Analysis of systems for the generation of electricity from solar radiation

The analysis developed here relates the annual electrical output of any type of solar-electric facility directly to the effective annual insolation received on its solar collectors per unit collector area. A general expression for the capacity factor of such a facility is derived through which the ratio of the actual annual electrical output to the maximum mean annual output without demand, generating and downtime reductions, and storage losses can be determined. A general expression for a solar availability factor is also obtained which measures the ratio of the maximum mean annual output of the solar facility to that of a conventional fuel-fired plant of the same installed capacity generating at full capacity continuously for a year. An expression for the fraction of the total electrical output supplied by the solar facility is also derived. The analysis takes full account of the daily and seasonal cycles of solar radiation and its intermittent stochastic character. All results are given for a unit area of solar collector and are thus independent of the size of the facility.The capital cost of solar-electric facilities is expressed in dollars for each kWh per yr of electrical output rather than dollars per kW of installed capacity as is customary for conventional electric generating plants. This cost in turn is divided among three components: for solar-electric generation, for nonsolar auxiliary power, and for storage. A general expression is derived in terms of actual or estimated component costs, and the results for solar generation and storage are shown in Figs. 4 and 5. The choice of solar collector area and of the relative dependence on storage and auxiliary nonsolar power is also discussed.     

Network constrained wind integration on Vancouver Island

The aim of this study is to determine the costs and carbon emissions associated with operating a hydro-dominated electricity generation system (Vancouver Island, Canada) with varying degrees of wind penetration. The focus is to match the wind resource, system demand and abilities of extant generating facilities on a temporal basis, resulting in an operating schedule that minimizes system cost over a given period. This is performed by taking the perspective of a social planner who desires to find the lowest-cost mix of new and existing generation facilities. Unlike other studies, this analysis considers variable efficiency for thermal and hydro-generators, resulting in a fuel cost that varies with respect to generator part load. Since this study and others have shown that wind power may induce a large variance on existing dispatchable generators, forcing more frequent operation at reduced part load, inclusion of increased fuel cost at part load is important when investigating wind integration as it can significantly reduce the economic benefits of utilizing low-cost wind. Results indicate that the introduction of wind power may reduce system operating costs, but this depends heavily on whether the capital cost of the wind farm is considered. For the Vancouver Island mix with its large hydro-component, operating cost was reduced by a maximum of 15% at a wind penetration of 50%, with a negligible reduction in operating cost when the wind farm capital cost was included.     

Optimal asset allocation of wind energy units in conjunction with demand response for a large‐scale electric grid

Demand response is considered to be a realistic and comparatively inexpensive solution aimed at increasing the penetration of renewable generations into the bulk electricity systems. The work in this paper highlights the demand response in conjunction with the optimal capacity of installed wind energy resources allocation. Authors proposed a total annual system cost model to minimize the cost of allocating wind power generating assets. This model contains capacity expansion, production, uncertainty, wind variability, emissions, and elasticity in demand to find out cost per hour to deliver electricity. A large‐scale electric grid (25 GW) is used to apply this model. Authors discovered that demand response based on interhourly system is not as much helpful as demand response grounded on intrahourly system. According to results, 32% wind generation share will provide the least cost. It is also worth noting that optimal amount of wind generation is much sensitive to installation cost as well as carbon tax.     

农作物秸秆气化发电系统经济性分析

对农作物秸秆气化发电系统投产前的最佳秸秆收集半径进行了分析,得出了最佳秸秆收集半径与电厂运行费用、运输费用、单位耕地面积秸秆年产量、秸秆收集系数之间的关系.对影响发电系统经济性的因素进行了敏感性分析,认为发电效率和上网电价是影响发电系统经济性的主要因素.     

Large-scale economic integration of electricity from short-rotation woody crops

This paper presents an assessment of the installation of a large-scale biomass scheme for production of electricity for distribution via the national grid in Spain. The biomass scheme studied is based on woody biomass (eucalyptus, acacia and poplar) as short rotation crops in arable lands. The site selection process has been carried out with a Geographical Information System (GIS). The criteria applied in the selection, cultivation and location of the plantation as well as the biomass power plants have taken into account environmental aspects and the economic costs, always pursuing the lowest energy cost and environmental impacts. The size of each power plant has been calculated taking into account the annual productivity of biomass and the available surface of arable non-irrigated land. The costs of energy crop production in each area have been calculated as well as the storage and transport costs to supply the power plants. The technologies considered for generating electricity are fluidized bed combustion (FBC) and biomass gasification integrated into a combined cycle (BIGCC). The costs of electricity, considering also the connection costs to the electricity grid, have been calculated for all power plants. Cost figures along the fuel cycle have been obtained and a sensitivity analysis of the most relevant variables has been made. The main conclusion of the analysis is that from an economic and environmental point of view, the scheme proposed is feasible.     

