Coal-fired Generation Research Articles

The use of coal combustion fly ash as a soil amendment in agricultural lands (with comments on its potential to improve food security and sequester carbon)

The growing dependence on coal-fired electricity generation has resulted accumulation of massive quantities of coal combustion by products such as fly ash and bottom ash which are regarded as problematic solid wastes all over the world. Being used beneficially in very less quantities, each year large amount of fly ash is disposed to arable lands which lead to degradation and contamination of land and ground water. However fly ash is identified as a useful soil ameliorant with its properties pertinent to the enhancement of soil fertility and productivity. Fly ash has the potential to improve soil physical, chemical and biological properties and is a source of readily available plant macro and micro-nutrients. Especially for countries whose soils show inherent structural and nutritional limitations for cropping and that need expensive and intensive management, fly ash creates a possible solution to improve crop yields and enhance food security. At the same time the soil added fly ash can involve in terrestrial carbon sequestration by enhancing the microclimate of the soils to facilitate organic matter humification to yield stable forms of soil carbon. This paper reviews the studies of fly ash as a soil amendment in order to present a comprehensive view of the possibility of using fly ash in agricultural lands to improve soil productivity while harvesting possible carbon sequestration benefits. Some identified adverse effects of fly ash addition that can hinder the crop growth in amended soils especially in long term applications have limited its potential use in cultivable lands. However more research work on existing gaps in knowledge to be filled (especially regarding the appropriate application rate and possible environmental contamination) may help to derive the maximum advantages of fly ash in terms soil improvement and waste disposal. The paper, in particularly examines the potential use of this plentiful solid waste material on soil amendment in Australian agricultural soils.

Renewable electricity and energy storage to permit retirement of coal-fired generators in Nova Scotia

In August 2011 Canada’s Environment Minister proposed performance standards aimed at retiring coal-fired electricity generators. In this study, an evaluation is made of future renewable electricity generation and gross electricity demand in Nova Scotia, Canada. These are coupled with an energy storage model for peak shaving and increased ramp-rate capabilities sufficient to retire coal-fired generation. The proposed storage system represents a feasible method to not only displace coal use, but to displace the need for fossil-fueled generating capacity as backup for renewable generators. Within the model, an aggregate electrical system load timeseries at 1h intervals is developed for Renewable Energy Standard years 2015 and 2020 using publicly available historical data and existing load growth projections. This is compared to renewable energy generation projections, with the difference between generation and demand used as the input to an energy storage model wherein storage augments dispatchable generating capacity. The model estimates energy storage characteristics required to limit peak conventional generation capacity and ramp-rates. A storage system comprised of 500MWh of energy storage, coupled to the projected effects of efficiency improvements is found to be adequate to insure reliability while retiring 600MW of coal generation capacity.

A Consideration of the Wind Power Benefits in Day-Ahead Scheduling of Wind-Coal Intensive Power Systems

This paper studies day-ahead unit commitment in wind-coal intensive power systems. Due to their long start up time, high start up cost, and high minimum stable output, coal-fired generators do not provide a favorable environment for accommodating variable wind generation. The reduced efficiencies resulting from the coal-fired generation side as measured in increased fuel consumption and CO2 emissions can greatly undermine the wind power benefits to the system if wind generation and coal-fired generation are not properly coordinated. Special attention in the study is given to the wind power benefits to the system in fuel savings and in reduction of CO2 emissions. Based on the wind power forecast, the stochastic nature of wind power is treated in two parts, i.e., wind power variability and wind power uncertainty. Unit commitment is studied using wind power variability and uncertainty separately in different wind power dispatch modes and using respectively different spinning reserve procurement strategies. System performance indices are then applied to determine the optimal wind power dispatch mode and optimal spinning reserve procurement strategy to capture optimal wind power benefits for the system. A simulation system characterized by typical wind-coal features is constructed to model and to conduct the studies. The results show that taking wind power curtailment as a control option and using wind as a reserve provider improve the wind power benefits to the system.

