Resources For Electricity Generation Research Articles

Optimal Design and Sizing of Integrated Centralized and Decentralized Energy Systems

Concerns over sustainability of fossil fuels, and increasing awareness for the environment have encouraged countries all over the world to shift from the heavy reliance on fossil fuel to renewable energy (RE) resources for electricity generation. Although implementation of RE has been on the rise, large-scale deployment of RE still remains a challenge, especially in terms of economic and technicality. This paper proposes the integration of the current energy system (centralised energy system, CEG running on mainly fossil fuels) with the new energy system (decentralised energy system, DEG). Numerical analysis is developed to solve and target the proposed multiple DEGs and CEG integrated system at its optimum design and sizing. Two existing numerical approaches in Power Pinch Analysis are applied, i.e. Power Pinch Analysis (PoPA) for a smaller scale decentralised energy systems while the net energy deficit will be satisfied in a centralised energy system via Electric System Cascade Analysis (ESCA). The designated combination of Power Pinch methodology in this study is based on an hourly scale operation of both systems. With case study of five (5) DEG(s), the analysis indicates that DEG 1 has 540 MWh for energy-related capacity and 70 MW for power-related capacity. DEG 2, 480 MWh and 70 MW, DEG 3, 480 MWh and 120 MW, DEG 4, 1,000 MWh and 150 MW, and DEG 5, 100 MWh and 90 MW. The CEG power plants should have a total capacity of 48.3 MW with energy storage of 270.6 MWh and 45.1 MW.

Network Losses-based Economic Redispatch for Optimal Energy Pricing in a Congested Power System

An efficient, low-cost and reliable operation of a power system by adjusting the available electricity generation resources to supply demand of the system is required to ensure satisfied economic plant dispatching. This paper proposes a scheme for economic redispatch model considering the transmission issues such as transmission congestion and network losses, in order to obtain an optimal energy price in supporting competitive electricity market under deregulated environment of a power system.

Collaboration protocols for sustainable wind energy distribution networks

Wind energy has attracted more attentions in recent decades as a green and sustainable electricity generation resource with little or no pollution. Fluctuations in output of wind turbines and their dependency on environmental conditions, however, limit their penetration into power grids. This research proposes a collaboration platform to overcome these challenges by collaboration among communities in the energy distribution network. First, a second order trigonometric regression model is applied to forecast energy demands, and a multiple linear regression model is used to predict energy output of a wind farm. Based on this information, communities in the network can initiate the collaboration process through the proposed platform, which is controlled by two collaboration protocols: Demand and Capacity Sharing Protocol (DCSP) and Best Matching Protocol (BMP). The protocols are applied to optimize communities' profit through matching the communities with excessive capacity with the ones with energy shortage so that they can create a sustainable distribution network. A simulation of three communities with three wind farms is conducted to measure the impact of the platform. The results show the sustainability of the energy network can be achieved by reduced demand loss and holding cost and improved collaborative capacity.

Influence of axial turbine efficiency maps on the performance of subcritical and supercritical Organic Rankine Cycle systems

The utilization of low-to-medium enthalpy geothermal resources for electricity generation is commonly done using the binary cycle power plant technology. The low temperature of the geothermal fluid necessarily results in low thermal efficiencies but it can be profitably used as a driver to reduce the equipment cost. In particular, single stage axial flow turbines, a cheaper option compared to multistage solutions, can be used due to the moderate enthalpy drop in the expansion process. In this work the design performance of ORCs (Organic Rankine Cycle systems) equipped with single stage axial flow turbines is optimized for utilization of a 150 °C geothermal fluid. Accurate predictions of turbine efficiency are included in the optimization procedure to take into account the influence of the thermodynamic cycle parameters, fluid properties and size on the maximum achievable efficiency. A set of six fluids is considered to examine a wide spectrum of design conditions. Results show that supercritical ORCs outperform subcritical ORCs even taking into account the detrimental effect of high expansion ratios on turbine efficiency. Hydrofluoroolefins are found to exhibit a net power output approximately equal or even higher than the best hydrofluorocarbons.

