Cost-optimal operation of energy storage units: Benefits of a problem-specific approach

• Novel optimization method to calculate optimal charging strategy for energy storage.
• Tremendous reduction in runtime and gain in efficiency under proven optimality.
• Optimal combinations of PtH converters and thermal storages including energy losses.
• Huge potential for cost savings as a result of optimal charging strategies.
• Potential to manage decentralized storage units via small ECUs in high resolutions.

The integration of large shares of electricity produced by non-dispatchable Renewable Energy Sources (RES) leads to an increasingly volatile energy generation side, with temporary local overproduction. The application of energy storage units has the potential to use this excess electricity from RES efficiently and to prevent curtailment. The objective of this work is to calculate cost-optimal charging strategies for energy storage units used as buffers. For this purpose, a new mathematical optimization method is presented that is applicable to general storage-related problems. Due to a tremendous gain in efficiency of this method compared with standard solvers and proven optimality, calculations of complex problems as well as a high-resolution sensitivity analysis of multiple system combinations are feasible within a very short time. As an example technology, Power-to-Heat converters used in combination with thermal storage units are investigated in detail and optimal system configurations, including storage units with and without energy losses, are calculated and evaluated. The benefits of a problem-specific approach are demonstrated by the mathematical simplicity of our approach as well as the general applicability of the proposed method.