Coal-fired Generation Research Articles

An all-condition simulation model of the steam turbine system for a 600 MW generation unit

Coal-fired generation units in China often operate under off-design loads. The off-design performance has important influence on operation energy consumption of generation units. An all-condition model is of critical importance for studying the off-design performance. In this paper, an all-condition simulation model of the steam turbine system for a 600 MW generation unit is built. Based on the actual system composition, the steam turbine system is divided into several sub equipment. A sub model is established for each device. In the turbine model, a parameter M is defined as the intermediate variable to calculate the extraction pressure of turbine. The operating data from a 600 MW generation unit are used to verify the all-condition model. The heater fouling conditions are also calculated. The result shows that the model successfully predicts the operation parameters under different loads and forecasts the thermal performance of typical equipment failure.

Life cycle engineering of production, use and recovery of self-chilling beverage cans

The chill-on-demand system is a new technology designed to provide cooled products on demand, thereby avoiding chilled storage. It uses the cooling effect provided by endothermic desorption of carbon dioxide previously adsorbed onto a bed of activated carbon and has the potential to be applied to any type of product that needs to be cold at the point of consumption. The principles of life cycle engineering have been utilized to evaluate the overall environmental performance of one possible application of this technology: a self-chilling beverage can, with a steel outer can to contain the beverage and an inner aluminium can to contain the adsorbent.An attributional life cycle assessment has been undertaken considering all the life cycle stages of a self-chilling can: manufacture of each part of the beverage container, its utilization, collection of the used can, and management of the waste by reuse, recycling and landfilling. Activated carbon production is included in detail, to assess its contribution to the overall life cycle. The results are compared with those for conventional aluminium and steel beverage cans stored in two types of retail chiller: a single door refrigerator and a large open-front cooler. A sensitivity analysis explores alternative scenarios for activated carbon production and for recovery of the can components post-use for reuse or recycling. The results highlight the importance of using activated carbon produced from biomass by a process with efficient use of low-carbon electrical energy, energy recovery from waste streams and appropriate air pollution control, and of achieving high rates of recovery, re-use and recycling of the cans after use. The results suggest limited markets into which the product might be introduced, particularly where it would displace inefficient chilled storage in an electricity system with a high proportion of coal-fired generation.

The search for most cost-effective way of achieving environmental sustainability status in electricity generation: Environmental life cycle cost analysis of energy scenarios

Over 80% of Alberta's electricity supply comes from fossil fuels; coal fired plants made up 43%. Alberta has announced its climate leadership plan, in which it is going to end electricity from coal and move towards sustainable power production. All categories of renewable energy sources, including bioenergy are expected to significantly contribute to the transition and transformation of Alberta's fossil-intensive electricity. As Alberta searches for measures to phasing out coal power plants, understanding the environmental and economic impact of alternatives can support decision-making. The main purpose of this research was to determine a cost-effective way of achieving environmental sustainability status in electricity generation. An environmental life cycle costing approach was applied to compare three biomass-based alternative scenarios, which represented energy transition and transformation in Alberta's electricity sector, with the prevailing scenario of coal-fired energy.All alternative energy scenarios showed environmental life cycle improvement from 47 to 92% for global warming, 46–90% for human health, and 47–91% for ecosystem impacts, when compared to a reference coal-fired generation scenario. On the other hand, the coal-fired electricity generation scenario demonstrated approximately 63–83% lower life cycle cost impact than alternative scenarios. The life cycle cost of wood biomass-based alternatives demonstrated 83–87% and 22–45% lower than the maximum and minimum average historical electricity generation cost for Alberta, respectively. Bioenergy can support the transition and transformation of coal power plants to a more sustainable power production.