Economic feasibility of electricity production from energy plantations present on community-managed forestlands in Madhya Pradesh,India

This paper assesses economic feasibility of utilizing community-managed degraded forest areas for raising energy crops and using the produced biomass for electricity production in the state of Madhya Pradesh, India through gasification technology. Three fast-growing species, three gasifiers of different capacities, three capital costs, and two scenarios of carbon payments were considered for analysis. Sensitivity and risk analyses were undertaken for determining the effects of variations in inputs on selected outputs. Results suggest that 5 million megawatt hour electricity can be generated annually which will prevent 4 million tons of carbon dioxide emissions per year. The production cost of a unit of electricity was found inversely related to the scale of production. The average cost of electricity at the consumer level produced using 100 kW gasifier was $0.15/kWh, which was greater than the price of electricity supplied from grid i.e. $0.08/kWh. The unit cost of producing electricity using Acacia nilotica was lowest among all the selected species. Technological advancements suitable government incentives are needed to promote electricity generation from forest biomass through gasification technology. This will help in spurring economic development and reducing overall ecological footprint of the state.     

生物质气化发电的经济效益分析

应用财务评价的方法分析了影响生物质气化发电经济效益的主要因素，从项目规模、出售电价和原料成本三个方面阐述了提高生物质气化发电经济效益的方法，提出了发展生物质气化发电技术的相关建议。     

Prospects of renewable energy utilisation for electricity generation in Bangladesh

Bangladesh has been facing a power crisis for about a decade, mainly because of inadequate power generation capacity compared with demand and the ageing infrastructure of many existing power generation facilities. Only 20% of the total population are connected to grid electricity—25% in urban areas and a mere 10% in rural areas where 80% of the total population resides. Currently, most power plants in Bangladesh (representing 84.5% of the total installed capacity) use natural gas—the main commercial primary energy source, with limited national reserves—as a fuel. Electricity supply to low-load rural and remote areas is characterised by high transmission and distribution costs and transmission losses, and heavily subsidised pricing.Renewable energy sources in Bangladesh, particularly biomass, can play a major role to meet electricity demands in the rural and remote areas of the country. The current study indicates that in 2003, the national total generation and recovery rates of biomass in Bangladesh were 148.983 and 86.276 Mtonne, respectively. In energy term, the national annual amount of the recoverable biomass is equivalent to 312.613 TWh. Considering the present national consumption of biomass, total available biomass resources potential for electricity generation vary from 183.865 to 223.794 TWh. Biomass energy potential in the individual districts of the country has been estimated for the planning small- to medium-scale biomass-to-electricity plants.     

Comparative analysis of Fischer-Tropsch and integrated gasification combined cycle biomass utilization

Use of agricultural biomass (switchgrass, prairie grasses) through Fischer-Tropsch (FT) conversion to liquid fuels is compared with biomass utilization via (IGCC) integrated gasification combined cycle electrical production. In the IGCC scenario, biomass is co-fired with coal, with biomass comprising 10% of the fuel input by energy content. In this case, the displaced coal is processed via FT methods so that liquid fuels are produced in both scenarios. Overall performance of the two options is compared on the basis of total energy yield (electricity, liquid fuels), carbon dioxide emissions, and total cost. Total energy yield is almost identical whether biomass is used for electrical power generation or liquid fuels synthesis. Carbon dioxide emissions are also approximately equal for the two pathways. Capital costs are more difficult to compare since scaling factors cause considerable uncertainty. With IGCC costs roughly equivalent for either scenario, cost differences between the pathways appear based on FT plant construction cost. Coal FT facility capital cost estimates for the plant scale in this study (721 MW_t LHV input) are estimated to be 410 (MUSD) million US Dollars while the similar scale biomass-only FT plant costs range from 430 MUSD to 590 MUSD.     

