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Author

Stephen E. Crane

Bio: Stephen E. Crane is an academic researcher. The author has contributed to research in topics: Energy storage & Compressed air. The author has an hindex of 5, co-authored 12 publications receiving 523 citations.

Papers
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Patent
25 Aug 2010
TL;DR: In this paper, a reversible air compressor-expander uses mechanical power to compress air and converts the energy stored in compressed air to mechanical power when it is acting as an expander.
Abstract: A compressed-air energy storage system according to embodiments of the present invention comprises a reversible mechanism to compress and expand air, one or more compressed air storage tanks, a control system, one or more heat exchangers, and, in certain embodiments of the invention, a motor-generator. The reversible air compressor-expander uses mechanical power to compress air (when it is acting as a compressor) and converts the energy stored in compressed air to mechanical power (when it is acting as an expander). In certain embodiments, the compressor-expander comprises one or more stages, each stage consisting of pressure vessel (the “pressure cell”) partially filled with water or other liquid. In some embodiments, the pressure vessel communicates with one or more cylinder devices to exchange air and liquid with the cylinder chamber(s) thereof. Suitable valving allows air to enter and leave the pressure cell and cylinder device, if present, under electronic control.

413 citations

Patent
14 Sep 2012
TL;DR: In this paper, an energy storage and recovery system employs air compressed utilizing power from an operating wind turbine, which is stored within one or more chambers of a structure supporting the wind turbine above the ground.
Abstract: An energy storage and recovery system employs air compressed utilizing power from an operating wind turbine. This compressed air is stored within one or more chambers of a structure supporting the wind turbine above the ground. By functioning as both a physical support and as a vessel for storing compressed air, the relative contribution of the support structure to the overall cost of the energy storage and recovery system may be reduced, thereby improving economic realization for the combined turbine/support apparatus. In certain embodiments, expansion forces of the compressed air stored within the chamber, may be relied upon to augment the physical stability of a support structure, further reducing material costs of the support structure.

48 citations

Patent
19 Sep 2012
TL;DR: In this article, an energy storage system utilizing compressed gas as a storage medium, may include one or more axial and centrifugal turbines configured to convert energy in gas expansion and compression processes.
Abstract: An energy storage system utilizing compressed gas as a storage medium, may include one or more turbines configured to convert energy in gas expansion and compression processes. One or more axial and centrifugal turbines may be used to store energy by compressing gas, and to recover energy from expanding gas. A plurality of orifices/nozzles may introduce a liquid into the gas as a heat exchange medium. Orifices/nozzles may be disposed on various surfaces of a turbine and/or in a separate mixing chamber flowing to a turbine. Structures of the turbine may be designed to mitigate damage caused by liquid injection, for example the turbine blades may be flexible and/or comprise impact-resistant materials.

24 citations

Patent
02 Mar 2012
TL;DR: In this article, an energy storage system according to the present invention can operate as a stand-alone storage system that connects electrically to the grid, it can be tightly integrated with a wind turbine, and/or it can operate with even higher efficiency by scavenging low-grade waste heat.
Abstract: Embodiments of the present invention use compressed air to store and deliver electrical, mechanical, and/or thermal power with high round-trip efficiency. Various embodiments may be scalable for use in a variety of environments—from wind farms to power plants to motor vehicles. An energy storage system according to the present invention can operate as a stand-alone storage system that connects electrically to the grid, it can be tightly integrated with a wind turbine, and/or it can be co-located with a thermal power generation facility and operate with even higher efficiency by scavenging low-grade waste heat.

16 citations

Patent
14 Sep 2012
TL;DR: In this article, an energy storage and recovery system employs air compressed utilizing power from an operating wind turbine, which is stored within one or more chambers of a structure supporting the wind turbine above the ground.
Abstract: An energy storage and recovery system employs air compressed utilizing power from an operating wind turbine. This compressed air is stored within one or more chambers of a structure supporting the wind turbine above the ground. By functioning as both a physical support and as a vessel for storing compressed air, the relative contribution of the support structure to the overall cost of the energy storage and recovery system may be reduced, thereby improving economic realization for the combined turbine/support apparatus. In certain embodiments, expansion forces of the compressed air stored within the chamber, may be relied upon to augment the physical stability of a support structure, further reducing material costs of the support structure.