The development of renewable energy resources in the State of Veracruz, Mexico

We summarize the current and potential use of renewable energy for the generation of electricity in the State of Veracruz, Mexico. We review data from national and state agencies informs and identify some of the challenges involved in the development of renewable energy resource for electricity generation. We conclude that the inclusion of renewable energy in the electricity mix of the State will make an important contribution in the transition from the current energy model to a more sustainable energy model.

Theoretical potential and utilization of renewable energy in Afghanistan

Nowadays, renewable energy is gaining more attention than other resources for electricity generation in the world. For Afghanistan that has limited domestic production of electric power and is more dependent on the unstable imported power from neighboring countries which pave the way to raise the cost of energy and increased different technical and economic problems. The employment of renewable energy would not only contribute to the independence of energy supply but also can achieve the socio-economic benefits for the country which is trying to rebuild its energy sector with a focus on sustainable energy for its population. From a theoretical point of view, there is a considerable potential of renewable energies such as solar energy, wind power, hydropower, biomass and geothermal energy available in the country. However, despite the presence of widespread non-agricultural and non-residential lands, these resources have not been deployed efficiently. This paper assesses the theoretical potential of the aforementioned types of renewable energies in the country. The study indicates that deployment of renewable energies can not only supplement the power demand but also will create other opportunities and will enable a sustainable energy base in Afghanistan.

OFF-GRID ELECTRICITY GENERATION WITH HYBRID RENEWABLE ENERGY TECHNOLOGIES IN IRAQ: AN APPLICATION OF HOMER

The current power system in Iraq used fossil fuels that effect an environmentally, also the power generated does not cover the power demand. In the other hand, to reduce the gap between the generation and the power demand suggested renewable energy alternative sources adding to power system, renewable energy is zero pollution. The purpose of this proposal is to find the preferable hybrid technology combination by a hybrid renewable energy resources for electricity generation to satisfy the electrical needs in a reliable manner of an off grid choosing small town, Bald Ruz in the state of Diyala, Iraq as case study. Three renewable resources, namely, solar photovoltaic systems, wind turbines, with natural gas generator are considered. The software used HOMER that offers optimal solution from the types of resources. The proposal estimates COE of energy of the optimized system is $0.998/kWh for stand-alone and $0.2/kWh for hybrid grid system.The PV system represents around 42% of power production small percentage for wind turbine that reaches to 6%.

Assessment of Feed-in Tariff Policy in Thailand: Impacts on National Electricity Prices

In Thailand, 67% (119,434 GWh) of primary energy resource for electricity generation relies on natural gas. Therefore, it may not be sustainable for the future, due to instability of energy resources. Thai government has launched the policy measure to motivate private sector for investment in electricity generation from renewable energy since 2007. It was called “Adder”. In 2012, the feed-in tariffs (FIT) measure has been announced by the National Energy Board in 2013 to replace adder because adder is paid on top of the retail electricity price but FIT is a fixed price. However, both adder and FIT subsidize so higher cost resulting in higher retail electricity price to customers. This study assesses impact on retail electricity price thru fuel adjustment charge (Ft) from Adder and FIT policy during 2010 to 2030 by using the alternative energy development plan (AEDP), optimization, and power development plan (PDP2010 rev.3). As a result, in 2030 in optimization case, subsidy on FIT will be about 48,873 million Baht while subsidy on adders will be about 53,416 million Baht. The FIT will increase average national electricity production cost in Ft mechanism by 0.013 Baht/kWh in 2030 while Adders will increase average national electricity production cost of 0.154 Baht/kWh in 2030. It is found that FIT scheme lowers burden of subsidy than adder scheme in both short and long terms. Therefore, if government encourages renewable power generation, the proper policy should be analyzed to balance the benefits of green electricity, investors and consumers.