Performance correlations for biomass gasifiers using semi‐equilibrium non‐stoichiometric thermodynamic models

Biomass gasification has been a viable alternative for decentralized electricity generation in developing countries. The efficiency of the biomass gasification process for operation of the engine‐generator set is mapped in terms of quality and quantity of the producer gas. In this study, we have attempted to devise generalized correlations for four principal parameters that form the benchmark for the performance of the gasifier. These parameters are lower heating value and net yield (per unit biomass) of producer gas, and volume fractions of CO and CO₂ in the gas resulting from biomass gasification process. The correlations have been constituted using simulations of gasification of three common biomass feedstocks (viz. rice husk, saw dust and corn cobs) using semi‐equilibrium non‐stoichiometric thermodynamic model. The independent variables used in the simulations are air ratio, carbon conversion, gasification temperature and three elemental ratios in the gasification mixture, viz. H/C, O/H and O/C. As many as eight expressions of linear and non‐linear type have been evaluated to best fit the simulations data for each performance parameter. On the basis of statistical indicators, the compatibility of the correlations for best fit of the data has been assessed. Finally, the predictions of the correlation have been tested against experimental data on gasification of different biomass. The best correlation for each performance parameter was chosen on the basis of least average absolute error and highest (absolute) regression coefficient. It was found that the set of best correlations could predict the values of performance parameters within engineering accuracy of ± 10–20%. The correlations proposed in this work are independent of the type of biomass gasifier. These correlations can form a useful tool for design and optimization of fixed or fluidized bed gasifier for any biomass feedstock. Copyright © 2011 John Wiley & Sons, Ltd.     

Parametric techno‐economic studies of coal/biomass co‐gasification for IGCC plants with carbon capture using various coal ranks,fuel‐feeding schemes,and syngas cooling methods

Because of biomass's limited supply (as well as other issues involving its feeding and transportation), pure biomass plants tend to be small, which results in high production and capital costs (per unit power output) compared with much larger coal plants. Thus, it is more economically attractive to co‐gasify biomass with coal. Biomass can also make an existing plant carbon‐neutral or even carbon‐negative if enough carbon dioxide is captured and sequestered (CCS). As a part of a series of studies examining the thermal and economic impact of different design implementations for an integrated gasification combined cycle (IGCC) plant fed with blended coal and biomass, this paper focuses on investigating various parameters, including radiant cooling versus syngas quenching, dry‐fed versus slurry‐fed gasification (particularly in relation to sour‐shift and sweet‐shift carbon capture systems), oxygen‐blown versus air‐blown gasifiers, low‐rank coals versus high‐rank coals, and options for using syngas or alternative fuels in the duct burner for the heat recovery steam generator (HRSG) to achieve the desired steam turbine inlet temperature. Using the commercial software, Thermoflow^®, the case studies were performed on a simulated 250‐MW coal IGCC plant located near New Orleans, Louisiana, and the coal was co‐fed with biomass using ratios ranging from 10% to 30% by weight. Using 2011 dollars as a basis for economic analysis, the results show that syngas coolers are more efficient than quench systems (by 5.5 percentage points), but are also more expensive (by $500/kW and 0.6 cents/kW h). For the feeding system, dry‐fed is more efficient than slurry‐fed (by 2.2–2.5 points) and less expensive (by $200/kW and 0.5 cents/kW h). Sour‐shift CCS is both more efficient (by 3 percentage points) and cheaper (by $600/kW or 1.5 cents/kW h) than sweet‐shift CCS. Higher‐ranked coals are more efficient than lower‐ranked coals (2.8 points without biomass, or 1.5 points with biomass) and have lower capital cost (by $600/kW without using biomass, or $400/kW with biomass). Finally, plants with biomass and low‐rank coal feedstock are both more efficient and have lower costs than those with pure coal: just 10% biomass seems to increase the efficiency by 0.7 points and reduce costs by $400/kW and 0.3 cents/kW h. However, for high‐rank coals, this trend is different: the efficiency decreases by 0.7 points, and the cost of electricity increases by 0.1 cents/kW h, but capital costs still decrease by about $160/kW. Copyright © 2016 John Wiley & Sons, Ltd.     

Potential for rural electrification based on biomass gasification in Cambodia

Around 76% of the 10,452 villages of Cambodia will still be without electricity in the year 2010. We examined the potential of biomass gasification fuelled by alternative resources of agricultural residues and woody biomass to increase rural power supply, using geographic and social economic databases provided by the Royal Government of Cambodia. About 77% of villages currently without electricity have sufficient land available for tree planting for electricity generation based on a requirement of 0.02 ha per household. Among 8008 villages with sufficient land, we assumed that those villages that had greater than 10% of households owning a television (powered by a battery or a generator) would have both a high electricity demand and a capacity to pay for electricity generation. Those 6418 villages were considered appropriate candidates for mini-grid installation by biomass gasification. This study demonstrated that while agricultural residues such as rice husks or cashew nut shells may have high energy potential, only tree farming or plantations would provide sufficient sustainable resources to supply a biomass gasification system. Cost per unit electricity generation by biomass gasification is less than diesel generation when the plant capacity factor exceeds 13%. In order to ensure long-term ecological sustainability as well as appropriate tree-farming technology for farmers, there is an urgent need for studies aimed at quantifying biomass production across multiple rotations and with different species across Cambodia.     

