The monetary and spatial constraints of this project drove the decision of designing a scaled-down prototype of a utility-sized CAES system. We used a 2-stage air compressor, with a mechanical efficiency of approximately 14%, and a storage capacity of 30 gallons. This compressor served the purpose of generating steady power output for approximately 5 minutes. However, we saw that at this small scale, our prototype can only achieve a roundtrip efficiency of approximately 1%. This is largely due to the fact that at this scale, the majority of the compressors available were designed to deal with the power demand of air tools and not the need for constant and steady output.
Based on our experience with the prototype, this project would only be feasible on a large commercial scale. For example, at an institution like Lafayette College, which is made up of various size and purpose buildings, the electrical load requirements are much greater. For this reason, investing in larger compression vessels could be justified. By implementing equipment capable of meeting the demand of an institution the size of Lafayette, we would be able to generate more electricity and increase the roundtrip efficiency of our system. Increasing the efficiency of the system is particularly of interest as our analysis showed that a system that is 70% can become profitable in areas with high electricity rates.
*The featured image shows a utility-scale CAES system designed by Hydrostor