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.

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.

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.

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%.

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.

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.

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.

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.

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.

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%.

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.

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.

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.

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.

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.

Over the past years there has been a dramatic increase in the regulatory requirements for low emissions. Renewable energy targets and CO 2 emissions markets drive the transition to a cleaner and renewable energy production system. In addition to increasing the overall plant cycle efficiency, there two principal means of the reduction of the CO 2 from coal fired power plants: by coal and biomass co-firing and by the capture and long term storage of the CO 2 emitted from power plant. Carbon dioxide capture and storage will involve substantial capital investment, accompanied by a significant power plant cycle efficiency penalty, and is not currently available on a fully commercial basis. Co-firing biomass, in comparison with other renewable sources, is the main contributor to technologies meeting the world’s renewable energy target. However, the impact of biomass co-firing on boilers performance and integrity has been modest. Operational problems associated with the deposition and retention of ash materials can and do occur on all the major gas-side components of combustion and boilers. The process occurs over a wide range of flue gas and surface temperatures, and dependent both on the characteristics of the ash and on the design and operation conditions of the furnace and boiler. Development and validation of the predictive models have been hindered significantly by the practical difficulties in the obtaining reliable data from the boilers operated with coal and biomass. Although specialized on–line deposition monitoring and sootblowing control systems are commercially available, but they are based on a very simple estimates of the fouling factors, which results in crude and not reliable approach to optimization of sootblowers operation. In the present paper an alternative approach and a new technique based on electro-optical sensor are demonstrated. The long term experience with the system attached to the furnace wall and capable to move the compact sensor in and out of the furnace, allowing to measure simultaneously deposits thickness and reflectivity, is described in details. Results of our study show that dynamics of both parameters on the operated power unit can be registered simultaneously in real time and then interpreted separately. Experiments have been carried out with different coal types at 575MW unit equipped with CE tangential boiler and 550 Mw equipped with B&W boiler with opposite fired burners. The measurements were performed in different locations of the furnace. It was shown that dynamics of thickness and reflectivity variation just after the wall cleaning activation are quite different. Situations have been registered where changes of reflectivity have a significant impact on heat transfer, comparable and sometimes even greater than that of growing fouling thickness. Technique and device exploited in this study appears to be a very useful tool for sootblowing optimization and, as a result, for improvement of boiler efficiency and reduction of water wall erosion and corrosion in both pulverized coal and co-firing boilers.

Concentrating solar power plants typically incorporate thermal energy storage, e.g. molten salt tanks. The broad category of thermochemical energy storage, in which energy is stored in chemical bonds, has the advantage of higher energy density as compared to sensible energy storage. In the ammonia-based thermal energy storage system, ammonia is dissociated endothermically as it absorbs solar energy during the daytime. The stored energy can be released on demand (for electricity generation) when the supercritical hydrogen and nitrogen react exothermically to synthesize ammonia. Using ammonia as a thermochemical storage system was validated at Australian National University (ANU), but ammonia synthesis has not yet been shown to reach temperatures consistent with the highest performance modern power blocks such as a supercritical steam Rankine cycle requiring steam to be heated to ∼650°C. This paper explores the preliminary design of an ammonia synthesis system that is intended to heat steam from 350°C to 650°C under pressure of 26 MPa. A two-dimensional pseudo-homogeneous model for packed bed reactors previously used at ANU is adopted to simulate the ammonia synthesis reactor. The reaction kinetics are modeled using the Temkin-Pyzhev reaction rate equation. The model is extended by accounting for convection in the steam to predict the behavior of the proposed synthesis reactor. A parametric investigation is performed and the results show that heat transfer plays the predominant role in improving reactor performance.

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.

Solar energy is a renewable energy source that can generate electricity. When there is much solar radiation, there is not always a need for all the energy from the solar, and when the weather is cloudy there may be too little energy to meet demand. Thus, it is often wise to implement energy storage in systems with a large share of renewable energy. Latent heat storage is one of the most efficient ways of storing thermal energy. Sodium Sulfate Decahydrate (Glauber’s salt) has a larger energy storage density and a higher thermal conductivity. So the present work, built solar chimney power plant of 2m-radius of collector and a 4m chimney height integrated by phase change materials. Aim of designing and building solar chimney to estimate the effect of adding phase change materials as well as to examine the effect of inclination angle (16°, 8°). The results show that maximum temperature difference between collector exit and the ambient reached to 23.7°C for case (i) and for 17.7°C case (ii), the maximum air velocity reached 2.25 m/s that in case (ii) and reached 2.05 m/s in case (i).and maximum collector efficiency can be reached to 8.925% in case (ii).

Achieving higher emission reductions on one hand and employing lower cost concepts on the other hand are desirable in designing future power generator systems. Hence, interdisciplinary studies in a form of system concept modeling should be employed to conceptualize and construct economic and efficient low-carbon system concepts. The concept modeling starts with simple idealized models that preserve the key structural features of a system and adds complex features in the following stages to elucidate principles, relationships, and interfaces. For wind systems, the essential features for concept modeling are wind and load variations, and the main goal is to obtain the cost of electricity delivered by the system as a function of wind penetration (emission reduction); more complex features (storage, photovoltaic, transmission, etc.) are added in the following stages. In this work, an interdisciplinary concept modeling is provided to estimate the magnitude of cost versus performance using the wind/load data from Pennsylvania New Jersey Maryland Interconnection (PJM) LLC, and cost estimations published by the Energy Information Agency. The results show that system total cost increases modestly at low penetration, and it increases more rapidly when wind curtailment becomes significant. Eventually storage becomes cheaper than curtailment. The key question that should be answered in this modeling is the magnitude of electricity cost for high penetration, low emission systems.