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Proceedings Papers
Proc. ASME. POWER2020, ASME 2020 Power Conference, V001T03A005, August 4–5, 2020
Paper No: POWER2020-16381
Abstract
This work investigates the integration of solid oxide fuel cells (SOFCs) and a small methanol/nitromethane fueled piston engine as a prospective hybrid powertrain for small unmanned aerial systems (UASs). The increased chemical energy density of a liquid fuel when compared to traditional batteries, along with ease of storage, accessibility, and refuel time make the use of a liquid fuel powered UAS preferable when compared to battery only power UAS’. Currently small UAS’ of increasing interest as a research area, as they have a wide application to a variety of fields. UAS’ are currently being used for precision agricultural crop management and water resource visual inspection. UAS’ are a cost effective avenue to survey water resources and track water runoff that is contaminating water resources. UAS’ can be easily automated and fitted with sensors and cameras capable of providing actionable feedback to the user. The use of UAS’ for land management and survey is expected to continue to expand. However, nearly all UAS’ are powered by a typical lithium polymer battery pack, giving an average endurance of approximately twenty minutes. This is acceptable to most hobbyists and for short filming duration; however, it limits UAS’ to only being able to be operated in close proximity to the user. Current power plants for UAS’ are not suited for long duration missions, such as the survey of water resources. Therefore, the development of a hybrid power plant is crucial for UAS’ to be utilized to their full potential as a survey tool. This work introduces a small internal combustion engine to act as a partial oxidation fuel reformer, producing high temperature exhaust and syngas. The exhaust of this engine is then analyzed as a fuel source for tubular SOFC’s. The SOFC is integrated into the exhaust of a 3.3 cm 3 nitromethane fueled two-stroke engine, achieving a maximum power of 680 mW/cm 2 . A theoretical comparison of flight time indicates that the modular hybrid system could increase a typical small UAS’ flight time beyond 1 hour. The system is capable of achieving a significantly higher energy density than traditional lithium polymer batteries.
Proceedings Papers
Proc. ASME. POWER2020, ASME 2020 Power Conference, V001T03A017, August 4–5, 2020
Paper No: POWER2020-16960
Abstract
Rising atmospheric CO 2 levels from significant imbalance between carbon emissions from fossil fuel utilization, especially for energy and chemicals, and natural carbon sequestration rates is known to drive-up the global temperatures and associated catastrophic climate changes, such as rising mean sea level, glacial melting, and extinction of ecosystems. Carbon capture and utilization techniques are necessary for transition from fossil fuel infrastructure to renewable energy resources to help delay the dangers of reaching to the point of positive feedback between carbon emissions and climate change which can drive terrestrial conditions to uninhabitable levels. CO 2 captured from the atmosphere directly or from flue gases of a power plant can be recycled and transformed to CO and syngas for use as energy and value-added chemicals. Utilizing renewable energy resources to drive CO 2 conversion to CO via thermochemical redox looping can provide a carbon negative renewable energy conversion pathway for sustainable energy production as well as value-added products. Substituted ferrites such as Co-ferrite, Mnferrite were found to be promising materials to aid the conversion of CO 2 to CO at lower reduction temperatures. Furthermore, the conversion of these materials in the presence of Al 2 O 3 provided hercynite cycling, which further lowered the reduction temperature. In this paper, Co-ferrite and Co-ferrite-alumina prepared via co-precipitation were investigated to understand their potential as oxygen carriers for CO 2 conversion under isothermal redox looping. Isothermal reduction looping provided improved feasibility in redox conversion since it avoids the need for temperature swinging which improves thermal efficiency. These efforts alleviates the energy losses in heat recovery while also reducing thermal stresses on both the materials and the reactor. Lab-scale testing was carried out at 1673 K on these materials for extended periods and multiple cycles to gain insights into cyclic performance and the feasibility of sintering, which is a common issue in iron-oxide-based oxygen carriers. Cobalt doping provided with lowering of reduction temperature requirement at the cost of oxidation thermodynamic spontaneity that required increased oxidation temperature. At the concentrations examined, these opposing phenomenon made isothermal redox operation feasible by providing high CO yields comparable to oxygen carriers in the literature, which were operated at different temperatures for reduction and oxidation. Significantly high CO yields (∼ 750 μmol/g) were obtained from Co-ferrite isothermal redox looping. Co-ferrite-alumina provided lower CO yields compared to Co-ferrite. The oxygen storage was similar to those reported in the literature on isothermal H 2 O splitting, but with improved morphological stability at high temperature, especially compared to ferrite. This pathway of oxygen carrier development is considered suitable with further requirement in optimization for scaling of renewable CO 2 conversion into valuable products.