The prospects for coal-fired power generation in Saudi Arabia

Almost all of Saudi Arabia's electric power generation is fueled by oil and gas. Plans for future capacity envisage nuclear and renewables supplementing this mix and thereby freeing up oil for other revenue-generating opportunities. Coal-fired generation has been promoted in some Gulf Cooperation Council (GCC) countries but not, so far, in the Kingdom. Our analysis finds that:•Imported coal would provide lower cost generation than either solar or nuclear power in the near-term.•At current administered prices of oil and gas, other resources of energy such as solar, nuclear, or imported coal are not competitive for power generation.•If decisions were made based on deregulated oil and gas prices:○At the reference coal price, only moderate levels of coal-fired capacity would be introduced. Having remaining capacity comprised of nuclear and solar would result in lower Saudi CO2 emissions from power generation than under a ‘business-as-usual’ scenario.○At the low coal price, CO2 emissions in 2030 cannot be maintained at their current level since coal, rather than solar and nuclear, is used to displace oil and gas from the generation fuel mix.Some forecasts of coal markets anticipate significant increases in real export prices, which would make coal-fired power generation unattractive compared to nuclear power.

Influence of class F fly ash and curing temperature on strength development of fly ash-recycled concrete aggregate blends

The environmental footprint for Portland cement production contributes to significant carbon dioxide emissions, particularly in the civil engineering industry. Alternative low-carbon binders to Portland cement have been increasingly sought in recent years by road construction companies. Fly ash (FA) is the by-product of coal-fired electricity generation in many developed and developing countries, and is traditionally stockpiled as a waste material at power plants. Recycled Concrete Aggregates (RCA) generated from demolition industries, has in recent years gained acceptance as cement stabilized pavement material. In this research, FA was evaluated as an alternative low-carbon binder for the stabilization of RCA as a road construction material. The substantial reduction in environmental impact of replacing general Portland cement by alternative binders such as FA, along with economic advantages of utilization of FA in construction activities tackles the negative landfilling impacts and carbon footprint of stabilization activities at the same time. The strength characterization of RCA stabilized with various FA content was evaluated by undertaking Unconfined Compressive Strength (UCS) tests on samples cured at ambient room temperature and at 40°C. The durability of the FA stabilized RCA under simulated traffic loadings was furthermore evaluated by performing repeated load triaxial tests to determine the resilient modulus (MR) of RCA samples when stabilized with FA. The micro-scale formation of bonds between the aggregates with different FA content and its effect on the strength of the stabilized RCA specimens was furthermore studied. RCA stabilized with 15% FA was found to be the optimum blend for road stabilization applications.

Technology adoption under time-differentiated market-based instruments for pollution control

Peak concentrations of ground-level ozone pose health risks to millions of U.S. citizens across the U.S. In order to reduce peak ozone concentrations, nitrogen oxide (NOx) emissions from the power sector, among others, have been regulated with technology-based standards or, more commonly in recent years, market-based instruments such as cap-and-trade programs. However, the lack of temporal flexibility in current designs of these market-based instruments limits their cost-effectiveness on days forecasted to have the highest levels of pollution, including ozone precursors such as NOx, and as further emission reductions are sought, the marginal cost of these approaches increases dramatically. In this paper, we compare three regulatory schemes for reducing NOx emissions on high-ozone days: time-differentiated pricing, which prices NOx emissions only on days with high-ozone concentrations; undifferentiated pricing, which represents current NOx emission regulations; and technology-based standards. We develop a novel model that captures for the first time both the short- and long-term response of generators, through redispatching and control technology adoption, to a dynamic pricing scheme such as time-differentiated pricing. Unlike prior studies on time-differentiated pricing, the heart of our model, a unit commitment model, accounts for inter-temporal constraints on power generation that may be crucial to accurately capturing the response of generators to a transient price signal. We apply this model to the Texas power system and find that while control technology adoption (specifically selective catalytic reduction) does occur at very high time-differentiated prices, time-differentiated pricing mainly affects emissions and costs through redispatching of gas- for coal-fired generation. Furthermore, we show that time-differentiated pricing, due to its targeted pricing mechanism, provides a more cost-effective approach than undifferentiated pricing or technology-based standards for reducing NOx emissions on high-ozone days, but is not cost-effective at reducing summer-wide NOx emissions. Our results illustrate the trade-offs between these regulatory approaches and suggest that states should consider dynamic pricing schemes such as time-differentiated pricing for achieving further reductions in peak ozone concentrations.