15 citations


Cited by
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Patent
25 Aug 2010
TL;DR: In this paper, a reversible air compressor-expander uses mechanical power to compress air and converts the energy stored in compressed air to mechanical power when it is acting as an expander.
Abstract: A compressed-air energy storage system according to embodiments of the present invention comprises a reversible mechanism to compress and expand air, one or more compressed air storage tanks, a control system, one or more heat exchangers, and, in certain embodiments of the invention, a motor-generator. The reversible air compressor-expander uses mechanical power to compress air (when it is acting as a compressor) and converts the energy stored in compressed air to mechanical power (when it is acting as an expander). In certain embodiments, the compressor-expander comprises one or more stages, each stage consisting of pressure vessel (the “pressure cell”) partially filled with water or other liquid. In some embodiments, the pressure vessel communicates with one or more cylinder devices to exchange air and liquid with the cylinder chamber(s) thereof. Suitable valving allows air to enter and leave the pressure cell and cylinder device, if present, under electronic control.

413 citations

Journal ArticleDOI
TL;DR: This paper comprehensively summarized the advantages and disadvantages of various ESS technologies and presented several evaluation indicators for quantitative analysis, and identifies critical challenges and promising opportunities.
Abstract: The composition of worldwide energy consumption is undergoing tremendous changes due to the consumption of non-renewable fossil energy and emerging global warming issues. Renewable energy is now the focus of energy development to replace traditional fossil energy. Energy storage system (ESS) is playing a vital role in power system operations for smoothing the intermittency of renewable energy generation and enhancing the system stability. We divide ESS technologies into five categories, mainly covering their development history, performance characteristics, and advanced materials. Biomass storage and gas storage are also discussed, which are not considered in most reviews. After detailed research, the rapid development of each technology in recent years is introduced, and some representative research works are surveyed. We comprehensively summarized the advantages and disadvantages of various ESS technologies and presented several evaluation indicators for quantitative analysis. Hybrid ESS is also considered based on the complex market demand. Then, we investigate the applications of various ESS technologies as short-term, medium-term, and long-term storages in power systems, covering the power generation, transmission and distribution, and end-user. Finally, this paper reviews global developing trends, and identifies critical challenges and promising opportunities.

162 citations

Patent
25 Mar 2009
TL;DR: In this paper, a low emission power generation in hydrocarbon recovery processes is described, which uses a hot gas expander and external combustor to compress air in the inlet compressor and generate power using hot carbon dioxide laden gas in the expander.
Abstract: Methods and systems for low emission power generation in hydrocarbon recovery processes are provided. One system includes integrated pressure maintenance and miscible flood systems with low emission power generation. An alternative system provides for low emission power generation, carbon sequestration, enhanced oil recovery (EOR), or carbon dioxide sales using a hot gas expander and external combustor. Another alternative system provides for low emission power generation using a gas power turbine to compress air in the inlet compressor and generate power using hot carbon dioxide laden gas in the expander. Other efficiencies may be gained by incorporating heat cross-exchange, a desalination plant, co-generation, and other features.

148 citations

Patent
28 Aug 2009
TL;DR: In this paper, a system for managing a supplemental gas supply in a breathing assistance system configured to provide breathing assistance to a patient includes a temperature sensor and a control system, which is configured to automatically control the flow of the supplemental gas based at least on the monitored temperature.
Abstract: A system for managing a supplemental gas supply in a breathing assistance system configured to provide breathing assistance to a patient includes a temperature sensor and a control system. The temperature sensor is configured to measure a temperature associated with a breathing assistance system configured to deliver a first gas and a supplemental gas toward a patient. The control system is configured to automatically control the flow of the supplemental gas based at least on the monitored temperature.

139 citations

Patent
09 Apr 2009
TL;DR: In this article, the authors describe methods and systems for the storage and recovery of energy using open-air hydraulic-pneumatic accumulator and intensifier arrangements that combine at least one accumulator with at least two intensifiers in communication with a high-pressure gas storage reservoir on a gas-side of the circuits and a combination fluid motor/pump, coupled to a combination electric generator/motor on the fluid side.
Abstract: The invention relates to methods and systems for the storage and recovery of energy using open-air hydraulic-pneumatic accumulator and intensifier arrangements that combine at least one accumulator and at least one intensifier in communication with a high-pressure gas storage reservoir on a gas-side of the circuits and a combination fluid motor/pump, coupled to a combination electric generator/motor on the fluid side of the circuits.

94 citations