Proceedings Papers
Proc. ASME. POWER2020, ASME 2020 Power Conference, V001T03A010, August 4–5, 2020
Paper No: POWER2020-16572
Abstract
The use of large-bore Otto gas engines is currently spreading widely considering the growing share of Power-To-Gas (P2G) solutions using renewable energies. P2G with a Combined Heat and Power (CHP) plant offers a promising way of utilizing chemical energy storage to provide buffering for volatile energy sources such as wind and solar power all over the world. Therefore, ambient conditions like air temperature, humidity and pressure can differ greatly between the location and time of engine operation, influencing its performance. Especially lean-burn Otto processes are sensitive to changes in ambient conditions. Besides, targeted use of humidity variation (e.g. through water injection in the charge air or combustion chamber) can help to reduce NO x emissions at the cost of a slightly lower efficiency in gas engines, being an alternative to selective catalytic reduction (SCR) exhaust gas aftertreatment. The ambient air condition boundaries have to be considered already in the early stages of combustion development, as they can also have a significant effect on generated measurement data in combustion research. To investigate the behavior, a test bench with a natural gas (CNG) powered single-cylinder research engine (piston displacement 4.77 1) at the Institute of Internal Combustion Engines (LVK) of the Technical University of Munich (TUM) was equipped with a sophisticated charge air conditioning system. This includes an air compressor and refrigeration dryer, followed by temperature and pressure control, as well as a controlled injection system for saturated steam and homogenizing containers, enabling the test bench to precisely emulate a widespread area of charge air parameters in terms of pressure, temperature and humidity. With this setup, different engine tests were conducted, monitoring and evaluating the engine’s emission and efficiency behavior regarding charge air humidity. In a first approach, the engine was operated maintaining a steady air-fuel equivalence ratio λ, fuel energy input (Q̇ fuel = const.) and center of combustion (MFB 50%) while the relative ambient humidity was varied in steps between 21% and 97% (at 22 °C and 1013.25 hPa). Results show a significant decrease in nitrogen oxides (NO x ) emissions (−39.5%) and a slight decrease in indicated efficiency (−1,9%) while hydrocarbon (THC) emissions increased by around 60%. The generated data shows the high significance of considering charge air conditioning already in the development stage at the engine test bench. The comparability of measurement data depends greatly on ambient air humidity. In a second approach, the engine was operated at a constant load and constant NO x emissions, while again varying the charge air humidity. This situation rather reflects an actual engine behavior at a CHP plant, where today often NO x –driven engine control is used, maintaining constant NO x emissions. The decrease in indicated efficiency was comparable to the prior measurements, while the THC emissions showed only a mild increase (5%). From the generated data it is, for instance, possible to derive operational strategies to compensate for changes in ambient conditions while maintaining emission regulations as well as high-efficiency output. Furthermore, the results suggest possibilities, but also challenges of utilizing artificial humidification (e.g. through water injection) considering the effects on THC emissions and efficiency. A possible shift of the knocking limit to earlier centers of combustion with higher humidity is to be investigated. The main goal is the further decrease of NO x emissions, increase of efficiency, while still maintaining hydrocarbon emissions.