Modeling the Electricity Sector: A Summary of Recent Analyses of New EPA Regulations

Several different economic models have been applied to try to understand how new regulations by the U.S. Environmental Protection Agency (EPA) could impact coal-fired generation in the United States as well as the electricity system as a whole. This paper provides an overview of many of the key studies and the models used to analyze the potential impacts of EPA’s rules. The regulations surveyed include the Cross-State Air Pollution Rule (CSAPR), the Mercury and Air Toxics Standards (MATS), the proposed Clean Water Act (CWA) Section 316(b) rule, and the proposed Coal Combustion Residuals (CCR) rule. The models generally agree that these regulations will result in coal plant retirements, though there is far less agreement on how much generation may retire. Assumptions about the price of natural gas and the expected stringency of regulations play a key role in determining modeling results. The models provide useful guidance for policymakers when considering the potential impact of EPA regulation.

Restrictions and Limitations for the Design of a Steam Generator for a Coal-fired Oxyfuel Power Plant with Circulating Fluidised Bed Combustion

As general restrictions for the design of Oxyfuel pulverised coal-fired (PC) steam generators are commonly known, the purpose of this work is to show general restrictions for the design of an Oxyfuel coal-fired steam generator using a circulating fluidised bed combustor (CFBC) with external heat exchangers (EHEs). For the CFBC restrictions result on the one hand out of the used fuels composition. On the other hand certain restrictions out of state-of-the-art and steam generator geometries have to be considered within the design.

Effect of Pond Ash on Pen Surface Properties

<abstract><title><italic>Abstract.</italic></title> The maintenance of feedlot pen surfaces, which includes removal of manure and replacement of fill soil, is a time-consuming and expensive process. Pond ash (PA), a by-product of coal-fired electrical generation, has been proposed as a feedlot pen surface amendment because of its foundational support characteristics. A study was conducted to compare the performance of PA-surfaced pens to traditional soil-surfaced (SS) pens. Four of eight SS pens (7.3 m × 20.7 m) were excavated to a depth of 0.5 m and resurfaced with PA. The remaining four pens were kept as SS. Eight heifers were housed in each pen (19 m² head^-1) for four feeding cycles that ranged from 73 to 172 days. Following each feeding cycle, the animals were removed and the pens were cleaned. A subsample of the accumulated manure was removed from each pen for analysis of total mass (TM), total solids (TS), volatile solids (VS), percent volatile solids (VS%), moisture, and ash content. Higher heating value (HHV) was estimated using the VS% and moisture content. As compared to the SS pens, surfacing pens with PA reduced TM by 34%, TS by 34%, and ash content by 46%. PA increased VS% by 70% and HHV by 75%. Restoring the PA-surfaced pens to the original grade required only 25% of the amount of fill material required for the SS pens. However, there were no differences in the total amount of VS removed. Harvested feedlot surface material (FSM) from the PA pens was more nutrient and energy dense, based on the increased VS% of the collected material. The increased density improved the economics of transport and handling, and allowed for greater energy recovery. In addition, the PA pens were less erodible than the SS pens.

Air Preheaters Operating Situation and Analysis in Coal-Fired Generators

To prevent and dispose all kinds of problems occurred in the air preheaters of the large coal-fired power plants and improve the performance of the air preheaters, the representative problems of the air preheaters in Henan province was summarized with the statistical method. With specific cases, its adverse impact for boilers and auxiliary machines were analyzed. The main reasons for causing these problems were design flaws, maintain undeserved, poor blowing effect and high sulfur content in coal that can cause acid corrosion to the air preheaters. A series of countermeasures were put forward to resolve the problems.