中型生物质气化发电CDM项目案例分析

以广东省生物质气化发电技术应用为清洁发展机制(CDM)项目案例,基于3个基准线,应用增量成本分析方法,计算了中型生物质气化发电作为CDM项目的单位碳减排成本,并对其进行了敏感性分析。结果表明,CDM项目的单位碳减排成本在10-36美元/tCO2之间,且年处理生物质量为0.99-2.97万t时能实现年CO2减排量在1705-6038 tCO2/a之间。     

Energy‐cost‐aware flow shop scheduling considering intermittent renewables,energy storage,and real‐time electricity pricing

The industrial sector is one of the major energy consumers that contribute to global climate change. Demand response programs and on‐site renewable energy provide great opportunities for the industrial sector to both go green and lower production costs. In this paper, a 2‐stage stochastic flow shop scheduling problem is proposed to minimize the total electricity purchase cost. The energy demand of the designed manufacturing system is met by on‐site renewables, energy storage, as well as the supply from the power grid. The volatile price, such as day‐ahead and real‐time pricing, applies to the portion supplied by the power grid. The first stage of the formulated model determines optimal job schedules and minimizes day‐ahead purchase commitment cost that considers forecasted renewable generation. The volatility of the real‐time electricity price and the variability of renewable generation are considered in the second stage of the model to compensate for errors of the forecasted renewable supply; the model will also minimize the total cost of real‐time electricity supplied by the real‐time pricing market and maximize the total profit of renewable fed into the grid. Case study results show that cost savings because of on‐site renewables are significant. Seasonal cost saving differences are also observed. The cost saving in summer is higher than that in winter with solar and wind supply in the system. Although the battery system also contributes to the cost saving, its effect is not as significant as the renewables.     

Integration of large-scale hydrogen storages in a low-carbon electricity generation system

This study investigates the overall feasibility of large energy storages with hydrogen as energy carrier onsite with a pre-combustion carbon capture and storage coal gasification plant and assesses the general impacts of such a backup installation on an electricity generation system with high wind power portion. The developed system plant configuration consists of four main units namely the gasification unit, main power unit, backup power unit including hydrogen storage and ancillary power unit. Findings show that integrating a backup storage in solid or gaseous hydrogen storage configuration allows to store excessive energy under high renewable power output or low demand and to make use of the stored energy to compensate low renewable output or high power demand. The study concludes that the developed system configuration reaches much higher load factors and efficiency levels than a plant configuration without backup storage, which simply increases its power unit capacity to meet the electricity demand. Also from an economical point of view, the suggested system configurations are capable to achieve lower electricity generation costs.     

The perspectives of energy production from coal‐fired power plants in an enlarged EU

The aim of this paper is to present the current status of the coal‐fired power sector in an enlarged EU (EU‐15 plus EU member candidate states) in relation with the main topics of the European Strategy for the energy production and supply. It is estimated that 731 thermoelectric units, larger than 100 MW_e, are operating nowadays, and their total installed capacity equals to 200.7 GW_e. Coal contribution to the total electricity generation with reference to other fuel sources, is by far more intensive in the non‐EU part (EU member candidate states), compared to the EU member states. It is expected that even after the enlargement, the European Union will strongly being related to coal. Enlargement will bring additional factors into play in order to meet the requirements of rising consumption, growing demand for conventional fuels and increasing dependence on imports. Besides the technology, boiler size, efficiency, age and environmental performance will determine the necessities of the coal‐fired power sector in each country. Depending on the case, lifetime extension measures in operating coal‐fired power plants or clean coal technologies can play an important role towards the energy sector restructuring. Low efficiency values in the non‐EU coal‐fired units and heavily aged power plants in EU countries will certainly affect decisions in favour of upgrading or reconstruction. The overall increase of efficiency, the reduction of harmful emissions from generating processes and the co‐combustion of coal with biomass and wastes for generating purposes indicate that coal can be cleaner and more efficient. Additionally, plenty of rehabilitation projects based on CCT applications, have already been carried out or are under progress in the EU energy sector. The proclamations of the countries' energy policies in the coming decades, includes integrated renovation concepts of the coal‐fired power sector. Further to the natural gas penetration in the electricity generation and CO₂ sequestration and underground storage, the implementation of CCT projects will strongly contribute to the reduction of CO₂ emissions in the European Union, according to the targets set in the Kyoto protocol. In consequence, clean coal technologies can open up new markets not only in the EU member candidate states, but also in other parts of the world. Copyright © 2004 John Wiley & Sons, Ltd.     