Proceedings Papers
Proc. ASME. POWER2019, ASME 2019 Power Conference, V001T02A003, July 15–18, 2019
Paper No: POWER2019-1944
Abstract
Traditional carbon capture technology has been shown to effectively capture emissions, but at a cost of reducing power plant output. Molten carbonate fuel cell technology (MCFC) has the potential to be able to concentrate plant carbon emissions into a gas stream that is suitable for storage while boosting total plant power output. When considering this type of technology, the original purpose and function of the power plant must be considered. In particular, gas turbines (GT) based natural gas combined cycle (NGCC), which are capable of dynamic load following operation, are likely to need to maintain operational flexibility. This work explores the retrofit of an existing GT with MCFC technology for carbon capture when the plant is operated at part load. Physical models for major plant components are built and used to select optimal operating set points such that operating cost is minimized. Special attention is given to ensuring feasible operation across all engine components. The results show MCFC operational parameters that minimize change in fuel cell operating conditions when the gas turbine is operated at part load.
Proceedings Papers
Proc. ASME. POWER2018, Volume 1: Fuels, Combustion, and Material Handling; Combustion Turbines Combined Cycles; Boilers and Heat Recovery Steam Generators; Virtual Plant and Cyber-Physical Systems; Plant Development and Construction; Renewable Energy Systems, V001T06A004, June 24–28, 2018
Paper No: POWER2018-7183
Abstract
Renewable energy is best utilized when partnered with energy storage to balance the variable supply with daily and seasonal grid demands. At the distribution level, in addition to meeting power demands, there is a need to maintain system voltage and reactive power / VAR control. Rotating machinery is most effective for VAR control at the substation level. This paper presents a patented MW-scale system that provides power from a hydrogen-oxygen-fueled combined cycle power plant, where the hydrogen and oxygen are generated from electrolysis using renewable wind or solar power. The steam generated from combustion is the working fluid for the power plant, in a closed loop system. Also presented is a discussion on a patented strategy for safe combustion and handling of hydrogen and oxygen, as well as how to use this combustion strategy for flame and post flame temperature control. Finally, a preliminary benefits analysis illustrates the various energy storage and distributed generation benefits that are possible with this system. Depending on the storage approach, energy storage — charge and discharge durations — of 4 to greater than 24 hours are possible, much longer than most battery energy storage systems. Benefits include not only peak shaving and VAR control, but also grid balancing services to avoid the “spilling” of excess renewable power when supply exceeds demand and fast ramping in the evening hours.
Proceedings Papers
Proc. ASME. POWER2018, Volume 1: Fuels, Combustion, and Material Handling; Combustion Turbines Combined Cycles; Boilers and Heat Recovery Steam Generators; Virtual Plant and Cyber-Physical Systems; Plant Development and Construction; Renewable Energy Systems, V001T06A010, June 24–28, 2018
Paper No: POWER2018-7271
Abstract
A shell and tube heat storage (1 MJ) has been designed computationally to enhance the heat transfer rate from heat transfer fluid (HTF) to the storage media. Concrete and water are considered as the sensible storage material and HTF, respectively. The system can be used to store the solar energy in the day time, which will be available in the absence of sunlight. Finite element based software, named COMSOL Multiphysics, is used for the study. The parameters analyzed, are tube outside diameter, radial distances between the tubes, number of tubes and inlet temperature of HTF. After a simulation time of 3000s, the increase of tube diameter from 1.03 to 1.71 cm is found to increase the average storage bed temperature by 6.3%. For the radial distances between the tubes to be 6 cm, the stored energy is maximum. The stored energies for 5 and 4 cm are 2.4 and 12.4% less than 6 cm, respectively, after duration of 6000s. The average bed temperature reaches to the steady state condition at 5147s with 19 tubes, whereas, with 25 tubes it takes 30.2% less time. Finally, the shell and tube heat storage has been optimized for higher heat transfer rate.
