Investigation of Technical Feasibility of Hybrid Compressed Air Cogeneration Systems under Energy-Flexible Operation

Abstract

The study investigates the effects of energy-flexible operation of hybrid compressed air systems in production processes with a view to efficiency and energy consumption. As energy costs become increasingly important in the economic considerations of industrial companies, integrating renewable energies necessitates the implementation of demand-side management capabilities to overcome the problem of intermittent energy production. One promising solution is hybridization, enabling energy systems to utilize multiple forms of energy. In the context of hybrid compressed air systems (CAS), it enables the use of gas, for example natural gas, hydrogen gas or biogas, and electricity for compressed air production, thus substituting electricity or gas demand on short- and long-term horizons. Advantages of such systems include the provision of energy flexibility as well as the variable supply of compressed air, process heat, and electricity through recuperation in the electric motor according to production plant consumption. However, the effects of energy-flexible operation on energy consumption and thus on the system's efficiency still needs to be fully understood. To this end, a demonstrator of a hybrid CAS cogeneration plant was built. Specific scenarios are used to analyze the effect on energy efficiency and the feasibility of energy-flexible operation. Despite slight reductions in efficiency during operation, the feasibility of operation was validated and valuable insights on further improvement were gained. With a view to the expected rising volatility in energy production, the hybrid approach represents an efficient, climate-friendly, energy-flexible, and resilient solution for compressed air production that could assist in expanding industrial demand-side management.