Emulation of an OWC Ocean Energy Plant With PMSG and Irregular Wave Model

Ocean energy is a promising resource for renewable electricity generation that presents many advantages, such as being more predictable than wind energy, but also some disadvantages such as large and slow amplitude variations in the generated power. This paper presents a hardware-in-the-loop prototype that allows the study of the electric power profile generated by a wave power plant based on the oscillating water column (OWC) principle. In particular, it facilitates the development of new solutions to improve the intermittent profile of the power fed into the grid or the test of the OWC behavior when facing a voltage dip. Also, to obtain a more realistic model behavior, statistical models of real waves have been implemented.

Co-optimization of electricity transmission and generation resources for planning and policy analysis: review of concepts and modeling approaches

The recognition of transmission’s interaction with other resources has motivated the development of co-optimization methods to optimize transmission investment while simultaneously considering tradeoffs with investments in electricity supply, demand, and storage resources. For a given set of constraints, co-optimized planning models provide solutions that have lower costs than solutions obtained from decoupled optimization (transmission-only, generation-only, or iterations between them). This paper describes co-optimization and provides an overview of approaches to co-optimizing transmission options, supply-side resources, demand-side resources, and natural gas pipelines. In particular, the paper provides an up-to-date assessment of the present and potential capabilities of existing co-optimization tools, and it discusses needs and challenges for developing advanced co-optimization models.

Characterization and modeling of the efficiency of photovoltaic systems

With the growing interest in protecting the environment by using renewable energy sources as alternatives for power generation and its application in the concept of distributed generation, this research focuses on the comparison of the efficiency of each of components of photovoltaic systems, including grid-connected photovoltaic system to isolates. Using mathematical models that characterize each of the components getting itself to determine the key factors affecting the efficiency of each of the systems. And finally it was determined how to increase efficiency and reduce the value of the electrical losses in photovoltaic systems; to optimize solar resources in electricity generation.

CO2 emissions from Iran's power sector and analysis of the influencing factors using the stochastic impacts by regression on population, affluence and technology (STIRPAT) model

ABSTRACTThe current status of CO2 emissions from Iran's power sector and the socio-economic factors that influence these emissions are fully covered in this paper. To begin, the amount of CO2 emissions is calculated based on the IPCC guidelines for national GHG inventories. The analysis of socio-economic influencing parameters is performed by the stochastic impacts by regression on population, affluence and technology (STIRPAT) model using population size, gross domestic product (GDP) per capita, electricity intensity and consumption of energy resources for electricity generation. Then CO2 emissions related to the electricity consumption in six sectors (residential, industrial, public, agriculture, trade and lighting) as well as grid losses and internal electricity consumption of power plants are estimated. Finally, CO2 emissions from Iran's power sector are compared with their alternatives in Turkey and China. The results indicate that CO2 emissions increased from 78.778 Tg in 2003 to 149.691 Tg in 2013, and the average CO2 specific emission factor is 571.29 g/kWh. The outputs of the STIRPAT model illustrate that population size, GDP per capita, electricity intensity and the consumption of fossil fuels for electricity generation positively influence CO2 emissions, while electricity generation by hydropower, renewable energies and nuclear energy negatively do.

Optimal Distribution of Electrical Energy Sources in Turkey with the Impact of the Kyoto Protocol

Power generation has a significant contribution in total emissions of CO2, the main culprit in global warming, all over the world as well as in Turkey. Therefore, ratification of Kyoto Protocol by Turkish Parliament necessitates revising the share of different energy resources in electricity generation to be able to reduce CO2 emissions. This study is an attempt to propose a solution to this problem. To this end, Turkey’s future long-term electrical energy demand is first estimated. Predicated on this future demand, we established an optimization model for the planning of electricity production by the year 2023, which is the 100th anniversary of the republic of Turkey. In this model, availability of CO2 capture and storage units is assumed, which constitute a prominent tool for reducing the CO2 emissions of fossil fuel fired power plants. The optimal solution has produced a distribution of energy sources between coal, natural gas, hydroelectricity and nuclear energies.