Proceedings Papers
Proc. ASME. POWER2018, Volume 1: Fuels, Combustion, and Material Handling; Combustion Turbines Combined Cycles; Boilers and Heat Recovery Steam Generators; Virtual Plant and Cyber-Physical Systems; Plant Development and Construction; Renewable Energy Systems, V001T06A011, June 24–28, 2018
Paper No: POWER2018-7291
Abstract
The synergy between solar photovoltaic (PV) systems and behind-the-meter battery storage to reduce utility costs in buildings has drawn increasing attention. This paper presents results of a case study involving an economic analysis of battery-supported PV systems for an existing two-story commercial building in Albuquerque, New Mexico under different utility rate tariffs. The building, with 17,430 ft 2 conditioned area, has been modeled in a detailed building energy simulation program, and hourly building electricity demand data and electricity demand generated using Typical Meteorological Year 2 (TMY2) weather file. The effect of strategies leading to demand leveling and demand limiting have also been discussed. Parametric analysis using System Advisor Model (SAM) software has been performed to determine the optimal sizing of the PV and battery systems for the given electric demand profiles under the assumed utility rate tariffs which will result in largest net present value (NPV). The results have been found to be highly sensitive to the costs of the PV systems and battery packs. Under the assumed realistic circumstances, we find that the inclusion of a battery pack in either a new or existing PV system does not improve the NPV even when the cost of battery storage is reduced from its current $250/kWh down to an unrealistic $50/kWh.
Proceedings Papers
Proc. ASME. POWER2018, Volume 1: Fuels, Combustion, and Material Handling; Combustion Turbines Combined Cycles; Boilers and Heat Recovery Steam Generators; Virtual Plant and Cyber-Physical Systems; Plant Development and Construction; Renewable Energy Systems, V001T06A030, June 24–28, 2018
Paper No: POWER2018-7548
Abstract
In this paper, the performance of Parabolic Trough Solar Collector (PTSC)-based power generation plant is studied. The effect of adding an Organic Rankine Cycle (ORC), and a Thermal Energy Storage (TES) system on the performance and financial metrics of the PTSC-power plant is investigated. Moreover, multiple organic working fluids for the ORC are compared in terms of the thermal and exergetic efficiencies, as well as the pumping power, and the most efficient fluid is selected. Further, the TES system is characterized by two-tank storage system with a storage period of 7 hours/24 hours. A yearly, monthly, and daily performance analyses are presented based on the Typical Meteorological Year (TMY) values for the city of Abu Dhabi, to study the improvement caused by the ORC and TES system. The simulation results show that Benzene is the most efficient organic fluid, as it showed the highest thermal and exergetic efficiency, and the lowest pumping power when compared to other organic fluids. In addition, the presence of the ORC increased the annual energy output of the power plant by 4%, while the addition of the TES increased the annual energy output by 68% and decreased the LCE by 29%. In the case where both the ORC and TES are added, the annual energy output increased by 72%, while the LCE decreases by almost 31%.
Proceedings Papers
Proc. ASME. POWER2018, Volume 1: Fuels, Combustion, and Material Handling; Combustion Turbines Combined Cycles; Boilers and Heat Recovery Steam Generators; Virtual Plant and Cyber-Physical Systems; Plant Development and Construction; Renewable Energy Systems, V001T06A025, June 24–28, 2018
Paper No: POWER2018-7474
Abstract
Numerical models for the evaluation of cryo-adsorbent based hydrogen storage systems for fuel cell vehicles were developed and validated against experimental data. These models simultaneously solve the conservation equations for heat, mass, and momentum together with the equations for the adsorbent thermodynamics. The models also use real gas thermodynamic properties for hydrogen. Model predictions were compared to data for charging and discharging both MOF-5™ and activated carbon systems. Applications of the model include detailed finite element analysis simulations as well as full vehicle-level system analyses. The present work provides an overview of the compacted adsorbent MOF-5™ storage prototype system, as well as a detailed computational analysis and its validation using 2-liter prototype test system. The results of these validated computational analyses are then projected to a full scale vehicle system, based on an 80 KW fuel cell with a 20 kW battery. This work is part of the Hydrogen Storage Engineering Center of Excellence (HSECoE), which brings materials development and hydrogen storage technology efforts address onboard hydrogen storage in light duty vehicle applications. The HSECoE spans the design space of the vehicle requirements, balance of plant requirements, storage system components, and materials engineering. Theoretical, computational, and experimental efforts are combined to evaluate, design, analyze, and scale potential hydrogen storage systems and their supporting components against the Department of Energy (DOE) 2020 and Ultimate Technical Targets for Hydrogen Storage Systems for Light Duty Vehicles.
