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Future Energy and Energy Security
Published in Anco S. Blazev, Energy Security for The 21st Century, 2021
Currently, high-power flywheels are used in many aerospace and UPS applications. Today 2 kW/6 kWh systems are being used in telecommunications applications. For utility-scale storage a “flywheel farm” approach can be used to store megawatts of electricity for applications needing minutes of discharge duration. Currently several “flywheel farm” facilities are in the planning or construction stages to sell regulation services into open ISO markets. — Compressed-air energy storage (CAES) uses off peak electricity to compress air into either an underground structure (e.g., a cavern, aquifer, or abandoned mine) or an above-ground system of tanks or pipes. The compressed air is then mixed with natural gas, burned, and expanded in a modified gas turbine. In a conventional gas turbine, roughly two thirds of the power produced is consumed in pressurizing the air before combustion. CAES systems produce the same amount of electric power as a conventional gas turbine power plant using less than 40% of the fuel.
Energy Storage Technologies for Microgrids
Published in Stephen A. Roosa, Fundamentals of Microgrids, 2020
CAES plants can be used for microgrid storage applications. However, variable loads can cause voltage and frequency instabilities [10]. To maintain system stability, microgrids must generate power based on present conditions [10]. Compressed air plants are similar to pumped hydro powerplants in terms of their applications, output, and storage capacities [11]. Instead of pumping water between reservoirs during periods of excess power, a CAES plant compresses ambient air and stores it under pressure in tanks, underground caverns, or depleted natural gas reservoirs [11]. This enables a CAES to be used to balance fluctuations in power generation and consumption since the excess power compresses and stores air [10]. When electricity is required, the pressurized air is heated and expanded in an expansion turbine driving a generator for power production [11]. The CAES uses an air flow controller to enable the microgrid to track the various load demands and maintain a stable frequency [10].
Advanced Energy Technologies
Published in Leonard L. Grigsby, and Distribution: The Electric Power Engineering Handbook, 2018
As the name implies, the compressed air energy storage (CAES) plant uses electricity to compress air, which is stored in underground reservoirs. When electricity is needed, this compressed air is withdrawn, heated with gas or oil, and run through an expansion turbine to drive a generator. The compressed air can be stored in several types of underground structures, including caverns in salt or rock formations, aquifers, and depleted natural gas fields. CAES technology has been in use for over 30 years. A 290 MW CAES plant started operation in Huntorf, Germany in 1978. This plant has demonstrated a 90% availability and 99% starting reliability. A 110 MW CAES plant went into commercial operation in McIntosh, Alabama in the United States in 1991. This plant stores compressed air in a 19-million-cubic-foot cavern mined from a salt dome and has a storage capacity for 26 h operation. For the last 20 years since the Alabama plant went into operation, there has not been any further commercial deployment of this technology. In the last few years there seems to have been a revival of interest in this technology, but no commercial power plant yet.
Enhancing electricity supply mix in Oman with energy storage systems: a case study
Published in International Journal of Sustainable Engineering, 2021
Mohammed Albadi, Abdullah Al-Badi, R. Ghorbani, A. Al-Hinai, Rashid Al-Abri
A Compressed Air Energy Storage (CAES) plant works by pumping and storing air in an underground cavity or a container when excess or low-cost electricity is available. The stored energy is recovered by mixing the compressed air with natural gas. This compressed mixture is burned and expanded in a modified thermal turbine. Typical underground storage options include extant cavities, aquifers, and abandoned mines. CAES designs include diabatic, adiabatic, and isothermal. However, currently only the diabatic method is used in the two CAES plants that are operational (Castellani et al. 2015). The first CAES power plant was built in Huntorf, Germany in 1978 with a capacity of 390 MW and a 41% round-trip efficiency (Chen et al. 2009). Two caverns (300,000 m3) are used to provide up to 425 kg/s of compressed air (up to 70 bars). The second CAES plant was commissioned in 1991 in McIntosh (Alabama, USA) (Radgen 2008). This 110 MW plant has a higher round trip efficiency of 54%, as it uses a recuperator to recover heat from the exhaust of the gas turbine.
Long-term stability of a lined rock cavern for compressed air energy storage: thermo-mechanical damage modeling
Published in European Journal of Environmental and Civil Engineering, 2020
Shuwei Zhou, Caichu Xia, Yu Zhou
In CAES, compressed air is used as the key carrier for power storage and generation. When the electricity supply is more than the demand, the underground CAES plant uses the surplus power to compress the air and store it in caverns (Zhou, Xia, Du, Zhang, & Zhou, 2015). When the electricity supply is less than the demand, the compressed air is discharged, mixed, and fired with gas fuels to run electrical power generators, subsequently exporting electricity. To ensure the performances and reliability of CAES plants, suitable reservoirs must be found, such as lined and unlined tunnels, shafts, and caverns. Two commercial CAES plants adopted salt rock reservoirs (Crotogino, Mohmeyer, & Scharf, 2001), while a verification project used a granite cavern (Stille, Johansson, & Sturk, 1994). For unlined rock caverns, natural groundwater (Allen, Doherty, & Fossum, 1982) or artificial water curtains (Lindblom, 1997) must be used to prevent air leakage from the caverns. Thus, another option, namely, lined rock cavern (LRC), has attracted more attention in recent years because it provides a wider field selection and has no limits in terms of the hydrogeological conditions and large cover depths (Kovári, 1993).
Modelling of a new hydro-compressed air-storage system
Published in International Journal of Sustainable Energy, 2018
Mohammad Ababneh, Adnan Ishtay
Renewable energy sources are essentially inexhaustible, but they are intermittent in nature (Suberu, Mustafa, and Bashir 2014). Therefore, providing reliable energy storage systems attached to the energy sources to store the excess energy can improve the energy sources’ overall efficiency (Zheng et al. 2014; Laijun et al. 2016). Compressed-air energy storage (CAES) system is a promising low-cost, long life, and clean technique to store excess energy in a compressed-air form by compressing ambient air in a storage cavity (Aneke and Wang 2016; Yao et al. 2016). However, most of the CAES research work was conducted for large-scale systems, and very little research work had addressed small-size systems (Abbaspour et al. 2013; Akinyele and Rayudu 2014) as large-scale CAES systems are highly dependent on special conditions of geological formation (Kim et al. 2012), feeding heat during discharging process, and dissipating heat during charging process (Mahlia et al. 2014; Venkataramani et al. 2016).