rates, temperatures and pressures) can vary freely. Technical relationships among them are used to systematize optimal values of design and operative variables of a CCGT power plant into optimal solution sets, named here as optimal solution families. From an operative and design point of view, the families of optimal solutions let knowing in advance optimal values of the CCGT variables when facing changes of power demand or adjusting the design to an available heat transfer area.     

The interaction of wind power generation with electricity demand in the context of a small grid

An investigation into the integration of the intermittent electricity output of a hypothetical wind farm in Malta with the actual electricity demand for one particular year is reported. Available hourly wind data from three sites for 2001 were analysed. The probability density of the load resulting from the reduction of the renewable output from the electricity demand on an hourly basis was determined by a convolution method. The calculated shift in the load duration extends over the whole spectrum of power demand. The equivalent power at the most favourable site was considerably higher than the nominal value commonly in use. In view of the limited availability of sites for wind farms in Malta rotor designs better suited to the lower wind speed régime inland should be considered.     

利用燃气—蒸汽联合循环改造老电厂

利用燃气－蒸汽联合循环对老电厂进行改造,能够提高能源的综合使用率,降低能耗,并有效利用老电厂的现有设备,可以减少投资并见效快,文章对利用燃气－蒸汽联合循环对老电厂进行改造的主要方式和热效率进行了分析。     

Simulation of a combined wind and solar power plant

The combined generation of electricity by wind and solar energy is a very attractive solution for isolated regions with high levels of yearly wind energy and insolation. A computer model is developed for the simulation of the electricity system of a Mediterranean island, including a wind power plant, a photovoltaic power plant and a storage system. In order to obtain an overall view of the system performance and economic aspects, the model also incorporates a number of diesel generators. Daily simulations for the Greek island Kythnos show that such a combined system of moderate size can provide a large fraction of the electrical energy requirements. Various parameters calculated in the simulation can be used to improve the configuration of the system and to estimate the cost of the electrical energy unit.     

Optimization of a combined wind and solar power plant

The paper is concerned with determining the optimized active areas of a photovoltaic conversion system, of a group of electricity generating wind machines and the optimal capacity of a battery storage system for a combined power plant. Minimization of the total life-cycle cost of the system is the criterion to obtaining the optimized parameters of the system. The algorithm consists of generating the system costs corresponding to various values of the parameters and to use these costs in a search procedure to determine the minimum. Each point is generated by a simulation program describing the system behaviour.     

Detailed study of the impact of co-utilization of biomass in a natural gas combined cycle power plant through perturbation analysis

Co-utilization of fossil fuels and biomass is a successful way to make efficient use of biomass for power production. When replacing only a limited amount of fossil fuel by biomass, measurements of net output power and input fuel rates will however not suffice to accurately determine the marginal efficiency of the newly introduced alternative fuel. The present paper therefore proposes a technique to determine the marginal biomass efficiency with more accuracy. The process simulation model for co-utilization of natural gas and a small perturbing fraction of biomass in an existing combined cycle plant (500 MW_th Drogenbos, Belgium) is taken as case study. In this particular plant, biomass is introduced into the cycle as fuel for a primary steam reforming process of the input natural gas.     

Energetic and exergetic performance evaluation of a combined heat and power system with the micro gas turbine (MGTCHP)

This study deals with the energetic and exergetic performance assessment of a combined heat and power system with micro gas turbine (MGTCHP). Quantitative energy and exergy balance for each component and the whole MGTCHP system was considered, while energy and exergy consumption within the system were determined. The performance characteristics of this MGTCHP system were evaluated using energy and exergy analyses methods. The energetic and exergetic efficiencies of the MGTCHP system are calculated as 75.99% with 254.55 kW (as 99.15 kW—electrical and 155.40 kW—hot water_{@363.15 K}) and 35.80% with 123.61 kW (as 99.15 kW—electrical and 24.46 kW—hot water_{@363.15 K}), respectively. The maximum energy loss and exergy consumption occur at 44.03 kW in the stack gas and 129.61 kW in the combustion chamber, respectively. Copyright © 2007 John Wiley & Sons, Ltd.     