Proceedings Papers
Proc. ASME. POWER2017-ICOPE-17, Volume 1: Boilers and Heat Recovery Steam Generator; Combustion Turbines; Energy Water Sustainability; Fuels, Combustion and Material Handling; Heat Exchangers, Condensers, Cooling Systems, and Balance-of-Plant, V001T04A037, June 26–30, 2017
Paper No: POWER-ICOPE2017-3443
Abstract
Due to the global warming, climate treaty regulations and credits have been enhanced. As a result, the Carbon Capture & Storage (CCS) technologies have been emerged. In this study, it is presented that is separating the CO 2 from Air by vortex generator. The vortex tube is a device to separate inlet gases to hotter and colder mixture than inlet by energy separation technology. In this study, the vortex tube is applied to CO 2 gas separation from air that is investigated under atmospheric temperature. Prior to feasibility experiment, transient response shows that the temperature separation is settled down in 3000 seconds. Experimental parameters of gas separation are pressures and concentrations of CO 2 that is mixed with air. Results show that CO 2 gas separation is proportional to operating temperature. The percentage of CO 2 gas separation is 7.4 % at 3bar g and cold mass fraction of 0.6. The gas separation is also affected by inlet CO 2 concentration.
Proceedings Papers
Osamu Kurata, Norihiko Iki, Takayuki Matsunuma, Takahiro Inoue, Taku Tsujimura, Hirohide Furutani, Akihiro Hayakawa, Hideaki Kobayashi
Proc. ASME. POWER2017-ICOPE-17, Volume 1: Boilers and Heat Recovery Steam Generator; Combustion Turbines; Energy Water Sustainability; Fuels, Combustion and Material Handling; Heat Exchangers, Condensers, Cooling Systems, and Balance-of-Plant, V001T04A026, June 26–30, 2017
Paper No: POWER-ICOPE2017-3277
Abstract
To protect against global warming, a massive influx of renewable energy is expected. Although hydrogen is a renewable media, its storage and transportation in large quantity is difficult. Ammonia, however, is a hydrogen energy carrier and carbon-free fuel, and its storage and transportation technology is already established. Although ammonia combustion was studied in the 1960s in the USA, the development of an ammonia combustion gas turbine had been abandoned because combustion efficiency was unacceptably low. Since that time, in the combustion field, ammonia has been thought of as a fuel N additive in the study of NOx formation. Recent demand for hydrogen carrier revives the usage of ammonia combustion, but no one has attempted an actual design setup for ammonia combustion gas turbine power generation. The National Institute of Advanced Industrial Science and Technology (AIST) in Japan successfully performed ammonia-kerosene co-fired gas turbine power generation in 2014, and ammonia-fired gas turbine power generation in 2015. In the facilities, a regenerator-heated, diffusion-combustion micro-gas turbine is used, and its high combustor inlet temperature enables high thermal efficiency of ammonia combustion compared with that of methane combustion. Adoption of the regenerator increased combustor inlet temperature and enhanced flame stability in ammonia-air combustion. Although NOx emission from a gas turbine combustor is high, a Selective Catalytic Reduction (SCR) after gas turbine combustor reduces NOx emission to less than 10 ppm. This means that the ammonia combustion gas turbine design, abandoned in the 1960s for its unacceptably low combustion efficiency, has performed successfully with regenerator and SCR technology. However, the weakness of these facilities was that they required large-size SCR equipment in order to suppress a high concentration of NOx. Although NOx reduction in the combustion process is desirable, low NOx combustion technology is difficult because ammonia had been thought of as a source of fuel-NO. In the case of premixed ammonia-air flame, there exists a low emission window of NOx and NH 3 in a certain equivalence ratio, but combustion intensity is very low because the laminar burning velocity of NH 3 -air is one-fifth that of CH 4 -air. This means that, when utilizing the window of premixed ammonia-air flame, scale-up of the combustion chamber or fuel additives for enhancement of flame stability is necessary. This study shows that the addition of H 2 is effective for low NOx combustion with high combustion efficiency. In addition, H 2 can be easily made from NH 3 decomposition. The other option is diffusion combustion. Further research on low NOx combustion is needed.