UK's Gas Heritage May Become Its Legacy

Guest editorial The United Kingdom is attempting to emulate the unconventional gas bonanza that has transformed the United States from having an energy industry that was in its “sunset” era to a nation rich in energy resources. The UK, which sits on significant shale reserves, wants to become part of this game-changing industry, viewing it as an exciting opportunity as it looks to revolutionize the energy landscape for the next generation. By its very nature, the country has a dense population with a rural and agricultural countryside and, though it boasts a huge offshore infrastructure, lacks onshore support and infrastructure. Add the obstacles of environmental concerns, a need to build awareness, and a cautious political uptake, it could take 2 more decades before investment decisions by industry could turn concern about the value of unconventionals into certainty. Unconventional gas has a particular production profile and economics; consequently, operators must be able to drill, produce, and build facilities within tight cost parameters, which can be marginal. The underpinning culture and supply chain in the North Sea is not as conducive to that development. Therefore, it is crucial that there is a fundamental shift in the approach toward equipment, infrastructure, service industry support, and onshore and community stakeholder engagement. Historically, the UK and Europe have engineered large gas deposits offshore and deployed pipeline and transport facilities to handle the delivery of large volumes of conventional high-pressure gas to market. Therefore, the existing base infrastructure presents a costly challenge for unconventional operators seeking entry into the industry. It is also true that where there has been the opportunity to turn gas into electricity by generation, both the generating and distribution network is geared to high-voltage, coal-fired power stations and nuclear electricity generation. The story now centers on the indigenous supply of natural gas. Five years ago, it looked as though the world might have only 50 to 60 years’ worth of gas. However, by some estimates, shale and other unconventional gas finds have increased that life span to 200 years or more. The successful exploration, appraisal, and development of UK onshore unconventional resources have the potential to provide a significant contribution to the hydrocarbon component of the nation’s balanced portfolio and strategy. Despite the technical, environmental, financial, and political challenges, the UK and other European countries, are taking the first tentative steps to establish the development of shale and coalbed methane. Coring activity is now under way in reservoirs to ascertain the presence of gas, geological permeability, and the natural fracture system within the rock, and that presents an encouraging commercial opportunity.

Key Aspects of Transitions Occurring in Electric Power Systems and Baseload Generation

Coal-fired generation has historically provided 70 percent or more of the baseload generation capacity in the eastern U.S. [Ventyx, 2012] and due to new environmental regulations combined with stable low cost natural gas, this percentage will likely decrease. New source performance standards (NSPS) proposed by the EPA [EPA, 2011] for greenhouse gas (GHG) mitigation put the electric power industry on a course that gradually eliminates coal generation from being a major source of electric power. With electricity being a fundamental service to all economic sectors, such a transition could potentially increase the cost of electricity to levels detrimental to U.S. economic growth. Transitioning away from coal to other fuels for electric power involves additional costs and key capabilities historically provided by coal generation. Three characteristics of coal-fired electric power are its baseload operating characteristics, the ability of it to provide system stability through generator response and turbine inertia, and the additional reliability assurance provided by on-site fuel supply. This paper provides an overview of these characteristics to heighten the awareness of the strengths provided by coal generation that have contributed to highly reliable and low cost electric power systems in the U.S.

Photovoltaic energy generation in Brazil – Cost analysis using coal-fired power plants as comparison

We make a brief analysis of the evolution of photovoltaic systems, highlighting the present situation worldwide and in Brazil. We compare costs of energy generation associated to photovoltaic and to coal-fired power plants. Coal-fired generation represents the eligible choice for the Brazilian State of Rio Grande do Sul, where thermal plants may use locally extracted coal. The production cost of the energy generated with coal is evaluated taking in account the effect of the invisible cost represented by externalities that affect human health. The price evolution of Photovoltaic modules is presented, as well as trends on decreasing costs for new installations. We also calculate the production cost of the AC energy generated by three photovoltaic plants, with different power, derived from a model. The model is used to make sensitive analysis based on the adjustment of some factors that directly affect Brazilian costs such as: insolation, module's custom and transportation taxes, effect of economy of scale, cost of money. A cost comparison is made between the two technologies and some government incentives are proposed to narrow the existing financial gap.

Projecting the external health costs of a coal-fired power plant: The case of Kusile

We examine an important subset of the expected health costs associated with the commissioning of Kusile, a new coal-fired electricity generation plant in South Africa. The subset of health impacts focuses on sulphur dioxides, nitrous oxides and large particulate matter (greater than 10 mm). The analysis makes use of the Impact Pathway Approach combined with the data transfer methodology. The plant, which is expected to contribute 4 800 MW of additional electricity to the South African grid is found to have modest health impacts, partly due to the limited additional pollutant emissions expected at the plant. Specifically, additional localised external health costs are found to be in the region of 0.09c/kWh to 6.08c/kWh. Limitations of the analysis are also examined.