Influence of Climate Policy and Market Forces on Coal-fired Power Plants: Evidence on the Dutch market over 2006-2014

Many governments aim to reduce the dependence on coal-fired generation to decrease carbon emissions. At the same time power markets with competition between independently operating power firms have been created which leave the actual decisions concerning electricity production to these firms. This paper analyzes the interaction between climate policies and policies to foster power markets. Using hourly plant-level data on the Dutch power market over 2006-2014, we find that the dispatch of fossil-fuel power plants is strongly influenced by relative fuel prices, despite the existence of several climate policy measures. Coal-fired power plants have become more important in the Dutch market since 2006, not only in share of total production, but also as provider of flexibility. Examining the short-term dispatch decisions and the past volatility in relative fuel prices, the maximum CO2 price which was needed to provide incentives for power producers to dispatch a gas-fired plant instead of a coal-fired plant was 43 euro/ton. We conclude that internalizing the external (CO2) costs by raising the CO2 price is a more appropriate measure than a forced closure of coal-fired power plants to align the principles of a market-based power industry and the wish to implement effective climate-policy measures at relatively low costs.

Long-term implications of sustained wind power growth in the United States: Direct electric system impacts and costs

This paper evaluates potential changes in the power system associated with sustained growth in wind generation in the United States to 35% of end-use demand by 2050; Wiser et al. (2016) evaluate societal benefits and other impacts for this same scenario. Under reference or central conditions, the analysis finds cumulative wind capacity of 404gigawatts (GW) would be required to reach this level and drive 2050 incremental electricity rate and cumulative electric sector savings of 2% and 3% respectively, relative to a scenario with no new wind capacity additions. Greater savings are estimated under higher fossil fuel costs or with greater advancements in wind technologies. Conversely, incremental costs are found when fossil fuel costs are lower than central assumptions or wind technology improvements are more-limited. Through 2030, the primary generation sources displaced by new wind capacity include natural gas and coal-fired generation. By 2050, wind could displace other renewables. Incremental new transmission infrastructure totaling 29 million megawatt-miles is estimated to be needed by 2050. In conjunction with related societal benefits, this work demonstrates that 35% wind energy by 2050 is plausible, could support enduring benefits, and could result in long-term consumer savings, if nearer-term (pre-2030) cost barriers are overcome; at the same time, these opportunities are not anticipated to be realized in their full form under “business-as-usual” conditions.

Quantifying the potential impacts of China's power-sector policies on coal input and CO2 emissions through 2050: A bottom-up perspective

This study evaluates four recent policies for China's power sector—mandatory renewable targets, green dispatch, carbon capture and sequestration development, and coal-fired generation efficiency improvements—and quantifies their energy and carbon dioxide (CO2) emissions reduction potential through 2050 using bottom-up energy modeling and scenario analysis. We find renewable targets and green dispatch have crucial interlinked impacts on energy and CO2 emissions that could change the shape and peak year of China's power-sector emissions outlook. Without either renewable targets or green dispatch, coal will likely continue dominating China's power mix and could delay the power-sector CO2 emissions peak to the late 2030s.

Engineering and Information Support for Monitoring of Fuel-Power Complex of the Irkutsk Oblast Using the Results of Remote Sensing

There were given the results of remote sensing disturbed lands of Irkutsk Oblast’s fuel-power complex. It was established structure of disturbed lands in the open-pit mining, as well as the lands of thermal power plants involved in coal-fired generation of heat and electricity. For coal mines proposed the use of land reclamation technology when combined stripping works with mining engineering reclamation stage, and for thermal power given recommendations for the use of manual techniques of ash storage while reducing costs for the construction of embanks and the reduction of polluting emissions and harmful substances during construction.