对9FA燃气轮机联合循环机组性能试验的思考

对9FA燃机联合循环性能试验中的一些问题进行了分析,如性能的修正、余热锅炉的性能考核、责任分摊等,并给出了作者的看法,供同行参考。     

Comparative evaluation of life cycle impact assessment software tools through a wind turbine case study

This paper seeks to analyse the differences between environmental impact assessment software tools by examining the results that they give when applied to a multi-megawatt wind turbine.Seven different life cycle impact assessment software tools are compared: CML 2001, Eco-indicator 99, Ecopoints 97, EDIP, EPS 2000, IMPACT2002 and TRACI.In Acidification and Eutrophication two groups are found: one includes the results provided by CML, Ecopoints 97, EDIP, EPS and TRACI and the other those of Eco-indicator 99 and Impact2002. In Abiotic Depletion all the results are similar except those of the EPS method, which gives negative figures. Likewise in Ozone Layer Depletion the results provided by Ecopoints 97 differ from the rest. In Human Toxicity and Ecotoxicity markedly different results are obtained by each of the LCIAs studied.In some categories major differences are found between the results provided by the 7 LCIAs examined. Which of the impact assessment software tools currently available in LCA software is chosen is therefore a critical issue. The results provided by the different software tools are not always similar, and this needs to be realised and taken into account when using the resulting data in decision-making processes.     

燃气轮机联合循环电厂孤网运行浅析

为保障电网安全,电网提出当省网220kV回路故障时,由联合循环电厂独立承担局部地区供电任务。本文是对联合循环机组正常运行时,如果电网系统突发故障,联合循环电厂如何调节,才能使局部供电稳定,在技术方面进行探讨。     

Highly efficient electricity generation from biomass by integration and hybridization with combined cycle gas turbine (CCGT) plants for natural gas

Integration/co-firing with existing fossil fuel plants could give near term highly efficient and low cost power production from biomass. This paper presents a techno-economical analysis on options for integrating biomass thermal conversion (optimized for local resources ∼50 MW_th) with existing CCGT (combined cycle gas turbine) power plants (800–1400 MW_th). Options include hybrid combined cycles (HCC), indirect gasification of biomass and simple cycle biomass steam plants which are simulated using the software Ebsilon Professional and Aspen Plus. Levelized cost of electricity (LCoE) is calculated with cost functions derived from power plant data. Results show that the integrated HCC configurations (fully-fired) show a significantly higher efficiency (40–41%, LHV (lower heating value)) than a stand-alone steam plant (35.5%); roughly half of the efficiency (2.4% points) is due to more efficient fuel drying. Because of higher investment costs, HCC options have cost advantages over stand-alone options at high biomass fuel prices (>25 EUR/MWh) or low discount rates (<5%). Gasification options show even higher efficiency (46–50%), and the lowest LCoE for the options studied for fuel costs exceeding 10 EUR/MWh. It can be concluded that clear efficiency improvements and possible cost reductions can be reached by integration of biomass with CCGT power plants compared to stand-alone plants.     

9FA型燃气轮机联合循环性能研究

1引言西气东输工程促进了沿线燃气轮机联合循环电厂的建设,减轻了中东部地区的环境排放压力。燃气轮机联合循环发电系统高效低污染、启停迅速、调峰能力强。西气东输管道沿线有25台F级燃气轮机联合循环机组,其中GE公司9FA型燃气轮机联合循环发电机组13台。如何保证系统的稳定安     

The impact of wind power on electricity prices

This paper investigates the impact of wind power on electricity prices using a production cost model of the Independent System Operator – New England power system. Different scenarios in terms of wind penetration, wind forecasts, and wind curtailment are modeled in order to analyze the impact of wind power on electricity prices for different wind penetration levels and for different levels of wind power visibility and controllability. The analysis concludes that electricity price volatility increases even as electricity prices decrease with increasing wind penetration levels. The impact of wind power on price volatility is larger in the shorter term (5-min compared to hour-to-hour). The results presented show that over-forecasting wind power increases electricity prices while under-forecasting wind power reduces them. The modeling results also show that controlling wind power by allowing curtailment increases electricity prices, and for higher wind penetrations it also reduces their volatility.     