Towards a Cleaner Environment with IRP—An Indian Case Study

In India`s technical evolution, as with many other nations, the power sector is faced with the twin challenges of increasing generating capacity to combat growing power shortages, and at the same time reducing the environmental degradation caused by electricity generation. This article examines the alternatives to traditional fossil-fuel-fired or large hydropower stations. The conclusion presents two scenarios, the first being the business as usual case where traditional coal-fired generation remains the mainstay of the Indian power sector; the other being an integrated resource planning (IRP) scenario. The installed capacity required and the consequent emissions of acid and greenhouse gases are compared between the two scenarios for different years.

Corrigendum to: Whitaker, M., G.A. Heath, P. O'Donoughue, and M. Vorum. Life cycle greenhouse gas emissions of coal‐fired electricity generation: Systematic review and harmonization. Journal of Industrial Ecology 16(S1): S53–S72.

Journal of Industrial EcologyVolume 16, Issue 6 p. 966-966 CORRIGENDUM Corrigendum to: Whitaker, M., G.A. Heath, P. O'Donoughue, and M. Vorum. Life cycle greenhouse gas emissions of coal-fired electricity generation: Systematic review and harmonization. Journal of Industrial Ecology 16(S1): S53–S72. First published: 27 August 2012 https://doi.org/10.1111/j.1530-9290.2012.00536.xRead the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article. Volume16, Issue6Special Issue: Sustainable Urban SystemsDecember 2012Pages 966-966 Translations 《产业生态学报》中文摘要 (JIE Chinese Abstracts) Resúmenes en Español de la Revista de Ecología Industrial (JIE Spanish Abstracts) RelatedInformation

A lot left over: Reducing CO2 emissions in the United States’ electric power sector through the use of natural gas

As the leading contributor of greenhouse gas emissions, the electricity sector stands to be impacted by policies seeking to curtail emissions. Instead of increasing electricity from renewable resources or nuclear power facilities, an alternative approach to reducing emissions in the electric power sector is changing the dispatch order of fossil fuels. Important differences between fossil fuels, and in the technologies used to burn them, make it possible to substantially reduce emissions from the sector. On average, each gigawatt-year of electricity generation switched from coal to natural gas reduces CO2 emissions by 59 percent. As a result of significant investments in natural gas fired power plants in the United States between 1998 and 2005, there is an opportunity for electricity producers to take advantage of underutilized capacity. This is the first study to closely examine the new capital additions and analyze the technical potential for reductions in emissions. The analysis finds that 188GW of capacity may be available to replace coal-fired baseload electricity generation. Utilizing this excess gas-fired capacity will reduce the sector's CO2 emissions by 23 to 42 percent and reduce overall U.S. CO2 emissions between 9 percent and 17 percent.

Mercury Emissions from the Coal-Fired Energy Generation Sector of the Russian Federation

This paper presents results from the United Nations Environment Programme (UNEP)-coordinated project, “Reducing Mercury Emissions from Coal Combustion in the Energy Sector”, implemented in the Russ...

Optimal generation dispatch with renewable energy embedded using multiple objectives

Traditional economic dispatch focuses mainly on minimizing the total operation cost of the power system. With the appearance of energy crisis and environmental pollution becoming a public issue, environmental effect of generator should be taken into consideration through the dispatch process. In this paper a multi-objective dispatch problem considering the integration of wind power is solved whose objectives include the generation cost, the reserve capacity and the environmental emission. To compromise different objectives, a coordination degree combined with a satisfaction degree are introduced in order to transform the multi-objective dispatch problem into a single-objective one, i.e., the optimal generation dispatch (OGD) model. Then the OGD is solved by a particle swarm optimization algorithm on an IEEE 30-bus system, with wind power generation and coal-fired generation embedded. The simulation results show that better results in terms of all the three objectives can be obtained from the OGD model, in comparison with two other multi-objective dispatch models. The simulation results also show that the integration of wind power will cause the increase of both the generation cost and the reserve capacity but will decrease the environmental emission.

What Can Meta‐Analyses Tell Us About the Reliability of Life Cycle Assessment for Decision Support?

