Reversible SOEC/ SOFC System

The proposed reversible solid oxide cell (rSOC) system generates 1 kW electrical power from stored H2 gas in fuel cell mode and produces H2 fuel from steam using 2 kW power in electrolysis mode.A 24-hour operation of the system will produce 1.4 kg of hydrogen and will require about 13 kg of water. Ideally, the water generated during fuel cell operation can be captured and reused for electrolysis. The rSOC system operates as both an electrolysis cell and fuel cell to time shift renewable power from when it is available to when it is needed. The system replaces a battery storage system for a solar power system and stores the excess solar power in the form of hydrogen. When solar power is not available, hydrogen is fed to the same solid oxide cells operating in fuel cell mode to produce power.  The Direct to Phase II effort extends functionality of the solid oxide device by combining advances made in three projects: Air Force STTR Phase I feasibility study that addressed an improved solid oxide fuel cell (SOFC) system for power generation for electric vertical take-off and landing aircraft (eVTOL) systems, with a demonstrated power output of 375 W using ammonia as a fuel for a 10 cell SOC stack; and a 1 kW power output from a 72 -cell stack in Phase II;Air Force Seedlings for Disruptive Change Program (SDCP) project that demonstrated additive printed solid oxide device that demonstrated power generation using bipropellant reactant simulants; andNASA SBIR project that demonstrated electrolysis of CO2 and steam to produce fuels via solid oxide electrolysis cells (SOEC). The proposed rSOC system addresses Operational Imperative 5: Resilient Basing. Certain critical operational tasks require uninterrupted availability of power. Facilities that are grid connected may also face brown outs in remote locations. The proposed system will produce fuel when electric power is available and produce electricity using the fuel when needed. The operational reversibility of the solid oxide stack allows operation in fuel production and electricity production modes using the same device.Operational Imperative 1: Space Order of Battle is addressed by the electric power generated by the proposed solution in SOFC operation. Spacecraft need assured access to electric power, typically provided by a combination of solar power and batteries. The closed rSOC system can have a specific energy and energy density far greater than any battery system.The rSOC system is at TRL 4 because it has been demonstrated only at the laboratory scale. This project will move system to TRL to 6 after delivery and demonstration at a selected Air Force laboratory site. The proposed rSOC system will produce hydrogen with an input of 2 kW and provide 1 kW of electricity using the generated hydrogen. A 24-hour operation of the system will produce 1.4 kg of hydrogen and will require about 13 kg of water.