In the Electric Reliability Council of Texas (ERCOT) compressed air energy storage (CAES) is currently viewed as the most promising energy storage technology due to Texas having suitable geology for CAES and few locations suitable for pumped-hydro storage. CAES is a proven technology but the economics for new facilities are uncertain. This work quantified the economic prospects for CAES in ERCOT as a function of installed wind capacity, natural gas price, and CAES capital cost. Two types of models were developed and used in this work. The first type of model was a CAES dispatch optimization model, which determined the maximum operating profits a CAES facility could earn given a set of electricity and ancillary services market prices. These models were used to examine several separate research questions relating to the maximum potential for CAES and the impact of uncertainty and other real-world complications. The models determined that the maximum operating profit from 2002-2010 varied widely from year to year and averaged $120-140/kW-year, which is likely below the operating profits required to justify investing in CAES. The models also determined that current price forecasting methods are sufficient to earn approximately 95% of the operating profits achievable with perfect knowledge of all prices in the year. The second type of model was a unit commitment model of ERCOT, which determined the least-cost operation of all the generators in the generation fleet to meet given load. The unit commitment model was used to determine electricity and ancillary service market prices under different assumptions about natural gas price, installed wind capacity, and installed CAES capacity. The CAES dispatch optimization model was then used to determine the operating profits of a CAES facility under these scenarios. CAES operating profits were found to increase with increasing natural gas price and installed wind capacity and to decrease with increasing installed CAES capacity. CAES operating profits were estimated to support installed CAES capacities from zero to more than 6 GW, depending on the natural gas price, installed wind capacity, installed CAES capacity, and the CAES capital costs. The strongest determinant of the maximum CAES capacity that would be profitable is the natural gas price, followed by the CAES capital costs. / text

This report presents an overview of the engineering considerations involved in the design of grid-scale battery energy storage systems. Grid-scale is defined here as systems over 1 MW in rated power, typically operated by a utility, independent power producer, or Independent System Operator (ISO). The physical components of a BESS are presented and explained, including power electronics, an introduction to various commercially available battery technologies, necessary control systems, and balance of plant hardware. Also presented are a variety of real-world applications of battery energy storage systems, showing how the specific application determines what mix of technology will be selected when designing the system, as well as explaining the foundation for the control algorithms. / text

Modern storage systems are complex. Simple direct-attached storage devices are giving way to storage systems that are flexible, network-attached, consolidated and virtualized. Today, storage systems have their own administrators, who use specialized tools and expertise to configure and manage storage resources. As a result, database administrators are no longer in direct control of the design and configuration of their database systems' underlying storage resources. This introduces problems because database physical design and storage configuration are closely related tasks, and the separation makes it more difficult to achieve a good end-to-end design. For instance, the performance of a database system depends strongly on the storage layout of database objects, such as tables and indexes, and the separation makes it hard to design a storage layout that is tuned to the I/O workload generated by the database system. In this thesis we address this problem and attempt to close the information gap between database and storage tiers by addressing the problem of predicting the storage (I/O) workload that will be generated by a database management system. Specifically, we show how to translate a database workload description, together with a database physical design, into a characterization of the I/O workload that will result. Such a characterization can directly be used by a storage configuration tool and thus enables effective end-to-end design and configuration spanning both the database and storage tiers. We then introduce our storage layout optimization tool, which leverages such workload characterizations to generate an optimized layout for a given set of database objects. We formulate the layout problem as a non-linear programming (NLP) problem and use the I/O characterization as input to an NLP solver. We have incorporated our I/O estimation technique into the PostgreSQL database management system and our layout optimization technique into a database layout advisor. We present an empirical assessment of the cost of both tools as well as the efficacy and accuracy of their results.

Initial experiments were conducted to determine the microbial development in blocks of ground beef. In the top layers of the meat, Pseudomonas spp. predominated. Attempts were made, as well, to measure the microenvironmental changes occurring in ground beef using pH, oxygen, and redox potential micro-electrodes. / Some of the extrinsic (relative humidity, O(,2)), as well as intrinsic factors (pH, redox potential, ions, nutrients) affecting microbial development in aerobically stored meats, were examined. The decrease in glucose levels observed during the aerobic storage of longissimus dorsi (l. dorsi) muscle at 4(DEGREES)C, was accompanied by an increase in the activity of glucose dehydrogenase, and by the appearance of gluconate and 2-ketogluconate on the meat surface. / The attachment of various meat spoilage organisms to l. dorsi muscle was studied. Generally, the pseudomonads attached in higher numbers than the other bacteria, but possessed lower attachment strengths. Investigations on the attachment of two competing organisms to l. dorsi muscle demonstrated that limited competition occurs between the organisms. / A model of the microbial ecology of aerobically stored fresh beef was developed, based on existing evidence. / Various chemicals were added to minced or whole meat to evaluate their effectiveness as food preservatives. As a single compound, potassium sorbate appeared to have the greatest potential as a meat preservative. Meats > into solutions of 5.0% potassium sorbate for 1 min had their shelf-life substantially increased as compared with control samples > into water.

Electric and hybrid electric vehicles’ batteries not only have great potential for alleviating the world’s gasoline consumption problem, but may also stand poised to secure the world’s renewable energy generation. Electric and hybrid electric vehicles’ batteries that have reached the end of their cycle life in vehicles may still have the capacity to be repurposed into stationary utility energy storage. However, the phenomenon known as battery aging must be given careful consideration in the construction of a repurposed battery energy storage system. The battery aging phenomenon reduces the battery’s nominal voltage, capacity and current rating, while increasing its internal resistance. These factors were taken into consideration for the development of the Repurposed Battery Energy Storage System (RBESS). The system utilizes a method called Multi-Level Interlaced Pulse Charging (MLIPC) which was developed for the RBESS to manage the battery’s voltage, current, and energy to extend the useful cycle life of the batteries. The repurposed battery energy storage system has been modeled in PSCAD/EMTDC and tested in a constructed hardware implementation of the system.