The body of life cycle assessment (LCA) literature is vast and has grown over the last decade at a dauntingly rapid rate. Many LCAs have been published on the same or very similar technologies or products, in some cases leading to hundreds of publications. One result is the impression among decision makers that LCAs are inconclusive, owing to perceived and real variability in published estimates of life cycle impacts. Despite the extensive available literature and policy need formore conclusive assessments, only modest attempts have been made to synthesize previous research. A significant challenge to doing so are differences in characteristics of the considered technologies and inconsistencies in methodological choices (e.g., system boundaries, coproduct allocation, and impact assessment methods) among the studies that hamper easy comparisons and related decision support. An emerging trend is meta-analysis of a set of results from LCAs, which has the potential to clarify the impacts of a particular technology, process, product, or material and produce more robust and policy-relevant results. Meta-analysis in this context is defined here as an analysis of a set of published LCA results to estimate a single or multiple impacts for a single technology or a technology category, either in a statisticalmore » sense (e.g., following the practice in the biomedical sciences) or by quantitative adjustment of the underlying studies to make them more methodologically consistent. One example of the latter approach was published in Science by Farrell and colleagues (2006) clarifying the net energy and greenhouse gas (GHG) emissions of ethanol, in which adjustments included the addition of coproduct credit, the addition and subtraction of processes within the system boundary, and a reconciliation of differences in the definition of net energy metrics. Such adjustments therefore provide an even playing field on which all studies can be considered and at the same time specify the conditions of the playing field itself. Understanding the conditions under which a meta-analysis was conducted is important for proper interpretation of both the magnitude and variability in results. This special supplemental issue of the Journal of Industrial Ecology includes 12 high-quality metaanalyses and critical reviews of LCAs that advance understanding of the life cycle environmental impacts of different technologies, processes, products, and materials. Also published are three contributions on methodology and related discussions of the role of meta-analysis in LCA. The goal of this special supplemental issue is to contribute to the state of the science in LCA beyond the core practice of producing independent studies on specific products or technologies by highlighting the ability of meta-analysis of LCAs to advance understanding in areas of extensive existing literature. The inspiration for the issue came from a series of meta-analyses of life cycle GHG emissions from electricity generation technologies based on research from the LCA Harmonization Project of the National Renewable Energy Laboratory (NREL), a laboratory of the U.S. Department of Energy, which also provided financial support for this special supplemental issue. (See the editorial from this special supplemental issue [Lifset 2012], which introduces this supplemental issue and discusses the origins, funding, peer review, and other aspects.) The first article on reporting considerations for meta-analyses/critical reviews for LCA is from Heath and Mann (2012), who describe the methods used and experience gained in NREL's LCA Harmonization Project, which produced six of the studies in this special supplemental issue. Their harmonization approach adapts key features of systematic review to identify and screen published LCAs followed by a meta-analytical procedure to adjust published estimates to ones based on a consistent set of methods and assumptions to allow interstudy comparisons and conclusions to be made. In a second study on methods, Zumsteg and colleagues (2012) propose a checklist for a standardized technique to assist in conducting and reporting systematic reviews of LCAs, including meta-analysis, that is based on a framework used in evidence-based medicine. Widespread use of such a checklist would facilitate planning successful reviews, improve the ability to identify systematic reviews in literature searches, ease the ability to update content in future reviews, and allow more transparency of methods to ease peer review and more appropriately generalize findings. Finally, Zamagni and colleagues (2012) propose an approach, inspired by a meta-analysis, for categorizing main methodological topics, reconciling diverging methodological developments, and identifying future research directions in LCA. Their procedure involves the carrying out of a literature review on articles selected according to predefined criteria.« less

Life Cycle Greenhouse Gas Emissions from Electricity Generation: A Comparative Analysis of Australian Energy Sources

