Systems for converting and storing energy

A system comprising:

• an electrolyzer coupled to a source of water and a power source, said electrolyzer configured to generate hydrogen and electrolyzer oxygen utilizing water from the water source and electrical power from the power source;
• a fuel cell system coupled to the electrolyzer to receive a flow of the hydrogen from the electrolyzer at an anode thereof;
• the fuel cell system coupled to an electrical load to provide electrical power thereto;
• the fuel cell system comprising a cathode having a cathode chamber coupled to a source of ambient air;
• an oxidant storage tank in communication with an outlet of the electrolyzer and receiving the electrolyzer oxygen from the electrolyzer, the electrolyzer oxygen having a higher concentration of oxygen than the source of the ambient air and having a positive pressure when stored in the oxidant storage tank;
• the oxidant storage tank coupled to the cathode chamber to allow a flow of the electrolyzer oxygen from the oxidant storage tank to the cathode chamber;
• a fuel cell oxidant concentration sensor located in said cathode and configured to determine a measured concentration of oxygen in said cathode of said fuel cell;
• and
• a controller coupled to said sensor and configured to control a flow control device to cause a flow of the electrolyzer oxygen at the positive pressure from the oxidant storage tank into the cathode chamber of the fuel cell in response to the controller determining that a cathode reaction of the fuel cell is oxygen limited based on the measured concentration of the oxygen determined by the sensor being compared to a predetermined oxygen concentration parameter, such that the electrolyzer oxygen substitutes for an amount of the ambient air from the source of ambient air to cause a concentration of oxygen in the cathode to be increased to a relative concentration greater than that of the ambient air by the flow of the electrolyzer oxygen at the positive pressure by the flow control device controlled by the controller to cause an increase in a power output of the fuel cell;
• and
• the controller configured to control the flow control device to reduce the flow of the electrolyzer oxygen from the oxidant storage tank in response to a second measured concentration of oxygen in said cathode of said fuel cell and a second comparison of the second measured concentration to the predetermined oxygen concentration parameter.