**Preface to "Advanced Modeling, Control, and Optimization Methods in Power Hybrid Systems - 2021"**

This reprint presents the latest solutions in fuel cell (FC) and renewable energy implementation in mobile and stationary applications. The implementation of advanced energy management and optimization strategies are detailed for fuel cell and renewable microgrids, and for the multi-FC stack architecture of FC/electric vehicles to enhance the reliability of these systems and to reduce the costs related to energy production and maintenance. Cyber-security methods based on blockchain technology to increase the resilience of FC renewable hybrid microgrids are also presented. Therefore, this reprint is for all readers interested in these challenging directions of research.

> **Nicu Bizon** *Editor*