Geothermal power plants: Evolution and performance assessments

This paper traces the technical development of geothermal plants from the very beginning, focusing on the efficiency of the geothermal-to-electrical energy conversion. The plants at Larderello (Italy) and Wairakei (New Zealand) are examined in some detail. Included are discussions and analyses of little-known plants in Africa and on the Italian island of Ischia that pioneered the development of geothermal energy conversion systems beyond the dry steam plants in Tuscany. Presented are important milestones in geothermal power plant development that opened the way to worldwide expansion of the use of geothermal resources for electricity generation. It is shown that while there has been a slight trend toward higher efficiency over the years, the improvement is less than has occurred in conventional fossil-fueled power plants. The efficiency gains result mainly from more elaborate conversion systems whose extra capital costs may not be justified in all cases. Nevertheless, the data show that geothermal power plants can be designed and built to achieve high efficiencies, comparable to or even greater than conventional plants when appropriate economic conditions and incentives exist.

Optimal grid design and logistic planning for wind and biomass based renewable electricity supply chains under uncertainties

In this work, the grid design and optimal allocation of wind and biomass resources for renewable electricity supply chains under uncertainties is studied. Due to wind intermittency, generation of wind electricity is not uniform and cannot be counted on to be readily available to meet the demand. Biomass represents a type of stored energy and is the only renewable resource that can be used for producing biofuels and generating electricity whenever required. However, amount of biomass resources are finite and might not be sufficient to meet the demand for electricity and biofuels. Potential of wind and biomass resources is therefore jointly analyzed for electricity generation. Policies are proposed and evaluated for optimal allocation of finite biomass resources for electricity generation. A stochastic programming model is proposed that optimally balances the electricity demand across the available supply from wind and biomass resources under uncertainties in wind speed and electricity sale price. A case study set in the American Midwest is presented to demonstrate the effectiveness of the proposed model by determining the optimal decisions for generation and transmission of renewable electricity. Sensitivity analysis shows that level of subsidy for renewable electricity production has a major impact on the decisions.

Security of Water Supply and Electricity Production: Aspects of Integrated Management

The share of renewable resources in electricity generation, e.g. in Germany, is increasing. The power sector is thus becoming more dependent on climate/weather parameters. During the summer months of the last decade, numerous thermal power plants in Europe had to be throttled due to water shortages and high water temperatures. At the same time, Europe was confronted with a reduction in hydropower production. One method of securing a future electricity supply is to increase the reliability of the water supply for power plants. In this paper, scenarios are presented for future electricity production by hydropower and thermal power plants in the Elbe river basin. Electricity production in hydropower plants will decline by approximately 13 % by 2050. This decline is due to climate change and it could be compensated for by optimizing and modernizing existing hydropower plants. Due to higher efficiencies and the conversion of plant cooling systems, no water shortages are expected in most thermal power plants. However, water shortages are expected to affect the plants in the city of Berlin. Inter- and intra-basin water transfers constitute a possible adaptation option. While the transfer of water from the river Oder would be the most cost-efficient solution from Berlin’s perspective, the transfer of water from the river Elbe would have additional positive effects in the upstream Spree river sub-basin.

Short-Term Wind Speed Forecasting Using Decomposition-Based Neural Networks Combining Abnormal Detection Method

As one of the most promising renewable resources in electricity generation, wind energy is acknowledged for its significant environmental contributions and economic competitiveness. Because wind fluctuates with strong variation, it is quite difficult to describe the characteristics of wind or to estimate the power output that will be injected into the grid. In particular, short-term wind speed forecasting, an essential support for the regulatory actions and short-term load dispatching planning during the operation of wind farms, is currently regarded as one of the most difficult problems to be solved. This paper contributes to short-term wind speed forecasting by developing two three-stage hybrid approaches; both are combinations of the five-three-Hanning (53H) weighted average smoothing method, ensemble empirical mode decomposition (EEMD) algorithm, and nonlinear autoregressive (NAR) neural networks. The chosen datasets are ten-minute wind speed observations, including twelve samples, and our simulation indicates that the proposed methods perform much better than the traditional ones when addressing short-term wind speed forecasting problems.

