Energy storage capacitors can typically be found in remote or battery powered applications. . Capacitors exhibit exceptional power density, a vast operational temperature range, remarkable reliability, lightweight construction, and high efficiency, making them extensively utilized in the realm of energy storage. There exist two primary categories of energy storage capacitors: dielectric. . This paper compares the performance of these technologies over energy density, frequency response, ESR, leakage, size, reliability, efficiency, and ease of implementation for energy harvesting/scavenging/hold-up applications. When power outages occur, ESSs also serve as backups for critical infrastructure.