Proceedings Papers
Proc. ASME. POWER2017-ICOPE-17, Volume 2: I&C, Digital Controls, and Influence of Human Factors; Plant Construction Issues and Supply Chain Management; Plant Operations, Maintenance, Aging Management, Reliability and Performance; Renewable Energy Systems: Solar, Wind, Hydro and Geothermal; Risk Management, Safety and Cyber Security; Steam Turbine-Generators, Electric Generators, Transformers, Switchgear, and Electric BOP and Auxiliaries; Student Competition; Thermal Hydraulics and Computational Fluid Dynamics, V002T09A020, June 26–30, 2017
Paper No: POWER-ICOPE2017-3684
Abstract
Undeveloped small hydropower generation sites are abundant throughout the water conveyance infrastructure and natural rivers in the United States. Due to its small scale, micro-hydro development requires substantial upfront capital costs, maintenance and operation costs for customized engineering and construction. The significant investments required for developing small hydropower are inhibiting for utilities, residential and commercial users to adopt. An inexpensive energy storage system and a well-designed power controls system can be integrated with small hydropower sites to increase its cost-effectiveness and reliability. This paper introduces the concept of storing low-power generated from small hydro turbines during long off-peak periods and dispatching at high-power as grid-quality electricity during peak periods. The use of an ultra-low cost thermal energy storage (ULCTES) system is examined. Boosting the power output for small hydro generation allows commercial users to avoid significant demand charges during operation, making small hydro an attractive cost saving strategy and therefore breaking down the cost barrier. The ULCTES operates much like a bulk power production unit and a peaker plant, in which it is capable of dispatching constant power over a long period during peak periods when conventional sources are unavailable. Improvements in system reliability and economic value are evaluated using microgrid optimization software HOMER Energy. In particular, two cases are studied with variations in types of end users and energy management goals. Energy costs savings, demand charges savings and renewable energy penetration are determined. Distributed energy storage systems are shown to reduce energy costs and increase the renewable energy penetration for commercial users. With ULCTES, microgrids have the flexibility to manage fluctuating renewable energy generation as well as respond to rapidly changing loads on a daily basis. A larger hydroelectricity system is shown to be more feasible with distributed energy storage systems for isolated users without any connection to the grid.
Proceedings Papers
Proc. ASME. POWER2016, ASME 2016 Power Conference, V001T11A003, June 26–30, 2016
Paper No: POWER2016-59077
Abstract
Refrigeration for the cold storage of perishable foods has been utilized for more than a century. The need for refrigerated storage grows with hot weather. The frozen food industry expanded many times in freezer storage in a few decades after World War II. Cold storage facilities are also significant energy consumers that call for attention to thermal behavior as it greatly influences the cost. Proper design to improve thermal behavior of a refrigerated space requires the knowledge of air distribution and thermal conditions within the space. The frozen food quality is sensitive to both storage temperature and fluctuation in temperature. The present work made use of a computational fluid dynamics technique to adequately predict the cold storage airflow pattern variations within the cold room under various evaporator’s arrangements of sizes, numbers and positions. Design parameters included local temperatures and velocity distributions inside a large cold store using standard k-e model with mesh element 5,400,000 tetrahedral cells. Different optional designs utilizing different number of evaporators were investigated as well as the locations of these evaporators according to load estimation of the cold store.
Proceedings Papers
Proc. ASME. POWER2016, ASME 2016 Power Conference, V001T08A006, June 26–30, 2016
Paper No: POWER2016-59235
Abstract
In this present paper, a performance analysis of an Integrated Solar Rankine Cycle (ISRC) is provided. The ISRC consists of a nanofluid-based Parabolic Trough Solar Collector (PTSC), and a Thermal Energy Storage System (TES) integrated with a Rankine Cycle. The effect of dispersing Copper ( Cu ) nanoparticles in a conventional heating fluid (Syltherm 800) on the output performance and cost of the ISRC is studied for different volume fractions, and for two modes of operation. The first mode assumes no storage, while the second assumes a storage system with a storage period of 7 hours. For the second mode of operation, the charging and discharging cycles are explained. The results show that the presence of the nanoparticles causes an increase in the overall energy produced by the ISRC for both modes of operation, and also causes a decrease in the Levelized Cost of Electricity (LEC), and an increase in the net savings of the ISRC. When comparing the two modes of operation it is established that the existence of a storage system leads to a higher power generation, and a lower LEC; however the efficiency of the cycle drops. It is seen that the maximum increase in the annual energy output of the ISRC caused by the addition of the nanoparticles is around 3.5%, while the maximum increase in the net savings is around 12.8%.