Reallocating Risks and Returns to Overcome Barriers to Scale Up of Distributed Electricity Resources

In this paper we consider adoption and scale up of a class of resources for electricity generation and management we call distributed electricity resources. Deployment of these resources requires, among others, bringing together assets that belong to diverse and geographically diffuse owners. Using the example of distributed solar electricity generation, we analyze the schemes that have been introduced so far to encourage/induce owners of distributed assets to make them available for solar electricity generation. The dominant model in distributed solar is long term power purchase agreements (PPA) offered to owners/consumers by a number of firms. We show that these agreements, viewed as financial contracts, (mis)allocate the electricity price risk to owners/consumers and impose limitations on scale up of distributed solar. By proper use of financial markets, it is possible, as we argue, to shift the electricity price risk from owners/consumers to parties that are better positioned to manage it. The proposed modified contracts simplify the adoption decision for owners/consumers and can lead to a wider adoption. We contend that removing barriers to scale up requires (i) eliminating the tight coupling between consumers and owners that current PPAs create and (ii) rewarding the owners unambiguously for the assets they provide for generation. These necessitate the transformation of the current intermediary firms into full-fledged distributed generators. We discuss the implications of such a transformation and show that the broad outline of our analysis can be used to assess scale up schemes in other domains of distributed electricity resources as well.

