Compressed Air Energy Transmission
Abstract
This research introduces compressed air energy transmission (CAET) via pipelines as a novel alternative to traditional electrical transmission. Unlike electrical systems that require separate energy storage solutions, CAET inherently stores energy within the compressed air pipeline, offering an efficient and cost-effective alternative. The study identifies key variables influencing system efficiency and costs, filling a gap in existing literature. Two compression/expansion processes, diabatic and isothermal, are analyzed, with the latter achieving 93% efficiency using an innovative approach. Power losses are calculated across three transmission system sections: compression, pipeline, and expansion. The analysis begins with a short pipeline to determine losses and extends to long-distance pipelines with optimized compressor station placement. Three decision variables, pipe diameter, number of pipes, and distance between compressor stations, are optimized to minimize total annual costs.
Comparing CAET with electrical transmission reveals that while CAET infrastructure may have slightly higher initial costs, its integrated energy storage capability offers significant advantages. A 100 km pipeline can store compressed air sufficient to deliver nominal power for over two hours. Integration with underground caverns for additional storage eliminates conversion losses inherent in electrical storage, improving overall system efficiency and reducing the levelized cost of storage.