Proceedings Papers
Proc. ASME. POWER2016, ASME 2016 Power Conference, V001T05A002, June 26–30, 2016
Paper No: POWER2016-59085
Abstract
The state-owned power utility, Eskom, generates about ninety five percent of the electricity produced in South Africa. Plans by the government of South Africa in the mid-nineteen nineties to restructure the electricity industry in the country prevented Eskom from embarking on capacity expansion activities when it was necessary. Load growth, as a result of economic growth and a national electrification programme, caused an erosion of the electricity reserve margin, which was quite massive in the early nineties. The large reserve margin then caused Eskom to reduce operating capacity by mothballing some generating plants and putting them in reserve storage. The current situation is that the reserve margin has dropped to about 17,4 percent and a capacity expansion programme is underway. Though the apparent reserve margin is within the desired range, plant unavailability has diminished the reserve margin in real terms and this does not leave Eskom with much room for planned maintenance and a buffer to manage unplanned maintenance, the result being that plant incidents and technical problems cannot easily be absorbed within the power system to avoid interruption of supply. Also, the new environmental legislation does not help the situation, as it has the potential to shut down generating plants that do not meet the new emissions standard. In addition, there have been problems with the New Build Programme that caused a delay, of over three years, in the delivery of new power, and to compound the problem the Energy Regulator refused recently Eskom’s application for additional tariff increase, which was requested to enable the company provide the finances to cover the shortfall in funding for operational expenses and the New Build Programme. As such, Eskom faces many challenges in meeting its obligation to South Africa, and interventions are in place to manage the situation. In the short term, the key to generation sustainability is improved plant health, brought about by on-time maintenance and correctly-scoped and no-slip outages. This paper presents an overview of the power situation in South Africa, explaining where the country has come from, the plan for long term security of supply, and the challenges faced by Eskom from the generation supply side in meeting the demand load in the short term. Trends in the performance indices indicative of plant health are examined and it is argued that executing planned plant maintenance will improve plant health and, hence, plant availability, which can bring about a turnaround in the short term power supply situation, as Eskom awaits new capacity from the New Build Programme.
Proceedings Papers
Proc. ASME. POWER2016, ASME 2016 Power Conference, V001T08A015, June 26–30, 2016
Paper No: POWER2016-59461
Abstract
Variability and uncertainty are the primary challenges for power generation from intermittent, non-dispatchable energy sources. This stochastic behavior could significantly increase the cost of energy. An earlier work developed an interdisciplinary economic model using three-year (2011–2013) wind/load data from two different sites, Pennsylvania New Jersey Maryland Interconnection LLC (PJM) in USA and EirGrid in Ireland. Results showed a wind plus natural gas system can reduce emission as much as 50% below that of an all-natural gas system, with only a slight increase in system cost. Energy storage can be a key element in obtaining energy and cost savings, together with providing availability, reliability, and security of energy supply to consumers. In this paper, grid-scale storage parameters variations (storage capacity, cost, and efficiency) are explored to obtain levelized cost trends for wind systems with storage.
Proceedings Papers
Proc. ASME. POWER2016, ASME 2016 Power Conference, V001T06A002, June 26–30, 2016
Paper No: POWER2016-59566
Abstract
A prototype water-glycerol two tank storage system was designed to simulate the fluidic properties of a high temperature molten salt system while allowing for room temperature testing of a low cost, small scale pneumatically pumped thermal storage system for use in concentrated solar power (CSP) applications. Pressurized air is metered into a primary heat transfer fluid (HTF) storage tank; the airflow displaces the HTF through a 3D printed prototype thermoplate receiver and into a secondary storage tank to be dispatched in order to drive a heat engine during peak demand times. A microcontroller was programmed to use pulse-width modulation (PWM) to regulate air flow via an air solenoid. At a constant frequency of 10Hz, it was found that the lowest pressure drops and the slowest flowrates across the receiver occurred at low duty cycles of 15% and 20% and low inlet air pressures of 124 and 207 kPa. However, the data also suggested the possibility of slug flow. Replacement equipment and design modifications are suggested for further analysis and high temperature experiments. Nevertheless, testing demonstrated the feasibility of pneumatic pumping for small systems.