Electricity generation is one of the major contributors to global greenhouse gas emissions. Transitioning the World’s energy economy to a lower carbon future will require significant investment in a variety of cleaner technologies, including renewables and nuclear power. In the short term, improving the efficiency of fossil fuel combustion in energy generation can provide an important contribution. Availability of life cycle GHG intensity data will allow decision-makers to move away from overly simplistic assertions about the relative merits of certain fuels, and focus on the complete picture, especially the critical roles of technology selection and application of best practice. This analysis compares the life-cycle greenhouse gas (GHG) intensities per megawatt-hour (MWh) of electricity produced for a range of Australian and other energy sources, including coal, conventional liquefied natural gas (LNG), coal seam gas LNG, nuclear and renewables, for the Australian export market. When Australian fossil fuels are exported to China, life cycle greenhouse gas emission intensity in electricity production depends to a significant degree on the technology used in combustion. LNG in general is less GHG intensive than black coal, but the gap is smaller for gas combusted in open cycle gas turbine plant (OCGT) and for LNG derived from coal seam gas (CSG). On average, conventional LNG burned in a conventional OCGT plant is approximately 38% less GHG intensive over its life cycle than black coal burned in a sub-critical plant, per MWh of electricity produced. However, if OCGT LNG combustion is compared to the most efficient new ultra-supercritical coal power, the GHG intensity gap narrows considerably. Coal seam gas LNG is approximately 13–20% more GHG intensive across its life cycle, on a like-for like basis, than conventional LNG. Upstream fugitive emissions from CSG (assuming best practice gas extraction techniques) do not materially alter the life cycle GHG intensity rankings, such is the dominance of end-use combustion, but application of the most recent estimates of the 20-year global warming potential (GWP) increases the contribution of fugitives considerably if best practice fugitives management is not assumed. However, if methane leakage approaches the elevated levels recently reported in some US gas fields (circa 4% of gas production) and assuming a 20-year methane GWP, the GHG intensity of CSG-LNG generation is on a par with sub-critical coal-fired generation. The importance of applying best practice to fugitives management in Australia’s emerging natural gas industry is evident. When exported to China for electricity production, LNG was found to be 22–36 times more GHG intensive than wind and concentrated solar thermal (CST) power and 13–21 times more GHG intensive than nuclear power which, even in the post-Fukushima world, continues to be a key option for global GHG reduction.

Diversification of fuel costs accounting for load variation

A practical mathematical programming model for the strategic fuel diversification problem is presented. The model is designed to consider the tradeoffs between the expected costs of investments in capacity, operating and maintenance costs, average fuel costs, and the variability of fuel costs. In addition, the model is designed to take the load curve into account at a high degree of resolution, while keeping the computational burden at a practical level.The model is illustrated with a case study for Indiana's power generation system. The model reveals that an effective means of reducing the volatility of the system-level fuel costs is through the reduction of dependence on coal-fired generation with an attendant shift towards nuclear generation. Model results indicate that about a 25% reduction in the standard deviation of the generation costs can be achieved with about a 20–25% increase in average fuel costs. Scenarios that incorporate costs for carbon dioxide emissions or a moratorium on nuclear capacity additions are also presented.

Microbial communities associated with wet flue gas desulfurization systems

Flue gas desulfurization (FGD) systems are employed to remove SOx gasses that are produced by the combustion of coal for electric power generation, and consequently limit acid rain associated with these activities. Wet FGDs represent a physicochemically extreme environment due to the high operating temperatures and total dissolved solids (TDS) of fluids in the interior of the FGD units. Despite the potential importance of microbial activities in the performance and operation of FGD systems, the microbial communities associated with them have not been evaluated. Microbial communities associated with distinct process points of FGD systems at several coal-fired electricity generation facilities were evaluated using culture-dependent and -independent approaches. Due to the high solute concentrations and temperatures in the FGD absorber units, culturable halothermophilic/tolerant bacteria were more abundant in samples collected from within the absorber units than in samples collected from the makeup waters that are used to replenish fluids inside the absorber units. Evaluation of bacterial 16S rRNA genes recovered from scale deposits on the walls of absorber units revealed that the microbial communities associated with these deposits are primarily composed of thermophilic bacterial lineages. These findings suggest that unique microbial communities develop in FGD systems in response to physicochemical characteristics of the different process points within the systems. The activities of the thermophilic microbial communities that develop within scale deposits could play a role in the corrosion of steel structures in FGD systems.