Integration of Renewables into the Ontario Electricity System

The Ontario electricity industry has a 'hybrid' structure: electricity is bought and sold in a competitive wholesale electricity market while supply mix planning and procurement are conducted through a government agency. Most generation is secured through long-term contracts. Aggressive renewable energy programs have led to rapidly growing renewable capacity, mainly wind generation. Coal-fired generation has been eliminated and electricity sales have dropped. The competitive hourly market price has declined and there is a clear merit-order effect: an increase of wind generation from 500 MW to 1500 MW can be expected to decrease price by 7 CAD/MWh. However, the all-in price, which incorporates contractually guaranteed supply prices, has risen from about 60 to 100 CAD/MWh between 2009 and 2014. Operational and market integration of renewable resources has been achieved relatively smoothly. The procurement process is over-centralized: increased reliance on market discipline and greater separation between governmental policy makers and regulators would enhance both the efficacy and efficiency of decarbonization policies.

Leveling the playing field of transportation fuels: Accounting for indirect emissions of natural gas

Natural gas transportation fuels are credited in prior studies with greenhouse gas emissions savings relative to petroleum-based fuels and relative to the total emissions of biofuels. These analyses, however, overlook a source of potentially large indirect emissions from natural gas transportation fuels, namely the emissions from incremental coal-fired generation caused by price-induced substitutions away from natural-gas-fired electricity generation. Because coal-fired generation emits substantially more greenhouse gases and criteria air pollutants than natural-gas-fired generation, this indirect coal-use change effect diminishes potential emissions savings from natural gas transportation fuels. Estimates from a parameterized multi-market model suggest the indirect coal-use change effect rivals in magnitude the indirect land-use change effect of biofuels and renders natural gas fuels as carbon intensive as petroleum fuels.

Method of flash evaporation and condensation – heat pump for deep cooling of coal-fired power plant flue gas: Latent heat and water recovery

Flue gas waste heat recovery and utilization is an efficient means to improve the energy efficiency of coal-fired power plants. At present, the surface corrosion and fouling problems of heat exchanger hinder the development of flue gas deep cooling. In this study, a novel flue gas deep cooling method that can reduce flue gas temperature below the dew point of vapor to recover latent heat and obtain clean water simultaneously is proposed to achieve improved energy efficiency. The heat transfer mode of this method is the direct contact mode, which takes the scrubber, e.g. the flue gas desulfurization (FGD) scrubber, as the deep cooling exchanger. The flash evaporation and condensation (FEC) device and heat pump (HP) are utilized to provide low-temperature medium, such as FGD slurry or water, for washing and deep cooling flue gas, to collect recovered water, and to absorb recovered waste heat. This method is called as the FEC–HP method. This paper elaborated on two optional models of the proposed method. The mechanism for recovering heat and water was also analyzed using the customized flue gas humidity chart, and the method to quantitate recovered heat and water, as well as the results of the case of a 300MW coal-fired generator set were provided. Net present value calculations showed that this method is profitable in the scenario of burning high-water-content coals. Several potential advantages of this method and suggestions for practical application were also discussed.

Spatially and Temporally Resolved Analysis of Environmental Trade-Offs in Electricity Generation.

The US power sector is a leading contributor of emissions that affect air quality and climate. It also requires a lot of water for cooling thermoelectric power plants. Although these impacts affect ecosystems and human health unevenly in space and time, there has been very little quantification of these environmental trade-offs on decision-relevant scales. This work quantifies hourly water consumption, emissions (i.e., carbon dioxide, nitrogen oxides, and sulfur oxides), and marginal heat rates for 252 electricity generating units (EGUs) in the Electric Reliability Council of Texas (ERCOT) region in 2011 using a unit commitment and dispatch model (UC&D). Annual, seasonal, and daily variations, as well as spatial variability are assessed. When normalized over the grid, hourly average emissions and water consumption intensities (i.e., output per MWh) are found to be highest when electricity demand is the lowest, as baseload EGUs tend to be the most water and emissions intensive. Results suggest that a large fraction of emissions and water consumption are caused by a small number of power plants, mainly baseload coal-fired generators. Replacing 8-10 existing power plants with modern natural gas combined cycle units would result in reductions of 19-29%, 51-55%, 60-62%, and 13-27% in CO2 emissions, NOx emissions, SOx emissions, and water consumption, respectively, across the ERCOT region for two different conversion scenarios.