Proceedings Papers
Proc. ASME. POWER2015, ASME 2015 Power Conference, V001T01A010, June 28–July 2, 2015
Paper No: POWER2015-49440
Abstract
Health and environmental consequences of conventional fossil fuels are drawing more interest in expanding the use of renewable energy sources. The primary challenges in supplying the required electricity from wind are the variability, uncertainty, and the cost of electric power generation. An earlier paper presented the results of a system concept tradeoff using one-year wind/load data from Pennsylvania New Jersey Maryland Interconnection LLC (PJM). While one year results showed a wind plus natural gas system can reduce CO 2 emission as much as 50% below that of an all-natural gas system with only a modest increase in system cost, typical power generation modeling extends to three years. In this work, the developed model is employed to estimate the magnitude of cost versus performance using three-year wind/load data at PJM in the United States and EirGrid in Ireland, and cost estimations published by the Energy Information Agency. The year to year variation at each region is studied and compared with each other. Also, the curtailment curve obtained from three years wind/load data is compared with that from one year to access the variance. The grid-scale storage parameter variations are studied to estimate the generation cost with storage as a function of emission levels.
Proceedings Papers
Antoni Gil, Daniel S. Codd, Lei Zhou, David Trumper, Ronald B. Campbell, Benjamin Grange, Nicolas Calvet, Peter Armstrong, Alexander H. Slocum
Proc. ASME. POWER2015, ASME 2015 Power Conference, V001T01A011, June 28–July 2, 2015
Paper No: POWER2015-49504
Abstract
A new concept of Thermal Energy Storage (TES) system based on current available technologies is being developed under the framework of the Masdar Institute (MI) and Massachusetts Institute of Technology (MIT) collaborative Flagship Program. The key feature of this concept lies on concentrating sun light directly on the molten salt storage tank, avoiding the necessity of pumping the salts to the top of a tower thereby avoiding thermal losses and pumping and electric tracing needs inherent in most conventional CSP plants. This Concentrated Solar Power on Demand (CSPonD) volumetric receiver/TES unit prototype will be tested in the existing MI heliostat field and beam down tower in Abu Dhabi (UAE) which will collect and redirect solar energy to an upwards-facing final optical element (FOE). These energy will be concentrated on the aperture of the prototype designed to store 400 kWh of energy allowing 16 hours of continuous production after sunset using Solar Salt (60%NaNO 3 + 40%KNO 3 ) as storage material. The tank is divided in two volumes: one cold in the bottom region, where Solar Salt is at 250 °C and another hot on the upper region, at 550 °C. A moving divider plate with active control separates both volumes. The plate includes mixing enhancement features to help with convection on the hot volume of salts. It’s expected that results will demonstrate the technical feasibility and economic viability of this concept allowing its scale up at commercial size.
Proceedings Papers
Proc. ASME. POWER2015, ASME 2015 Power Conference, V001T10A004, June 28–July 2, 2015
Paper No: POWER2015-49813
Abstract
In order to understand how a boiler is performing/ operating, it is critical to obtain data throughout its operation. Data collection and storage methods have evolved through the years improving the quality and quantity of the data. Data is valuable for tracking current unit performance, troubleshooting and helping to narrow down any potential issues/ concerns with performance. Proper use of data collection and analysis may minimize the need for scheduled performance testing except when specific data points are required. This paper will discuss how sensitivity analysis can be utilized to determine the effect lack of/poor quality data has on the desired analysis. It discusses data collection and evaluation for various cases and the relevant ASME codes. Other key features of the paper are the various methods available for data representation, allowing the engineer to easily track key operating parameters.