A system is disclosed to generate electric power from a chemical hydride. A fuel cartridge produces hydrogen by reacting a liquid with a chemical hydride. A fuel cell stack generates electric power using an oxygen source and the produced hydrogen. An electric power storage device is coupled with the fuel cell stack. The electric power storage device stores and supplies electric power. One or more liquid sources inject the liquid into the fuel cartridge at a variable rate. A controller calculates a liquid injection rate for the one or more liquid sources based on power demands of an electric load.