Biomass co-firing options on the emission reduction and electricity generation costs in coal-fired power plants

Co-firing offers a near-term solution for reducing CO₂ emissions from conventional fossil fuel power plants. Viable alternatives to long-term CO₂ reduction technologies such as CO₂ sequestration, oxy-firing and carbon loop combustion are being discussed, but all of them remain in the early to mid stages of development. Co-firing, on the other hand, is a well-proven technology and is in regular use though does not eliminate CO₂ emissions entirely. An incremental gain in CO₂ reduction can be achieved by immediate implementation of biomass co-firing in nearly all coal-fired power plants with minimum modifications and moderate investment, making co-firing a near-term solution for the greenhouse gas emission problem. If a majority of coal-fired boilers operating around the world adopt co-firing systems, the total reduction in CO₂ emissions would be substantial. It is the most efficient means of power generation from biomass, and it thus offers CO₂ avoidance cost lower than that for CO₂ sequestration from existing power plants. The present analysis examines several co-firing options including a novel option external (indirect) firing using combustion or gasification in an existing coal or oil fired plant. Capital and operating costs of such external units are calculated to determine the return on investment. Two of these indirect co-firing options are analyzed along with the option of direct co-firing of biomass in pulverizing mills to compare their operational merits and cost advantages with the gasification option.     

风力发电技术探讨

近年来随着可持续发展的需要、技术的进步、环境保护意识的增强和有关政策的制定,风力发电技术有了长足的进步,风电产业已发展成为每年有数十亿美元的世界性大市场,世界总装机容量已超过13000MW,近几年更是以超过30%的速度增长,是发展最快的一种新能源技术。随着风力发电技术的推广、建设规模的扩大和风力发电产业市场化的深入,在风电设备制造、风电场运行管理、电能质量控制、风电环保问题以及风电与其它形式能源的联合使用等方面还存在一系列技术问题。要使风力发电成为人类发展的一种主要能源,有赖于这些问题的解决。我国风力发电研究已…     

光伏发电在我国电力能源结构中的战略地位和未来发展方向

前 言 在可再生能源的家族中，资源量最大、分布最普遍的是太阳能，事实上，其它可再生能源也间接来自于太阳能。全球权威能源机构预测，到本世纪中期太阳能将成为人类能源构成中的重要组成部分，而到本世纪末太阳能将成为人类能源构成中的主要部分。我国陆地表面每年接受太阳辐射能相当于约49000亿tce（标准煤），全国三分之二的国土面积年日照在2200小时以上，年太阳辐射量超过5000焦／米^2（相当于170千克标准煤／米^2），太阳能资源丰富，是中华民族赖以生存，永续繁衍的最宝贵的资源。     

Safe and waste-free technologies using hydrogen electric power generation

A task of the Arctic integrated development affects the development of the new safe and waste-free technologies of waste processing using hydrogen electric power generation. This problem is multifaceted and concerns both large port cities and small towns, mines, islands, platforms, mining and processing plants, etc., despite the fact that many of them have not removed the wastes from their previous activities. The presence of melting permafrost, especially in the Western part of the Russian Arctic, high logistics costs, a small number of indigenous people and mainly rotational method of development make use of new technologies for the production of electricity, heat, water treatment, which provide the use of hydrogen power on the basis of liquefied natural gas (LNG). The use of LNG as a fuel is not effective enough, especially in the Arctic, given the low efficiency of diesel and gas turbine power plants, as well as the environmental degradation from their use. A more effective, environmentally friendly and integrated solution is the use of hydrogen electric power generation together with hydrogen fuel cells (HFC).The structure and method of waste-free technologies of waste processing are analyzed. The structure of wastes is multifaceted and contains: the most common solid waste from industry and life, including natural and man-made landfills; liquid wastes including sewage sludge from household and rainwater, oil-containing and other industrial wastes; leachate from landfills, including landfill gases; wastes resulted from transportation and transshipment of oil products, etc.In the paper purification methods are described; industrial shipping equipment and its characteristics for the application at facilities of the Arctic are presented. These installations include: incinerators, installations for treatment and filtrate of sewage from municipal solid wastes (MSW), desalination plants of reverse osmosis, snow-and ice-melting installations, cleaning and filtration of flue gases with an emphasis on methods of electric cleaning, cargo arms for loading and unloading the oil products and hazardous wastes. The advantages of hydrogen sources and energy storage using LNG in the Arctic both in terms of energy efficiency and ecology, the possibility of their use in conjunction with the above waste treatment plants are shown.Characteristics of solid oxide fuel cells (SOFC) and solid polymer fuel cells and their scope are presented. For the most dynamically developing solid oxide elements, their characteristics in the traditional and cogeneration cycles are given and the scope of their application in small and distributed energy at power up to 10 kW is shown. Atmospheric hybrid schemes for thermodynamic efficiency are significantly inferior to schemes under pressure, but in large-capacity plants, for example, with coal gasification, they can be quite promising. Modern SOFC work under pressure of 7–9 bar; with the growth of their capacity over 1–5 MW in hybrid power plants (HPPs) it is necessary to increase the pressure up to 11 bar and even more. For HPPs with capacity over 10 MW, cogeneration cycle with gas turbines (CCGT) is the most efficient. The highest electrical efficiency of HPPs with the capacity over 10 MW reaches 75% with the use of CCGT and boilers at three pressure units with intermediate superheating.The paper presents the characteristics of traditional sources of electricity based on ship and aircraft gas turbine units operating on LNG, which can be used in autonomous power supply networks of Arctic facilities. Their advantages in terms of specific power in comparison with diesel power plants and storage devices are shown, but high LNG consumption and environmental indicators limit their use in the Arctic, taking into account the logistics problems. Comparison of the energy efficiency of traditional sources and hydrogen storage shows significant advantages of the latter, and if the efficiency of traditional sources increases with their power, the efficiency of storage devices does not change in the entire range of capacities. This circumstance makes the use of hydrogen sources and accumulators uncontested in the field of small capacities typical for Arctic consumers, especially taking into account the possibilities for safe and waste-free technology for processing industrial and life wastes.     