Logistics cost analysis of rice straw for biomass power generation in Thailand

The logistics of the fuel supply have a large impact on the economy of a biomass power generation facility, especially for low density biomass fuels like straw. A detailed cost analysis of a typical rice straw logistics process for two baling options in three regions of Thailand shows that the costs for all logistics operations vary from a minimum of 18.75 USD/t for small rectangular bales in the Northern region of Thailand to maximum 19.89 USD/t for large rectangular bales in the North-eastern region. The difference in costs is not very significant due to the higher ownership and operating costs of the equipment for using large rectangular bales; however, the specific fuel consumption cost is substantially lower by around 17.5% and a total transport cost reduction is about 31.5%. Analysis of the logistics economies of scale for projected power plant capacities of 2-35 MW_e showed that each doubling the capacity of the energy facility increases the specific costs of the logistics operations only by around 4% in all regions.     

Energy potential through agricultural biomass using geographical information system—A case study of Punjab

Agricultural biomass has immense potential for power production in an Indian state like Punjab. A judicious use of biomass energy could potentially play an important role in mitigating environmental impacts of non-renewable energy sources particularly global warming and acid rain. But the availability of agricultural biomass is spatially scattered. The spatial distribution of this resource and the associate costs of collection and transportation are major bottlenecks for the success of biomass energy conversion facilities. Biomass, being scattered and loose, has huge collection and transportation costs, which can be reduced by properly planning and locating the biomass collection centers for biomass-based power plants. Before planning the collection centers, it is necessary to evaluate the biomass, energy and collection cost of biomass in the field. In this paper, an attempt has been made to evaluate the spatial potential of biomass with geographical information system (GIS) and a mathematical model for collection of biomass in the field has been developed. The total amount of unused agricultural biomass is about 13.73 Mt year⁻¹. The total power generation capacity from unused biomass is approximately 900 MW. The collection cost in the field up to the carrier unit is US$3.90 t⁻¹.     

A study of the installed capacity and electricity quality of a fuel cell‐independent microgrid that uses locally produced energy for local consumption

Reducing the rates of nuclear power generation for all electric power sources has been seriously discussed in Japan since the accident at the Fukushima No. 1 nuclear power plant in March 2011. Thus, the distributed power supply is expected to expand. The local production of safe and clean energy for local consumption is greatly needed in Japan. In this paper, the Saroma Lake green microgrid (SLMG), a fuel cell microgrid using tidal power generation and photovoltaics, has been planned. Energy balance equations were used to investigate this system's method of operation. Further simulated analysis of the facility, its operation cost, and the electric power quality of the network were conducted using MATLAB/Simulink, and the relationships among the capacity of a facility, the cost, and supply rate of green energy and the electric power quality (interphase voltage, frequency, and higher harmonic wave) of the power network were clarified. The total projected cost of the equipment and operation for introducing the proposed SLMG is ¥1,500,000,000/10 years. Increasing the supply rate of green energy and reducing the facility cost will require the introduction of biofuels and the reduction of the facility costs of solid oxide fuel cells in the SLMG. Copyright © 2012 John Wiley & Sons, Ltd.     

世界风力发电现状与前景预测

全球可再生能源发电装机容量中风电占有压倒性优势,今后可望成为欧洲、亚洲、北美的主要电力来源.2011年中国以62GW的累计装机容量蝉联世界第一,按照我国“十二五”规划目标,预计到2015年风电装机容量将达到1×108kW,年发电量1900×108kW·h.GWEC和Greenpeace预测,今后20年风力发电将成为世界主力电源,2030年装机容量有可能达到23×108kW,可供应世界电力需求的22％.欧美正大力开发海上风电产业.欧洲是世界海上风电发展的先驱和产业中心,欧洲企业不仅拥有自己的核心技术,而且还向世界各地输出技术,今后欧洲海上风力发电将急速增长.美国采取与英国、德国等欧洲厂家相同的战略,大力发展海上风力发电.我国海上风电产业刚刚起步,预计2015年海上风电装机500×104kW.日本学者大岛教授推算了不同电源的发电成本:包括政府财政补贴,运行年限30年的核电站发电成本为12.06日元/(kW·h);按标准设备利用率,风力发电成本11.30日元/(kW·h),与核电相比已经有竞争力.假设风况好时设备利用率达到35％,发电成本为7.95日元/(kW·h),比核电低得多.