Assessment of the Huntorf compressed air energy storage plant performance under enhanced modifications

•Presenting a comprehensive technical information of Huntorf plant.•On-design energy and exergy study of Huntorf plant.•Studying the effect of ambient air properties on plant performance.•Improving plant performance by four enhanced modification methods.•Contribution of a novel very high-temperature heat pump. A parametric study of Huntorf Plant as the first commercialized Compressed Air Energy Storage has been undertaken to highlight the strength and weaknesses in support of a well-defined engineering procedure. In lieu of detailed data on plant characteristics, the site specific technical information has been collected, analyzed, and complemented by four simulations that integrate the effects of plant performance-enhancing methods such as regeneration, cooling, hot/cold water injection, steam injection, heat recovery by heat pump and energy recovery by turbo-expander. Firstly, given the avoidable irreversibilities at the exhaust, recuperation and regulating valve replacement with a turbo-expander was established to compensate plant irreversibilities. Secondly, the effects of a vapor compression refrigeration equipped with evaporative cooling were also studied, along with assessing five refrigerants, to decrease the compression work. In the third simulation, the effect of utilization of the hot and cold water injection was investigated. It was shown that water injection by two cooling mechanisms such as evaporation and wet-compression enhances plant Round Trip Efficiency. Finally, in steam injection investigation, the required heat source was provided by employing a novel very high-temperature heat pump. The evaluation of novel combined solutions revealed that the regeneration, compression cooling, water and steam injection improve plant round trip efficiency by 37.81%, 3.22%, 2.5% and 2.78% respectively.