Equity and electric power generation facility location in California

An alternative to cost/benefit analysis for analyzing the equity of electric power generation facility location, utilizing the potential for air quality degradation, is developed and applied to California. Siting issues motivating disagreement on facility location are reviewed. Equity concepts are introduced, and their implementation is discussed. Several measures for assessing the equity of facility location are proposed, and the equities of existing facility locations in California are analyzed for each measure. Equity considerations for future siting decisions are examined.     

基于最大电功率跟踪的风力发电系统幂指数趋近滑模控制

文章考虑机组转轴摩擦损耗和发电机本体的电损耗,从减小发电功率损耗、提高整机风电转换效率出发,设计了一种基于MPPT原理下的最大电功率点跟踪(MEPT)控制策略,该策略在考虑转轴摩擦损耗和发电机绕组损耗基础上,推导出发电机最大电功率跟踪输出控制模型方程。采用转矩跟踪型MPPT控制策略,利用动态滑模控制原理,设计了基于幂指数趋近律的风电系统MEPT滑模功率控制器。控制律引入输入变量的积分,在时间上形成滑模控制的动态连续性,抑制了MEPT功率跟踪的抖振,增强了控制精度、平滑性与鲁棒性。通过静、动态多种风况的Matlab仿真实验,验证了MEPT控制的正确性。     

Thermodynamic analysis of combined electric power generation and water desalination plants

The performance of three systems combining reverse osmosis (RO) to produce drinkable water and a steam power plant is modeled and calculated. The RO subsystem incorporates a power recovery unit: a hydraulic turbine in the first two cases and a pressure exchange unit (PES) in the third case. The coupling between the RO and power plant subsystems is only mechanical in the first case (the power plant provides mechanical power to the pumps of the RO subsystem) while in the two other cases the coupling is both mechanical and thermal (part of the heat rejected by the condenser of the power plant is transferred to the seawater). The effects of feed water flow rate and salinity, energy recovery system (hydraulic turbine or pressure exchanger) and operating pressures on the energy and exergy efficiencies and on the permeate quantity and quality are analyzed. Energy and exergy fluxes for all the components, as well as the quantity of drinkable water produced by each of these systems, are also compared for identical operating conditions.     

Private electric power generation as an alternative in Nigeria

About 9% of the energy mix in Nigeria is in the form of electricity. It is a major source of energy for the urban population. In the recent past, there has been consistent failure of electricity supplied by the public organisation. Consumers are now turning to private means to meet their electricity needs. We have assessed the electricity supplies from the national grids and from private electricity generators.     

