• Energy Research

In this thesis, the author describes various evaluation criteria, in particular the C-rate (charge/discharge-rate), of energy storage (ES) systems to explain the efficiency and technical benefits of battery-ultracapacitor hybrid energy storage (HES), and the technical characteristics of subsequently derived short-duration and long-duration type ES. In addition, for effective use of energy storage, a straightforward state of charge (SOC) correction method for energy neutral operation is proposed, and through a simple comparative example of ES operation, the effectiveness of HES in relation to simple ES is explained. A case is considered in which a hybrid ES controls the wind power ramp rate to comply with the regional system operator’s smoothing requirement, and an operation method is suggested through simulation. The simulation is carried out using a frequency spectrum analysis of wind power output profile and the C-rate of the hybrid storage system, and an energy neutral operation method for ES is proposed based on the simulated charging/discharging power sharing profile and SOC variations of the Li-battery and the ultracapacitor.

The idea for this meeting evolved from interest expressed by members of the Chicago Section of the Electrochemical Society in convening a symposium on the development of high-energy secondary batteries. The relevance of this subject is evidenced by the several research programs that have been initiated recently in the United States and Europe to develop advanced batteries for use as energy storage devices on electric utility networks and as power sources for electric automobiles.

Storage is today the greatest challenge facing energy engineers. The cost of solar and wind energy has plummeted, and triggered a revolutionary decentralization process in the power generation sector. This ongoing transformation calls for improved energy storage technologies. Owing to the intermittent and unpredictive nature of renewables, whose penetration on the electric grid is growing fast, the need has emerged for both short and long-term electricity storage. Two electrochemical technologies, both based on the use of solid state ionic conductors, that can tackle this problem are lithium ion batteries (LIBs), for short-term storage; and solid oxide cells (SOCs) for seasonal storage. This thesis comprises three parts, addressing three key factors for the design and optimization of systems such as LIBs and SOCs, namely material catalytic performance and long-term stability, and fabrication and manufacturing. First, we study the influence of the fabrication parameters, such as deposition temperature and laser fluence, on the performance of Ta substituted Li 6.4 La 3 Zr 2 O 12 (LLZO) thin films, a promising solid electrolyte for all solid LIB. Next, we investigate alternative methods to improve the long-term stability of La doped BaFeO 3-δ (BLF). This excellent SOCs’ material suffers from segregation of Ba to the surface, which hinders its high activity. First, we prepare thin films of BLF via Pulsed Laser Deposition (PLD), and either coat them with ZrO 2 via Atomic Layer Deposition (ALD) or co-doped them with Zr. Afterwards, we analyze the composition of the various films, with particular attention for the concentration of Ba via angle resolved XPS. Finally, we investigate the effects of niobium (Nb) substitution into PrBaCo 2 O 5+δ (PBC), which is among the best materials for SOCs. Substituting Nb was reported to be beneficial both in terms of enhanced catalytic activity and stability. We synthesize the material containing different amounts of Nb, and characterize its structure and electro-catalytic performance.

The first U.S. demonstration of the NGK sodium/sulfur battery technology was launched in August 2002 when a prototype system was installed at a commercial office building in Gahanna, Ohio. American Electric Power served as the host utility that provided the office space and technical support throughout the project. The system was used to both reduce demand peaks (peak-shaving operation) and to mitigate grid power disturbances (power quality operation) at the demonstration site. This report documents the results of the demonstration, provides an economic analysis of a commercial sodium/sulfur battery energy storage system at a typical site, and describes a side-by-side demonstration of the capabilities of the sodium/sulfur battery system, a lead-acid battery system, and a flywheel-based energy storage system in a power quality application.

An estimate was made of the cost of commercial manufacture of batteries for load-leveling in utility networks, based on the lithium-aluminum/iron sulfide system. The battery design chosen is the 0.92-kWh cell proposed for the BEST Facility. The manufacturing plant was sized to produce 5000 of such cells per day. These cells are assembled for sale in battery cases or sub-modules, 24 cells to a case. The plant investment is estimated to be $12,500,000. A selling price of $29.16 per kWh is projected; this price yields a 25 percent return on invested capital. An allowance for recycle lithium yields a net price of $27.33 per kWh.

A study of lead-acid batteries for peaking power applications and the auxiliaries required for an operable system has been completed. The results of the study are presented in a three-volume report. The present volume summarizes the salient points and conclusions derived from the study. 3 figures, 4 tables. (RWR)

A detailed study was made of a postulated 1000-MWh per year lead--acid battery business dedicated to supplying a single design of 40-MWh peaking power batteries to electric utilities. State-of-the-art industrial technology is assumed, but the manufacturing facility and business organization is tailored to the one product. Analysis of the product costs and business expenses associated with such an operation indicates that substantially lower selling prices can be realized as compared with normal industrial battery pricing. Under the low-risk conditions assumed, the selling price would be $36.90/kWh at the 4-h rate. Advanced technology would reduce the cost to $31.62/kWh. 21 figures, 31 tables. (RWR)

Energy arbitrage is a potential revenue stream for battery operators with access to variable electricity prices. However, the power shifted by grid-scale energy storage has the potential to influence the production mix in real time, impacting the carbon emissions of the electricity system. Little research is available on the CO₂ emissions induced by arbitrage operations, and studies that consider arbitrage-related CO₂ emissions often neglect battery degradation. To address this gap, this study proposes a novel modeling and assessment framework based on mixed-integer linear programming to analyze the trade-offs between profit and CO₂ emissions of battery arbitrage operations as well as the impact of degradation on arbitrage profit and emissions. We present the results in terms of Pareto-optimal solutions that identify maximum profit and minimum CO₂ emissions. We illustrate our model through a case study in Germany and we show that performing maximum-profit arbitrage increases the system emissions by up to 7.5 tCO₂ per MWh of storage capacity (or about 12% of battery life cycle emissions per year). 60% of the added emissions can be avoided by sacrificing only 1.5% to 2.7% of the net arbitrage profit, and CO₂-neutral operation can be achieved by sacrificing about 7% of the profit. Our findings also highlight the importance of modeling battery degradation, as degradation-unaware arbitrage models may lead to a substantial profit loss (potentially to negative profits) and higher CO₂ emissions (up to +260%) with respect to degradation-aware models. Energy Conversion and Management: X, 22 ISSN:2590-1745 ISSN:0196-8904

The Research and Engineering Operation of Bechtel Corporation conducted an engineering study of a 20-MW lead--acid battery energy storage demonstration plant. Ten alternative designs were evaluated. Basically, the configurations proposed for the demonstration plants are those of the mature plants which would follow. The designs of the individual plants are based on the cell designs and the means used to house the cells. Initially, proposed cell designs from five manufacturers were considered. To conform with the level of effort allowed for this engineering study, two manufacturers' cells (one open-tank design and one sealed cell design) were selected by ERDA and Bechtel as being representative. These designs formed the basis for the detailed evaluation conducted in this study. The plant and battery configurations evaluated in the study are a large open-tank cell, configured in rows and housed in four buildings; a sealed cell, configured in a single layer of close packed rows in a single building; a sealed cell, configured in a three-tiered arrangement in a single building; and a sealed cell, configured with groups of cells housed in weatherproof modules and placed outdoors. Annual operating costs based on these mature plant costs show lead--acid load-leveling plants are generally not economically competitive with the alternatives when no consideration is given to their other possible benefits to the power system. However, application of credits (e.g., transmission line or spinning reserve credits) can make such plants economically competitive with gas turbine peaking units in specific situations. 46 figures, 25 tables. (RWR)