浮游植物群落对海南小水电建设的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 浮游植物群落对海南小水电建设的响应 DOI: 10.5846/stxb201205300790 作者: 作者单位: 海南省环境科学研究院,海南省环境科学研究院,暨南大学水生生物研究中心,海南省环境科学研究院 作者简介: 通讯作者: 中图分类号: 基金项目: 2009年海南省重点科技项目(KJXM20090002) Responses of phytoplankton community to the construction of small hydropower stations in Hainan Province Author: Affiliation: Hainan Research Academy of Environmental Sciences,Hainan Research Academy of Environmental Sciences,Institute of the Hydrobiology,Jinan University,Hainan Research Academy of Environmental Sciences Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为探讨浮游植物群落对海南省小水电建设的响应,分别在海南省主要河流的上游支流已建小水电的蓄水水域与河道、规划(未建)小水电河段采集浮游植物样品进行比较分析。共鉴定出浮游植物种类62个属178种,曲壳藻(Achnanthaceae)、异极藻(Gomphonema)、菱形藻(Nitzschia)、颗粒直链藻(Melosira granulat)、席藻(Phormidium)、颤藻(Oscillatoria)、小球藻(Chlorella vulgaris)、平裂藻(Merismopedia)、舟形藻(Navicula)为主要的优势藻类,浮游植物丰度在5.1-163.6×104 个/L之间,浮游植物Shannon-Wiener多样性指数在2.73-4.53之间。研究结果表明,小水电建设对浮游植物的种类组成、优势种、丰度及多样性均有较大的影响。就浮游植物优势种而言,规划小水电河道以蓝藻及部分硅藻为主要优势种,已建小水电河道曲壳藻、异极藻、菱形藻等大型硅藻为主要优势种。在浮游植物组成及生物多样性上,未建小水电河道浮游植物Shannon-Wiener多样性指数略高,且种属分布更加均衡,而已建设水电站均趋向某一类藻占主导优势种。就浮游植物丰度而言,规划小水电河道浮游植物丰度均保持在20-30×104 个/L内,已建小水电河段浮游植物保持在5-160×104 个/L内且浮游植物丰度差异性较规划小水电大,小水电建设促进了浮游植物丰度的提升,但降低了浮游植物群落结构的稳定性、均衡性。虽然存在水电站阻隔,同一河流水系浮游植物种属来源仍可表现一定的趋同性,梯级水电特别是相邻水电间浮游植物群落组成存在较大的相似性。 Abstract:Small hydropower stations (SHS) not only play an important role in electricity generation and water resource regulation in mountain areas, but also at the same time, impose ecological and environmental impacts. To study the responses of phytoplankton community in rivers with construction of SHS, samples of phytoplankton from 7 rivers in Hainan Province where SHS had been or will be built were taken and analyzed. According the results, a total of 178 phytoplankton species belonging to 62 genera were identified, and the dominant species includes Achnanthaceae, Gomphonema, Nitzschia, Melosira granulat, Phormidium, Oscillatoria, Chlorella vulgaris, Merismopedia, and Navicula. Phytoplankton abundance in rivers was from 5.1×104cells/L to 63.6×104cells/L, the diversity index was from 2.73 to 4.53, and Desmids had been found in most SHS. SHS had a great influence on phytoplankton biomass, species composition and dominant species in the rivers. Comparing with thfe rivers with SHS, the rivers without SHS had higher Shannon-Wiener diversity index and the composition of phytoplankton species were more balanced, Cyanobacterias and some Diatoms always dominated the phytoplankton community in the rivers, such as in NDJ-JJ-9 (Cyanophyta 25.7%,Chlorophyta36.9%, Bacillariophyta 36.1%), ZBJ-MMD-11 (Cyanophyta 41.8%, Chlorophyta 33.2%,Bacillariophyta 23.1%), and WLH-SX-13(Cyanophyta 29.1%, Chlorophyta 25.2%, Bacillariophyta 38.8%). In the rivers with SHS, large diatom Achnanthacea,Gomphonema and Nitzschia becoming predominated were common, such as in CHJ-YJ-1 (Bacillariophyta 91.3%), CHJ-YJ-2 (Bacillariophyta 65.9%), and NDJ-GL-6 (Bacillariophyta 56.5%).To phytoplankton abundance, most rivers without SHS were 20-30×104cells/L, while the rivers with SHS were widely different 5-160×104cells/L. The rivers with SHS had higher average abundance and abundance difference index than the ones without SHS. The construction of SHS had changed the hydrodynamic of the rivers, and the changed hydrodynamic might had played an important role in the phytoplankton community. In mountain areas of Hainan province, most rivers were Shallow with less water flow. Stable water environment was suitable for Cyanobacterias and some Diatoms in the river without any SHS. Once SHS had been built, agitation of water body increased and lager Diatoms such as Achnanthaceae Gomphonema and Nitzschia might be dominated. The construction of SHS would also promoted the biomass of the river, but weaken the stability and proportionality of phytoplankton community by increasing fluctuation and agitation. Among cascade SHS, the barrier of the stations, the phytoplankton community could still be some similar especially between adjacent SHS. The correlation coefficient of phytoplankton community between adjacent SHS were all over 0.9 with highly significant correlation(P<0.01). 参考文献 相似文献 引证文献

Assessment of the Present and Future Offshore Wind Power Potential: A Case Study in a Target Territory of the Baltic Sea Near the Latvian Coast

Offshore wind energy development promises to be a significant domestic renewable energy source in Latvia. The reliable prediction of present and future wind resources at offshore sites is crucial for planning and selecting the location for wind farms. The overall goal of this paper is the assessment of offshore wind power potential in a target territory of the Baltic Sea near the Latvian coast as well as the identification of a trend in the future wind energy potential for the study territory. The regional climate model CLM and High Resolution Limited Area Model (Hirlam) simulations were used to obtain the wind climatology data for the study area. The results indicated that offshore wind energy is promising for expanding the national electricity generation and will continue to be a stable resource for electricity generation in the region over the 21st century.