Concerns generated by islanding [electric power generation]

The purpose of this article is to discuss islanding operation and to provide end-users with items to consider when determining distributed generation plant and equipment design requirements. Islanding is operating an electric generating plant without an external voltage and frequency reference. Operating in parallel is the opposite of islanding. This article attempts to describe the valid concerns that grid operators have regarding distributed generators. Grid computing could offer an inexpensive and efficient means for participant to compete in providing reliable, cheap and sustainable electrical energy supply. With a keen awareness of the issues involved and open communication among the grid operators, generator control system manufacturers, clients and design firms, distributed generators can be operated in islanded mode without negatively impacting the grid and can continue to support facility operations.     

High efficiency electric power generation: The environmental role

Electric power generation system development is reviewed with special attention to plant efficiency. It is generally understood that efficiency improvement that is consistent with high plant reliability and low cost of electricity is economically beneficial, but its effect upon reduction of all plant emissions without installation of additional environmental equipment, is less well appreciated. As CO₂ emission control is gaining increasing acceptance, efficiency improvement, as the only practical tool capable of reducing CO₂ emission from fossil fuel plant in the short term, has become a key concept for the choice of technology for new plant and upgrades of existing plant. Efficiency is also important for longer-term solutions of reducing CO₂ emission by carbon capture and sequestration (CCS); it is essential for the underlying plants to be highly efficient so as to mitigate the energy penalty of CCS technology application. Power generating options, including coal-fired Rankine cycle steam plants with advanced steam parameters, natural gas-fired gas turbine-steam, and coal gasification combined cycle plants are discussed and compared for their efficiency, cost and operational availability. Special attention is paid to the timeline of the various technologies for their development, demonstration and commercial availability for deployment.     

Comparison of flexibility options to improve the value of variable power generation

As the share of variable generation in power systems increases, there is increasing value in more flexible use and generation of electricity. The paper compares the economic value of several flexibility options in a large power system with a large amount of reservoir hydro power. Generation planning models are needed to consider the impact of flexibility options on other investments in a power system. However, generation planning models do not include all the relevant operational details. The approach in the paper combines a generation planning model with a unit commitment and dispatch model. The results demonstrate the value of coupling the heat and power sectors and the value of transmission. Low-cost electricity storage does not appear to be as decisive in the Northern European context with wind power as the main variable generation source. The paper also addresses methodological issues related to the inclusion of operational constraints in generation planning.     

Design of electric power generation systems using waste heat energy

The recent energy crisis forces engineers to take into account reduction of electricity consumption as well as heat energy consumption in industry. As it is very difficult to save the amount of electricity, they have tried to recover electric power using waste heat energies. In this paper, the possibilities of electric power recovery from waste heat energies are discussed based on the relationship between supply heat sources and demand heat sources in chemical process systems. In solving such problems, the following difficulties appear: calculation of maximum quantity of generated electric power, determination of a suitable working fluid and its temperatures in the Rankine cycle, and so on. The proposed method can solve them using the temperature-enthalpy diagram and, furthermore, has the advantage of being able to design a final heat exchanger network with heat exchangers in a power plant by means of a synthesis method using the same diagram.     

Global warming and electric power generation: What is theconnection?

The greenhouse effect is explained, followed by a discussion of the US fossil fuel use and its contribution of greenhouse gases. US electric utilities' share of CO₂ and other emissions is quantified, including the effects of using various fuels. The possible recovery and disposal of CO₂ from power-plant flue gases is also discussed. The information presented should help prepare electric utilities to address future public concerns and the related regulatory pressures regarding the utility's role in carbon-dioxide proliferation and global warming     

Sulphur dioxide from electricity generation Policy options for pollution control

The authors examine the policy options which are available for the control of sulphur dioxide emissions from conventional thermal power stations. Knowledge of these options, their costs of implementation, their probable effectiveness, and the dates when they can be implemented, is necessary for the taking of rational decisions on, for example, the specification of optimal SO₂ emission standards. The emphasis is on the technical aspects of the alternative control technologies. The effects of SO₂ emissions on health and the environment are considered briefly and trends in SO₂ concentration levels and emissions are discussed. Policy options for the control of SO₂ emissions from conventional thermal power stations are then reviewed and assessed.     

国内风力发电的现状和前景

分析了我国的风能资源和风力发电的现状，探讨了在风力发电时要注意的几个问题，并对我国风力发电的发展前景提出了看法。     

A neuro-fuzzy program approach for evaluating electric power generation systems

This paper uses neuro-fuzzy programming to perform a comparison between the different electricity power generation options for Jordan. Different systems are considered: in addition to fossil fuel power plants, nuclear, solar, wind, and hydropower systems are evaluated. Based on cost-to-benefit ratios, results show that solar, wind, and hydropower are considered to be the best systems for electricity power generation. On the other hand, nuclear electricity turns out to be the worst choice, followed by fossil fuel electric power.     

