A munitions energy system combines various sources of energy generation with energy storage to provide power to a munition through various stages of the munition's operation. The system uses energy harvesting technologies which convert energy captured from the environment of the munition to electrical power which can be used to meet the munition's power needs. Energy can be harvested from the mechanical, thermal, and electromagnetic environment of the munition. The harvested energy can be stored by the system for later use. The system can also receive energy from conventional sources such as batteries and manage the energy from all sources to meet the power requirements of the munition.