Indications for a changing electricity demand pattern: The temperature dependence of electricity demand in the Netherlands

This study assesses the electricity demand pattern in the relatively temperate climate of the Netherlands (latitude 52°30′N). Daily electricity demand and average temperature during the period from 1970 until 2007 are investigated for possible trends in the temperature dependence of electricity demand. We hypothesize that the increased use of cooling applications has shifted the temperature dependence of electricity demand upwards in summer months. Our results show significant increases in temperature dependence of electricity demand in May, June, September, October and during the summer holidays. During the period studied, temperature dependence in these months has shifted from negative to positive, meaning that a higher temperature now leads to an increased electricity demand in these months, rather than a decreased demand as observed historically. Although electricity demand in countries with moderate summer temperatures such as the Netherlands generally peaks in winter months and shows a minimum in summer months, this trend may signal the development of an additional peak in summer, especially given the expected climatic change. As power generating capacity may be negatively influenced by higher temperatures due to decreasing process cooling possibilities, an increasing electricity demand at higher temperatures may have important consequences for power generation capacity planning and maintenance scheduling.     

Germany's nuclear power plant closures and the integration of electricity markets in Europe

This paper examines the potential implications of national policies that lead to a sudden increase of wind power in the electricity mix for interconnected European electricity markets. More specifically, it examines market integration before and after the closures of eight nuclear power plants that occurred within a period of a few months in Germany during 2011. The short- and- long run interrelationships of daily electricity spot prices, from November 2009 to October 2012, in: APX-ENDEX, BELPEX, EPEX-DE, EPEX-FR, NORDPOOL, OMEL and SWISSIX; and wind power in the German system are analysed. Two MGARCH (Multivariate Generalized Autoregressive Conditional Heteroscedasticity) models with dynamic correlations are used to assess spot market behaviour in the short run, and a fractional cointegration analysis is conducted to investigate changes in the long-run behaviour of electricity spot prices. Results show: positive time-varying correlations between spot prices in markets with substantial shared interconnector capacity; a negative association between wind power penetration in Germany and electricity spot prices in the German and neighbouring markets; and, for most markets, a decreasing speed in mean reversion.     

Analytical method for evaluation of gas turbine inlet air cooling in combined cycle power plant

Gas turbine inlet air cooling technologies (GTIAC), mainly including chilling with LiBr/water absorption chiller and fogging as well, are being used during hot seasons to augment the power output. To evaluate the general applicability of inlet air cooling for gas–steam combined cycle power plant (GTCCIAC), parameters such as efficiency ratio, profit ratio and relative payback period were defined and analyzed through off-design performances of both gas turbine and inlet air cooling systems. An analytical method for applicability evaluation of GTCCIAC with absorption chiller (inlet chilling) and saturated evaporative cooler (inlet fogging) was presented. The applicability study based on typical off-design performances of the components in GTCCIAC shows that, the applicability of GTCCIAC with chilling and fogging depends on the design economic efficiency of GTCC power plant. In addition, it relies heavily on the climatic data and the design capacity of inlet air cooling systems. Generally, GTCCIAC is preferable in the zones with high ambient air temperature and low humidity. Furthermore, it is more appropriate for those GTCC units with lower design economic efficiency. Comparison of the applicability between chilling and fogging shows that, inlet fogging is superior in power efficiency at t_a = 15–20 °C though it gains smaller profit margin than inlet chilling. GTCC inlet chilling with absorption chiller is preferable in the zones with t_a > 25 °C and RH > 0.4.     

The impact of wind generation on the electricity spot-market price level and variance: The Texas experience

The literature on renewable energy suggests that an increase in intermittent wind generation would reduce the spot electricity market price by displacing high fuel-cost marginal generation. Taking advantage of a large file of Texas-based 15-min data, we show that while rising wind generation does indeed tend to reduce the level of spot prices, it is also likely to enlarge the spot-price variance. The key policy implication is that increasing use of price risk management should accompany expanded deployment of wind generation.     

The field performance of a remote 10 kW wind turbine

The collection and analysis of 15 months of continuously recorded field data from a small remote wind–diesel power system at a coastal farm site are reported. The paper focuses on the available wind data and the performance of the 10 kW Bergey wind turbine.     

The impact of the first oil crisis on energy demand in Korea

This paper investigates how the first oil crisis affected energy demand in Korea. First, annual growth rates in energy consumptions for pre-and post-crisis periods are compared. Second, the price and income elasticities of energy sources estimated from the 1961–1972 and 1961–1976 observations are compared. Third, F-test is performed with an oil demand equation to see whether a structural change in oil demand occurred after the first oil crisis. The author concludes that the impact of the first oil crisis in Korea was not serious enough to cause a structural change in oil demand.