Fueling power plants with high sulfur coal in compliance with emission standards

We compare the economics of the two most advanced strategies for meeting current SO₂ emission standards in power plants fueled with high sulfur coal. One strategy calls for converting high sulfur coals to clean synfuels before combustion. The other involves direct coal burning, followed by fuel gas desulfurization (FGD). Our results show that the FGD route is preferable.Advantages of FGD over the coal conversion route are the following. The total capital and operating costs for FGD are almost an order of magnitude lower, thermal efficiencies are higher, and utility requirements are lower. The FGD systems have been in operation since 1968 and, after initial problems, have been operated reliably and at availability acceptable to the utility industry. About 80% of existing power plants, according to one survey, can be retrofitted with FGD. Even with possible breakthroughs in coal-conversion technologies, it appears that FGD will remain the economically preferred route to desulfurization.     

A review on distributed generation impacts on electric power system

In 2021, the world's total installed capacity of generation units based on renewable energy sources (not including hydropower) amounted to about 1674 GW: over 825 GW and 849 GW of wind and solar power plants were installed respectively. The growing of the installed capacity of these distributed generators is a response to the increasing the power consumption, global environmental issues and has also become possible due to the development of technology in field of power semiconductor devices. However, on the way of large-scale implementation of distributed generators based on renewable energy sources, traditional electric power system meets new challenges to ensure the reliability and sustainability of new electric power systems with renewable energy sources. In particular, distributed generators change processes in the electric power system, impact to the parameters and power balance, change the magnitude and direction of power flow and short-circuit current, which determines the need to update the settings of the relay protection and automation systems of traditional electric power system and to coordinate their operation with automatic control systems of installed distributed generators. The above-mentioned tasks form a number of scientific research directions, one of which is a task of determining optimal size and location of distributed generators. The main purpose of this optimization task is to reduce power losses, operating and total electricity cost, improve the voltage profile, etc. In addition, the correct and reasonable placement of distributed generators defines an effective planning of the operating modes of electric power system and power plants (especially based on renewable energy sources, the operating modes of which depend on weather conditions and can be sharply variable).The paper highlighted the impacts of distributed generators on power losses, the voltage level, maintaining the power balance and the possibility of participating in the frequency regulation, and short-circuit current in power system. The optimization criteria, the main limiting conditions, as well as methods for solving this optimization problem are considered. This review will help the System operators and investing companies, especially in Russia, to form the main aim, objective function and constraints that will aid to meet their load demand at minimum cost and to choose from the options available for optimization of location and capacity of distributed generators.     

Energy storage-based power buffering control for photovoltaic power generation system

光伏发电系统输出的最大功率随外界环境变化而波动,无法满足负荷的供电需求,针对该问题,建立了基于储能系统的光伏发电系统结构,介绍了光伏发电系统运行原理,分析了系统功率与直流母线电压的关系,设计了无源式储能系统和有源式储能系统对功率进行缓冲以满足控制目标.仿真结果表明,有源式储能系统较无源式储能系统有更好的功率调节作用,通过双向DC-DC变换器的储放能量自动切换控制,使得光伏发电系统输出的功率与负荷需求功率良好匹配,直流电压稳定.     

Evaluation of the flat-plate solar collector system for electric power generation

The simplest method of utilizing the energy of the sun to generate electric power is to use a flat-plate collector system. Flat-plate collectors have no tracking mechanism, make use of both direct and diffuse radiation, have no focusing arrangements and are less costly per square foot than parabolic trough collectors, paraboloid of revolution collectors or heliostats. The main disadvantage to the flat-plate collector system is the relatively low temperatures reached by the collector surface ( 300°F maximum).This evaluation of the flat-plate collector system was designed to determine the number of flat-plate collectors required to generate a given amount of electricity with optimum efficiency. Variable parameters are the temperature of the heat transport fluid, both to and from the collector field. In the analysis, the efficiency of the flat-plate collectors was coupled to the efficiency of the thermal cycle to calculate optimal overall system effeciencies. Overall system efficiencies for the system are on the order of 3·5 per cent or less. Over two million 4 ft by 4 ft collectors would be required to produce 100,000 kW(e).Based on the results of this analsis, it can be shown that the limiting factor in the use of the flat-plate collector system for electric power generation is the efficiency of the collectors. An increase in the overall system efficiency can occur only if the collector efficiency can be increased at the higher surface tempertures.