Assessment of the Cost and Environmental Impact of Residential Demand-Side Management

A detailed study of the potential impact of low-voltage (LV) residential demand-side management (DSM) on the cost and greenhouse gas (GHG) emissions is presented. The proposed optimization algorithm is used to shift noncritical residential loads, with the wet load category used as a case study, in order to minimize the total daily cost and emissions due to generation. This study shows that it is possible to reshape the total power demand and reduce the corresponding cost and emissions to some extent. It is also shown that, when the baseload generating mix is dominated by coal-fired generation, the daily profiles of GHG emissions and cost conflict, such that further optimization of the cost leads to an increase in emissions.

Environmental Performance of Hypothetical Canadian Pre-Combustion Carbon Dioxide Capture Processes Using Life-Cycle Techniques

The methodology of life-cycle assessment was applied in order to evaluate the environmental performance of a hypothetical Saskatchewan lignite-fueled Integrated Gasification Combined Cycle (IGCC) electricity generation, with and without pre-combustion carbon dioxide (CO2) capture from a full life-cycle perspective. The emphasis here is placed on environmental performance associated with air contaminants of the comparison between IGCC systems (with and without CO2 capture) and a competing lignite pulverized coal-fired electricity generating station in order to reveal which technology offers the most positive environmental effects. Moreover, ambient air pollutant modeling was also conducted by using American Meteorological Society/Environmental Protection Agency Regulatory Model (AERMOD) air dispersion modeling to determine the ground-level concentration of pollutants emitted from four different electricity generating stations. This study assumes that all stations are located close to Estevan. The results showed a significant reduction in greenhouse gas (GHG) emissions and acidification potential by applying both post-combustion and pre-combustion CO2 capture processes. The GHG emissions were found to have reduced by 27%–86%, and IGCC systems were found to compare favorably to pulverized coal systems. However, in other environmental impact categories, there are multiple environmental trade-offs depending on the capture technology used. In the case of post-combustion capture, it was observed that the environmental impact category of eutrophication potential, summer smog, and ozone depletion increased due to the application of the CO2 capture process and the surface mining coal operation. IGCC systems, on the other hand, showed the same tendency as the conventional coal-fired electricity generation systems, but to a lesser degree. This is because the IGCC system is a cleaner technology that produces lower pollutant emission levels than the electricity generating station; thus, the benefits of capture are reduced on a comparative basis. The results from air dispersion analysis showed that the maximum ground-level concentrations of pollutants from all electricity generating stations are in compliance with all air quality standards, except for Co, Pb and Ni. The IGCC with capture revealed the lowest nitrogen dioxide (NO2) ground-level concentration compared to all other scenarios. Moreover, IGCC systems both with and without pre-combustion CO2 capture revealed no ground-level concentration of trace elements. This is because the IGCC system operates with an acid gas cleaning process that removes most of the trace contaminants from the syngas.