No description available.

The use of a direct method for measuring respiration and transpiration rates may lead to better storage control systems and closer observation of storage losses. A laboratory scale environmental chamber was constructed and provided with a fan and adjustable louver to obtain variable ventilation flow rates. Flow rates were determined using a pressure sensor and fan characteristic curves which were determined experimentally. A regression equation representing the flow rate versus pressure relation was derived and used for estimating the flow rates throughout the study. / Respiration and transpiration were simulated using precision heat sources ranging from 15 to 105W in 15W interval and an evaporative pad. Measured wet and dry bulb temperatures and ventilation flow rates were used for the estimation of heat and moisture generated inside the chamber. The work was performed in two parts. In the first, precision heat sources were used and the heat balance equation components were solved. / In the second part, heat and moisture were generated inside the chamber, heat and moisture balance equations as well as psychrometric equations were solved. (Abstract shortened by UMI.)

Caching is a classical but effective way to improve system performance. To improve system performance, servers, such as database servers and storage servers, contain significant amounts of memory that act as a fast cache. Meanwhile, as new storage devices such as flash-based solid state drives (SSDs) are added to storage systems over time, using the memory cache is not the only way to improve system performance. In this thesis, we address the problems of how to manage the cache of a storage server and how to utilize the SSD in a hybrid storage system. Traditional caching policies are known to perform poorly for storage server caches. One promising approach to solving this problem is to use hints from the storage clients to manage the storage server cache. Previous hinting approaches are ad hoc, in that a predefined reaction to specific types of hints is hard-coded into the caching policy. With ad hoc approaches, it is difficult to ensure that the best hints are being used, and it is difficult to accommodate multiple types of hints and multiple client applications. In this thesis, we propose CLient-Informed Caching (CLIC), a generic hint-based technique for managing storage server caches. CLIC automatically interprets hints generated by storage clients and translates them into a server caching policy. It does this without explicit knowledge of the application-specific hint semantics. We demonstrate using trace-based simulation of database workloads that CLIC outperforms hint-oblivious and state-of-the-art hint-aware caching policies. We also demonstrate that the space required to track and interpret hints is small. SSDs are becoming a part of the storage system. Adding SSD to a storage system not only raises the question of how to manage the SSD, but also raises the question of whether current buffer pool algorithms will still work effectively. We are interested in the use of hybrid storage systems, consisting of SSDs and hard disk drives (HDD), for database management. We present cost-aware replacement algorithms for both the DBMS buffer pool and the SSD. These algorithms are aware of the different I/O performance of HDD and SSD. In such a hybrid storage system, the physical access pattern to the SSD depends on the management of the DBMS buffer pool. We studied the impact of the buffer pool caching policies on the access patterns of the SSD. Based on these studies, we designed a caching policy to effectively manage the SSD. We implemented these algorithms in MySQL's InnoDB storage engine and used the TPC-C workload to demonstrate that these cost-aware algorithms outperform previous algorithms.

Electric and hybrid electric vehicles’ batteries not only have great potential for alleviating the world’s gasoline consumption problem, but may also stand poised to secure the world’s renewable energy generation. Electric and hybrid electric vehicles’ batteries that have reached the end of their cycle life in vehicles may still have the capacity to be repurposed into stationary utility energy storage. However, the phenomenon known as battery aging must be given careful consideration in the construction of a repurposed battery energy storage system. The battery aging phenomenon reduces the battery’s nominal voltage, capacity and current rating, while increasing its internal resistance. These factors were taken into consideration for the development of the Repurposed Battery Energy Storage System (RBESS). The system utilizes a method called Multi-Level Interlaced Pulse Charging (MLIPC) which was developed for the RBESS to manage the battery’s voltage, current, and energy to extend the useful cycle life of the batteries. The repurposed battery energy storage system has been modeled in PSCAD/EMTDC and tested in a constructed hardware implementation of the system.

This study investigates respiration rate of potatoes (Solanum tuberosum L.) under real and experimental storage conditions. Real storage conditions were obtained by building a small-scale storage facility equipped with two independent storage bins including all controls. Each bin was filled with 2.5 metric tons of potatoes and these were stored for five months. Temperature, relative humidity, air flowrate and other operational parameters were collected. Also, mass loss and CO2 analyses were performed. / A heat and moisture balance was applied to quantify heat and moisture rates produced by potatoes and were converted to respiration rates as CO 2 produced (ml.kg-1.h-1). Evaporation rates were also determined (g.kg-1.h -1). The balance was mainly applied on data collected from specific periods in which steady conditions were imposed; heaters and humidifiers were turned off and fans were operated to circulate air at a given flowrate for more than 8 h/day over a two month period. Respiration rates were determined as rates of heat produced (W) with stability and acceptable accuracy for a relatively large facility. Respiration rates were converted to CO2 production (ml.kg-1.h-1), and these agreed fairly with ranges reported in the literature. Simultaneously, respiration rates were measured by in-store CO2 analysis, and later they were measured under laboratory conditions using a closed gas analysis system. Comparing these with rates obtained by the heat and moisture balance, the later were slightly higher. Mass losses were also obtained by both weight losses and moisture balance; results from the two methods were quite similar and comparable with those reported in the literature. / Under experimental conditions, respiration rates were measured for healthy, diseased and sprouted tubers using a gas analysis method. This experiment demonstrated the need for a more extensive investigation of disease development and its relation to respiration rates, and the need for a faster and more convenient gas analysis system. (Abstract shortened by UMI.)