Canary in a Coal Mine: Infant Mortality, Property Values, and Tradeoffs Associated with Mid-20th Century Air Pollution

Pollution is a common byproduct of economic activity. Although policymakers should account for both the benefits and the negative externalities of polluting activities, it is difficult to identify those who are harmed and those who benefit from them. To overcome this challenge, our paper uses a novel dataset on the mid-20th century expansion of the U.S. power grid to study the costs and the benefits of coal-fired electricity generation. The empirical analysis exploits the timing of coal-fired power plant openings and annual variation in plant-level coal consumption from 1938 to 1962, when emissions were virtually unregulated. Pollution from the burning of coal for electricity generation is shown to have quantitatively important and nonlinear effects on county-level infant mortality rates. By 1962, it was responsible for 3,500 infant deaths per year, over one death per thousand live births. These effects are even larger at lower levels of coal consumption.We also find evidence of clear tradeoffs associated with coal-fired electricity generation. For counties with low access to electricity in the baseline, increases in local power plant coal consumption reduced infant mortality and increased housing values and rental prices. For counties with near universal access to electricity in the baseline, increases in coal consumption by power plants led to higher infant mortality rates, and lower housing values and rental prices. These results highlight the importance of considering both the costs and benefits of polluting activities, and suggest that demand for policy intervention may emerge only when the negative externalities are significantly larger than the perceived benefits.

Rural electrification in India: Galilee Basin coal versus decentralised renewable energy micro grids

The state of Bihar in India has approximately 75 million people with no access to electricity. The government of India has pursued a policy of rural electrification through the provision of centralised coal-fired power which has been unable to resolve the low levels of electrification. Coal supply woes in India have led Indian companies to pursue new coal mines in Australia's Galilee Basin. The costs of these mining ventures will be high due to the mining infrastructure required and long transport distances to rural India. A high level analysis of mining, transport and power station investment to meet rural demand in Bihar shows that the absolute investment requirement using coal, especially coal sourced from Australia, as an expensive option. Pursuing electrification through village level, renewable energy micro-systems provides more flexibility. Pollution costs associated with coal-fired generation, employment benefits associated with many village implementations and a rural load unsupported by industry load, show a benefit associated with decentralised, renewable energy electrification.

Modelling the impact of energy policies on the Philippine economy: Carbon tax, energy efficiency, and changes in the energy mix

As part of its global obligations to responding to climate change, the Philippines is committed to limiting future emissions growth through policy interventions such as funding research on mitigation and direct regulation of energy efficiency requirements. The Philippines is also interested in extensions of such policies, including the use of carbon taxes, measures to enhance energy efficiency, and changes to the country’s electricity generation mix.This paper develops a computable general equilibrium (CGE) model of the Philippine economy to analyse the effects of such climate change policy options in the period to 2020. The modelling results indicate that given the current level of development in the Philippine electricity generation and transport sectors, even relatively modest measures have marked impacts on emissions with marginal economic impacts. A carbon tax of $US5 per a tonne, results in a 9.8% reduction in emissions and a 0.5% reduction in GDP from baseline levels to 2020. Similarly, a 2% increase in energy efficiency throughout the Philippine economy results in an 8.5% reduction in emissions and 0.6% reduction in GDP compared to the underlying baseline of no policy response. Finally, a 10% shift in the coal-fired generation capacity results in an 11.0% reduction in emissions with GDP in fact increasing by 1.9% over baseline levels.

Magnetic Evaluation for Uprating 400 mW Coal Fired Generator

One of the considerations many power plants today is whether they can get more power out of their existing equipment especially generator. However, it is required design review and feasibility study in order to extend the operating life and increase the capability and reliability. In this study, analysis of magnetic field was performed due to power uprating in order to prevent a saturation of the magnetic field in the core laminate which can lead to the emergence of heat concentration. Based on the results of magnetic analysis using finite element, there are no saturation of the magnetic field in the core lamination which can lead to the magnetic saturation and heat concentration, both for existing and uprating conditions.Therefore, the increasing a design margin on the generators from the current design of the margin of 471,000 kVA to 494,550 kVA with the 0.85 power factor will not pose a problem as long as all of the following recommendations can be implemented. Although it is predicted, there will be no saturation and hotspots on the generator, but the risk of temperature rise due to the uprating should be reduced by replacing the stator winding using the Full Class F Insulation which is resistant to temperatures up to 155 °C.